Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics > Exam 2: Genetic Code and Translation > Flashcards

Exam 2: Genetic Code and Translation Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

haploinsufficiency

A

situation of having of only a single functioning copy of a gene is not enough for normal function, so that the loss of function mutations cause a dominant phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the one gene, one enzyme hypothesis

A

gene typically specifies a protein in a one-to-one relationship

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

evidence to support the one gene, one enzyme hypothesis: why make mutants (beadle and tatum)

A
  • beadle and tatum exposed Neurospora to radiation to introduce mutations
  • descendants of the irradiated spores were taken and grown on complete medium (sugar, salts, aas, vitamins)
  • once each spore had established a growing colony, piece of colony was transferred into another tube containing minimal medium (sugar, salts, biotin)
  • few colonies could not grown on minimal medium and were nutritional mutants that would eventually die bc they could not make a particular essential molecule out of the minimal nutrients
  • complete medium would “rescue” the mutant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

evidence to support the one gene, one enzyme hypothesis: pinpointing the broken pathway

A

to figure out which metabolic pathway was “broken” in each mutant beadle and tatum:

  • grew each mutant on minimal medium supplemented with either the full set of aas or the full set of vitamins/sugars
  • if the mutant grew on the vitamin medium but not the aa medium, it must be unable to make one or more vitamins
  • if a mutant grew on minimal medium containing all 20 aas they would next test it in 20 different vials, each containing minimal medium plus one of the 20 aas. if a mutant grew in one of these vials, they knew the aa in that vial must be the end product of the pathway disrupted in the mutant
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

one gene one enzyme hypothesis today:

A
  • some genes encode proteins that are not enzymes (enzymes are just one category of protein; many non-enzyme proteins in cells, and these proteins are also encoded by genes)
  • some genes encode a subunit of protein, not a whole protein (a gene encodes one polypeptide, meaning one chain of aas. some proteins consist of several polypeptides from different genes)
  • some genes don’t encode polypeptides, some genes encode functional RNA molecules rather than polypeptides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

proteins are _ consisting of aas linked by _

A

polymers; linked by peptide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

primary structure:

A

aa sequence (order of aas as they are attached)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

secondary/tertiary structures:

A

folding of primary sequence establishes catalytic site, contact points for dna binding proteins; folded structure of polypeptide that makes protein function and is critical to tertiary structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

two or more polypeptide chains associate to from _ structure

A

quaternary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does auxotroph mean

A

an auxotroph is an organism with a mutation that prevents synthesis of a nutritional component (an aa) necessary for growth; beadle and tatum created

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

beadle and tatum concluded that

A

each enzyme was encoded by a single gene that was mutated, thus a single gene encodes a single enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

aa are joined together by

A

peptide bonds (carboxyl group of one aa is covalently attached to the amino group of another aa)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

spliceosome and ribosome have multiple _

A

subunits; quaternary structure come together to make the machine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

polymer that consists of only one kind of monomers is called:

A

homopolymer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

polymer which consists of more than one kind of monomers is called:

A

copolymer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

the poly-U experiment: how nirenbery and mattaei developed a method for identifying the aa specified by a homopolymer

A
  • synthetic RNA made of only uracil units to 20 test tubes each with 1 radioactively labeled aa and 19 unlabeled aas
  • synthetic RNA made of multiple units of uracil instructed a chain of aas to add phenylalanine; the poly-U served as a messenger directing protein synthesis
  • proved that messenger RNA transcribes genetic information from DNA, directing the assembly of aas into complex proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how did the nirenberg and matthae break the genetic code

A
  • using the poly-U as a model, identified nucleotide combinations for the incorporation of other aas
  • found that the coding units for aas contain 3 nucleotides
  • combining four nucleotides in three-letter codes yeilded 64 possible combinations (4x4x4)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

how many stop codons?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the start codon?

A

AUG methionine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how many sense codons??

A

61; remaining 61 codes for 20 aas thus there are more than one codon for one aa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

why is there degeneracy of the genetic code

A

although each codon is specific for only one aa or stop signal, the genetic code is degenerate because a single aa may be coded for by more than one codon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

synonymous codons:

A

codons that specify the same aa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

isoaccepting tRNAs:

A

different tRNAs that accept the same aa but have different anticodons

24
Q

degenerate code:

A

aa may be specified by more than one codon

25
Q

sense codons encode:

A

encoding aa

26
Q

wobble hypothesis

A
  • 3rd base in an mRNA codon can undergo non-Watson-Crick base pairing with the 1st base of a tRNA anticodon
  • explains why multiple codons can code for a single aa; one tRNA molecule can recognise and bind to more than one codon and why there is variability btwn many codons, that encode the same aa, is in their 3rd base
27
Q

reading frame:

A

three ways in which the sequence can be read in groups of three. each different way of reading encodes a different aa sequence

28
Q

nonoverlapping:

A

a single nucleotide may not be included in more than one codon

29
Q

the universality of the code:

A

nearly universal, but with some exceptions (bacteria has codons diff from euks and mito make their own special tRNA for their codons)

30
Q

wobbly hypothesis and why advantageous:

A

for certain tRNAs, inappropriate aa is incorporated which increases variation among generations

31
Q

translation of an mRNA takes place on the _

A

ribosome

32
Q

translation proceeds from the _- end of the mRNA to the _’ end

A

5’ to 3’

33
Q

what are the steps to translation

A
  1. binding of aa to tRNA ie chargin
  2. initiation of translation
  3. elongation of the peptide chain
  4. termination
34
Q

the specificity btwn an aa and its tRNA is determined by:

A

each individual aminoacyl-tRNA synthesis

35
Q

there are exactly _ different aminoacyl-tRNA syntheses in a cell

A

20

36
Q

an aa attaches to the _’ end of a tRNA

A

3’

37
Q

charging of tRNAs

A

part of tRNA encodes sequence that stores which aa they will attach to and what is their anticodon (noncoding RNA)

38
Q

t/f: the sequence of the tRNA is how aa specificity is established

A

true

39
Q

t/f: certain positions on tRNA molecules are recognized by the appropriate mRNA

A

false; recognized by the appropriate aminoacyl-tRNA synthetase

40
Q

at the end of tRNA charging, an aa is linked to its appropriate tRNA via:

A

ATP, AMP is released

41
Q

what is the energy molecule for translation

A

GTP

42
Q

initiation factors IF-3:

A

initiator tRNA with N-formylmethionine attached to form fmet-tRNA

43
Q

what is the consensus sequence in bacterial cells (proks) and it is recognized by the _ unit of ribosome

A

the shine-dalgarno and recognized by the small unit of ribosome for attachment to mRNA

44
Q

the _ sequence in euk cells facilitates the identification of the start codon

A

kozak sequence; signals the beginning of the the coding sequence

45
Q

IF-3 binds to the _ subunit

A

small subunit preventing the large subunit form binding thus allowing small subunit to attach to mRNA

46
Q

a tRNA charged with _ forms a complex with IF-2 and GTP

A

N-formylmethionine

47
Q

at the end of initiation:

A

the ribosome is assembled on the mRNA and the first tRNA is attached to the initiation codon

48
Q

the _ of euk mRNA plays a role in the initiation of translation

A

poly(A) tail; proteins that attach to the 3’poly(A) tail interact with cap-binding proteins and enhance the binding of the ribosome to the 5’ end of the mRNA

49
Q

what are the 3 steps that comprise elongation of translation

A
  1. charged tRNA binds to A site of ribosome
  2. formation of peptide bond between P and A site
  3. Ribosome translocates to next codon
50
Q

fmet-tRNA occupies the _ site of the ribosome

A

P site

51
Q

what are release factors

A

proteins that are triggered by the presence of the stop codon to bind to the ribosome and facilitate release of the polypeptide

52
Q

translation ends when

A

a stop codon is encountered

53
Q

conclusion of translation

A

through the process of translation, aas are linked in the order specified by the mRNA

54
Q

polyribosome

A

an mRNA with several ribosome attached

55
Q

t/f: an mRNA may be transcribed simultaneously by several ribosomes

A

true; in euks, are attached to RER and in proks, free in cytoplasm

56
Q

what primarily determines the secondary and tertiary structures of a protein?

A

the primary structure is determined by the aa sequence

Genetics (37 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions