Lecture--Chapter 12 Flashcards Preview

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Flashcards in Lecture--Chapter 12 Deck (84)
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1

Chromosomes have a DNA helix of 2 strands, which are complexed with _____.

proteins

2

The relaxed DNA molecule of a single chromosome is longer than the ________ of the cell.

greatest dimension

3

Human genome (23 chromosomes) is about _____ long.

1 meter

4

To fit into cells, DNA must be ____.

compacted

5

generally a single circular DNA helix

bacterial chromosome

6

main chromosome + any plasmids:

genome

7

Multiple copies of genome may be present during times of _____.

fast growth

8

Genome is located as a _____, not in a nucleus.

nucleoid

9

bacterial "chromosome" (lacks chromatin)

genophore

10

Bacterial chromosome is a few million ____ in length.

nucleotides

11

E. coli has ~______ base pairs.

4.6 million

12

Haemophilus influenzae has ~_____ base pairs.

1.8 million

13

structural genes (encoding proteins)

transcribed gene sequences

14

intergenic regulatory regions

nontranscribed DNA segments

15

start site for DNA replication

origin of replication

16

Bacterial DNA must be packed about ______ smaller than its relaxed length.

1000-fold

17

Intergenic and repetitive sequences include regions with roles in ______.

chromosome packing

18

With bacterial DNA. compaction is largely accomplished by ____ and ____.

looping; supercoiling

19

additional coils due to twisting forces

supercoil

20

different structural conformations of a molecule

topoisomer

21

Coiled coils form loops in response to _____.

twisting forces

22

_____ supercoiling is the ______ state.

negative; normal

23

Negative supercoiling creates tension which promotes _____.

strand separation

24

Negative supercoiling: DNA replication in _____.

cell division

25

Negative supercoiling: DNA transcription for ______.

gene expression

26

Supercoiling is _____.

regulated

27

enzymes that either create or reduce supercoiling

topoisomerases

28

reduce ("relax") negative supercoiling

type I topoisomerases

29

break a single strand, allow rotation around the unbroken strand, and re-form phosphodiester backbone

type I topoisomerases

30

creates negative supercoiling

DNA gyrase