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Life Science 3 > Lecture 14 > Flashcards

Lecture 14 Flashcards

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Biology 101 flashcards
1
Q

In prokaryotes, transcription and translation occur –

A

simultaneously

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2
Q

Messenger RNA (mRNA): carries genetic information transcribed from DNA in the form of a series of 3-nucleotide sequences, called –, each of which specifies a particular amino acid.

A

codons

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3
Q

Transfer RNA (tRNA): small RNA chain ( –nucleotides) that is key to deciphering the codons in mRNA

A

74-93

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4
Q

Each amino acid contains its own subset of –.

A

tRNAs

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5
Q

The correct tRNA with its attached amino acid is selected at each step (Each tRNA molecule contains a three-nucleotide sequence, an –, that can base-pair with its complementary codon in the mRNA.

A

anticodon

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6
Q

– associates with a set of proteins to form ribosomes that composed of a large and small subunit

A

Ribosomal RNA (rRNA)

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7
Q

Ribosomes bind tRNAs associated with amino acids and – an mRNA molecule, catalyzing the assembly of amino acids into

A

physically move along

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8
Q

The genetic code is –

A

universal (with some exceptions… mitochondria, protozoa)

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9
Q

The DNA code is – (there is more than one codon for each aa)

A

degenerate

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10
Q

All 64 codons are used: 61 of them can be assigned to certain amino acids, the other three are –

A

stop signals

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11
Q

One of the codons can act both as an amino acid codon (for – ) and as a start signal.

A

Met

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12
Q

The different amino acids have different numbers of

–

A

accompanying codons.

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13
Q

The frequency of the codons and the frequency of their amino acid is –.

A

correlated

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14
Q

An exception is Arg, that has six codons but is – regarding its frequency in proteins.

A

underrated

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15
Q

T/F: the codons are assigned randomly

A

false

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16
Q

The first two nucleotides of a codon have a – than the third one.

A

higher informational value

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17
Q

Synthesis of all polypeptide chains in prokaryotic and eukaryotic cells begins with the amino acid – .

A

methionine

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18
Q

In most mRNAs, the start (initiator) codon specifying this amino-terminal methionine is –.

A

AUG

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19
Q

Exceptions of star codons:

A

GUG & UUG in prokaryotes and CUG in eukaryotes

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20
Q

stop (termination) codons that mark the – of polypeptide chains.

A

carboxyl terminus

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21
Q

An – is the nucleotide sequence between a start codon and a stop codon.

A

open reading frame (ORF)

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22
Q

As seen from studies of mutant proteins, such as hemoglobin from sickle cell anemia, the mutant form contains – amino acid substitution

A

ONLY ONE

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23
Q

The genetic code is – because each nucleotide is part of only one codon, resulting in only one amino acid replacement

A

non-overlapping

24
Q

Depending on where you start, any nucleotide sequence can be read as – different “reading frames”

A

three

25
Q

The vast majority of mRNAs can be read in only one frame (ORF) because stop codons encountered in the other two possible reading frames – before a functional protein is produced.

A

terminate translation

26
Q

Insertions or deletions of bases not in multiples of 3 will result in a frameshift.

A

Frameshift mutations

27
Q

All tRNAs are about the same length – & structure

A

80 nt long

28
Q

tRNA contains – loops

A

3

29
Q

the anticodon loop contains an anticodon region that – the codon in mRNA.

A

complements

30
Q

An amino acid is covalently attached to the acceptor stem at the 3􏰁 tail of –

A

CCA

31
Q

each tRNA is matched with its amino acid long before it reaches the ribosome…this is done with a collection of 20 enzymes called .

A

aminoacyl-tRNA synthetases

32
Q

ARS charge each tRNA with the – , thus allowing each tRNA to make the proper translation from the genetic language of DNA into the amino acid language of proteins

A

proper amino acid

33
Q

Most cells make – different aminoacyl-tRNA synthetases, for each type of amino acid.

A

20

34
Q

ARS recognize their tRNA molecules

using the –

A

anticodon

35
Q

Each aminoacyl tRNA synthetase recognizes – and all tRNAs that recognize codons for that aa

A

one particular amino acid

36
Q

tRNA molecules are also recognized using segments on the acceptor end and bases elsewhere in the molecule, particularly – (discriminator base)

A

nucleotide 73

37
Q

An amino acid is covalently linked to tRNAs at the – by aminoacyl-tRNA synthetases (an ATP requiring reaction)

A

2’ or 3’ OH

38
Q

ARS can proofread and remove incorrect aa

A
39
Q

– specifies the amino acid incorporation

A

tRNA

40
Q

Fritz and Lipmann discovered that Amino acids are

A

illiterate

41
Q

– different tRNAs have been identified in bacterial cells

A

30-40

42
Q

A single tRNA anticodon is able to recognize more than one codon corresponding to a given amino acid due to

A

nonstandard pairing between bases in the 􏰀wobble􏰂 position

43
Q

wobble position

A

the 3rd base (3’) in an mRNA codon and the corresponding first base (5’) in the tRNA anticodon

44
Q

prok and euk wobble codon base: U

A

possible anticodons: A, G, I

45
Q

prok and euk wobble codon base: C

A

possible anticodons: G or I

46
Q

prok wobble codon base: A

A

possible anticodons: U, I

47
Q

prok wobble codon base: G

A

possible anticodons: C or U

48
Q

euk wobble codon base: A

A

possible anticodons: U

49
Q

euk wobble codon base: G

A

possible anticodons C

50
Q

unusual nucleotide

A

inosine

51
Q

A site

A

new aminoacyl-tRNA comes in

52
Q

P site

A

growing polypeptide

53
Q

E site

A

exit

54
Q
  • finding the start codon and assembling the ribosomal subunits
A

Initiation

55
Q
  • reading the mRNA sequence and polymerizing the addition of corresponding amino acids to growing polypeptide chain
A

Elongation

56
Q
  • recognition of the stop codon and release of the new polypeptide
A

Termination

Life Science 3 (20 decks)

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