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OPTOM 8060 - BioChem Midterm 1 > Proteins > Flashcards

Proteins Flashcards

midterm 1

1
Q

Protein roles in the body (6 of them)

A
  1. mechanical support
  2. control of growth & differentiation
  3. catalysis
  4. transport/storage
  5. nerve propagation
  6. immune protection
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2
Q

Protein roles in the eye (5 of them)

A
  1. support structure & clarity of the cornea
  2. participate in variable light refraction of the lens
  3. initiate transduction of light into electric signaling
  4. generate IOP
  5. lyse bacteria in the precornial tear film
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3
Q

peptide bond

A

-covalent bond between amino group of one AA and the carboxylate group of another
-dehydration synthesis (condensation rxn): H2O molecule is released

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4
Q

peptide bond properties in proteins

A

partial double-bond character, rigid and planar, trans configuration, uncharged but polar

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5
Q

what causes protein degradation in the body? lens? cornea?

A
  • proteases
  • caspases
  • matrix metalloproteinases (MMP)
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6
Q

Protein structure

A

defines the function, determined by the sequence of AA

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7
Q

Primary structure of a protein

A

a unique sequence of amino acids

required for understanding:
1. structure of a protein
2. mechanism of action/function
3. relationship to other proteins w/ similar physiological roles

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8
Q

secondary structure of a protein

A

“local folding” from repeated H bonding within a chain
common arrangements: a-helix, B-pleated sheets

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9
Q

globular vs fibrous protein structure

A

globular: mixed secondary structure
fibrous: mainly one kind of secondary structure

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10
Q

alpha helix structure

A
  • stabilized by hydrogen bonds between atoms of the polypeptide back bone
  • very stable
  • R-groups are outside the helix
    -ex. keratin
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11
Q

Beta sheet

A
  • H bonding to adjacent chains
    -gives a flattened structure
  • either parallel or antiparallel
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12
Q

tertiary structure

A

-entire 3D structure of a single-chain polymer
-refers to final arrangement of domains
- stabilized by side chains: ionic bridges, H bonds, disulfide bonds, hydrophobic interactions

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13
Q

quaternary structure

A

spatial arrangement of a macromolecule’s individual subunits

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14
Q

protein denaturation definition

A

protein alteration from its native form
- unfolding and disorganization of a protein’s secondary, tertiary, and quaternary structures
- WITHOUT hydrolysis

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15
Q

protein denaturation causes and result

A

causes: heat, detergents, strong acids/bases
results: loses function, may be reversible though

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16
Q

molecular chaperones

A

chaperones bind reversibly to unfolded polypeptide segments and prevent misfolding/premature aggregation

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17
Q

heat shock proteins

A

major class of molecular chaperones
- synthesized in response to heat shock, or other stresses in cells

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18
Q

fibrous protein

A

proteins characterized by polypeptide chains in a stiff, elongated strand or sheet, tend to form fibers

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19
Q

fibrous examples and function

A

keratin, collagen, elastin
- resist stretching and provide shape and tensile strength
- structural role, rather than dynamic

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20
Q

collagen structure

A

collagen molecule: 3 alpha-chain polypeptides coiled around each other (triple helix)
collagen fibril: many collagen molecules
collagen fibers: may collagen fibrils

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21
Q

vit c in collagen

A

hydrolyzes proline to hydroxy proline, critical for collagen formation

22
Q

type I collagen location

A

major connective tissues of skin, bone, tendon, blood vessels, and corneal stroma

23
Q

type II collagen location

A

cartilage, vitreous

24
Q

type III collagen location

A

found along type I in skin, arteries, and muscle, also in iris

25
Q

type IV collagen location

A

basement membranes of various tissues (descemet’s membrane, lens capsule)

26
Q

elastin

A

fibrous, insoluble protein, present w/ collagen in the CT
responsible for elasticity
elastic fibers: elastin core & microfibrils

27
Q

marfan’s syndrome

A

mutations in the fibrillin gene causes autosomal dominant trait
clinical manifestations: disorders of cardiovascular, musculoskeletal, and ophthalmic systems

28
Q

CT fibrous components

A

collagen & elastin

29
Q

CT cellular components

A

fibroblasts, keratocytes

30
Q

CT ground substance

A

GAG (glycosaminoglycans), proteoglycans, glycoproteins
- bind tissue together and provide support for the organs and other structures of the body

31
Q

glycosaminoglycans (GAG) structure and classes (6)

A

long unbranched polysaccharides, highly hydrophilic
1. hyaluronate (vitreous humor)
2. chondroitin sulfate (vitreous humor)
3. dermatan sulfate (cornea)
4. keratan sulfate (cornea)
5. heparan sulfate
6. heparin

32
Q

proteoglycans

A

core protein to which at least 1 GAG chain is covalently attached
participate w/ collagen and elastin, in the organization of the extracellular matrix

33
Q

globular proteins

A

folded into a spherical shape, water-soluble protein characterized by a compact structure

34
Q

globular protein functions (3 of them)

A

enzymes, transporters, regulatory proteins (metabolic pathways and gene expression)

35
Q

Hemoglobin

A

brings O2 from the lungs to the tissue
4 subunits each containing a heme prosthetic group
- 4 binding sites, which are Fe

36
Q

Heme

A

site for reversible oxygen binding
- Fe2+ for both hemoglobin and myoglobin
- Fe2+ is oxidized to Fe3+
-protein portion prevents permanent oxidation

37
Q

hemoglobin binding

A

oxygen binding alters the structure of the entire hemoglobin
- T “taut” state (deoxyhemoglobin)
- R “relaxed” state (oxyhemoglobin)
- hemoglobin is an allosteric protein and has cooperative binding

38
Q

T to R transition

A

iron shifts from being “domed” to being planar configuration

39
Q

myoglobin

A

heme protein found in heart and skeletal muscle
acts as oxygen reservoir and oxygen carrier for O2 transport within muscle cells

40
Q

myoglobin binding

A

one O2 binding site (1 heme molecule)
non-cooperative binding of oxygen

41
Q

oxygen pressure on Hb rxn

A

rxn favors oxyhemoglobin w/ an increase in oxygen pressure (lungs)
rxn favors deoxyhemoglobin with decrease in oxygen pressure (tissues)

42
Q

myoglobin vs hemoglobin curves

A

myoglobin: parabolic curve
hemoglobin: sigmoidal curve

43
Q

sigmoidal curve means

A

cooperative interaction between binding sites

44
Q

rightward curve means? caused by?

A

rightward shift means lower oxygen affinity
caused by “allosteric effectors”
1. increase in pCO2
2. increase in temp (exercise/fever)
3. decrease in pH (exercise)
4. increase in [2,3-BPG]
5. combo of these

45
Q

2,3-biphosphoglycerate (2,3-BPG)

A

abundant in RBC’s
modulates oxygen dissociation from Hb
-binds to deoxy-Hg and stabilizes the T state, which decrease O2 affinity and promotes O2 release

46
Q

leftward shift means? caused by?

A

means an increase of O2 affinity
caused by positive allosteric effectors or allosteric activators, ex. oxygen and carbon monoxide

47
Q

Bohr effect

A

reduction in O2 binding w/ lowered pH (increased [H+]) or increased pCO2
-both stabilize the T-state

48
Q

CO2 to bicarbonate

A

-for efficient transport, CO2 is converted to carbonic acid in the RBC’s by carbonic anhydrase
- then spontaneously loses a H+ to become bicarbonate

49
Q

principal buffers in the blood

A

bicarbonate-carbonic acid: plasma
hemoglobin: RBC’s
Protein functional groups: both

50
Q

flow of CO2 in the body

A

CO2 in tissues is converted to bicarbonate and transported to the lungs, then converted back to CO2 in the lungs and eliminated there

51
Q

2 types of acidosis

A

acidosis: when pH <7.35
respiratory acidosis: can’t efficiently expire CO2 (acid) from lungs
metabolic acidosis: kidney’s reduced ability to retain bicarbonate (base)

52
Q

2 types of alkalosis

A

alkalosis: when pH >7.45
metabolic alkalosis: kidney’s hyper ability to retain bicarbonate
respiratory alkalosis: eliminates too much CO2 from lungs

OPTOM 8060 - BioChem Midterm 1 (8 decks)

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