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Genetics 2 > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

DNA… Is fixed across the same species but…changes

A

Quantity
Sequence

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2
Q

DNA. Repair percent

A

90-99

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3
Q

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

A

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

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4
Q

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

A

Post synthetic modification
Distribution variable
Repression

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5
Q

Animal cytosine
Plants cytosine

A

CpG
CNG

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6
Q

What is Dnmt1
Has very strong preference to

A

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

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7
Q

Methylation pattern is
Lack of dnmt1 causes

A

Inherited
Embryonic lethality

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8
Q

Dnmt3a and dnmt3b have the ability to

A

DeMethylate and introduce de novo methylations in gametogenesis

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9
Q

Absence of dnmt3
Dnmt3b function
Deficiency

A

Lethal
Methylates centromeric regions
Deficiency causes ICF syndrome

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10
Q

Methylation sequence during mammalian development

A

Preimplantation low
Implantation high

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11
Q

Rett syndrome

A

Mutations in MeCP2 gene that reads and binds to methylated DNA

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12
Q

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

A

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

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13
Q

L1 and IAP retrotransponsons are never

A

DNA sequences that move around the genome but cant once methylated

Unmethylated

Inherited demethylated from mother then methylated

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14
Q

Alu
Why

A

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

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15
Q

Methylation amount in different organisms

A

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

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16
Q

5methylcytosine in vertebrates vs invertebrates

A

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

17
Q

Deamination

A

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

18
Q

4 values of methylation

A

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

19
Q

Transponsons what are they
Use
Danger
Other name

A

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

20
Q

Failure in methylation in hybrid marsupials can cause

A

Activation to retroviral elements and cause chromosome remodeling

21
Q

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

A

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

22
Q

Gene number is …..than the total DNA
Percentage

A

Less than
5800 to 39000
Only 10% of total genome

23
Q

The larger the genome the….the…

A

Larger the repetition

24
Q

Repetitive DNA types
Regarded as
Except

A

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

25
Q

Satellite types

A

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

26
Q

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

A

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

27
Q

Some defects

A

Unequal crossing over due to repeated sequnce
Gene conversion
Replication slippage

28
Q

What is gene conversion

A

DNA sequence replaces a homologous sequence so that they become exact

29
Q

Repeated genes
What are they
Often concentrated in…
Like

A

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

30
Q

Protein families

A

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

31
Q

What is ICF syndrome

A

Immunodeficiency Centromeric instability and facial anomalies
A disease of DNA methylation

32
Q

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

A

Extensive variation
Sequence

33
Q

C value paradox the ..of DNA in…

A

Amount
Haploid genome

34
Q

Tandem repeats are referred to as

A

Satellites

35
Q

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

A

CA
GA/AT

36
Q

Microsatellites are less common in…

A

Coding regions
And telomeres

37
Q

Damage agent repair
Pyrimidine dimer
Alkylation and depurination
Mispaired bases

A

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

Genetics 2 (10 decks)

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