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MCAT Biology Flashcards

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1
Q

Water:

H-bond

Rxns

A

Major solvent for life

H-bonding: maintains liquid state, facilitates hydrophillic/phobic interactions

Rxns: dehydration/condensation, hydrolysis

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2
Q

Lipids

8 types of molecules

fatty acids

A

Fatty acids, triacylglycerols, phospholipids, glycolipids, steroids, terpenes, eicosanoids, lipoproteins

FA: carboxylic acid w/ carbon chain (usually even numbered, maximum 24 C’s, saturated/unsaturated), building block for lipids

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3
Q

Triacylglycerols

Phospholipids

Glycolipids

A

glycerol backbone—3 FAs, fats/oils (adipocytes), store energy, insulation

glycerol backbone–2 FA + 1 phosphate group, amphipathic (polar/nonpolar ends), membranes

glycerol–FAs + carbohydrates, membranes of myelinated cells, amphipathic

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4
Q

Steroids

Terpenes

Eicosanoids

A

4 rings, vitamin D, cholesterol

vitamin A

20 C, local hormones: blood pressure, body temperature, smooth muscle
Prostaglandins (inhibited by aspirin), thromboxanes, leukotrienes

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5
Q

Lipoproteins

A

ADD

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6
Q

Peptide bond

R-groups

Structure: 1 - 4, types, tertiary influences

Globular/Structural

A

NH2-CR-carbonyl-NH-CR-carbonyl-OH

R-group: can be polar/non, basic/acidic

1’ - # and sequence
2’ - local folding, alpha helix, beta sheet
3’ - overall shape, influenced by disulfide bonds (2 cysteines), electrostatics (R ions), H-bond, vanderwalls, HYDROPHOBICS
4’ - multiple chains/subunits, prosthetic groups

tend to have specific complex function vs provide support/structure

glycoproteins, proteoglycans, cytochromes

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7
Q 
Protein selective denaturation:
urea
salt/pH
mercaptoethanol
organics
heat
A

H-bonds

electrostatics (ions)

disulfides

hydrophobic interactions

denatures everything

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8
Q

Carbohydrates, Cn(H2O)n

types

alpha/beta

glycogen

digestion

A

hexose,pentose,form rings (anomers at C1):

alpha: anomeric hydroxyl + methoxy on opp
beta: anomeric hydroxyl + methoxy same side

glucose w/ 1-4A and 1-6A chains, storage

Plants: starch = 1-4A, cellulose = 1-4B chain
1-4B animals can’t digest, bacteria can

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9
Q

Nucleotide

components
form,bonds
examples

A

triphosphate-5 C sugar (ring)-nitrogenous base
nucleoside=5C + base (no triphosphate)

polymers (DNA,RNA): phosphodiester bond
double helix

ATP: adenosine triphosphate
also cyclic AMP, NADH, FADH2

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10
Q

Minerals

what are they, function

A

dissolved inorganic ions

create electrochemical gradients, assist in transport
structure in matrices (bone)
cofactors in proteins (prosthetic group like heme)

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11
Q

Enzymes

what are they?
how do they work?
effects T, pH, concentrations

A

globular proteins w/ cofactor = cosubstrate or prosthetic group (gets reverted back by end of reaction) like AT, vitamins, metal ions

increase rxn rate, lower activation energy
bind substrate at active site (specificity)
lock+key vs induced fit

T: increases rate until enzyme denatured
pH: enzyme/rxn occurs in given range
substrate conc: rate plateaus as enzyme is saturated

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12
Q

Enzyme inhibition

irreversible
competitive
non-competitive

A

bind covalently to enzyme, can be highly toxic: penicillin

bind active site (often resemble substrate)
lower Km (not Vmax), increase substrate to overcame effects
bind alternate site, often work on multiple enzymes
lower Vmax (not enzyme affinity)
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13
Q

Enzyme regulation

5 types

A

proteolytic cleavage: zymogen/proenzymes get cut to become irreversibly activated

reversible covalent: phosphorylation (kinase) or other modifier

control proteins: subunits (calmodulin, G-protein) can activate/inhibit

allosterics: cofactors change conformation of enzyme, inhibit/activate

neg/pos feedback loop: products loop back to earlier in pathway to affect enzymes

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14
Q

Enzyme classification

names+function

A

suffix -ase, contains N, subject to denaturation

kinase (phosphorylates) [hexokinase-glucose]
phosphatase (dephosphorylates)

oxidoreductase
transferase
hydrolase
isomerase
lyase (synthase): cut, add to double bond
ligase (synthetase): addition, requires ATP

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15
Q

Cellular metabolism

A

anabolic (synthesis), catabolic (breakdown)

  1. macromolecule to constituents
  2. constituents to acetyl CoA, pyruvate/metabolites, ATP/NADH/FADH2 (oxidation w/o oxygen)
  3. w/ oxygen: metabolites to citric acid cycle, oxidative phosphorylation, lots of ATP/NADH/FADH2
  4. w/o oxygen: NAD+/byproducts are expelled as waste

respiration = energy aquisition, aerobic/anaerobic

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16
Q

Glycolysis

general overview
products, stages, type of energy

A

Step 1: glucose to 2 pyruvate/ATP/NADH
occurs in cytosol, all living things

6C stage: expends 2 ATP, primes
3C stage: synthesizes 4 (total) ATP when dephosphorylating each (2) molecule (net 2 ATP)

substrate-level phosphorylation: energy is gained by dephosphorylating a high energy compound

phosphorylations: requires energy, ionizes molecule –> polar molecule cannont pass through membranes

17
Q

Glycolysis

some specifics

A

Some steps:

(hexokinase: reversible in liver) -> gluc-6-phos
- > gluc-1-phos (can go to liver to form glycogen)
- > fruc-6-phos
- > (irreversible) fruc-1-6-biphos
- > PGAL x2 …..
- > 2 pyruvate

18
Q

Fermentation

type of respiration
products

A

Step 2 and 3: anaerobic, no oxygen present

pyruvate -> ethanol (in microorganisms/yeast) or lactic acid (in humans) + NAD+ -> expelled as waste

NADH is oxidized to NAD+, recycled in glycolysis (as coenzyme)

19
Q

Aerobic respiration

products
location/movement

overall rxn

A

Step 3: oxygen present

pyruvate, NADH (move to matrix of mitochondrion by facilitated diffusion, through porin)
-> acetyl CoA (enters Krebs/Citic Acid cycle)

Overall: including Krebs and glycolysis, net 36 ATP
gluc + O2 -> CO2 + H2O

20
Q

Krebs/Citric acid cycle

A

1 glucose = 2 pyruvate = 2 acetyl CoA = 2 turns of cycle

All catabolism:
FA: carbon chains converted to acetyl CoA, glycerol to PGAL to pyruvic acid
Proteins: deaminated, converted to pyruvic acid or acetyl CoA

21
Q

Electron transport chain

Oxydative phosphorylation

A

High energy electrons (from NADH) passed down chain to oxygen (final acceptor - forms H2O)

Energy generated is used to establish proton-motive force (proton gradient) by pumping protons into intermembrane space (has lower pH)

ATP synthase creates ATP:
2-3 ATP from 1 NADH
2 ATP from 1 FADH2

22
Q

DNA

components
bases
bond

A

nucelotides w/ 4 bases

adenosine, guanine (3 H-bonds) = purines (two rings)
thymine(uracil), cytosine (3 H-bonds) = pyrimidines

phosphodiester bond: 5’-5C sugar-phosphate-3’
Bases on 1’ Carbon on sugar

double strand w/ complement strands
major/minor grooves in double helix

23
Q

The gene

Eukaryotes v prokaryotes
Euchromatin vs hetero

genome

A

code for polypeptides (one), messenger, ribosomal, transfer RNA

multiple copies of genes vs one of each

coding, non-repetitive, active transcription vs tightly packed and inactivated

26,000 - 38,000 genes humans
DNA to RNA to peptides/aminos

24
Q

Replication

properties
start: replisome
basic process
end

A

semiconservative, bidirectional

replisome: origin of replication, replication fork, leading lagging strand

helicase unwinds, primase builds primer (10 riboNTs), DNA polymerase reads 3to5, builds 5to3 (pyrophosphate hydrolysis), exonuclease proofreads

lagging strand has SSB tetromeres for stability, DNA polymerase formas okazaki fragments, primers removed, DNA ligase joins them

telomeres: eukaryotes, repeated 6 nucleotides, prevent end erosion, telomerase

25
Q

RNA

properties
types

A 
DNA = deoxy (lost oxy)
RNA = 2' C still has hydroxyl (-OH)

single strand, uracil, moves through nuclear pores (leaves nucleus)

messenger: code proteins in cytosol
ribosomal: form ribosomes (w proteins), synthesized in nucleolus
transfer: collect aminos in cytosol

MCAT (1 decks)

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