Chapter 10

Question 1

What is supercoiled DNA?

Answer 1

DNA that is more compact than its relaxed counterpart

Question 2

Underwound DNA is (negatively or positively) supercoiled?

Answer 2

Negatively

Question 3

Overwound DNA is (negatively or positively) supercoiled?

Answer 3

Positively

Question 4

What is the purpose of underwound DNA?

Answer 4

To allow chromosomes to fit within the nucleus

Question 5

Type I topisomerases do what?

Answer 5

Change the supercoiled state by creating a transient break in one strand of the duplex

Question 6

Type II topisomerases do what?

Answer 6

Make a transient break in both strands of the DNA duplex, can also tie a DNA molecule into knots or untie DNA knots

Question 7

Define: Transient

Answer 7

Lasting for a short time

Question 8

Define: Denaturation

Answer 8

Ability to separate into its separate components

Question 9

Thermal denaturation

Answer 9

DNA melting

Question 10

How can you monitor thermal denaturation?

Answer 10

The increase in absorbance of UV light by dissolved DNA

Question 11

Higher the GC content (higher or lower) the melting temp?

Answer 11

Higher

Question 12

Higher AT (higher or lower) the melting temp?

Answer 12

Lower

Question 13

Define: Renaturation

Answer 13

When single-stranded DNA molecules are capable of reassociating

Question 14

Reannealing is also known as

Answer 14

Renaturation

Question 15

What are the 3 broad classes of DNA sequences?

Answer 15

• highly repeated fraction
• moderately repeated fraction
• nonrepeated fraction

Question 16

Highly repeated DNA sequences represent how much total DNA?

Answer 16

1-10%

Question 17

What are satellite DNAs?

Answer 17

Short sequences that tend to evolve very rapidly

Question 18

What are minisatellite DNAs?

Answer 18

Unstable and tend to be variable in the population; form the basis of DNA fingerprinting

Question 19

What are microsatellite DNAs?

Answer 19

Shortest sequences and typically found in small clusters; implicated in genetic disorders

Question 20

FISH stands for

Answer 20

Fluorescent In Situ Hybridization

Question 21

What are FISH?

Answer 21

Fluorescent probes are generated towards a specific DNA sequence which allows determination of its location within the genome

Question 22

What are FISH commonly used for?

Answer 22

Visualize repetitive sequences like that found in satellite DNA localized in the centromeric regions of chromosome, or determining location of single copy genes

Question 23

SINEs stand for:

Answer 23

Short Interspersed Elements

Question 24

LINEs stand for:

Answer 24

Long Interspersed Elements

Question 25

Where are noncoding elements found in the genome?

Answer 25

Throughout the genome, and grouped into SINEs or LINEs

Question 26

What is polyploidization?

Answer 26

Whole-genome duplication

Question 27

What is Whole-genome duplication?

Answer 27

offspring that have 4 chromosome homologs rather than 2

Question 28

Where are whole-genome duplication typically found?

Answer 28

In higher order plants

Question 29

Mechanism is whole-genome duplication

Answer 29

2 related species can mate to form a hybrid organism with the combined chromosomes from both parents

Question 30

How can duplication occur in DNA sequences?

Answer 30

Unequal crossing, plays role in evolution

Question 31

What are pseudogenes?

Answer 31

Genes that resemble active genes but are inactive

Question 32

Where can DNA duplication occur?

Answer 32

Within a portion of a single chromosome

Question 33

What are transposons?

Answer 33

Jumping genes

Question 34

Transposons require what? (3)

Answer 34

- transposase enzyme - certain sequences that are transposon sequence - target site

Question 35

Transposable elements appear to have done what?

Answer 35

Given rise to genes and advanced eukaryotes

Question 36

How many genes does a human have approximately?

Answer 36

20,000

Question 37

What is alternative splicing?

Answer 37

When a single gene can encode a number of related proteins

Question 38

What are microRNAs?

Answer 38

Noncoding RNAs that can have gene regulatory functions

Question 39

Define: Intergenic

Answer 39

Majority of the genome lies between protein coding genes and is intergenic

Question 40

What are structural variants?

Answer 40

Large changes range from hundreds to millions of base pairs in length