Genomic Structure and Organization

Question 1

packaging of DNA in the nucleus in bacteria

Answer 1

• negative supercoiling
• compact structure is called nucleoid
• nucleoid exists in the cytosol with a few attachments to the membrane

Question 2

packaging of eukaryotic DNA in the nucleus

Answer 2

Dna is confined to the nucleus and wrapped around histones

Question 3

nucleosome

Answer 3

• DNA wrapped around histones

- portion of DNA that can’t be digested

Question 4

SINES

Answer 4

short interspersed elements

Question 5

LINES

Answer 5

long interspersed elements

Question 6

Alu sequences

Answer 6

-named bc Alu1 restriction site found in sequences

Question 7

intron sequences

Answer 7

• increases the size of the eukaryotic genome

- some eukaryotic genes (like histones) don’t have introns

Question 8

gene variants

Answer 8

• may be expressed in different tissues or at different stages of development
• some produced via alternate splicing, but many have a completely separate gene

Question 9

pseudogenes

Answer 9

• role is not understood

- not true gene!

Question 10

nuclear envelope

Answer 10

• contains pores to allow free diffusion of small molecules bw nucleus and cytoplasm
• exportins and importins assist with selective transport of RNA and protein
• since protein synthesis occurs in cytoplasm and mRNA synthesis occurs in nucleus, transcription and translation cant be directly coupled

Question 11

H1

Answer 11

• associated with linker DNA
• helps form higher order structure
• only histone not inside of histone core

Question 12

H2A and H2B

Answer 12

two of each form histone

Question 13

H3

Answer 13

octamer core of nucleosome

Question 14

euchromatin

Answer 14

chromatin during interphase that is active

Question 15

heterochromatin

Answer 15

chromatin during interphase that is transcriptionally inactive

Question 16

restriction enzymes

Answer 16

• specific for DNA sequences and methylation states

- may generate blunt ends or 5’ or 3’ overhangs

Question 17

DNA fingerprinting

Answer 17

• uses restriction fragment length polymorphisms
• generates DNA fingerprint that establishes identity of individual
• PCR use
• not actually fingerprinting!

Question 18

size of human genome

Answer 18

• 3 billion base pairs
• 20,000-25,000 genes
• any 2 humans differ in DNA at 1 base pair per 1000 base pairs

Question 19

PCR

Answer 19

• polymerase chain rxn
• able to exponentially amplify small amounts of DNA in vitro
• requires thermostable DNA polymerase, a pair of oligonucleotide primers, dNTPS, and a DNA template