Chapter 9: DNA Structure and Replication

Question 1

DNA Polymerase

Answer 1

Catalyzes the addition of nucleotides as the new DNA chain grows to the 3’ end of each new strand

Question 2

How is DNA replicated?

Answer 2

DNA replication is semiconservative

Question 3

What is semiconservative in DNA replication

Answer 3

It is where each parent strand acts as a template for synthesis of a new strand where two replicated DNA molecule each contain one parent strand and one newly synthesized strand

Question 4

Leading Strand

Answer 4

is synthesized continuously

Question 5

Lagging Strand

Answer 5

Is synthesized in pieces called Okazaki fragments held together by ligase

Question 6

Ligase

Answer 6

The enzymatic glue that holds Okazaki fragments

Question 7

Origin of Replication (ori)

Answer 7

Is the place where the pre-replication complex binds. Binding occurs when proteins in the complex recognize specific DNA sequences within the ori

Question 8

Chargaff’s Rule

Answer 8

Is the amount of adenine = the amount of thymine and the amount of guanine = the amount of cytosine

Question 9

Why are mutation rates so much lower than expected?

Answer 9

DNA polymerase has proofreading capabilities and mismatched-repair occur

Question 10

How does DNA polymerase replicates DNA?

Answer 10

It replicates it by adding nucleotides only to the 3’ end of each growing strand

Question 11

New synthesized DNA goes in what direction?

Answer 11

It goes in the 5’ to 3’ direction

Question 12

DNA Proofreading

Answer 12

It occurs right after DNA polymerase inserts a nucleotide.

Question 13

Mismatch Repair

Answer 13

Occurs after DNA has been replicated and is a second set of proteins surveys the newly replicated molecule

Question 14

What does DNA proofreading do?

Answer 14

When a DNA polymerase recognizes a mispairing of bases, it removes the improperly introduced nucleotide and tries again

Question 15

What does mismatch repair do?

Answer 15

It looks for mismatched base pairs that were missed in proofreading and removes the incorrect nucleotides and then has DNA polymerase insert the correct sequence

Question 16

Mutations

Answer 16

Are changes in the nucleotide of sequence of DNA that are passed on from one cell or organism to another. It may or may not affect the phenotype

Question 17

What are the two types of mutations?

Answer 17

Somatic mutations

Germline mutation

Question 18

Somatic Mutation

Answer 18

It occur in the somatic (body) cells of a multicellular organism that are passed onto the daughter cells during mitosis and in turn to the offspring of those cells. These mutations are not passed on to gametes

Question 19

Germline Mutation

Answer 19

It occurs in the cells of the germ line - the specialized cells that give rise to gametes and gametes with this mutation will pass it on to a new organism at fertilization

Question 20

Silent Mutation

Answer 20

They do not affect gene function and are mutations in DNA that are not expressed or mutations within an expressed region that do not have any effect on the encoded protein. Most mutations in large genomes are silent

Question 21

Loss of Function Mutation

Answer 21

It can result in either the loss of expression of a gene or in the production of a nonfunctional protein or RNA (usually seen in recessive inheritance)

Question 22

Gain of Function Mutation

Answer 22

It leads to a protein with an altered function and usually shows dominant inheritance and is common in cancer

Question 23

Conditional Mutation

Answer 23

This causes their phenotypes only under certain restrictive condition (usually under temperature)

Question 24

Miessence Mutation (Single point Mutation)

Answer 24

Is the addition or subtraction of a single nucleotide base that results in an altered phenotype or creates different amino acid

Question 25

Chromosomal Mutation

Answer 25

They are extensive and they change the position or cause a DNA segment to be duplicated or lost

Question 26

Deletion mutation of chromosomes

Answer 26

It is the removal of part of the genetic material and the consequences can be severe or even fatal

Question 27

Duplication mutation of the chromosome

Answer 27

It can be produced at the same time as deletions and would arise if homologous chromosomes broke at different positions and then reconnect with the wrong partners.

Question 28

Inversion mutation of the Chromosome

Answer 28

Is the result of breaking and rejoining chromosomes by removing a segment of DNA and reinsert it into the same location of the chromosome that’s in the wrong direction

Question 29

Translocation mutation of the chromosome

Answer 29

Results when segments of chromosomes break off and become joined to different chromosomes

Question 30

What are the benefits of Mutations?

Answer 30

1. May cause an advantageous change in offspring

2. May provide the raw material for evolution in the form of genetic diversity