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Cell Bio > Proteins - Exam 1 > Flashcards

Proteins - Exam 1 Flashcards

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Biology 101 flashcards
1
Q

building blocks of proteins

A

amino acids

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2
Q

amino acids linked by

A

peptide bonds, generate H2O

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3
Q

what is the amino terminus

A

beginning of all proteins; methyeline

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4
Q

what is the carboxyl terminus

A

end of all proteins

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5
Q

how are dietary proteins digested (2 steps)

A

first by proteolytic enzymes of the GI tract, then by cleavage by pancreatic proteases in the small intestine

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6
Q

3 things that make up an amino acid

A

amino group, an acid (carboxyl group), & side chain

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7
Q

amino acids with nonpolar side chains (9)

A

alanine, glycine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tyrptophan

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8
Q

bends in polypeptide chains due to

A

proline

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9
Q

characteristics of amino acids with nonpolar side chains

A

don’t gain or lose electrons, cluster together, hydrophobic effect,

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10
Q

proline characteristics

A

nonpolar, secondary amino group (imino acid) makes it rigid

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11
Q

amino acids with uncharged polar side chains (6)

A

asparagine, glutamine, serine, threonine, tyrosine, cysteine

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12
Q

disulfide bonds due to

A

cysteine

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13
Q

characteristic of amino acids with uncharged polar side chains

A

0 net charge

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14
Q

which 2 uncharged polar side chains can lose a proton at alkaline pH

A

cysteine & tyrosine

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15
Q

which 3 uncharged polar side chains can contain a polar hydroxyl group that participates in hydrogen bond formation

A

serine, threonine, & tyrosine

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16
Q

amino acids with acidic (-) side chains (2)

A

aspartic acid & glutamic acid

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17
Q

characteristic of amino acids with acidic side chains

A

proton donors, physiological pH fully ionized COO-

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18
Q

what is physiological pH

A

7.4

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19
Q

amino acids with basic (+) side chains (3)

A

arginine, histidine, lysine

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20
Q

characteristic of amino acids with basic side chains

A

accept protons, physiological pH fully ionized & positively charged

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21
Q

which amino acid with a basic side chain acts as a buffer & why

A

histidine; can be either positively charged or neutral depending on environment’s pH

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22
Q

what 2 alpha amino acids are not found within proteins & where are they found

A

triiodothyronine & thyroxine ; thyroid

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23
Q

hydroxylation of tryptophan yields ______ ; function

A

serotonin ; NT & paracrine hormone

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24
Q

acetylation and methylation of serotonin yields ______ ; function

A

melatonin ; reproductive activity

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25
Q

hydroxylation of tyrosine yields (pathway)

A

dopa -> dopamine -> adrenaline/norepinephrine -> alpha adrenoreceptor & beta adrenoreceptor

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26
Q

decarboxylation of histidine yields ______ ; function

A

histamine ; allergic rxns

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27
Q

peptide hormone produced in the hypothalamus for uterine contractions & milk secretion

A

oxytocin

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28
Q

peptide hormone produced in the hypothalamus for maintenance of water balance

A

ADH (antidiuretic hormone)

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29
Q

peptide hormone used for energy production in the muscles & cardiac cells

A

creatine

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30
Q

peptide hormone that is a vasoactive substance

A

bradykinin

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31
Q

peptide hormone that is a vasoconstrictor

A

angiotensin II

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32
Q

polypeptide hormone used for secretion of gastric glands in the stomach

A

gastrin

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33
Q

polypeptide hormone used to stimulate pancreas & liver secretion

A

CCK

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34
Q

polypeptide hormone produced by alpha cells in the pancreas

A

glucagon

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35
Q

polypeptide hormone produced in the heart for regulation of blood volume & pressure

A

ANP (atrial natriuretic peptide)

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36
Q

mutation where the base change codes for the SAME amino acid

A

silent

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37
Q

mutation where the base change codes for a DIFFERENT amino acid

A

missense

38
Q

mutation where the base change codes for a STOP codon

A

nonsense

39
Q

mutation where a base is added or deleted

A

frame-shift

40
Q

mutation where base change generates a splice site

A

splice site

41
Q

genetic code has how many combination possibilities and codes for how many amino acids

A

64 ; 20

42
Q

what are the 3 stop codons & 1 start codon

A

UAG, UGA, UAA ; AUG

43
Q

the first codon in the eukaryotic mRNA codes for

A

methionine

44
Q

which cells can make mRNA in both the nucleus and the cytosol

A

eukaryotic

45
Q

differences between DNA vs RNA

A

deoxyribose vs ribose ; thymine vs uracil

46
Q

what are introns

A

noncoding sections of DNA

47
Q

what is alternative splicing and what cell type uses it

A

removal of intron(s) ; bacteria

48
Q

benefits of alternative splicing

A

generate different proteins isoforms, increases viability

49
Q

what is tRNA and how does it work

A

transfer RNA “clover leaf”; attachment site for an amino acid at the 3’ end and an anticodon on the other end that pairs with a codon on the mRNA

50
Q

tRNA significance

A

adapter for alternative splicing & codon recognition

51
Q

what are the 3 sites on a ribosome

A

A, P, E

52
Q

eukaryotic ribosomes have 2 subunits:

A

60 & 40

53
Q

which ribosomal site binds an incoming aminoacyl-tRNA

A

A

54
Q

which ribosomal site has peptidyl-tRNA which carries the chain of already synthesized amino acids

A

P

55
Q

which ribosomal site has empty tRNA and is where it exits

A

E

56
Q

RER-ribosomes function

A

synthesize proteins that need to be exported from the cell or put into cell membranes

57
Q

cytosolic ribosomes synonym & function

A

“free” ribosomes ; synthesize cytosolic proteins or those meant for the nucleus , mitochondria, or peroxisomes

58
Q

what are the 3 steps of protein synthesis

A

initiation, elongation, termination

59
Q

describe initiation step

A

assembly before peptide bonds form

60
Q

describe elongation step

A

adding amino acids to the carboxyl end of the chain (5’ -> 3’), bind at A site, make peptide at P site, mRNA move

61
Q

describe termination step

A

when one of the stop codons reaches the A site

62
Q

proteins in the cytosol can go where

A

nucleus, mitochondria, peroxisomes, plastids

63
Q

proteins in the ER can go where

A

Golgi, endosomes, lysosomes, secretory vesicles, membrane

64
Q

N-terminal signal sequence

A

import into the ER or mitochondria

65
Q

C-terminal signal sequence

A

retention in the lumen of the ER

66
Q

internal signal sequence

A

import into nucleus or peroxisomes

67
Q

the ER synthesizes which 3 proteins

A

lysosomal, secretory, and membrane

68
Q

what is the SRP and what does it do

A

signal recognition particle ; binds to the new protein after recognition, binds to the SRP receptor in the ER membrane, gets placed in the translocation protein using energy, SRP released (protein will be in the ER of the lumen)

69
Q

type I arrangement

A

c terminus is in the cytosol

70
Q

type II arrangement

A

n terminus is in the cytosol

71
Q

2 examples of membrane proteins

A

LDL receptor & GLUT 1

72
Q

what are the 4 structures of proteins

A

primary, secondary, tertiary, quaternary

73
Q

what are the 3 folding patterns of proteins in the secondary structure

A

alpha helix, beta sheet, beta bend/turn (proline kink)

74
Q

structure of an alpha helix & example

A

within membrane, every 4 amino acids = 1 hydrogen bond, side chains face outside, “spiral”; keratin

75
Q

structure of a beta sheet

A

all amino acids make bonds “pleats”, side chains not involved, can either be parallel (c terminus same end) or antiparallel (c terminus different ends)

76
Q

structure of a beta bend

A

proline, make a compact shape, connect alpha helix and beta sheets, can link 2 antiparallel B sheets, can link parallel B sheets by crossing over and connecting at either top or bottom

77
Q

describe vesicular transport

A

brings proteins to larger organs

78
Q

vesicular transport pathway

A

RER -> coated with COPII -> membrane -> microtubules -> cis Golgi (if not coated will go elsewhere)

79
Q

what does SNARE stand for and why do we need it

A

soluble NSF attachment protein ; to recognize coated/envelope proteins

80
Q

example of SNARE and it’s function

A

synaptobrevin ; fusion of synaptic vesicles with the plasma membrane (Botox inhibits this)

81
Q

clathrin-coated vesicles

A

within Golgi, protein can be modified and then released into cytosol via coated vesicles (circular)

82
Q

what is NLS and it’s function

A

nuclear transport signal ; moving protein from rER into nucleus via active transport

83
Q

how does NLS work

A

in the middle of polypeptide chain: protein binds with importin receptor -> nuclear pore

84
Q

Golgi apparatus structure consists of what 3 areas

A

cis, trans, medial

85
Q

protein phosphorylation takes place where

A

cis Golgi

86
Q

O-glycosylation takes place where

A

medial and trans Golgi

87
Q

where are proteins packed into vesicles

A

trans Golgi net

88
Q

what are chaperones and how do they work (folding cyclus)

A

heat stable proteins, hydrolyze ATP to bind to recognize new protein, makes ADP, stays until protein makes right shape, if protein doesn’t make right shape it will get discarded in ER

89
Q

what is N-glycosylation

A

ER -> attach sugar to Asn

90
Q

what is O-glycosylation

A

Golgi -> attach sugar to Ser/Thr

91
Q

importance of O-glycosylation

A

functional conformation of protein

92
Q

synthesis of glycoproteins occurs where and requires what

A

in ER, out cytosol; dolichol, sugar, Asn

Cell Bio (16 decks)

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