Lecture 14

Question 1

In prokaryotes, transcription and translation occur –

Answer 1

simultaneously

Question 2

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.

Answer 2

codons

Question 3

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

Answer 3

74-93

Question 4

Each amino acid contains its own subset of –.

Answer 4

tRNAs

Question 5

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.

Answer 5

anticodon

Question 6

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

Answer 6

Ribosomal RNA (rRNA)

Question 7

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

Answer 7

physically move along

Question 8

The genetic code is –

Answer 8

universal (with some exceptions… mitochondria, protozoa)

Question 9

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

Answer 9

degenerate

Question 10

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

Answer 10

stop signals

Question 11

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

Answer 11

Met

Question 12

The different amino acids have different numbers of

–

Answer 12

accompanying codons.

Question 13

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

Answer 13

correlated

Question 14

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

Answer 14

underrated

Question 15

T/F: the codons are assigned randomly

Answer 15

false

Question 16

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

Answer 16

higher informational value

Question 17

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

Answer 17

methionine

Question 18

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

Answer 18

AUG

Question 19

Exceptions of star codons:

Answer 19

GUG & UUG in prokaryotes and CUG in eukaryotes

Question 20

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

Answer 20

carboxyl terminus

Question 21

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

Answer 21

open reading frame (ORF)

Question 22

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

Answer 22

ONLY ONE

Question 23

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

Answer 23

non-overlapping

Question 24

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

Answer 24

three

Question 25

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.

Answer 25

terminate translation

Question 26

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

Answer 26

Frameshift mutations

Question 27

All tRNAs are about the same length -- & structure

Answer 27

80 nt long

Question 28

tRNA contains -- loops

Answer 28

3

Question 29

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

Answer 29

complements

Question 30

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

Answer 30

CCA

Question 31

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

Answer 31

aminoacyl-tRNA synthetases

Question 32

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

Answer 32

proper amino acid

Question 33

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

Answer 33

20

Question 34

ARS recognize their tRNA molecules | using the --

Answer 34

anticodon

Question 35

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

Answer 35

one particular amino acid

Question 36

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

Answer 36

nucleotide 73

Question 37

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

Answer 37

2' or 3' OH

Question 38

ARS can proofread and remove incorrect aa

Question 39

-- specifies the amino acid incorporation

Answer 39

tRNA

Question 40

Fritz and Lipmann discovered that Amino acids are

Answer 40

illiterate

Question 41

-- different tRNAs have been identified in bacterial cells

Answer 41

30-40

Question 42

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

Answer 42

nonstandard pairing between bases in the 􏰀wobble􏰂 position

Question 43

wobble position

Answer 43

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

Question 44

prok and euk wobble codon base: U

Answer 44

possible anticodons: A, G, I

Question 45

prok and euk wobble codon base: C

Answer 45

possible anticodons: G or I

Question 46

prok wobble codon base: A

Answer 46

possible anticodons: U, I

Question 47

prok wobble codon base: G

Answer 47

possible anticodons: C or U

Question 48

euk wobble codon base: A

Answer 48

possible anticodons: U

Question 49

euk wobble codon base: G

Answer 49

possible anticodons C

Question 50

unusual nucleotide

Answer 50

inosine

Question 51

A site

Answer 51

new aminoacyl-tRNA comes in

Question 52

P site

Answer 52

growing polypeptide

Question 53

E site

Answer 53

exit

Question 54

- finding the start codon and assembling the ribosomal subunits

Answer 54

Initiation

Question 55

- reading the mRNA sequence and polymerizing the addition of corresponding amino acids to growing polypeptide chain

Answer 55

Elongation

Question 56

- recognition of the stop codon and release of the new polypeptide

Answer 56

Termination