Week 3

Question 1

____% of the human genome is repeated sequences

Answer 1

50%

Question 2

Why do histone’s bind tightly to DNA?

Answer 2

they’re positive and attracted to negative DNA

Question 3

If there are 50,000 origins of replication, what is the max number of replication forks?

Answer 3

100,000

Question 4

Example of areas of genome that isn’t protein encoding exons relating to transcription

Answer 4

sequences that ensure transcription of proper gene at right time, level, and space

Question 5

bacteriophage

Answer 5

virus that infects bacteria

Question 6

bp per human genome and per human

Answer 6

3 BILLION per genome, 2 genomes per human so 6 BILLION per human

Question 7

______ protein coding genes across ____ PAIRS of chromosomes

Answer 7

19,000. 23.

Question 8

Is genome size correlated with number of genes, organism complexity, or size?

Answer 8

No!

Question 9

What percent of human genome encodes protein?

Answer 9

1.5%

Question 10

What percent of the human genome is repetitive DNA?

Answer 10

50%

Question 11

Types of unique sequences (3)

Answer 11

exons (transcribed and translated), introns (transcribed but spliced out before translation), non-repetitive DNA like promoters

Question 12

Types of repeated sequences (6)

Answer 12

segment duplications - thousands to 200,000 duplicated bp’s
simple repeats - example CAG repeated 30-100s of times
mobile genetic elements (control paste):
DNA-only transposons - only DNA
retrotransposons - sometimes made into RNA
LINEs - long interspersed nuclear elements (>=500 bps)
SINEs - short interspersed nuclear elements (<=500 bps)

Question 13

prokaryotic nucleoid

Answer 13

DNA condensed through folding 1000 fold complexed with proteins but no nuclear membrane

Question 14

eukaryotic nuclear membrane

Answer 14

2 membranes /phospholipid bilateral: outer and inner

Question 15

FISH

Answer 15

FLUORESCENT IN SITUATION HYBRIDIZATION - diagnostic technique to detect for specific sequences

Question 16

FISH steps

Answer 16

1. fluorescent dye
2. denature both substances
3. mix together
4. cool
5. will bind and be fluorescent if sequence is there

Question 17

chromosome painting hybridization

Answer 17

like FISH but uses tons of probes with different colours

Question 18

chromatin

Answer 18

dynamic (more or less compact) with DNA accessible for transcription, replication and repair

Question 19

retrotransposons

Answer 19

sometimes made into RNA

Question 20

LINEs bp length

Answer 20

> =500

Question 21

SINEs bp length

Answer 21

<=500

Question 22

segment duplications bp length

Answer 22

1000s to 200,000

Question 23

simple repeats repeat number

Answer 23

30-100

Question 24

DNA wraps around _________ protein ____ and about ____ bp around each protein

Answer 24

histone, x1.7, 147 bp

Question 25

linker DNA bp length

Answer 25

80 bp b/w nucleosomes

Question 26

chromatin fiber of packed nucleosomes are ____ nm

Answer 26

30

Question 27

nuclease

Answer 27

chops up linker DNA

Question 28

a mitotic chromosome _______ fold shorter than full length

Answer 28

10,000

Question 29

In interphase, most DNA in ______ form

Answer 29

30 nm fibre

Question 30

histones are rich in ______ and _______ which are _________ charged

Answer 30

lysine and arginine, positively

Question 31

4 histone proteins in the _________ core

Answer 31

H2A, H2B, H3, H4, octamer (2 of each)

Question 32

what is the 5th histone protein not in the octamer core?

Answer 32

H1: on outside, clips DNA off protein bead. without it, DNA falls off

Question 33

nucleosome core particle

Answer 33

core histones + DNA around it

Question 34

nucleosome

Answer 34

nucleosome core particle (core histones and surrounding DNA) + H1 + linker DNA

Question 35

What aids in forming chromatin loops?

Answer 35

some DNA sequences matched and held by NON-HISTONE CLAMP PROTEINS

Question 36

euchrimatin vs heterochromatin

Answer 36

eu = less compact hetero = more compact

Question 37

Chromatin remodelling complexes and histone modifying enzymes

Answer 37

proteins that can make changes in chromatin structure and alter access to DNA for replication or transcription

Question 38

Heterochromatin

Answer 38

highly condensed chromatin During mitosis and meiosis moving chromosomes around so we want them compact

Question 39

heterochromatic regions of interphase chromosomes are areas where gene expression is _______.

Answer 39

suppressed

Question 40

Barr body

Answer 40

super condensed second inactive X chromosome

Question 41

in all female cells, which X chromosome is Barr body

Answer 41

half have 1 inactive, half have the other

Question 42

Why are chromosomes made heterochromatic

Answer 42

not enough space and information isn’t being used to make RNA or take part in gene expression

Question 43

Euchromatin

Answer 43

regions where genes tend to be expressed

Question 44

What three things modulate the reversible switching from euchromatic to heterochromatic regions

Answer 44

covalent modification of histones, the presence of chromatin remodelling complexes, and RNA polymerase (transcription) complexes

Question 45

interphase chromosomes are in ________ regions of nucleus

Answer 45

discrete

Question 46

Transcription factories

Answer 46

Areas of nucleus with lots of enzymes and materials for transcription, sometimes jeans get moved to these factories

Question 47

RNA synthesized from

Answer 47

Ribonucleoside triphosphates (NTPs)

Question 48

Nucleotides are linked by

Answer 48

Phosphodiester bonds

Question 49

Rules of DNA replication

Answer 49

1. DNA is anti-parallel 2. New DNA is synthesized from 5’ to 3’ 3. Template strand is read 3’ to 5’ 

Question 50

Three models of DNA replication

Answer 50

1. unidirectional growth of single strands from two starting points quick. [Linear virus, No Okazaki fragments] 2. unidirectional growth of two strands from one starting point [some plasmids] 3. Bidirectional growth from one starting point - Origin of replication [eukaryotes and bacteria]

Question 51

Where does DNA replication start

Answer 51

A – T rich areas, Initiator proteins

Question 52

What shape are bacterial chromosomes? how many origins of replication are there?

Answer 52

Circular, 1