Genetic Code and Translation Flashcards Preview

Medical Biochemistry > Genetic Code and Translation > Flashcards

Flashcards in Genetic Code and Translation Deck (64):
1

how are RNA and DNA written (named)?

5' to 3'

2

how are proteins written (named)?

from the N-terminus to the C-terminus

3

what RNA are most responsible for translation?

rRNA, tRNA, mRNA

4

how can 4 bases specify the 20 different amino acids

some amino acids MUST have more than 1 codon - the code is redundant

5

how are mRNA messages read?

genetic code is non-overlapping, no spaces

6

how many reading frames does dsDNA have?

3 possible reading frames on top
3 possible reading frames on bottom
= 6 reading frames

7

insertion or deletion of one or two nucleotides will lead to what?

frameshift mutation

8

what will insertion or deletion of three nucleotides lead to?

inframe mutation (insertion or deletion)

9

what happens when there is insertion or deletion of any multiple of 3 (3,6,9,12)?

nucleotides will lead to larger inflame mutations

10

what are the stop codons?

UGA
UAG
UAA

11

what is the start codon?

AUG

12

what is special about tryptophan and methionine?

only has 1 codon to code for it

13

in most amino acids, there can be more than 1 _____ to specify that amino acid.

codon

14

why is the genetic code NEARLY universal?

mitochondria has differences, not as many base pairing like in our chromosomal nuclei

15

what are ribosomes? what are they made of?

they are the RNA machine
made of 2/3 RNA and 1/3 protein
Prokaryotes - odd
Eukaryotes - even

16

why aren't the 50S and 30S additive?

they are not perfect spheres, they are different shapes

17

where on the tRNA is the amino acid attachment site?

3' OH

18

where are 3 bases on the mRNA recognized by base pairing?

anticodon loop

19

what does the anticodon loop 5' position "wobble" position have?

Inosinate

20

because of insinuate what can happen?

multiple base pair to different positions on the mRNA

21

what is the wobble hypothesis?

predicted base pair between the 5' position of the anticodon and the 3' position of the codon

22

if there are 61 codons, how many tRNA do you need?

less than 61 because some tRNAs can read more than 1 codon

23

what is a charged tRNA?

tRNA carrying amino acid - covalently bonded

24

how is the reaction of amino acid attachment onto tRNA driven?

by hydrolysis of pyrophosphate

25

what are the steps in forming a polypeptide polymer from an RNA template?

acitvation of the monomer
initiation
elongation
termination
processing the polymer

26

one mRNA has how many reading frames

3

27

what does snoRNA do?

splice rRNA

28

what does snRNA do?

splice mRNA

29

how many reading frames does ds DNA have?

6

30

which ribosome is bigger E or P?

eukaryote - more proteins

31

what can I pair with?

U, C or A

32

what happens during activation of translation?

to charge tRNA
1. enzyme bound amino-acid-adenylate
2. formation of amino acyl tRNA

33

what do eukaryotes use as the first amino acid in translation?

AUG - methionine Met

34

what do prokaryotes use as the first amino acid in translation?

N-formyl methionine

35

prokaryotes have 2tRNAs for methionine what do they do?

one allows formation of fMet, the other recognizes internal AUG codons

36

when is GTP hydrolysized during initiation?

as the 50S subunit joins to form the 70S complex ribosome

37

where is shine delgarno sequence found? what does it have?

only in prokaryotes - sequence is purine (A,G) rich and resides a few bases 5' to start the condon

38

what are the 3 steps in elongation (translation)?

binding of aminoacyl tRNA
formation of peptide bond
translocation of mRNA relative to ribosome

39

what catalyzed the activity of the portino of the 50S ribosome in elongation?

ribozymes

40

What is EF-G

prokaryotic - GTPase protein

41

what is EF-G in eukaryotes called?

EF-2

42

why does the zymogen activateion of an inactive precursor even happen post translation?

to protect the cell from begin digested by its own products - digestive proteins, capases to activate apotheosis

43

how many nucleotide bases are in a codon?

3

44

what are the codons for glycine (gly)/

GG -A
GG-U
GG- C
GG-G
*can have any nucleotide base in third position (3')

45

what structure of tRNA resembles a clover leaf?

secondary

46

what nucleotide bases are at the 3' end OH group where the aa attaches?

CCA

47

what is special about the tRNA alanine with IGC anticodon?

3 codons for alanine so I can bind with U C or A

48

what permits the base pairing between two purines?

adenosine/ionsine arrangement between codon/anticodon

49

what is the only free aminoacyl-tRNA to bind to the P site first in prokaryotes?

tRNA fMet

50

Catalyzed by an enzymatic activity of the RNA portion of the 50S ribosome

–a Ribozyme

51

prokaryotes: polycistronic or monocistronic?

poly

52

eukaryotes: polycistronic or monocistronic?

mono

53

what is interesting about prokaryotic translation?

transcription and translation are coupled

54

why isn't eukaryotic translation not coupled?

because of nuclear membrane

55

how many tRNA do eukaryotic and prokaryotes have?

2 each

56

why do they need 2 tRNAs

the idea is to get the FIRST Met to the Psite to allow initiation

57

on what amino acids does protein phosphorylation by a kinase take place?

Ser/Thr
more common than tyrosine phosphorylation
phophate is transfered from ATP to protein

58

what is an example of a tyrosine kinase?

insulin receptor - phosphate is transfered from ATP to protein tyrosine

59

what way do glycan groups always face in glycosylation?

always face extracellular side

60

what is O linked glycolsylation of Ser/Thr?

glycolsylation of the OH gropus

61

what is N linked glycosylation

glycosylation of asparagine not glutamine!!!

62

how does the cell target RAS to the plasma membrane?

lipid anchor mechanism

63

What is preproinsulin?

Translation of the polypeptide is directed into the lumen of the rER and forms “preproinsulin”

64

how is proinsulin formed?

The signal sequence is cleaved in the lumen of the rER