CELL & MOLEC QUIZ 1 STUDY GUIDE

Cell Theory

All biological organisms are composed of cells; cells are the unit of life; all life come from preexisting life.

Resolving power of light microscopy

200 nanometers

Resolving power of electron microscopy

.2 nanometers

Prokaryotic cells

lack membrane-bound organelles; retain plasma membrane, cytoplasm, ribosomes, and DNA

Eukaryotic cells

contain nucleus, E.R., Golgi apparatus, lysosomes, chloroplasts, mitochondria; larger and more complex

3 domains of life

Eukarya, Archaea, Bacteria

LUCA

Last Universal Common Ancestor; potential thermophile, in deep sea vents without oxygen

How can bacteria readily adapt to a changing environment despite having a small, stream-lined genome?

Lateral Gene Transfer - prokaryotes exchange genes with neighbors

smaller genomes = more successful

According to Nick Lane, how did the first eukaryotic cell arise? 

An archaean cell engulfed a bacterium (LECA); this allowed the endosymbiotic bacteria to lose ~99% of its genome

Nucleus

stores DNA

Mitochondria

generates useable energy; contains inner and outer membrane

Chloroplasts

create energy from sunlight

Endoplasmic Reticulum

creation, modification, and transport of proteins

Golgi apparatus

transportation + sorting of proteins

Cytoskeleton

cell structure, mitosis & meiosis

What are the reactant and product molecules produced in cellular respiration?

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

What is the endosymbiotic theory?

mitochondria and chloroplasts in eukaryotic cells originated from ancient bacteria that were engulfed by larger cells

How do cells exchange material with the external environment?

Diffusion through the plasma membrane

Microtubules (Cytoskeleton)

support shape, move chromosomes during cell division, enable organelle movement

Actin Filaments (Cytoskeleton)

plasma membrane; mechanical support, enables cell movement

Intermediate Filaments

structural support

What makes model organisms like D. melanogaster, C. elegans, and D. rerio useful for studying cell biology?

Readily accessible and easily modifiable

How do genome size and number of genes in various model species differ?

Genome Size: Increases from smaller genomes in D. melanogaster and C. elegans to larger genomes in Danio rerio, Mus musculus, and Homo sapiens

Number of Genes: Varies, with C. elegans having a higher gene count relative to its genome size, while Danio rerio and Mus musculus have more genes overall but also larger genomes

What is the atomic number of an atom?

number of protons found in the nucleus of that atom.

What is the mass number of an atom?

total number of protons and neutrons in its nucleus.

What are isotopes?

different forms of the same chemical element that have the same number of protons but different numbers of neutrons.  (Carbon-14, 6 protons and 8 neutrons)

How much does a mole of NaCl weigh?

Na mass number = 22.99. Cl mass number = 35.453

22.99 + 35.453 = 58.44

How much does .5 of a mole of NaCl weigh?

58.44/2 = 29.22

Covalent Bonds

Electrons are shared

Non-polar: shared equally

Polar: 1 atom is more electronegative than the other

Ionic Bonds

Electrons are transferred, leaving one ion positive and the other negative

Hydrogen Bonds

hydrogen atom bonds to a strongly electronegative atom ( O — H )

How do electrons influence the activity of atoms?

Determines reactivity, ability to gain or lose electrons, & formation of chemical bonds

Calculating pH of a solution

pH = -log [H₃O⁺]

Find pH of a 0.0025 M HCl solution.

pH = -log (0.0025) = -(-2.60) = 2.60

What is the main building block of plasma membranes?

Phospholipids

What are the building blocks of nucleotides?

Nitrogen base, 5-carbon sugar, one or more phosphate groups

Saturated Fatty Acids

Single bonded, solid at room temperature (butter)

Unsaturated Fatty Acids

Double bonded, not solid (olive oil)

What does amphipathic mean?

Having both hydrophilic and hydrophobic parts (ex. phospholipid bilayer with hydrophilic head and hydrophobic tail)

Structure of DNA

Double-helixed, with a deoxyribose sugar and thymine base. Contains Cytosine, Guanine, Adenine, Thymine

Structure of RNA

Single-stranded, with a ribose sugar and uracil base. Contains Cytosine, Guanine, Adenine, Uracil

How do you determine the possible number of DNA or RNA molecules made from a given number of nucleotides?

The number of possible DNA or RNA molecules is 4ⁿ, where n is the number of nucleotides.

How do you determine the possible number of polypeptide chains made from a given number of amino acids?

The number of possible polypeptide chains is 20ⁿ, where n is the number of amino acids.

How are proteins synthesized?

Dehydration reaction & loss of a water molecule

Primary Protein Structure

sequence of amino acids held together by peptide bonds

Secondary Protein Structure

a-helixes and B-pleated sheets maintained by hydrogen bonds

Tertiary Protein Structures

3-D shape, interactions with R-groups and all types of bonds

Quaternary Protein Structure

multiple polypeptide chains

How to denature proteins

• Expose to high heat

• Alter pH of a solution

• Expose to alcohol

• Reducing & oxidizing agents

• Concentrated brine solution

How do misfolded proteins lead to neurodegenerative diseases?

Aggregate and damage cells & whole tissues. Usually due to an abnormally expanded range of sequence copies

• Huntington’s: CAG

  • Normal: 9 - 37

  • Abnormal: 37 - 121

Chaperone Proteins

• Guide folding of newly synthesized peptide chains to save energy & prevent misfolding (requires ATP hydrolysis)

• Form isolation chambers to prevent single chains from aggregating

a-helixes

N-H is Hydrogen-bonded to C=O of a neighboring peptide bond in some chain

B-helixes

Several segments held together by Hydrogen bonding between adjacent strands

Coiled Coils

Formed when 2-3 helixes wrap around one another. Twist facing inward due to non-polarity

Amyloid Fibers

• Stacking of sheets allows some misfolded proteins to aggregate

• Associated with Alzheimer’s & prion diseases

• Used by infection bacteria for biofilms that enable colonization of host tissues

Ligand

Any substance that binds to a proteins; must fit perfectly; binds proteins to the substrate

Antibodies

Formed from 2 identical light polypeptide chains and 2 identical heavy polypeptide chains

How are infections handled?

Antibodies attack antigens on the viruses, raising body temperature & denaturing proteins

Catalyzing Chemical Reactions

• Enzymes make & break covalent bonds at will w/o being consumed

• Lower activation energy required to start reactions

• Bind 2 substrate molecules to encourage reactions

Feedback Inhibition

Enzyme that acts early in a reaction pathway is inhibited by a late product

Allosteric Enzymes

Have 2+ binding sites that influence each other based on if they are on or off ATP/phosphate groups, acetyl groups, ubiquitin, GTP binding proteins

Unidirectional Movement

• ATP Hydrolysis allows motor proteins to produce directed movements

• Coupling conformational change with ATP Hydrolysis makes movement unidirectional

Hydrolase

General term for enzymes that catalyze a hydrolytic cleavage reaction

Nuclease

Breaks down nucleic acids by hydrolyzing bonds between nucleotides

Protease

Breaks down proteins by hydrolyzing peptide bonds between amino acids

Ligase

Joins 2 molecules together; DNA ligase joins two DNA strands together end to end

Isomerase

Catalyzes the rearrangement of bonds within a single molecule

Polymerase

Catalyzes polymerization of bonds within a single molecule

Kinase

Catalyzes the addition of phosphate groups to molecules. Attach phosphate groups to proteins

Phosphatase

Catalyzes the hydrolytic removal of a phosphate group from a molecule

Oxido-reductase

Catalyze reactions in which one molecule is oxidized and another is reduced

ATPase

Hydrolyzes ATP