Chapter 16

Question 1

What are the base pairing rules?

Answer 1

A con T & G con C

Question 2

define transformation

Answer 2

transformation is the change in genotype and phenotype due to assimilation of foreign DNA

Question 3

what is a virus?

Answer 3

a virus is DNA (sometimes RNA) enclosed by a protective coat, often simply protein

Question 4

what is DNA made of?

Answer 4

DNA is a polymer of nucleotides; consisting of a nitrogenous base, a sugar, and a phosphate group

Question 5

how do the number of A&T and G&C compare?

Answer 5

in any species, the number of AT bases are equal and the number of GC bases are equal (understood because of the double helix)

Question 6

what is the DNA molecule made up of structure wise?

Answer 6

A DNA molecule is made up of two strands, forming a double helix

Question 7

What is semiconservative replication?

Answer 7

In DNA replication, each parental molecule unwinds and two new daughter strands are built based on the base pairing rules

Question 8

What unwinds DNA strands?

Answer 8

helicase

Question 9

Which strands are new and old in DNA replication?

Answer 9

Each daughter molecule has one old strand and one newly made strand

Question 10

how were nucleotides labeled for old and new strands in experiment?

Answer 10

matthew meselson and franklin stahl: labeled old nucleotides with a heavy isotope and new ones with a lighter isotope

Question 11

what is a replication fork?

Answer 11

a Y shaped region where new DNA strands are elongating at the end of each replication bubble

Question 12

what are helicases?

Answer 12

helicases are enzymes that untwist the double helix at the replication forks

Question 13

what is the goal of all the players in replication?

Answer 13

to copy all of the DNA to get ready for cell division

Question 14

what are single-strand binding proteins?

Answer 14

they bind to and stabilize single-stranded DNA

Question 15

what does topoisomerase do?

Answer 15

topoisomerase corrects “overwinding” ahead of replication forks by breaking, swiveling, and rejoining DNA strands

Question 16

DNA polymerase cannot?

Answer 16

DNA polymerase cannot initiate synthesis of a polynucleotide; can only add nucleotides to an existing 3’ end

Question 17

the initial nucleotide strand is ?

Answer 17

a short RNA primer

Question 18

what is primase?

Answer 18

primase is an enzyme that can start an RNA chain from scratch and adds RNA nucleotides one at a time using the parental DNA as a template (5-10 nucleotides long, 3’ is the starting point for new DNA strand)

Question 19

what does primase do?

Answer 19

it lays down the short RNA primer, then DNA polymerase 3 attaches to primer and starts to elongate by adding nucleotides to RNA primer

Question 20

in what direction are nucleotides added?

Answer 20

5’ to 3’

Question 21

in what direction do DNA strands elongate?

Answer 21

5’ to 3’

Question 22

what is DNA ligase?

Answer 22

an enzyme that seals the bonds between restriction fragments

Question 23

what do DNA polymerase do?

Answer 23

DNA polymerases are enzymes that catalyze the elongation of new DNA at a replication fork

Question 24

what do DNA polymerases require?

Answer 24

DNA polymerases require a primer and a DNA template strand

Question 25

each nucleotide that is added to a growing DNA strand is a ?

Answer 25

nucleoside triphosphate

Question 26

how many RNA primers are needed for replication?

Answer 26

only one

Question 27

what happens to elongate the lagging strand?

Answer 27

it is replicated going away from the replication fork, so any RNA nucleotides of primer from 5’ have to be removed by polymerase 1 and replaced with DNA nucleotides
- the lagging strand is synthesized as a series of segments called Okazaki fragments that are joined together by DNA ligase

Question 28

what are telomeres?

Answer 28

telomeres are special nucleotide sequences at ends of eukaryotic DNA molecules to postpone erosion of genes near ends of DNA molecules