Chapter 10

Question 1

how does a mutant phenotype arise?

Answer 1

from a change in the protein’s amino acid sequence

Question 2

transcription

Answer 2

information in a DNA sequence is copied into a complementary RNA sequence

Question 3

translation

Answer 3

RNA sequence is used to create the amino acid of a polypeptide

Question 4

template strand

Answer 4

transcribed to produce an RNA strand by complementary base pairing

Question 5

mRNA

Answer 5

processed in nucleus and moves to the cytoplasm

Question 6

ribosome

Answer 6

protein synthesis factory

Question 7

rRNA

Answer 7

one of them catalyses a peptide bond formation between amino acids to form a polypeptide

Question 8

tRNA

Answer 8

can bind specific amino acid and recognise a specific sequence of nucleotides in mRNA

Question 9

how many kinds of RNA polymerases are there in bacteria and archaea?

Answer 9

just one

Question 10

how many kinds of RNA polymerases are there in eukaryotes?

Answer 10

several kinds

Question 11

do RNA polymerases require a primer?

Answer 11

no

Question 12

promoter

Answer 12

a special DNA sequence to which RNA polymerase binds very tightly

Question 13

transcription initiation site

Answer 13

part of the promoter where transcription begins

Question 14

elongation

Answer 14

RNA polymerase unwinds the DNA and reads the template strand in the 3’ to 5’ direction

Question 15

how does RNA polymerase add new nucleotides to the RNA molecule?

Answer 15

by complementary base pairing with nucleotides in the template strand of the DNA

Question 16

how is the termination of transcription specified?

Answer 16

by particular base sequences

Question 17

coding regions

Answer 17

sequences within a DNA molecule that are eventually translated as proteins

Question 18

introns

Answer 18

noncoding sequences that interrupt the coding region

Question 19

exons

Answer 19

transcribed regions that are interspersed with the introns

Question 20

pre-mRNA

Answer 20

primary mRNA transcript

Question 21

nucleic acid hybridisation

Answer 21

allows us to locate introns within a eukaryotic gene

Question 22

probe

Answer 22

single-stranded nucleic acid from another source

Question 23

RNA splicing

Answer 23

removes the introns and splices the exons together

Question 24

consensus sequences

Answer 24

short stretches of DNA that appear with little variation in many different genes

Question 25

snRNPs

Answer 25

bind the consensus sequences

Question 26

spliceosome

Answer 26

a large RNA-protein complex that cuts pre-mRNA, releases introns, and joins the ends of the exons together

Question 27

5' cap

Answer 27

added to the 5' end of the pre-mRNA as it is transcribed to facilitate the binding of mRNA to the ribosome for translation

Question 28

poly A tail

Answer 28

added to the 3' end of the pre-mRNA at the end of transcription

Question 29

codons

Answer 29

genetic information in an mRNA molecule, specifies a particular amino acid

Question 30

start codon

Answer 30

the initiation signal for translation (methionine)

Question 31

stop codons

Answer 31

terminate translation (UAA, UAG, and UGA)

Question 32

redundant code

Answer 32

more than one codon for the amino acid

Question 33

ambiguous code

Answer 33

single codon specifies two or more different amino acids

Question 34

silent mutatinos

Answer 34

can occur because of the redundancy of the genetic code

Question 35

missense mutations

Answer 35

result in a change in the amino acid sequence

Question 36

nonsense mutations

Answer 36

result in a premature stop codon

Question 37

frame-shift mutations

Answer 37

result from the insertion or deletion of one or more base pairs within the coding sequence

Question 38

what are the functions of tRNA?

Answer 38

bind to specific enzyme, bind to mRNA, interact with ribosomes

Question 39

anticodon

Answer 39

triplet of bases at the midpoint on the tRNA chain which is complementary to the mRNA codon

Question 40

wobble phenomenon

Answer 40

cell can get by with two-thirds of the total number of RNA species

Question 41

what does the large subunit of eukaryotic ribosomes contain?

Answer 41

3 different ribosomal RNA molecules and 49 protein molecules

Question 42

what does the small subunit of eukaryotic ribosomes contain?

Answer 42

1 rRNA molecule and 33 proteins

Question 43

A site

Answer 43

where the charged tRNA anticodon binds to the mRNA codon

Question 44

P site

Answer 44

where the tRNA adds its amino acid to the polypeptide chain

Question 45

E site

Answer 45

where the tRNA resides before being released from the ribosome

Question 46

what is the order of the three binding sites in ribosomes?

Answer 46

A, P, E

Question 47

initiation complex

Answer 47

consists of a charged tRNA and a small ribosomal subunit

Question 48

what does the large subunit catalyse?

Answer 48

breaks the bond between methionine and its tRNA in the P site, and catalyses the formation of a peptide bond between the methionine and the amino acid attached to the tRNA in the A site

Question 49

peptidyl transferase activity

Answer 49

breaks and reforms peptide bond

Question 50

ribozyme

Answer 50

RNA and enzyme

Question 51

what happens when a stop codon enters the A site?

Answer 51

it binds a protein release factor, allowing for hydrolysis of the bond between the polypeptide chain and the tRNA in the P site

Question 52

polyribosome

Answer 52

assemblage consisting of a strand of mRNA with its beadlike ribosomes and their growing polypeptide chains

Question 53

where does protein synthesis begin?

Answer 53

on free ribosomes floating in the cytoplasm

Question 54

signal sequence

Answer 54

short stretch of amino acids that indicates where in the cell the polypeptide belongs

Question 55

proteolysis

Answer 55

the cutting of a polypeptide chain

Question 56

glycosylation

Answer 56

addition of carbohydrates to proteins to form glycoproteins

Question 57

phosphorlyation

Answer 57

addition of phosphate groups to proteins and is catalysed by protein kinases