11.3 , 11.4 , 14.1 , 14.2

Question 1

DNA replication

Answer 1

DNA can be copied… the original strands are used as templates for the synthesis of new DNA strands

Question 2

Daughter strands

Answer 2

Newly made strands

Question 3

Parent strand

Answer 3

The original DNA

Question 4

Semiconservative model

Answer 4

Double stranded DNA is half conserved following the replication process so the new double stranded DNA contains one parental strand and one daughter strand

Question 5

Conservative mechanism

Answer 5

Both parental strands of DNA remain together following DNA replication

Question 6

Dispersive mechanism

Answer 6

Segments of parental DNA and newly made DNA are interspersed in both strands following the replication process

Question 7

What type of experiment was used to find out what model was right for DNA replication?

Answer 7

Experiments used isotope labeling of nitrogen which is found in DNA

**newly made strands were labeled with light nitrogen and original strands remained labeled heavy form

Question 8

Origin of replication

Answer 8

Site within a chromosome that serves as a starting point for DNA replication

Question 9

DNA helicase

Answer 9

Bonds to one of the DNA strands and travels in the 5’ to 3’ direction towards the fork

Question 10

DNA topoisomerase

Answer 10

Alleviates knots that may be caused by action of DNA helicase

Question 11

Single-strand binding proteins

Answer 11

Coat DNA strands to prevent them from re-forming a double helix

Question 12

DNA polymerase

Answer 12

Responsible for covalently linking nucleotides together to form DNA strands

Question 13

Deoxynucleoside triphosphates

Answer 13

Nucleotides with three phosphate groups

Question 14

DNA primase

Answer 14

Makes a complementary primer that is actually a short segment of RNA which starts/ primes the process of DNA replication

Question 15

DNA polymerase can only synthesis in what direction?

Answer 15

the 5’ to 3’ direction

Question 16

Leading strand

Answer 16

Strand made in same direction that fork is moving

Question 17

Lagging strand

Answer 17

Made as a series of small fragments called Okazaki fragments that is synthesized in the opposite direction of the replication fork

Question 18

DNA ligase

Answer 18

Catalysts the formation of a covalent bond between two DNA fragments to complete the replication process in the lagging strand

Question 19

Proofreading of DNA

Answer 19

DNA polymerase can identify a mismatched nucleotide and remove it from the daughter strand

Question 20

Telomere

Answer 20

Ends of eukaryotic chromosomes that have short nucleotide sequences that are repeated many times

Question 21

Telomerase

Answer 21

Prevents chromosome shortening by attaching many copies of a DNA repeat sequence to ends of chromosomes

**essentially lengthens the DNA strand

Question 22

Mutation

Answer 22

defined as a heritable change in the genetic material

Question 23

Mutations cause….

Answer 23

1. The base sequence within a gene to be changed

2: one or more base pairs can be added to or removed from a gene

Question 24

Point mutation

Answer 24

Affects only a single base pair within the DNA

Question 25

Silent mutations

Answer 25

Do not alter the amino acid sequence of the polypeptide even though the nucleotide sequence has changed

Question 26

Missense mutations

Answer 26

Base substitution that changed a single amino acid in a polypeptide sequence

Question 27

Nonsense mutation

Answer 27

Involves change from a normal codon to a stop codon

Question 28

Frameshift mutations

Answer 28

Involves addition or deletion of nucleotides that are not in multiples of three

Question 29

Spontaneous mutations

Answer 29

Result from abnormalities in biological processes

Question 30

Induced mutations

Answer 30

Caused by environmental agents that enter the dell and alter the structure of DNA

Question 31

Mutagens

Answer 31

Agents that cause mutations

Question 32

Chemical mutagens

Answer 32

Can covalently modify the structure of nucleotides

**can disrupt appropriate pairing between nucleotides by alkylation of bases within DNA

Question 33

Physical mutagens

Answer 33

DNA molecules are also sensitive to physical agents such as radiation

Question 34

Ames test

Answer 34

Test used to see if a substance can cause a mutation

Question 35

Individual nucleotides bond between what type of bonding?

Answer 35

Hydrogen bonding

Question 36

How can we explain such a remarkably high fidelity for DNA replication?

Answer 36

• hydrogen bonding between A and T or between G and C is more stable than between mismatched pairs
• DNA polymerase can identify a mismatched nucleotide and remove it from the daughter strand (proofreading)

Question 37

Germ line cells

Answer 37

Cells that give rise to gametes

Question 38

Somatic cells

Answer 38

Constitute all cells of the body except for the germ line

Question 39

Germ line mutation leads to…

Answer 39

Entire organism carries mutation and half of the gametes carry the mutation

Question 40

Somatic cell mutation …

Answer 40

• receive a patch of affected area

- none of the gametes carry the mutation