Lecture 3

Question 1

DNA… Is fixed across the same species but…changes

Answer 1

Quantity
Sequence

Question 2

DNA. Repair percent

Answer 2

90-99

Question 3

Methylation is an….that does not…..
Function
Can cause….
What is it..

Answer 3

Epigenetic modification
Follow genetics rules
Controls gene expression
Mutations
Adding methyl group to cytosine

Question 4

5 methyl cytosine is a ….
Its ….in genomes is…
Associated with gene…

Answer 4

Post synthetic modification
Distribution variable
Repression

Question 5

Animal cytosine
Plants cytosine

Answer 5

CpG
CNG

Question 6

What is Dnmt1
Has very strong preference to

Answer 6

DNA methyltransferase enzyme that adds methyl groups to DNA bases
Already methylated CpG on the other strand

Question 7

Methylation pattern is
Lack of dnmt1 causes

Answer 7

Inherited
Embryonic lethality

Question 8

Dnmt3a and dnmt3b have the ability to

Answer 8

DeMethylate and introduce de novo methylations in gametogenesis

Question 9

Absence of dnmt3
Dnmt3b function
Deficiency

Answer 9

Lethal
Methylates centromeric regions
Deficiency causes ICF syndrome

Question 10

Methylation sequence during mammalian development

Answer 10

Preimplantation low
Implantation high

Question 11

Rett syndrome

Answer 11

Mutations in MeCP2 gene that reads and binds to methylated DNA

Question 12

CpG islands are….. regions rich in
Associated with
Exceptions when it is methylated

Answer 12

CG normally unmethylated
Gene promoters
Inactive x chromosome at dose compensation
Imprinted genes that either 1 copy is active (mother or father)

Question 13

L1 and IAP retrotransponsons are never

Answer 13

DNA sequences that move around the genome but cant once methylated

Unmethylated

Inherited demethylated from mother then methylated

Question 14

Alu
Why

Answer 14

Inherited methylated from mother but unmethylated from father then remethylated
Gene regulation and genomic stability

Question 15

Methylation amount in different organisms

Answer 15

Caenorhabditis undetected
Drosophila very low
Mammals 2-7%
Plant 33%

Question 16

5methylcytosine in vertebrates vs invertebrates

Answer 16

genes in unmethylated
Gene can be found in methylated (invertebrates)

Question 17

Deamination

Answer 17

Amino grp removed from base
DNA:
cytosine>uracil (not a normal base usually fixed )
5methylcytosine>thymine

Question 18

4 values of methylation

Answer 18

1.Cancer related (hypermethylation in tumor suppressor or hypomethylation in oncogenes)
2.satellites and heterochromatin DNA heavily methylated demethylated will cause decondensation and genomic instability as well as alter gene expression
3. Transposons inactivation
4. Hybrid marsupials failure of methylation leads to chromosomal remodelling and activation of retroviral elements

Question 19

Transponsons what are they
Use
Danger
Other name

Answer 19

Replicate and jump from one part to another in the DNA
Evolution and genetic diversity
Too much activity will cause genetic instability and disease
Interspersed repetitive sequence

Question 20

Failure in methylation in hybrid marsupials can cause

Answer 20

Activation to retroviral elements and cause chromosome remodeling

Question 21

The C value paradox
DNA is …grams and….m
Variation in … does not equal…
Example

Answer 21

Amount of DNA in a haploid cell does not relate to organism complexity
6-7pg. 2m
Size, variation in general
Syntenic genes in pufferfish and human

Question 22

Gene number is …..than the total DNA
Percentage

Answer 22

Less than
5800 to 39000
Only 10% of total genome

Question 23

The larger the genome the….the…

Answer 23

Larger the repetition

Question 24

Repetitive DNA types
Regarded as
Except

Answer 24

Tandem block
Interspersed throughout but not block
Junk
Telomeres a d drosophila heterochromatin

Question 25

Satellite types

Answer 25

Mini, VNTR 10-100 0.5-30kb Micro no more than 6 usually 2 or 3 in all organisms distributed throughout the chromosme Less common in coding regions and telomeres Calssiccal

Question 26

Classical satellites Number Percent Several...can...in the same... Rich in Very short repeats cause...

Answer 26

2-7bp 2 crab 6 mammals 7 drosophila Can be up to half the genome Types occur block AT and CG than main band Strand asymmetry difference between the 2 strands

Question 27

Some defects

Answer 27

Unequal crossing over due to repeated sequnce Gene conversion Replication slippage

Question 28

What is gene conversion

Answer 28

DNA sequence replaces a homologous sequence so that they become exact

Question 29

Repeated genes What are they Often concentrated in... Like

Answer 29

RNA/ 5S rRNA/tRNA/ histones Genes with products req in large quantities which are kept identical Specific regions of the chromosomes 18s and 28 s

Question 30

Protein families

Answer 30

Globins each with a distinct function do not form clusters Homeobox genes are related in function and forms clusters

Question 31

What is ICF syndrome

Answer 31

Immunodeficiency Centromeric instability and facial anomalies A disease of DNA methylation

Question 32

There is....in bothe the amount of DNA between species and its ....within individuals

Answer 32

Extensive variation Sequence

Question 33

C value paradox the ..of DNA in...

Answer 33

Amount Haploid genome

Question 34

Tandem repeats are referred to as

Answer 34

Satellites

Question 35

The most common dinucleotide in human and drosophila is... Plants..

Answer 35

CA GA/AT

Question 36

Microsatellites are less common in...

Answer 36

Coding regions And telomeres

Question 37

Damage agent repair Pyrimidine dimer Alkylation and depurination Mispaired bases

Answer 37

UV- photorepair Chemicals-excision repair Replication errors-mismatch repair