Chapter 6: DNA Replication

Question 1

What is the first thing that happens during DNA replication?

Answer 1

The DNA uncoils

Question 2

What is the next thing DNA does after uncoiling?

Answer 2

The DNA then unwinds.

Question 3

helicase enzyme

Answer 3

unwinds the DNA like a zipper by breaking the hydrogen bonds

Question 4

What happens to the DNA after helicase unwinds it?

Answer 4

The bases of the template strands are exposed

Question 5

Complementary base pairing

Answer 5

New DNA nucleotides will form complementary base pairing with the template strands

Question 6

How many hydrogen bonds form between an adenine base and a thymine base?

Answer 6

2 hydrogen bonds

Question 7

How many hydrogen bonds form between cytosine and guanine?

Answer 7

3 hydrogen bonds

Question 8

What is a purine

Answer 8

A double-ring structure

Question 9

Which nitrogenous bases are purines

Answer 9

Adenine and Guanine

Question 10

What are pyrimidines

Answer 10

A single-ring structure

Question 11

Which nitrogenous bases are pyrimidines

Answer 11

Thymine, Cytosine, Uracil

Question 12

How can you remember which nitrogenous bases are purines?

Answer 12

Purine = two “n” in the name

Adenine and Guanine

Question 13

How to remember which nitrogenous bases are pyrimidines?

Answer 13

Pyrimidines = one “y” in the name

Thymine, Cytosine

Uracil? - Always pair it with thymine

Question 14

phosphodiester bond

Answer 14

bond that forms between sugar and phosphate group to form the backbone of

Question 15

DNA polymerase

Answer 15

an enzyme that synthesizes the new DNA strands by joining the nucleotides together forming the phosphodiester bonds in the sugar-phosphate backbone

Question 16

What direction are new nucleotides added in?

Answer 16

5’ to 3’ direction

Question 17

antiparallel

Answer 17

DNA strands run in opposite directions of each other

Question 18

How does DNA polymerase add nucleotides on the lagging strand?

Answer 18

DNA polymerase detaches and moves up the strand, but a gap is left between

Question 19

leading strand

Answer 19

the formation of the new strand is continuous

Question 20

lagging strand

Answer 20

the new strand is fragmented

Question 21

okazaki fragments

Answer 21

fragments left behind by the DNA polymerase on the lagging strand

Question 22

DNA ligase

Answer 22

an enzyme that joins the okazaki fragments by forming the phosphodiester bonds between them

Question 23

How is the process of DNA replication sped up in eukaryotes?

Answer 23

DNA replication occurs at multiple origins along a DNA molecule/ happens at multiple points

Question 24

what forms when the two parent DNA strands are separated at an origin?

Answer 24

a replication fork

Question 25

Chromatin

Answer 25

Dna wrapped around histone proteins

Question 27

gene

Answer 27

a sequence of nucleotides that forms part of a DNA molecule

Question 28

why can't DNA communicate with ribosomes?

Answer 28

DNA is too large to leave the nucleus and ribosomes are in the cytoplasm

Question 29

how to solve DNA and ribosome communication problem?

Answer 29

a "middle man" is used to copy the sequence of bases in a gene and carry the information to the ribosomes

Question 30

what is the middle man in this process

Answer 30

mRNA

Question 31

protein synthesis process

Answer 31

1. transcription 2. translation

Question 32

transcription

Answer 32

the formation of mRNA in the nucleus, represents a copy (transcript) of the DNA code

Question 33

translation

Answer 33

decoding the mRNA transcript by a ribosome to synthesize a polypeptide

Question 34

codon

Answer 34

set of 3 bases

Question 35

what must happen to the two strands of DNA to copy a gene

Answer 35

they must separate

Question 36

one strand will act as a "________" strand

Answer 36

template

Question 37

RNA polymerase

Answer 37

synthesizes a complementary mRNA

Question 38

where does RNA polymerase start transcription?

Answer 38

binding to the promoter region

Question 39

when does RNA polymerase stop transcription

Answer 39

when it reaches the terminator sequence at the end of a gene

Question 40

primary transcript

Answer 40

initial RNA molecule that is produced

Question 41

what must happen to the primary transcript before it leaves the nucleus

Answer 41

it must be modified

Question 42

how is the primary transcript modified

Answer 42

splicing, capping, tailing

Question 43

splicing

Answer 43

non-coding sequences (introns) and remaining coding sequences (exons) are joined

Question 44

capping

Answer 44

a "cap" (modified guanine nucleotide) is added to the 5' end

Question 45

tailing

Answer 45

a poly-A "tail" (string of adenine bases) is added to the 3' end

Question 46

purpose of the cap and tail

Answer 46

protect the mRNA from being digested by enzymes when it leaves the nucleus

Question 47

start codon

Answer 47

AUG

Question 48

what happens as the ribosome reads the mRNA codon?

Answer 48

another type of RNA called tRNA delivers the corresponding amino acid

Question 49

anticodon

Answer 49

a set of 3 nucleotides that are complementary to an mRNA codon

Question 50

gene mutation

Answer 50

a change in the sequence of DNA nucleotides

Question 51

when does gene mutation occur?

Answer 51

when a wrong nucleotide is inserted during DNA replication or when mutagens damage DNA

Question 52

base substitution/ point mutation

Answer 52

a base is replaced by a different base

Question 53

silent base mutation

Answer 53

a mutation that doesn't change the amino acid coded for by that DNA triplet, doesn't change protein's primary structure

Question 54

base insertion

Answer 54

a base is added

Question 55

base deletion

Answer 55

a base is deleted

Question 56

frameshift mutations

Answer 56

base insertion and deletion, changes all amino acids from the point of mutation and onward