B2-014 - Genomic DNA and Nucleic Acids

Question 1

Describe human DNA structure

Answer 1

Anti-parallel strands with major and minor grooves

Question 2

Whats the size of the human genome

Answer 2

3 million bases

Question 3

how many genes are coding

Answer 3

20,296

Question 4

how many non coding genes are there

Answer 4

25,173

Question 5

what is a pseudogene

Answer 5

non expressed “broken” genes

Question 6

how big is the mitochondrial genome

Answer 6

17000, 14 - protein coding, 23 rRNA/tRNA

Question 7

What is the inter-individual variation in the genome

Answer 7

3-3.5 million nucleotide differences

Question 8

how many copy number variations are there

Answer 8

1000

Question 9

how many chromosomes are there

Answer 9

22 autosomes and 2 sex chromosomes

Question 10

Most human cells are…

Answer 10

diploid, 46 chromosomes per cell

Question 11

how long is the human genome

Answer 11

2 meters long

Question 12

what is chromatin

Answer 12

a protein DNA complex that packages DNA and regulates transcription

Question 13

what is euchromatin

Answer 13

light staining, gene rich, actively transcribes genes, structurallly open

Question 14

what is heterochromatin

Answer 14

dark staining, repetitive and gene free, structurally compact

Question 15

what is constitutive heterochromatin

Answer 15

repeats, telomeres, centromeres

Question 16

what is facultative chromatin

Answer 16

developmentally silenced genes

Question 17

Where is DNA methylation most common

Answer 17

on cytosine bases in 5’ CpG pairs (CG-GC)

70% of cytosine bases are demethylated

Question 18

What happens when DNA gets methylated

Answer 18

irreversible packaging of DNA into transcriptionally silent chromatin
It can be reversed but its cumberson and this makes it LONG TERM MODIFICATION

Question 19

DNA-CH3 spreads along DNA molecule unless

Answer 19

specific mechanisms stop it

Question 20

DNA methylation is important in regulation

Answer 20

constitutive heterochromatin, silencing of tissue specific genes,

Question 21

in cancer what role does methylation play

Answer 21

silencing (methylation) of tumor suppressor genes

Question 22

what is special about female X chromosomes

Answer 22

one is always hypermethylated to silence it

Question 23

Histone proteins are rich in what

Answer 23

basic residues (Arg, Lys)

Question 24

How is phosphate backbone charged

Answer 24

negatively

Question 25

What are the histone n terminal tails exposed to do

Answer 25

site of modifications that alter chromatin structure

Question 26

what do histone modifications do

Answer 26

regulate gene transcription and open and close chromatin structure

Question 27

what does acettylation do to chromatin

Answer 27

makes it looser, raises potential for transcription

Question 28

what does methylation do to chromatin

Answer 28

adds a ch3, Lysin and arginine, depends

Question 29

histone modifications differ from DNA methylation how

Answer 29

its dynamic and fast

Question 30

what does acetylation do to lysine

Answer 30

makes it neutrally charges as opposed to positively

Question 31

what enzyme acetylates lysine

Answer 31

HAT - acetyl coa acetyltransferase

Question 32

what are epigenetics

Answer 32

information in DNA not based on nucleotide sequence but is still inherited, such as imprinting

Question 33

epigenetic silencing

Answer 33

a gene being methylated and shut down

Question 34

chromatin

Answer 34

what DNA is packaged into

Question 35

when is chromatin most compact

Answer 35

prophase and metaphase (least during interphase)

Question 36

types of repeats

Answer 36

interspersed and tandem

Question 37

LINEs are

Answer 37

Long interspersed Nuclear elements - 20% of human genome

Question 38

LINes transpose how

Answer 38

via RNA intermediate

Question 39

SINEs are

Answer 39

Short Interspered Nuclear Elements also known as Alu repeats

Question 40

how are SINEs moved

Answer 40

theyre inactive but can be moved by active transposons

Question 41

what are HERVs

Answer 41

human endogenous retroviruses

Question 42

can HERVs be transposed

Answer 42

no, theyre inactive

Question 43

what is the 4th type of intersperesed repeats

Answer 43

DNA transposon fossils, cant transpose

Question 44

Types of tandem repeats

Answer 44

satelline, minisatellite DNA, microsatellite DNA

Question 45

what is special about microsatellites and minisatellites DNA

Answer 45

used for DNA fingerprinting

Question 46

whats the third type of duplications

Answer 46

segmental

Question 47

are repetitive elements "junk" DNA?

Answer 47

no

Question 48

what are repetitive elements uses

Answer 48

transposons (SINE/LINE) contribute to molecular evolution

Question 49

what is chromatin status of repetitive DNA?

Answer 49

most is methylated, heterochromatin silent and unexpressed

Question 50

how much of the human genome is repetitive?

Answer 50

about half