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BIOL1115 LECTURE > Chapter 3,17 > Flashcards

Chapter 3,17 Flashcards

1
Q

How does each amino acid differ from one another?

A

from the molecular structure of their R-group

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2
Q

why is the α carbon in glycine not asymmetrical?

A

glycine only has 3 unique groups

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3
Q

how does cysteine differ from other amino acids?

A

has a sulfhydryl functional group, can form disulphide bonds

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4
Q

what kind of turn can a protein with glycine make?

A

tight turns b/c of how small glycine is

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5
Q

what is special about proline’s shape?

A

R-group connects to amino group in backbone

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6
Q

what does proline do in proteins?

A

affects flexibility, found in permanently locked turns

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7
Q

what kind of bonds are between double bonded carbon and peptide bonds in polypeptides?

A

a partial double bond

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8
Q

why can’t peptide bonds rotate?

A

peptide bonds have 2nd resonance form, C=O and N-H reside in a single plane

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9
Q

what is the difference between proteins and polypeptides?

A

proteins - correctly folded
polypeptides - not correctly folded

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10
Q

what bonds are present in primary structures?

A

peptide bonds

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11
Q

what bonds are present in secondary structures?

A

hydrogen bonds between peptide backbones, which determine polypeptide orientation (a helices or b pleated sheets)

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12
Q

what bonds are present in tertiary structures?

A

ionic, hydrogen, and covalent bonds (such as disulfide bonds) between R-groups, as well as hydrophobic forces in nonpolar interior

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13
Q

what bonds are present in quaternary structures?

A

weak bonds

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14
Q

is a polypeptide’s primary structure disrupted when denatured?

A

No, peptide bonds are polar covalent, hard to break

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15
Q

how is a polypeptide’s primary structure read?

A

from amino end to carboxyl end

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16
Q

what is an α helix?

A

tightly twisted coil, stabilized by hydrogen bonds btwn an amino acid’s carbonyl group and an amino acid’s amino group 4 residues away

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17
Q

what is a β sheet?

A

pleated sheet stabilized by hydrogen bonds between carbonyl groups in one chain and amino groups in other chain

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18
Q

what is a tertiary structure?

A

protein’s 3D shape, made of several secondary structures, formed from weak bonds and interactions btwn R-groups

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19
Q

how is the ball-and-stick model useful for illustrating tertiary structures?

A

shows atoms and bonds

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20
Q

how is the ribbon model useful for illustrating tertiary structures?

A

shows a helices and b sheets of secondary structures in proteins

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21
Q

how is the space-filling model useful for illustrating tertiary structures?

A

shows actual size, shape, and contour of protein

22
Q

the tertiary structure determines a protein’s function by:

A

contours and distribution of charge on outside

presence of cavities

23
Q

what are functions of proteins?

A

enzymes, defense, storage, transport, hormonal, structural, contractile and motor, receptor and communication

24
Q

what factors causes a protein to denature?

A

pH, temp, salt conc.

25
Q

how is renaturation possible in proteins?

A

intact primary structure,

optimal conditions return

26
Q

what components are required for translation?

A

mRNAs, tRNAs, Ribosomes, Aminoacyl-tRNA-synthetase, release factor

27
Q

what is translation?

A

mRNA sequence specifies order of amino acids in a polypeptide

28
Q

how is genetic code universal?

A

all codons specify same amino acids in all organisms

29
Q

how is genetic code unambiguous?

A

each codon codes for only one amino acid

30
Q

how is genetic code redundant?

A

many amino acids are specified by more than one codon

31
Q

how is genetic code being universal useful?

A

biotechnology, genetic engineering

32
Q

what do ribosomes facilitate?

A

process of translation

33
Q

what three sites does the large subunit of a ribosome contain?

A

A, P, and E sites

34
Q

what is the A site?

A

aminoacyl - holds aminoacyl tRNA

35
Q

what is the P site?

A

peptidyl - holds tRNA with growing polypeptide attached

36
Q

what is the E site?

A

exit, holds a tRNA that will exit

37
Q

what are codons?

A

continuous, non-overlapping groups of three nucleotides

38
Q

what are tRNAs?

A

transfer RNAs bind to amino acids and bring them to mRNA at ribosome during translation

39
Q

what is an aminoacyl-tRNA or charged-tRNA?

A

tRNA that is linked to its amino acid

40
Q

what is an anticodon?

A

sequence in tRNA that is complementary to codon sequence in mRNA

41
Q

how do the anticodon and codon pair?

A

in an antiparallel direction

42
Q

what do aminoacyl-tRNA-synthetases do?

A

catalyze addition of amino acids to tRNAs

43
Q

how many aminoacyl-tRNA-synthetases are there?

A

20, one for each amino acid in proteins

44
Q

how is genetic code redundant?

A

wobble hypothesis - only the first 2 bases of codon have precise pairing with the bases of anticodon of tRNA, while pairing btwn 3rd bases of codon and anticodon may wobble

45
Q

what are the four main wobble base pairs?

A

G-U
I-U
I-A
I-C

46
Q

what does the wobble hypothesis allow?

A

phenomenon permits a single tRNA to recognize more than 1 codon, allows mRNA codons to be translated w/ fewer than 61 tRNAs required w/o wobble

47
Q

what are 3 separate processes of translation?

A

initiation, elongation, termination

48
Q

what is process of initiation in translation?

A
  1. mRNA binds to small subunit
  2. Initiator aminoacyl-tRNA binds
  3. Large subunit of ribosome binds
49
Q

what is process of elongation in translation?

A
  1. incoming aminoacyl tRNA
  2. peptide-bond formation
  3. translocation
50
Q

what is process of termination in translation?

A
  1. release factor binds to stop codon
  2. polypep. & uncharged tRNAs release
  3. ribosome subunits separate
51
Q

what is cotranslational folding?

A

protein folding occurs simultaneously as polypeptide chain extended during elongation

52
Q

what is a release factor?

A

protein that binds to A site of ribosome when stop codon is encountered

BIOL1115 LECTURE (11 decks)

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