PCB Spring 2026, Final Review, Iclickers + Test Bank

Which of the following are found in all cell types?

a) double-stranded DNA

b) plasma membrane

c) ribonucleoproteins

d) a and b, but not c

e) all of these

e) all of these

All cells contain the genetic material, the outer barrier controlling what enters/leaves, and the ribosomes that help make proteins

Mycoplasma genitalium is a procaryotic organism. Which of the following features would you expect this cell to have?

a) double stranded DNA

b) circular DNA

c) plasma membrane

d) all of these

e) none of these

d) all of these

Mycoplasma genitalium is a prokaryote, so it has dsDNA, circular DNA, and plasma membrane

There are approximately 100 billion-trillion (10^22) stars in the known universe. Are there more or less procaryotic cells on earth?

a) more

b) less

a) more

there are 1x10^9 more

Where in the cell would you expect to find ionic bonds?

a) on the surface of a chaperone protein

b) on the outside of a DNA molecule

c) near the interior of a large protein

d) any of these places

e) none of these places

c) near the interior of a large protein

Ionic bonds inside proteins are often called salt bridges. They are strongest when buried away from water, because water can weaken ionic interactions by surrounding charged groups

During digestion, the molecules in a Chik-fil-A sandwhich are:

a) oxidized

b) reduced

c) isomerized

d) synthesized

e) caramelized

a) oxidized

During digestion, food molecules are broken down and later used for energy. In metabolism, nutrients lose electrons/hydrogen, meaning they are oxidized; this helps release energy for the cell

Which of the following eukaryotic features evolved as a result of the earlier evolution of the nucleus:

a) larger genome

b) presence of a true cytoskeleton in animal cells

c) presence of mitochondria

d) all of these

e) none of these

d) all of these

The evolution of the nucleus helped eukaryotic cells become mjore complex, allowing larger genomes, more advanced cytoskeleton, and support for organelles like mitochondria

Enzymes are able to make unfavorable reaction favorable.

a) true

b) flase

b) flase

Enzymes speed up reactions by lowering activation energy, but they do not change whether a reaction is energetically favorable

What is an "activated carrier" such as ATP actually carrying?

a) carbon

b) energy

c) water

d) vesicles

e) proteins

b) energy

Activated carries like ATP temprarily store and transfer usable energy to power cellular reactions, such as building molecules, transport, or movement

The energy carried by ATP is in what form?

a) electrons

b) carbohydrate

c) hydrogen ions

d) heat

e) photons

a) electrons

ATP carries energy in the form of high-energy electrons in its chemical bonds. When ATP is broken down, that energy can be transferred to power cell processes

The reaction of ATP -> ADP + P, is a favorable reaction. What prevents the terminal P from just falling off all the time?

a) unique divalent bond

b) high activation energy

c) special laws of chemistry that apply to cells

d) nothing - it does fall off all the time

e) gorilla glue

b) high activation energy

ATP breakdown is energetically favorable, but the terminal phosphate does not fall off constantly because the reaction still needs activation energy to start. Enzymes help lower that barrier when the cell needs ATP energy

Alpha helix and beta sheet protein structures are maintained by what type of bond/interaction?

a) hydrogen bonds

b) covalent disulfide bonds

c) van der Waals attractions

d) ionic bonds

e) hydrophobic interactions

a) hydrogen bonds

Alpha helices and beta sheets are secondary protein structures. They are stabilized by hydrogen bonds between the protein backbone atoms

The quaternary structure of a protein complex is maintained primarily by:

a) peptide bonds

b) ionic bonds

c) noncovalent hydrogen bonds

d) covalent bonds

e) phosphodiester bonds

c) noncovalent hydrogen bonds

Quaternary structure is how multiple protein subunits stick together. It is mainly maintained by noncovalent interactions, including hydrogen bonds, ionic interactions, and hydrophobic interactions.

Which of the following is a component of activation energy:

a) energy required to put reactants into proper orientation

b) energy required to pass through unstable intermediates

c) energy required to prpduce higher energy products

d) a and b, but not c

e) a, b, and c

d) a and b, but not c

Activation energy includes the energy needed to:

- line reactants up in he proper orientation

- pass through an unstable transition state/intermediate

Procaryotic organisms possess which of the following genes:

a) genes that code for DNA polymerase

b) genes that code for RNA polymerase

c) genes that code for histone proteins

d) a and b, but not c

e) a, b, and c

d) a and b, but not c

Procaryotes need DNA polymerase to copy DNA, and RNA polymerase to make RNA from DNA

The eucaryotic cell wall is:

a) evolutionarily related to bacterial cell walls

b) structurally identical to bacterial cell walls

c) evolutionarily unrelated to bacterial cell walls

c) evolutionarily unrelated to bacterial cell walls

Eukaryotic cell walls, like plants or fungi, are made of materials such as cellulose or chitin. Bacterial cell walls are made of peptidoglycan, so they are not the same structure or evolutionary origin.

Where does the enzyme lysozyme get the energy required to bend the glycosidic bond?

a) ATP

b) sunlight

c) favorable conformational change

d) sulphur bonds

c) favorable conformational change

Lysozume does not use ATP. Binding the substrate causes a favorable shape change in the enzyme-substrate complex, which helps bend/strain the glycosidic bond and makes it easier to break

The quaternary structure of a protein complex is maintained primarily by:

a) peptide bonds

b) ionic bonds

c) weak noncovalent interactions

d) covalent bonds

c) weak noncovalent interactions

Quaternary structure is the way multiple protein subunits associate. It is mainly held together by weak noncovalent forces, like hydrogen bonds, ionic interactions, van der Waals forces, and hydrophobic interactions

The telomerase sequence added to the end of a chromosome by telomerase functions to:

a) facilitate complete replication of the lagging strand

b) mask the chromosomal end to prevent unintended recognition by repair mechanisms

c) initiate transcription of the telomeric region

d) terminate transcription of the telomeric region

e) facilitate complete replication of the leading strand

a) facilitate complete replication of the lagging strand

Telomerase adds extra DNA repeats to chromosome ends so the lagging strand can be fully replicated without it losing important genetic information

Most mutations:

a) lead to beneficial changes in protein structure

b) are silent

c) are quickly folded into heterochromatin

d) are quickly and efficiently repaired

e) are cancer-causing

b) are silent

Most mutations do not cause major changes to proteins. Many are silent because they either occur outside coding regions or do not change the amino acid sequence

Eucaryotic RAD51 and procaryotic RecA are homologous. Homologous proteins:

a) look and/or function alike by coincidence, they are unrelated

b) look and/or function alike due to common ancestry

c) look alike but function differently

d) function alike but look different

e) are coded from homologous chromosomes

b) look and/or function alike due to common ancestry

Homologous proteins are related by evolutionary ancestry. They often have similar structures or functions because they came from a shared ancestral gene

Which of the following would have the highest permeability across the lipid bilayer?

a) bicarbonate ion (HCO3-)

b) glycine

c) nitrogen gas (N2)

d) glucose

e) sucrose

c) nitrogen gas (N2)

Small, nonpolar molecules cross lipid bilayers most easily. N2 is small and nonpolar, while ions and sugars are polar/charged and need transport proteins

Fundamental difference between electrically excitable cells and those that are not is:

a) generation of a membrane potential

b) presence of Na-K pumps

c) low intracellular Na concentrations

d) ability to maintain osmotic balance

e) presence of voltage-gated Na channels

e) presence of voltage-gated Na channels

Many cells have membrane potentials, Na/K pumps, and osmotic balance. Electrically excitable cells are different because they have voltage-gated Na channels, allowing rapid action potentials

Organelle lumens and the extracellular environment are:

a) biochemically distinct

b) topographically equivalent

c) continuous

d) a and b are correct (but not c)

d) a and b are correct, but not c

Organelle lumens and the extracellular space are topographically equivalent because vesicles can connect these spaces through membrane trafficking. However, they are not always physically continuous at the same time

Which of the following is true regarding Rab GTPases?

a) assure specificity between vesicle and target

b) anchor coatomer coats to membranes

c) exist as sets of complementary pairs

d) catalyze formation of clathrin vesicles

e) unlike other GTPases, Rab is active in its GDP form and inactive in its GTP form

a) assure specificity between vesicle and target

Rab GTPases help vesicles recognize and dock at the correct target membrane. They are active when bound to GTP and inactive when bound to GDP

In mitochondria, electron transport leads to the pumping of H+. Where do these pumped protons come from?

a) surrounding aqueous environment

b) acetyl CoA

c) NADPH

d) FADH2

e) ATP

a) surrounding aqueous environment

The electron transport chain uses energy from electrons to pump H+ ions already present in the mitochondrial matrix/aqueous environment into the intermembrane space

In eucaryotes, the molecule in the mitochondrial electron transport chain with the highest affinity for electrons is:

a) oxygen

b) carbon dioxide

c) water

d) quinone

e) cytochrome

a) oxygen

Oxygen has the highest affinity for electrons in the mitochondrial electron transport chain, it is the final electron acceptor, and when it accepts electrons it helps form water

G-proteins are GTPases with built-in GAP and GEF function. This means that:

a) they are able to catalyze GTP hydrolysis

b) they are able to force dissociation of GDP

c) they use GTP-GDP switching to control activity

d) a and b, but not c

e) a, b, and c

e) a, b, and c

G-proteins act like molecular switches:

- GAP function helps hydrolyze GTP -> GDP

- GEF function helps release GDP so GTP can bind

- This GTP/GDP switching controls whether the protein is active or inactive

Endocrine signaling:

a) operates very rapidly

b) requires the circulatory system

c) operates over short distances only

d) requires an action potential

e) requires neurotransmitter release

b) requires a circulatory system

Endocrine signaling uses hormones that travel through the bloodstream to reach distant target cells. It is usually slower and longer-distance than nervous signaling

Cyclic AMP (cAMP) is a:

a) common secondary messenger

b) common membrane-bound signaling molecule

c) common type of G-protein

d) mediator of steroid hormone activity

e) electron transport protein

a) common secondary messenger

cAMP is a second messenger inside cells. It helps pass signals from receptors on the cell surface to targets inside the celll, often activating protein kinase A

How are actin filaments and microtubules similar?

a) both are hollow

b) both are dynamic

c) both require GTP

d) both require ATP

e) both use dimers as building blocks

b) both are dynamic

Both actin filaments and microtubules can rapidly grow and shrink by adding or removing subunits. Actin mainly uses ATP while microtubules use GTP

Which type of motor protein carries endosomes towards the center of the cell?

a) myosin II

b) actin

c) dynein

d) kinesin

e) helicases

Dynein moves cargo towards the minus end of microtubules, which is usually near the center of the cell. Kinesin usually moves cargo outward

Which of the following is not involved in cell cycle control?

a) activation of Cdk's

b) degradation of cyclins

c) synthesis of cyclins

d) changes in Cdk concentration

e) extracellular signals

d) changes in Cdk concentration

Cell cycle control depends on cyclin levels changing, which activate Cdks. Cdk concentration usually stays relatively constant; it is in their activity, not amount, that changes

Colchicine is a chemical that prevents polymerization of tubulin dimers. If this chemical is added to cells as the mitotic spindle is forming, the spindle will:

a) become rigid

b) fail to disassemble during anaphase

c) grow abnormally large

d) be unable to capture sister chromatids

e) function normally

d) unable to capture sister chromatids

Colchicine prevents tubulin polymerization, so microtubules cannot properly form the mitotic spindle. Without spindle microtubules, the cell cannot attach to and separate sister chromatids

The intrinsic apoptosis pathway may proceed as a result of:

a) activation of the extrinsic pathway

b) inactivation of anti-apoptotic proteins

c) release of mitochondrial proteins into the cytosol

d) a and b (but not c)

e) a, b, and c are all correct

e) a, b, and c are all correct

The intrinsic apoptic pathway involves the mitochondria. It can be triggered by signals from the extrinsic pathway, by loss of anti-apoptotic protein activity, and by release of mitochondrial proteins like cytochrome c into the cytosol

A loss-of-function mutation in a gene coding for a pro-apoptotic protein would most immediately result in:

a) a cancerous cell

b) prolonged cell life

c) rapid cell death

d) uncontrolled proliferation

e) non-viable cell

b) prolonged cell life

A pro-apoptotic protein helps trigger cell death if it loses function; apoptosis is reduced, so the cell may survive longer than normal

A decrease in extracellular Ca2 would inhibit cell adhesion by:

a) preventing the synthesis of cadherin proteins

b) prevent association of neighboring cadherins

c) ubiquitination of cadherin subunits

d) depolarizing cadherin proteins

e) removing cadherin proteins from membranes

b) prevent association of neighboring cadherins

Cadherins are Ca2 dependent adhesion proteins, if extracellular Ca2 decreases, cadherins cannot properly bind to cadherins on neighboring cells, so cell-cell adhesion is weakened

The "immortal strand" hypothesis suggests that:

a) stem cell DNA is made from especially stable nucleotides

b) stem cell DNA can be used to convert an ordinary cell into a stem cell

c) stem cell DNA segregates such that the original template DNA is inherited by only one of the two daughter cells

d) DNA never dies

c) stem cell DNA segregates such that the original template DNA is inherited by only one daughter cell

The "immortal strand" hypothesis says stem cells may keep the older original DNA strands during division, while the newer copied strands go ot the other daughter cell. This may help protect stem cells from replication errors

Adult stem cells:

a) are of little value to researchers

b) remain tissue-specific forever

c) can differentiate into cell types other than the source tissue

d) can not be grown in culture

e) terminally differentiated embryonic stem cell

c) can differentiate into cell types other than the source

Adult stem cells are usually more limited than embryonic stem cells, but they can sometimes differentiate into related or even different tissue cell types under certain conditions

Proteins are able to bind to which kind of these biological molecules

a. other proteins

b. lipids

c. sugars

d. a, b, but not c

e. a, b, and c (other proteins, lipids, sugars)

e. a, b, and c (other proteins, lipids, sugars)

Proteins can bind many biological molecules, including other proteins, lipids, and sugars. Binding depends on shape and chemical interactions.

In cells, the strongest chemical interaction is

a. covalent bond

b. ionic bond

c. hydrogen bond

d. van der waals interactions

e. hydrophobic interactions

a. covalent bond

In cells, covalent bonds are the strongest chemical interactions because atoms share electrons. Ionic, hydrogen, van der Waals, and hydrophobic interactions are weaker/noncovalent.

The majority of biological catalysts are made from

a. nucleic acids

b. glycolipids

c. phospholipids

d. amino acids

e. recycled catalytic converters

d. Amino acids

Most biological catalysts are enzymes, and most enzymes are proteins made from amino acids.

In the "ABC" class of protein transport pump, the conformational changes that lead to translocation of the transported substance are caused by...

a. a proton gradient

b. a spinning protein roder

c. repeated cycles of ATP binding and hydrolysis

d. repeated cycles of GTP binding and hydrolysis

e. singing of the alphabet song

c. Repeated cycles of ATP binding and hydrolysis

ABC transporters are ATP-binding cassette pumps. They use ATP binding and ATP breakdown to change shape and move substances across membranes.

Which of the following is false regarding prokaryotic cells?

a. possesses a cell wall

b. reproduce by binary fission

c. do not exist as true metazoans

d. utilize double-stranded DNA

e. synthesizes its own proteins

a. possesses a cell wall

Many prokaryotes have a cell wall, but not all do. For example, Mycoplasma lacks a cell wall. The other statements are generally true for prokaryotic cells.

The evolution of the nucleus in eukaryotic organisms has allowed

a. segregation of DNA from other cellular processes

b. tight packaging of the DNA molecule

c. increase in the size of the DNA molecule

d. both a and b (segregation of DNA from other cellular processes and tight packaging of the DNA molecule)

d. both a and b (segregation of DNA from other cellular processes and tight packaging of the DNA molecule)

The nucleus allows eukaryotic cells to separate DNA from other cellular processes and helps with tight DNA packaging using histones/chromatin.

When a carbohydrate is oxidized it loses both ____ and ____

a. oxygen, electrons

b. electrons, energy

c. energy, carbon

d. entropy, polarity

e. deginity, self respect

b. electrons, energy

When a carbohydrate is oxidized, it loses electrons. As those electrons are removed, the molecule also loses stored chemical energy, which the cell can capture for ATP production.

What is meant by high specificity between two molecules?

a. highly complementary electrochemical properties

b. highly complementary physical shape

c. very similar atomic weight

d. both a and b (Highly complementary physical shape and highly

complementary electrochemical properties)

d. both a and b (Highly complementary physical shape and highly

complementary electrochemical properties)

High specificity means two molecules interact because they have:

- complementary shapes

- complementary electrochemical properties (charges/polarity)

Both are important for precise molecular binding.

Entropy is a measure of the

a. the rate of a reaction

b. the amount of energy contained within a particular bond

c. the amount of energy possessed by a particular molecule

d. the amount of disorder within a system

e. the number of coins in a bottle

d. the amount of disorder within a system

Entropy measures how disordered or random a system is. Higher entropy means greater randomness.

A protein's secondary structure is maintained by

a. peptide bonds

b. hydrogen bonds

c. phosphodiester bonds

d. amino bonds

e. municipal bonds

b. hydrogen bonds

Secondary structures like alpha helices and beta sheets are stabilized by hydrogen bonds between the protein backbone atoms.

Binding of a ligand to a specific enzyme binding site involves___

a. usually involves numerous weak non covalent bonds

b. usually requires ATP

c. usually involves covalent bond formation

d. a, b, but not c

e. a and b only

a. usually involves numerous weak non covalent bonds

Ligand binding is usually based on many weak interactions, like hydrogen bonds, ionic interactions, van der Waals forces, and hydrophobic interactions. It usually does not require ATP or covalent bond formation.

12. Activation energy is a property of...

a. all types of chemical reactions

b. all favorable reactions

c. only unfavorable reactions

d. only biochemical reactions

e. only catalyzed reactions

a. all types of chemical reactions

Every chemical reaction has an activation energy, which is the energy needed to start the reaction, even if the reaction is favorable overall.

Which of the following is NOT a universal feature of all cells

a. take up matter from their surroundings

b. use energy from sunlight to build macromolecules

c. store hereditary information as DNA

d. use RNA to direct protein synthesis

e. all of the above

b. use energy from sunlight to build macromolecules

Not all cells perform photosynthesis. However, all cells:

- take up matter from surroundings

- store hereditary information as DNA

- use RNA in protein synthesis.

Hydrophobic side chains on the outside of a protein would indicate what?

a. an enzyme catalyzed reaction

b. a transport protein

c. a water soluble protein

d. a miscoded protein

e. a structural protein

b. a transport protein

Hydrophobic side chains on the outside usually indicate the protein interacts with the lipid membrane. Membrane transport proteins often have hydrophobic outer regions that face the hydrophobic membrane interior.

Many protein catalysts utilize both acids and bases by...

a. catalyzing the production of acid

b. catalyzing the production of base

c. using properties of both simultaneously

d. maintaining the proper ph

e. proteins should never use acids and bases together, it's unsafe

c. using properties of both simultaneously

Many enzymes use acid-base catalysis, where amino acid side chains donate or accept protons during the reaction to help bonds break or form.

Hydrogen bonds are common in all cells because

a. hydrogen atoms naturally attract other atoms

b. hydrogen containing molecules are usually in the sea

c. hydrogen is the most abundant atom in a cell

d. many of the covalent bonds involving hydrogen are polar

e. the instructor said so

d. many of the covalent bonds involving hydrogen are polar

Hydrogen bonds form when hydrogen is covalently bonded to electronegative atoms like oxygen or nitrogen, creating partial charges that attract other polar molecules.

Which of the following would involve an unfavorable reaction

a. the removal of an unnatural base by glycolysis

b. depurination of guanine due to thermal fluctuations

c. deamination of cytosine to reveal uracil

d. pyrimidine demineralization

e. studying for a cell biology exam

d. pyrimidine demineralization

The other examples are spontaneous DNA damage reactions that can happen naturally. Studying requires energy input and effort, so it is the unfavorable reaction in this joke-style question.

The enzymatic activity of many proteins can be altered by adding a phosphate group via class of enzymes called...

a. kinases

b. ligases

c. hylosetrics

d. phosphatases

e. phosphate addition bases

a. kinases

Kinases add phosphate groups to proteins. This process is called phosphorylation and can change a protein’s activity, shape, or function.

The hydrolysis of ATP...

a. energetically unfavorable

b. always coupled to an energetically unfavorable reaction

c. requires an enzyme to proceed

d. decreases the entropy of the system

e. had a negative delta G value

e. had a negative delta G value

ATP hydrolysis is energetically favorable, meaning it releases free energy and has a negative ΔG. Cells often couple it to unfavorable reactions, but not always.

Polar covalent bonds...

a. electron sharing between two oppositely charged ions

b. unequal sharing of electrons between atoms of two different electronegativity

c. the surrounding on ions by water molecules

d. produces molecules that are hydrophobic

e. a type of electrostatic interaction

b. unequal sharing of electrons between atoms of two different electronegativity

Polar covalent bonds happen when atoms share electrons unequally, creating partial positive and partial negative charges. Water has polar covalent bonds.

Cells often assemble large complexes from smaller preformed molecules, the advantage of this method is...

a. efficient control of assembly

b. fewer genes required

c. less energy is required

d. a and b but not c

e. all are correct. Efficient control of assembly, fewer genes are required, and less energy is required

e. all are correct. Efficient control of assembly, fewer genes are required, and less energy is required

Building large complexes from smaller subunits is useful because cells can:

- control assembly more efficiently

- reuse the same subunits, so fewer genes are needed

- save energy compared with making one huge structure from scratch

Phosphorylation of an enzyme can affect protein function by...

a. altering the proteins conformation

b. opening or closing building sites elsewhere on the protein

c. denaturing of the protein

d. a, b, but not c are correct. (Altering the protein's conformation, opening or

closing the binding sites elsewhere on the protein)

e. a, b, and c are all correct

d. a, b, but not c are correct. (Altering the protein’s conformation, opening or

closing the binding sites elsewhere on the protein)

Phosphorylation adds a phosphate group, which can change a protein’s shape and open or close binding sites. It usually regulates the enzyme rather than completely denaturing it.

Which enzyme is directly responsible for activation of GTP binding proteins?

a. guanine nucleotide exchange factor (GEF)

b. GTPase activating protein

c. RAS

d. protein kinase

e. protein phosphatase

a. guanine nucleotide exchange factor (GEF)

GEFs activate GTP-binding proteins by helping them release GDP so that GTP can bind. The GTP-bound form is the active form.

The delta G value of an unfavorable reaction can be made negative by...

a. increasing the concentration of the reactant

b. increasing the concentration of the product

c. raising the temperature

d. decreasing the temperature

e. the change in G value of reactions cannot be changed

a. increasing the concentration of the reactant

Increasing reactant concentration pushes the reaction forward, which can make ΔG more negative and help an unfavorable reaction become favorable

Which of the following is not an electrostatic interaction

a. hydrogen bonds

b. ionic bonds

c. hydrophobic interactions

d. van der waals interactions

e. none of these

c. hydrophobic interactions

Hydrophobic interactions are caused by nonpolar molecules avoiding water, not by attraction between electrical charges. Hydrogen bonds, ionic bonds, and van der Waals forces all involve electrostatic effects

Alpha helices and beta pleated sheets are very common protein structures because they...

a. involve interactions between peptide bonds

b. involve common side plates

c. are easily viewed using light microscopes

d. exact reason for common occurrence is unknown

e. something indecipherable

a. involve interactions between peptide bonds

Alpha helices and beta sheets are common because they form hydrogen bonds between the backbone/peptide bonds of the protein, not mainly between side chains

Small nuclear ribonucleoproteins (snRNPs)

a. involved in initiation of transcription

b. found only in eukaryotes

c. assembled in the cytosol

d. involved in the synthesis of mRNA

b. found only in eukaryotes

snRNPs are part of the spliceosome, which removes introns from pre-mRNA. Since this RNA splicing process is mainly a eukaryotic feature, snRNPs are found only in eukaryotes.

DNA replication requires...

a. topoisomerases

b. deoxyribonucleoside triphosphates

c. ribonucleic triphosphates

d. a & b only

e. all of these

e. all of these

DNA replication requires:

- Topoisomerases to relieve DNA twisting tension

- Deoxyribonucleoside triphosphates (dNTPs) as DNA building blocks

- Ribonucleic triphosphates (NTPs) because RNA primers made by primase are needed to start replication.

It is theorized that DNA synthesis occurs only in the 5' to 3' direction because...

a. The repair machinery operates in reverse and could only proofread in the 3' to 5' direction

b. The direction of synthesis was originally selected arbitrarily by evolution and is now fixed

c. It is only 5' to 3' on the leading strand, on the lagging strand it is 3' to 5'

d. 3' to 5' synthesis is biochemically not possible

e. Bond energy for correcting errors is always available via incoming nucleotides

e. Bond energy for correcting errors is always available via incoming nucleotides

DNA polymerase adds new nucleotides using the energy from the incoming nucleotide triphosphate. This allows proofreading/correction while still keeping energy available to continue DNA synthesis.

Eukaryotic ribosomes...

a. Example of a ribonucleoprotein

b. Transcribed from special non-gene regions of DNA

c. Present in relatively small quantities in most cells due to the limitation of cell volume

d. A & B only not C

e. A, B & C are all correct

a. Example of a ribonucleoprotein

Ribosomes are made of rRNA and proteins, so they are ribonucleoproteins

Homologous recombination...

a. Usually results in crossover

b. Often occurs during interphase

c. Can occur between any two random DNA sequences

d. Is a relatively rare event

e. Occurs in reproductive cells

b. Often occurs during interphase

Homologous recombination is used to repair DNA damage, especially after DNA replication in interphase, when a sister chromatid is available as a template.

The fundamental difference between a virus and other types of mobile genetic elements is that...

a. Viral genetic elements carry sequences that code for coat proteins

b. Viral genomes do not require homology in order to recombine

c. Viral genomes employ a copy and paste mechanism and therefore increase their presence in the genome

d. Viruses as a group recombine much more frequently than other types of mobile elements

e. Viral recombination activity is damaging, whereas the other types of recombination are not

a. Viral genetic elements carry sequences that code for coat proteins

Viruses are different because they encode coat/capsid proteins, allowing their genetic material to be packaged and spread between cells or organisms.

During replication the sliding ring protein is necessary because...

a. The double helix must be pried open

b. Single-stranded DNA is unstable

c. Okazaki fragments must be sealed together

d. RNA primer synthesis is difficult to initiate

e. DNA polymerase alone does not remain associated with the DNA template

e. DNA polymerase alone does not remain associated with the DNA template

The sliding ring, or sliding clamp, keeps DNA polymerase attached to the DNA template so it can copy long stretches of DNA without falling off.

Multiple replication origins are required in eukaryotes because...

a. Eukaryotic genomes are so large that it would take too long to copy it all from a single origin

b. There are numerous tightly packed regions of heterochromatin that must be opened up

c. Replication must begin in noncoding regions, which in eukaryotes are numerous and discontinuous

d. One origin is required for each Okazaki fragment synthesized on the lagging strand e. Each telomere requires its own replication origin

a. Eukaryotic genomes are so large that it would take too long to copy it all from a single origin

Eukaryotic chromosomes are very large, so cells use many origins of replication at the same time to copy DNA efficiently.

Phosphorylation of the RNA polymerase II "tail"...

a. Transitions it from binding conformation to elongation conformation

b. Results in a conformation that sequesters mRNA processing proteins

c. Phosphates derived from helicase activity d. A & B but not C

e. All of them: A, B & C

e. All of them: A, B & C

Phosphorylation of the RNA polymerase II tail helps the enzyme shift into elongation mode and helps recruit/sequester mRNA processing proteins needed for RNA processing during transcription.

Which of the following would not be involved in the synthesis of a tRNA molecule?

a. RNA polymerase

b. snRNPs

c. Termination DNA sequence

d. Promoter DNA sequence

e. Ribonucleoside triphosphates

b. snRNPs

snRNPs are mainly involved in splicing pre-mRNA, not making tRNA. tRNA synthesis still needs RNA polymerase, a promoter, termination sequence, and ribonucleoside triphosphates.

Processing of pre-mRNA includes addition of a guanine nucleotide "cap"...

a. To the 3' end as it emerges

b. To the 5' end as it emerges

c. To the 5' end after splicing is complete

d. To each intron/exon splice junction

e. To identify polycistronic mRNAs

b. To the 5’ end as it emerges

A modified guanine cap is added to the 5’ end of pre-mRNA soon after it begins emerging from RNA polymerase. This helps protect the mRNA and supports later translation.

The fundamental difference between two different cells within the same organism is...

a. Different protein composition

b. Different patterns of gene expression

c. Differences in DNA sequences

d. A & B but not C

e. All of them are correct

d. A & B but not C

Most cells in the same organism have the same DNA, but they express different genes, which gives them different proteins and functions.

Which of the following would be an unfavorable event?

a. Removal of an unnatural base by glycolysis

b. Depurination due to thermal fluctuations c. Deamination of cytosine or adenine

d. Thymine dimer formation

e. Studying for a cell bio exam

d. Thymine dimer formation

Thymine dimers require energy input from UV light, so their formation is unfavorable without that energy.

The telomeric sequence added to the end of a chromosome by telomerase functions to...

a. Complete replication of the lagging strand

b. Mask the chromosomal end to prevent accidental recognition by repair mechanisms

c. Initiate transcription of the telomeric region

d. Terminate transcription of the telomeric region

e. Complete replication of the leading strand

a. Complete replication of the lagging strand

Telomerase extends chromosome ends so the lagging strand can be fully replicated.

Which of the following statements is NOT correct regarding the eukaryotic ribosome?

a. Consists of one large and one small ribonucleoprotein subunit

b. Assembly of subunits requires the import of cytoplasmically derived proteins

c. Subunits are exported individually from the nucleus

d. "Small" subunit is responsible for catalyzing formation of peptide bonds during translation

e. Assembly of subunits occurs in the nucleolus

d. "Small" subunit is responsible for catalyzing formation of peptide bonds during translation

The large ribosomal subunit, not the small subunit, catalyzes peptide bond formation.

The evolutionarily oldest example of recombination is seen in...

a. DNA double strand break repair

b. Mitotic recombination

c. Activity of mobile genetic elements

d. Bacterial control of gene expression

e. Movement of viruses between lytic and prophage phases

a. DNA double strand break repair

Recombination likely first evolved as a way to repair broken DNA, especially double-strand breaks.

Flipping out refers to...

a. Enzyme mediated turning of heterochromatin during replication

b. The process used by chaperones to fix misfolded proteins

c. The lowering of the polymerase tail following phosphorylation

d. The temporary separation of DNA base from its complement to allow close inspection

e. Your state of mind as you prepare for a cell bio exam

d. The temporary separation of DNA base from its complement to allow close inspection

DNA repair enzymes can "flip out" a base from the DNA helix to inspect it for damage.

Endonucleases are...

a. Large cytosolic proteins which degrade marked proteins

b. Stabilizing structure on the ends of proteins

c. Specific classes of phosphatase proteins

d. Enzymes able to digest nucleic acids from an internal position

e. Individual RNA subunits in a ribonucleoprotein complex

d. Enzymes able to digest nucleic acids from an internal position

Endonucleases cut nucleic acids within the strand, unlike exonucleases, which remove nucleotides from the ends.

Nucleotide excision repair differs from base excision repair in that it...

a. Is designed to identify and repair large regions of damage

b. Does not involve DNA ligase

c. Does not require DNA polymerase to fill removed damaged regions

d. Is more of a proofreading mechanism than a repair mechanism

e. Uses a different class of glycosylase than base excision repair does

a. Is designed to identify and repair large regions of damage

Nucleotide excision repair removes larger damaged DNA segments, such as thymine dimers, while base excision repair fixes smaller damaged bases.

In eukaryotic organisms, all proteins initially begin with methionine because...

a. Only methionine carries the energy required for formation of the first peptide bond

b. Methionine is evolutionarily older than any other amino acid, and its use as an initiator has been conserved

c. Only methionine can bind to the 5' cap located at the end of all mRNAs

d. Methionine happens to be the amino acid carried by the special initiator tRNA

e. Methionine is the only amino acid that can attract and bind to the large ribosomal subunit

d. Methionine happens to be the amino acid carried by the special initiator tRNA

Translation starts with a special initiator tRNA, and in eukaryotes this tRNA carries methionine.

Aminoacyl-tRNA synthetases...

a. Family of enzymes which attach amino acid to tRNAs

b. Family of enzymes which synthesize tRNAs from specific DNA sequences

c. Enzymes responsible for transport of tRNAs to the ribosome

d. Enzymes which chemically modify some of the bases in newly synthesized tRNAs

e. Enzymes which degrade tRNAs which have already added their amino acid

a. Family of enzymes which attach amino acid to tRNAs

Aminoacyl-tRNA synthetases “charge” tRNAs by attaching the correct amino acid to the correct tRNA.

Transfer RNAs (tRNA molecules)...

a. Transfer genetic code from nucleus to cytoplasm

b. Largest of all RNA types

c. Constitutes the majority of RNAs in a cell d. Most contain many codons

e. Brings high energy bonds to the site of translation

e. Brings high energy bonds to the site of translation

tRNAs carry amino acids to the ribosome. The amino acid is attached by a high-energy bond, which helps drive peptide bond formation during translation.

Mobile genetic elements such as viruses and transposons continue to exist because...

a. Their mechanisms are too advanced for the cell's defenses to control

b. Their activity is so infrequent that there is no real effect on DNA

c. The occasional DNA rearrangements and additions are beneficial in the long term

d. Their continued existence is still a scientific mystery

e. Even evolution needs a few play toys

c. The occasional DNA rearrangements and additions are beneficial in the long term

Mobile genetic elements can cause mutations, but they also create genetic variation that can be useful for evolution.

Holliday junction

a. Bond between mRNA codons and tRNA exon codons

b. Site of replication fork initiation

c. Heteroduplex formed during some homologous recombination events

d. Site where topoisomerase 2 attaches during replication

e. Small Florida city known for its pecan clusters and discount Disney tickets

c. Heteroduplex formed during some homologous recombination events

A Holliday junction is a crossed DNA structure formed during homologous recombination.

Eukaryotic replication forks

a. Move much more quickly than prokaryotic forks

b. Do not move in pairs in opposite directions

c. Different groups of forks become active at different times during S phase

d. Begin in heterochromatin earlier than euchromatin

e. Move much more slowly through heterochromatin than euchromatin

c. Different groups of forks become active at different times during S phase

Eukaryotic DNA replication happens in stages during S phase, with different origins/forks activated at different times.

The term polycistronic refers to...

a. The tendency of RNA molecules to fold into themselves

b. The simultaneous synthesis of several different proteins from the same mRNA

c. The ability of some proteins to fold into more than one functional tertiary structure

d. A misfolded protein in the process of degradation

e. A mechanism in multicellular organisms allowing alternative protein synthesis

b. The simultaneous synthesis of several different proteins from the same mRNA

Polycistronic mRNA contains coding sequences for multiple proteins, common in prokaryotes.

Which of the following regarding the eukaryotic large ribonucleoprotein subunit is correct?

a. Protein component synthesized in the cytosol

b. RNA components synthesized in the nucleus

c. Subunit assembled in a nucleolus

d. A & B but not C

e. A, B & C all correct

e. A, B & C all correct

Ribosomal proteins are made in the cytosol, rRNA is made in the nucleus/nucleolus, and ribosomal subunits are assembled in the nucleolus.

In prokaryotes, the energy for opening up the DNA double helix prior to transcription is derived from...

a. Sigma factor activity

b. Conformational change

c. ATP hydrolysis

d. A & B but not C

e. All of them are correct answers

d. A & B but not C

In prokaryotes, RNA polymerase and sigma factor bind the promoter and cause a conformational change that opens the DNA. ATP hydrolysis is not required.

Most mutations within DNA protein coding regions...

a. Lead to beneficial changes in protein structure

b. Go unnoticed because they are either deleterious or have no effect on protein structure

c. Are quickly silenced by being folded into heterochromatin

d. Are quickly and efficiently repaired

e. Can be repaired by drinking large quantities of MonaVie

b. Go unnoticed because they are either deleterious or have no effect on protein structure

Most mutations are not beneficial. Many have no effect because of redundancy in the genetic code, while harmful ones are often removed by selection.

In E. coli, allolactose binds to a regulatory protein and removes it from the promoter, allowing transcription of the Lac operon to proceed. This regulatory protein is classified as...

a. A sigma factor

b. A repressor

c. An activator

d. Assist factor

e. A chaperone

b. A repressor

The Lac repressor normally blocks transcription. When allolactose binds it, the repressor releases DNA, allowing the Lac operon to be transcribed.

RecA protein...

a. Facilitates directed branch migration during recombination

b. ATPase

c. Possesses multiple DNA binding sites

d. A & B is correct but not C

e. All of them are correct

e. All of them are correct

RecA helps with homologous recombination, uses ATPase activity, and can bind DNA during strand exchange.

mRNA splicing...

a. Can be used to produce several different proteins from a single pre-mRNA

b. Universal step in processing of pre-mRNA produced by all cell types

c. Mechanism by which axons are removed from eukaryotic pre-mRNA

d. Autocatalytic process of the pre-mRNA

e. Occurs in the nucleus of eukaryotic cells but in the cytoplasm/nucleolus region in prokaryotes

a. Can be used to produce several different proteins from a single pre-mRNA

Alternative splicing allows one pre-mRNA to be processed in different ways, producing different protein versions in different cells or conditions.

In E. coli, cAMP binds to a regulatory protein and causes it to attach to the promoter, allowing transcription of the Lac operon to proceed. This regulatory protein is classified as...

a. A sigma factor

b. A repressor

c. An activator

d. An assist factor

e. A chaperone

c. An activator

cAMP binds CAP, which helps RNA polymerase bind the promoter and increases transcription. That makes it an activator.

During replication, the DNA double helix must be kept open by single-stranded binding proteins because...

a. Otherwise the helix will develop negative supercoiling

b. To prevent association of the Okazaki fragments before they can be joined by ligase

c. To allow the helicase enzyme success to the DNA

d. To prevent the single-stranded DNA from reannealing or base pairing with itself

e. Provide a surface upon which the topoisomerases can bind

d. To prevent the single-stranded DNA from reannealing or base pairing with itself

Single-stranded binding proteins stabilize separated DNA strands so they do not pair back together before replication.

The eukaryotic nucleolus is...

a. Region within the nucleus where ribonucleoprotein assembly takes place

b. Another name for the spliceosome

c. Regions of the nucleus where the heterochromatin region of chromosomes reside

d. Regions of the nucleus kept deliberately free of reactions so as to interfere with the chromosomes

e. Hypothetical regions not yet proven to exist

a. Region within the nucleus where ribonucleoprotein assembly takes place

The nucleolus is where rRNA is made and ribosomal subunits begin assembling.

Retroviruses...

a. Code for an enzyme called reverse transcriptase

b. Code for proteins which provide a protective coating

c. A class of mobile genetic elements

d. A & B but not C

e. All the above are correct

e. All the above are correct

Retroviruses encode reverse transcriptase, have protective viral coat proteins, and are considered mobile genetic elements.