Lecture 26 - Genome Structures and DNA Replication

Question 1

how many base pairs does the human genome have?

Answer 1

~3x10^9

Question 2

how long is the entire DNA double helix if unpackaged?

Answer 2

1m

Question 3

genome ____ and _____ vary widely across ______

Answer 3

• size and gene

- species

Question 4

what are 5 levels of chromosome packaging?

Answer 4

1. Linker DNA
2. 10 nm fibers
3. 30 nm fibers
4. chromosomes

Question 5

how are eukaryotic DNAs packaged?

Answer 5

into nucleosomes by histone proteins

Question 6

what are histone proteins?

Answer 6

they package eukaryotic DNAs into nucleosomes

Question 7

_____ structure influences expression

Answer 7

chromatin

Question 8

______ modifications also influence expression

Answer 8

histone

Question 9

where are histone tails modified?

Answer 9

-on N-terminal regions that protrude from the nucleosome core region

Question 10

how are histone tails modified?

Answer 10

-methylated, acetylated, phosphorylated, or ubiquintinated at specific amino acids

Question 11

modification of one site on histone influence the modification of _______

Answer 11

a second site

Question 12

what do nucleosome-remodeling complexes do?

Answer 12

rearrange DNA packaging around nucleosomes

Question 13

what does chromatin remodeling do?

Answer 13

ATP-dependent chromatin remodeling exposes DNA binding sites

Question 14

DNA methylation also exerts _______

Answer 14

epigenetic control

Question 15

where does DNA replication initiate?

Answer 15

-at specific chromosomal sites (origins of replication, ori)

Question 16

organisms that have circular DNA (eg bacteria) also have ______

Answer 16

replication terminus regions (ter)

Question 17

organisms that have linear DNA (eg humans) often have _______ and

Answer 17

multiple ori

entire DNA is replicated without specific ter sequences

Question 18

human chromosomes have ______ and _______

Answer 18

centromeres and telomeres

Question 19

can replication of linear DNA copy the template to the very end?

Answer 19

no

Question 20

what happens because replication of linear DNA cannot copy the template to the very end?

Answer 20

-telomeric DNA sequences must be added to the ends of the chromosome to protect them from being omitted from the copy

Question 21

what do telomeric sequences usually consist of?

Answer 21

T and G

Question 22

where does DNA replication initiate?

Answer 22

at replication origins