Cell Bio Final

amino acids and nucleic acids

These cellular molecules are comprised of C, H, O and N:

Each amino acid has a unique R group that dictates how the protein folds and behaves

If the core backbone of polypeptudes is composed of the same molecule, how is it that proteins fold into different shapes and perform different functions?

The ER but not the cytosol

Disulfide bonds within or between proteins require an oxidative environment to form. Which of the following parts of the cell meet this condition?

Enzymes help the reaction occur by lowering the activation energy of the chemical reaction.

Enzymes catalyze chemical reactions in the cell. What does this mean and how do they accomplish this?

as transmembrane proteins, then are cleaved and joined to the GPI group on the lumen surface of the ER membrane

GPI-anchored proteins are synthesized…

protein is identified by carbohydrate modification, exits ER via retrotranslocon, ubiquitinated, degraded via lysosome

What is the correct pathway for proteins that are seriously misfolded?

ribosomal subunits

The nucleolus is the site where ___ is/are assembled.

euchromatin

Chromatin that contains sequences that are transcribed is packaged as

Rab/tethering factor interactions

Vesicles recognize their target locations through

late endosomes

transport vesicles carrying acid hydrolases fuse with

COPI

Which coat protein would you expect to be coating a vesicle carrying proteins from the Golgi that are targeted for the ER?

binding of GTP

The ability of ARF to bind the adaptor protein during vesicle budding is regulated by

Ran

What does not play a role in the transport of mRNAs out of the nucleus: Ran; completion of 5’ cap, 3’ poly A tail, and splicing; or exporter complex

both the inner nuclear envelope membrane and the chromatin

the nuclear lamina binds to

glycolipids

which class of lipids is synthesized in the Golgi apparatus

transport the proteins from the Golgi apparatus back to the ERn

A KDEL sequence serves as an ER retention signal for proteins by binding to KDEL receptors that

CO2

Chloroplasts can synthesize carbohydrates. What is the starting material for this process?

Chromosome movement during anaphase A

Which of the following movements is not based on actin-myosin interactions? Cell migration (crawling) over surfaces; chromsome movements during anaphase A; cytokinesis of animal cells

Tim

Which of the following is not involved in the initial transport of a protein across the mitochondrial outer membrane from the cytosol: Tim; Hsp70; Tom; ATP

dynein movement causing the sliding of microtubules

The beating of cilia and flagella occurs by means of

the rate of GTP-bound tubulin additoin relative to the rate of tubulin GTP hydrolysis

whether a microtubule shrinks or grows is determined by

cleaved by mitochondrial matrix processing peptidase

The amino terminal presequence on proteins imported into the mitochondrial inner membrane is

treadmilling

In actin filaments assembly, the process in which ATP-actin monomers are added ot the plus end of the filament while at the same time ADP-actin monomers are dissociating form the minus end of the filament is referred to as

cell-cell contact via protein mediated binding of intermediate filaments

desmosomes are specialized junctions that are involved in

interpolar

The microtubules that overlap in the center of the mitotic spindle are called ___ microtubules

acetyl CoA; CO2, NADH, FADH2

The citric acid cycle consists of the oxidation of ___ to produce ___

chemiosmotic coupling

The electrons carried by NADH and FADH2 produced during the breakdown of one glucose molecule are passed through the mitochondrial ETC to oxygen. This process drives the synthesis of 32-34 ATP molecules. This is an example of:

Light energy absorbed by photosystems I and II generate energetic electrons that cause the cytochrome bf complex to pump protons across the thylakoid membrane; these protons drive ATP synthase to synthesize ATP

atp is synthesized in photosynthesis by these means

dynein

A male patient at a medical clinic presents with infertility due to nonmotile sperm and an inability to clear mucous from his respiratory tract. Other tissues are normal. You suspect that these symptoms may be caused by mutant

storage of starch

amyloplast

chloroplasts not exposed to light

etioplast

store carotenoids

chromoplast

store fats

elaioplast

providing mechanical strength for cells

intermediate filaments function in

oxidize certain organic molecules and degrade the H2O2 produced by these reactions

the major function of peroxisomes is to

ATP and a proton gradient across the inner membrane

the import of mitochondrial matrix proteins from the cytoplasm requires

It is supported by the nuclear lamina

What is true of the nuclear envelope?

In the cytosol

Proteins that have lost their nuclear localization signal and are then injected into the cytoplasm of cultured cells will localize

1. Exportin/Ran complex binds to NES of cargo protein

2. Export complex leaves nucleus following the Ran/GTP concentration gradient

3. Ran GAP hydrolyzes GTP to GDP

4. Export complex dissociates

5. Ran/GDP and exportin are trafficked back into the nucleus

Order of events for transport out of the nucleus

proteins embedded in the ER membrane

membranes associated proteins are trafficked through the ER as

Final destinations of proteins that are translated on free ribosomes

nucleus and mitochondria

1. Translation pauses

2. CC allows SRP to bind SRP receptor and be directed into ER membrane

The signal peptide serves an important function on proteins that are trafficked through the ER. The signal peptide is recognized by the the SRP. What two things results from binding of the signal peptide by SRP?

enzymatic coupling of these two reactions allows the energy of ATP hydrolysis to drive the synthesis of glucose-6-phosphate

The hydrolysis of ATP to ADP and phosphate allows glucose-6-phosphate to be synthesized from glucose and phosphate because the

pyruvate

what is a product of glycolysis that is transported into the mitochondria

The ETC occurs here and the high impermeability of the inner membrane is essential to electron flow

The inner membrane of the mitochondria is important to ATP production in the cell. What process occurs here and what property of this membrane is essential to the proper function of the mitochondria?

An electrochemical gradient is made of an electrical (charge) and chemical (protons) gradient that drives the movement of protons for ATP synthesis. The gradient stores energy so that ATP synthase can actually produce ATP.

Define electrochemical gradient and what is the function of the electrochemical gradient established in the mitochondria?

rate of photosynthesis

Which of the following signals does not control plastid development: Exposure of plant to sunlight; rate of photosynthesis; type of tissue cell resides in

catalase

what is the enzyme that neutralizes H2O2 in the peroxisome

ATP synthase is located in both the inner mitochondrial membrane and thylakoid membrane. H+ concentration is higher in both the intermembrane space and thylakoid lumen. ATP is produced in the matrix and stroma.

Name the equivalent locations in the mitochondria and chloroplast where ATP is synthesized

G actin-ADP subunits dissociating form an actin filament

Treadmilling allows actin to be a dynamic structure in the cell. This process includes:

Myosin uses energy from ATP to be able to physically move along actin filaments.

Myosin motors convert chemical energy into kinetic energy. What does this mean?

ATP us hydrolyzed, putting myosin in the cocked position. It then foes back to its initial form, pulling the actin with it.

What causes the power stroke in muscle contractions?

dynamic instability

The microtubule behavior in which individual microtubules alternate between cycles of growth and shrinkage is called

phospholipids

The plasma membrane’s barrier to passive diffusion is primarily a function of the membrane’s

in the outer leaflet

Plasma membrane glycolipids are found

0 mV

What would be the resting potential across an artificial membrane if all charged molecules on both sides were equally permeable?

unfavorable direction, always coupled to another reaction or source of energy

active transport is transport in an energetically

allowing short, controlled calcium increases to be used as intracellular signals

calcium levels remain low in the cytosol

caveolin

coated pits are converted to coated vesicles during endocytosis by formation of rings of the protein

The channels close when the concentration of sodium gets too high inside the cell. The negative charges inside the cell depolarize the channel and it undergoes a CC, closing it off.

During an action potential, sodium channels self-inactivate. What does this mean and how is this accomplished?

thick peptidoglycan wall outside the plasma membrane

Gram positive bacteria have a

fibronectin and integrin interactions

cells adhere to collagen fibers via

in the plasma membrane

cellulose synthase in plants is located

ECM is composed of collagen, elastin, proteoglycans, and adhesive glycoproteins. These components provide flexibility, anchor points, strength, and stability.

What is the composition of the ECM and how do its components and their interactions provide stability and structural support in multicellular animals?

Auxin binds to cels on the shaded side of the plant. This causes that side of the plant to lengthen more than the side towards the sun, bending the stem towards the light.

Explain how plants are able to grow towards the light without undergoing mitosis.

Excess unfolded proteins in the ER

What activates the UPR response?

1. ER expands to allow room for unfolded proteins

2. Proteins IRE1, ATF6, and PERK identify unfolded proteins or BiP and produce necessary transcription factors.

What two things happen in the cytosol once the UPR response is activated?

To produce transcription factors that activate genes like lipids, chaperones, and enzymes to restore protein folding ability.

What is the end target of the UPR response process?

• RanGAP would normally hydrolyze GTP causing a CC in which Ran drops the cargo protein and GTP becomes GDP. Result —> GDP

• If GTP cannot by hydrolyzed, RanGTP cannot change shape and won’t drop the cargo protein. This means the cargo can leave the nucleus but will not be released elsewhere in the cell.

• All RanGTP will be occupied holding cargo and ultimately export will be unsuccessful

A mutation in the RanGAP protein results in the inability of the protein to hydrolyze GTP. How would this mutation change the process of export from the nucleus?

A protein changes shape and fucntion because of an interaction with another molecule

Define conformational change

1. SRP

2. GTP bound to SRP is hydrolyzed and SRP leaves

3. Ribosome and SS are transferred to translocon and translation can resume

Choose one step in cotranslational translocation where a CC occurs. 1. what is the protein that the CC occurs in? 2. What causes the CC? 3. What is the result of the CC?

M) inner mitochondrial membrane C) thylakoid membrane

Location of ETC in mitochondria and chloroplast

H+ gradient for both

Source of energy used to produce ATP in mitochondria and chloroplast

M) intermembrane space C) thylakoid lumen

Location of high H+ concentration in mitochondria and chloroplast

M) NADH and FADH2 C) water splitting in PSII

source of electrons for ETC in mitochondria and chloroplast

M) mitochondrial matrix C) stroma

location of ATP production in mitochondria and chloroplast

• Ca2+

• When Ca2+ concentrations is high, it binds to troponin

• This CC moves tropomyosin from covering actin bdining sites, allowing myosin heads to bind

Actin myosin interactions are responsible for muscle contraction. What ion regulates actin/myosin interactions? How does this ion initiate muscle contraction?

• Anaphase A requires depolymerization of + end of kinetochore microtubules attached to centromere to move chromatids

• no depolymerization = no separated chromatids = no cell division

• Anaphase B uses depolymerization of + end of astral microtubules to pull poles to opposite ends

• no depolymerization = no poles to opposite ends = no cell division

• treatment —> no cell division —> cancer can’t spread

The anticancer drug taxol works by binding to B-tubulin. This prevents depolymerization of microtubules and promotes polymerization. In terms of M phase of the cell, how would this specifically impact anaphase A and anaphase B?

• Interpolar: do not touch each other directly but interact to push poles away from the midline

• Kinetochore: dynamic (+) end attaches to centromeres of chromatids to pull chromatids apart

• Astral: does not directly attach but + end interacts with plasma membrane to pull poles away from each other

The mitotic spindle is necessary for the correct completion of mitosis during M phase of the cell cycle. There are three specific types of microtubules involved in this process: interpolar, kinetochore, and astral. What is the role of each of these microtubules?

fibronectin

Tissue cells are connected to the ECM by receptors that bind to an adhesive protein called

collagens

cell adhesion molecules can be divided into four major groups. Which of the following is not one of those groups? selectins, integrins, collagens

gram negative bacteria are surrounded by a thin cell wall beneath an outer membrane

this is true of gram negative bacteria and gram positive bacteria

transmembrane proteins; collagen, fibronectin, and laminin

integrins are ___ that bind to ___

small and hydrophobic

molecules that diffuse passively across the plasma membrane most rapidly are

intermediate filaments

desmosomes are linked to cytoplasmic

• Outer leaflet: phosphatidylcholine, sphingomyelin

• Inner leaflet: phosphatidylethanolamine, phosphatidylserine

What describes the distribution of phospholipids in the plasma membrane

ligand gated

channels that open in response to neurotransmitters or other signal molecules are called ___ channels

in the plasma membrane

cellulose synthase in plants is located

in an energetically unfavorable direction always coupled to another reaction or source of energy

active transport is transport

active transport

coupled transport of glucose and Na+ into the intestinal epithelial cell is an example of

psuedopodia

Which of the following is not involved in receptor mediated endocytosis: clathrin, psuedopodia, receptor proteins

action of the Na+-K+ pump

The Na+ and K+ ion gradients across the plasma membrane are produced primarily by the

they keep the Na+-glucose cotransporter in the apical membrane and the glucose-facilitated transporter in the basolateral membrane

what is the role of tight junctions in the transport of glucose across the intestinal epithelium

proteoglycan, fibronectin, collagen

These cell wall/ECM components belong in animals

peptidoglycan

This cell wall/ECM component belongs in bacteria

chitin

This cell wall/ECM component belongs in fungi

cellulose

This cell wall/ECM component belongs in plants

nerve cells would adhere to one another and epithelial cells would adhere to one another

if developing pre-nerve cells expressing only N-cadherin on their surfaces were mixed with epithelial cells expressing only E-cadherin, what would be the most likely result?

IV

basal laminae are a meshwork of fibrils composed primarily of type ___ collagen

1. the neuron is at resting membrane potential, maintained by ion gradients and the sodium-potassium pump

2. the membrane potential reaches threshold, triggering the opening of voltage gated Na+ channels

3. Na+ ions rapidly enter the cell, causing depolarization of the membrane potential

4. Na+ channels self-inactivate while K+ channels remain open, causing hyperpolarization

5. Voltage gated K+ channels open, allowing K+ to exit the cell, leading to repolarization of the membrane

Steps of an action potential in order