Module 6

Question 1

Griffith experiments

Answer 1

dead type S cells were able to transform type R cells into type S through DNA

Question 2

Avery, MacLeod and McCarty

Answer 2

Only DNase was able to stop transformation, not RNase or protease. So the genetic information substance must be DNA, not RNA or proteins

Question 3

Hershey and Chase

Answer 3

DNA gets injected into cells from viruses, not proteins –> DNA must be genetic material

Question 4

A nucleotide has

Answer 4

a phosphate group, a pentose sugar, and a nitrogenous base

Question 5

Purines (double ring)

Answer 5

A and G

Question 6

Pyrimidines (single ring)

Answer 6

T, C, and U

Question 7

DNA directionality

Answer 7

5’ to 3’

Question 8

phosphodiester linkage

Answer 8

connects the 5’ carbon of one nucleotide to the 3’ carbon of an adjacent nucleotide

Question 9

The backbone is comprised of

Answer 9

phosphate groups and sugar

Question 10

Linus Pauling

Answer 10

proposed a-helix (single strand)

Question 11

Rosalind Franklin

Answer 11

found that DNA must be helical and have more than one strand

Question 12

Chargaff’s rule

Answer 12

percent A = percent T and percent C = percent G

Question 13

Watson and Crick

Answer 13

double strand helix

Question 14

DNA sequences are necessary for

Answer 14

synthesis of RNA and cellular proteins, Replication of chromosomes, proper segregation of chromosomes, and compaction of chromosomes

Question 15

prokaryotes

Answer 15

bacteria and archaea, circular chromosomal DNA, single type of chromosome

Question 16

DNA supercoiling

Answer 16

the formation of additional coils due to twisting forces, a way to compact the DNA

Question 17

Positive supercoil

Answer 17

twisted in the same direction as the DNA is wound, no stress on strands

Question 18

negative supercoil

Answer 18

twisted in the opposite direction as the DNA is wound, stress on strands help them separate for replication and transcription

Question 19

introns

Answer 19

noncoding intervening sequences

Question 20

Origins of replication

Answer 20

chromosomal sites necessary to initiate DNA replication, occur about every 100,000 bp

Question 21

Centromeres

Answer 21

Regions that play a role in segregation of chromosomes

Question 22

telomeres

Answer 22

prevent chromosome shortening

Question 23

unique or non-repetitve sequences

Answer 23

found once or twice in a genome, includes protein-coding genes and intergenic regions, make up ~41% of human genome

Question 24

moderately repetitive sequences

Answer 24

found a few hundred to several thousand times, genes for rRNA and histones, sequences that regulate gene expression and translation, transposable elements

Question 25

highly repetitive sequences

Answer 25

found tens of thousands to millions of times, each copy is relatively short, some sequences are interspersed throughout the genome, other sequences are clustered together in tandem arrays

Question 26

tandem arrays

Answer 26

non-transposable elements

Question 27

Transposition

Answer 27

the integration of small segments of DNA into a new location in the genome

Question 28

Transposable Elements

Answer 28

small, mobile segments of DNA

Question 29

Simple transposition

Answer 29

TE moves to a new target site

Question 30

Retrotansposition

Answer 30

TE moves via an RNA intermediat

Question 31

Direct Repeats

Answer 31

flank TEs, identical base sequences that are oriented in the same direction and repeated

Question 32

Inverted Repeats

Answer 32

DNA sequences that are identical but run in opposite directions, contains gene for transposase, which catalyzes the transposition event

Question 33

LTR retrotansposons

Answer 33

contain long terminal repeats at both ends

Question 34

autonomous elements

Answer 34

TEs that contain all of the information necessary for transposition or retrotransposition

Question 35

non-autonomous elements

Answer 35

TEs that lack a gene that is necessary for transposition

Question 36

transposase removal

Answer 36

recognizes the inverted repeats at the ends of a TE and brings them close together to dimerize, cleave the outside of the IRs and remove the segment

Question 37

transposase insertion

Answer 37

cleaves the target DNA at staggered sites (one on each strand), inserts the TE, DNA repairs sections with gaps creating direct repeats on both ends of the TE

Question 38

Reverse transcriptase

Answer 38

TE --> RNA --> synthesizes a new double stranded DNA molecule --> intergrase adds new strands to old DNA strand by recognizing LTRs

Question 39

LINEs

Answer 39

Long Interspersed elements

Question 40

SINEs

Answer 40

Short interspersed elements

Question 41

Nucleosome

Answer 41

8 histone proteins + 146 or 147 bp

Question 42

SMC proteins

Answer 42

cause loops to form

Question 43

CCCTC binding factor

Answer 43

stabilize loops

Question 44

Heterochromatin

Answer 44

tightly compacted regions of chromosomes, transcriptionally inactive

Question 45

Euchromatin

Answer 45

less condensed, transcriptionally active

Question 46

Condensin 1

Answer 46

creates big main loops during chromosome condensation

Question 47

condensin 2

Answer 47

creates smaller loops within the big main loop

Question 48

cohesin

Answer 48

promotes binding between sister chromatids during mitosis and meiosis