9.6 DNA Replication and Chromosome Structure/DNA Structure ILM

Question 1

what are the two prymidines? is this one or two rings?

Answer 1

one ring, cytosine and thymine

Question 2

how are nucleotides strung together? what kind of bond?

Answer 2

phosphodiester bond

Question 3

what disease is characterized by abnormally short telomere sequences? affects skin, nails, bone marrow cells. gives effect of premature aging

Answer 3

dyskeratosis congenita

Question 4

what happens when telomeres become too short?

Answer 4

cells become senescent and stop dividing

Question 5

telomerase is re-activated in what types of cells?

Answer 5

cancer cells

Question 6

special repeating segments at the end of DNA

Answer 6

telomeres

Question 7

What enzyme gets rid of the RNA priming fragments on the lagging strand?

Answer 7

ribonuclease H

Question 8

what are the two purines? is this one or two rings?

Answer 8

two rings, adenine and guanine

Question 9

What enzyme combines fragments with the growing strand by joining OH on a 3’ end with a triphosphate on a 5’ end?

Answer 9

DNA ligase

Question 10

the nucleotides in DNA and RNA are based off a ___ carbon sugar (number)

Answer 10

5

Question 11

what direction can DNA synthesis occur in?

Answer 11

5’ to 3’ direction

Question 12

the leading strand in DNA synthesis is replicated __________, while the lagging strand is replicated _____________.

Answer 12

continuously, discontinuous

Question 13

What enzyme synthesizes telomeres?

Answer 13

telomerase

Question 14

a nucleotide consists of 3 things. What are they?

Answer 14

a simple sugar, a phosphate group, and a base

Question 15

in double helix structure, how are the two strands of DNA held together? what force?

Answer 15

hydrogen bonding

Question 16

What enzyme sits on DNA above the replication fork and ensures correct unwinding of the strand? Making sure there are no knots or anything.

Answer 16

topoisomerase

Question 17

DNA polymerase does not have inherent affinity for DNA. What complex keeps DNA polymerase attached to DNA?

Answer 17

sliding clamp complex

Question 18

what are the pairs of nucleotides? (purine and prymidine pairing)

Answer 18

A-T, C-G

Question 19

there are 4 bases in DNA nucleotides. What are they?

Answer 19

thymine, adenine, cytosine, guanine

Question 20

what enzyme does most of the DNA synthesis?

Answer 20

DNA polymerase

Question 21

if RNA, then _____ is replaced by a ______ (nucleotide names)

Answer 21

thymine, uracil

Question 22

are DNA residues positive or negative?

Answer 22

negative

Question 23

which is more stable, A-T rich DNA or C-G rich DNA? Why?

Answer 23

C-G rich DNA, they make 3 H bonds between nucleotides (instead of the 2 by A-T)

Question 24

what site allows duplicated DNA molecules to be pulled apart into daughter cells during cell division?

Answer 24

centromeres

Question 25

are histone proteins positive or negative?

Answer 25

incredibly positive

Question 26

DNA polymerase can’t begin synthesis without a primer. There needs to be either a DNA or RNA primer for it to extend synthesis. What enzyme makes the RNA primers for the lagging strand?

Answer 26

DNA primase

Question 27

when is telomerase enzyme active? (normal, 3 places)

Answer 27

gamete formation, adult stem cells, embryonic stem cells

Question 28

in DNA, the sugar of the nucleotide is called _____________

Answer 28

deoxyribose

Question 29

in RNA, the sugar of the nucleotide is called ______

Answer 29

ribose

Question 30

what unwinds DNA?

Answer 30

DNA helicase