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Genetics > Week 11 > Flashcards

Week 11 Flashcards

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Biology 101 flashcards
1
Q

Major genome sequence variation

A

indels
translocaton
iversion

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2
Q

Duplication

A

a special subtype of insertions

they increase the copy number of genes

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3
Q

Large scale genome changes

A

Cytogenetics
PCR
DNA sequencing

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4
Q

Cytogenetics

A

What you can see down a microscope:

Karyotype
salivary gland giant chromosomes

Autosomes are organized based on size

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5
Q

Karytope chromosome types

A

depends on the location of the centromere

metacentric (middle centromere)

submetacentric (slightly before center)

acrocentric (closer to the one side)

telocentric (end of the chromosome)

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6
Q

human chromosome

A

no telocentric chromosomes

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7
Q

Drosophila giant polytene chromosomes

A

during salivary gland development cell division stops

DNA keeps replicating

homologs are aligned

protein associate differentially along the chromosomes creating a specific banding pattern when stained

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8
Q

PCR detection of genome variation

A

microsatellites or short tandem repeat

there can be variation at these loci due to slippage and translocation

use reverse PCR primers (2 on each strand) to detect the STRs

allows you to tell if an individual is heterozygous or homozygous for tandem repeats

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9
Q

Chromosomal deletions

A

multiple genes affected
effect on recombination frequency
complementation analysis
cytogenetics and PCR

If the deletion is large enough we can detect it in the karyotype

lethal when homozygous

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10
Q

Chromosomal deletion: effect on recombination frequency

A

decreases recombination frequency

if deletion is 10mu the map distance between two genes will decrease

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10
Q

Chromosomal deletion: effect on recombination frequency

A

decreases recombination frequency

if deletion is 10mu the map distance between two genes will decrease

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11
Q

Polytene chromosome deletions

A

because the homolohues align you get a bubble wt info not present on the chromosome forms a bulb

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12
Q

PCR analysis of chromosomal deletions

A

we get product from the deletion (primers designed for the deleted chromosome)

wt would be to long to detect

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13
Q

Chromosome duplications

A

Duplication are copy number variation that you can see through a microscope

Tandem duplication

Displaced duplication

Reverse duplication

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14
Q

Polytene chromosome duplication

A

duplicated homolog forms a bulge on the wt homolog

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15
Q

Use of duplication

A

allows us to test for haploinsufficiency

if the addition of the functional duplicated gene resues the phenotype we are dealing with haploinsufficient

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16
Q

Duplication of genes

A

increases gene dosage

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17
Q

Copy number variants in humans

A

estimated that between 5-10% of the human genomic sequence are copy number variants

smaller duplication

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17
Q

Copy number variants in humans

A

estimated that between 5-10% of the human genomic sequence are copy number variants

smaller duplication

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18
Q

origin of deletions and duplications

A

generally associated with recombination between repeated DNA sequence

transposons and other repeated sequences

genetic variation can be due to repetitive dna sequence recombining

19
Q

Types of inversions

A

paracentric: around the centromere

pericentric inversion: inversions containing the centromere

20
Q

Genes at breakpoints will be affected

A

genes can be split in half resulting in a null loss of function

genes can be linked to a new regulatory sequence resulting in gain-of-function

21
Q

Effect of inversion on recombination frequency

A

any recombination within the inverted region results in non-viable gametes

only viable recombinants are going to occur just outside the inverted region

shrinks map distance between genes flanking the inversion

22
Q

Non-reciprocal translocation

A

portion of the chromosome is duplicated into another chromosome

a displaced duplication

23
Q

Reciprocal translocation

A

exchange beween chromosome arms

24
Q

Effects of translocation

A

splitting of genes at breakpoints (lf)

gene is next to a new DNA sequence (gf)

25
Q

Oncogenes as a gain of function

A

Bcl-2 gain of function, the gene is translocated to another chromosome arm containing a Igg heavy chain promoter

lots of Bcl2 is produced leading to cell survival and reducing apoptosis

26
Q

Adjacent 1 segregation

A

horizontal between chromosomes

translocated genes are missing from either gamete

27
Q

Adjacent 2 segregation

A

vertical segregation results in missing genes on the untranslocated arm in the gametes

inviable gametes

rare

28
Q

Alternate segregation

A

normal chromosomes move to one side

translocated chromosomes move to the other side

viable gametes

29
Q

Aneuploidy Types

A

Nullisomy: 2n-2

Monosomy: 2n-1

Trisomy: 2n+1

Tetrasomy: 2n+2

30
Q

Nullisomy

A

loss of a pair of chromosomes

31
Q

Monosomy

A

loss of a single chromosome

32
Q

Trisomy

A

addition of an extra chromosome

33
Q

Tetrasomy

A

addition of a pair of chromosomes

34
Q

Mitotic nondisjunction

A

both sister chromatids are pulled to one pole resulting in the cells with different number of chromosomes

35
Q

Gynandromorph

A

one side has male tissue the other side has female tissue

non-disjunction of x chromosomes during female development

36
Q

Meiotic Nondisjunction

A

Nondisjuction at Meiosis I

Nondisjunction at Meiosis II

37
Q

Nondisjunction at Meiosis

A

Homologoues chromosomes move to the same pole during meiosis

2 gametes are missing chromosomes

fertilization results in trisomy and monosomy

37
Q

Nondisjunction at Meiosis

A

Homologoues chromosomes move to the same pole during meiosis

2 gametes are missing chromosomes

fertilization results in trisomy and monosomy

38
Q

Non disjunction at Meiosis II

A

Sister chromatids are pulled to the same pole

1 gamete is missing chromosomes, fertilization results in two viable gametes, trisomy and monosomy

39
Q

Trisonomy 21

A

progeny can survive with an extra chromosome 21 because it doens’t contain that much info and it is not lethal

92% of down’s

75% are maternal in origin

majority arise at meiosis I

40
Q

Inheritance of recessive cystic fibrosis

A

not always mendelian

uniparental disomy

non-disjunction at meiosis II

fertilization of the gamete containing the two CF+ alleles resulting in trisonomy

If the cell divides normally the progeny will not survive, if non-disjunction occurs during cell division of the embryo, it will be viable and have cystic fibrosis

41
Q

Polyploidy

A

Change in the number of sets of chromosomes (all chromosomes)

2n to 3n to 4n

2n to 4n is a whole genome duplication

42
Q

Whole genome duplication durgin vertebrate evolution

A

genomes have duplicatede so that all genes have a copy number of 4

Occurs in the hox2 genes (important for determining which body part develops where)

Four copies of each Hox gene, some have been lost during vertebrate evolution.

43
Q

Autopolyploidy (Mitotic)

A

Mitotic

no division of the nucleus, stimulate non-division by treating cells with colchicine (microtubules can’t breakdown)

44
Q

Autopolyploidy (Meiotic)

A

All homologous chromosomes go to one pole

gametes contain two copies of each homologous chromosomes (2n instead of n) fertilization results in 3n cells

45
Q

segregation of 3n or odd n chromosomes

A

this is the origin of seedless fruits

the gametes are so unbalanced and inviable that no seeds form

results in problems at meiosis

random number of each one of these chromosome

more chromosomes result in more unbalanced gametes

46
Q

Allopolyploidy

A

fusion of gametes from two distinct species

inviable gametes, each chromosome is different from one another, random segregation of the chromosomes

Genetics (16 decks)

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