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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
type IV collagen location
basement membranes of various tissues (descemet's membrane, lens capsule)
26
elastin
fibrous, insoluble protein, present w/ collagen in the CT responsible for elasticity elastic fibers: elastin core & microfibrils
27
marfan's syndrome
mutations in the fibrillin gene causes autosomal dominant trait clinical manifestations: disorders of cardiovascular, musculoskeletal, and ophthalmic systems
28
CT fibrous components
collagen & elastin
29
CT cellular components
fibroblasts, keratocytes
30
CT ground substance
GAG (glycosaminoglycans), proteoglycans, glycoproteins - bind tissue together and provide support for the organs and other structures of the body
31
glycosaminoglycans (GAG) structure and classes (6)
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
proteoglycans
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
globular proteins
folded into a spherical shape, water-soluble protein characterized by a compact structure
34
globular protein functions (3 of them)
enzymes, transporters, regulatory proteins (metabolic pathways and gene expression)
35
Hemoglobin
brings O2 from the lungs to the tissue 4 subunits each containing a heme prosthetic group - 4 binding sites, which are Fe
36
Heme
site for reversible oxygen binding - Fe2+ for both hemoglobin and myoglobin - Fe2+ is oxidized to Fe3+ -protein portion prevents permanent oxidation
37
hemoglobin binding
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
T to R transition
iron shifts from being "domed" to being planar configuration
39
myoglobin
heme protein found in heart and skeletal muscle acts as oxygen reservoir and oxygen carrier for O2 transport within muscle cells
40
myoglobin binding
one O2 binding site (1 heme molecule) non-cooperative binding of oxygen
41
oxygen pressure on Hb rxn
rxn favors oxyhemoglobin w/ an increase in oxygen pressure (lungs) rxn favors deoxyhemoglobin with decrease in oxygen pressure (tissues)
42
myoglobin vs hemoglobin curves
myoglobin: parabolic curve hemoglobin: sigmoidal curve
43
sigmoidal curve means
cooperative interaction between binding sites
44
rightward curve means? caused by?
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
2,3-biphosphoglycerate (2,3-BPG)
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
leftward shift means? caused by?
means an increase of O2 affinity caused by positive allosteric effectors or allosteric activators, ex. oxygen and carbon monoxide
47
Bohr effect
reduction in O2 binding w/ lowered pH (increased [H+]) or increased pCO2 -both stabilize the T-state
48
CO2 to bicarbonate
-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
principal buffers in the blood
bicarbonate-carbonic acid: plasma hemoglobin: RBC's Protein functional groups: both
50
flow of CO2 in the body
CO2 in tissues is converted to bicarbonate and transported to the lungs, then converted back to CO2 in the lungs and eliminated there
51
2 types of acidosis
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
2 types of alkalosis
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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