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Genetics Flashcards

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1
Q

What is a chromosome

A

A chromosome carries genetic information. When the cell is not dividing, the nucleic material is spread out as chromatin

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2
Q

Haploid, diploid, and what is special about an organisms chromosomes

A

Haploid: one set of each unique chromosome
Diploid: two sets of each unique chromosome
The number of chromosomes is mostly unique to an organisms

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3
Q

Euploidy vs aneuploidy

A

Correct number of chromosomes vs incorrect number of chromosomes

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4
Q

Wheat: 6n, 42c, how many types of chromosome?

A

7

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5
Q

Define phenotype and genotype

A

Observable expression of genotype
Unique set of DNA

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6
Q

Law of segregation

A

Two alleles for each gene separate during gamete formation

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7
Q

Law of independent assortment

A

Alleles of genes on non homologous chroms assort independently during gamete formation

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8
Q

Chromosome theory of inheritance

A

Genes have specific loci along chromosomes and chromosomes undergo segregation and indepdent assortment

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9
Q

Make development requires

A

A gene on y Chrom: SRY

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10
Q

Fathers: pass X linked alleles to
Mothers: pass X linked alleles to

A

All daughters not sons
Both

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11
Q

Homozygous for allele

A

Inherited same alleles of a gene from each parent

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12
Q

For males you can’t use homozygous use

A

Hemizygous

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13
Q

In human the male phenotype is determined by

A

Presence of Y Chrom, had SRY switch

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14
Q

Haplodilpoid sex determination

A

Controlled via fertilization, leads to higher social interrelatedness

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15
Q

Unicellular organisms like mushrooms have 7 mating types that are only compatiable with one other at a given time

A

Ensure genetic diversity and maintain resistance to environmental change

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16
Q

Sex determination in humans vs crocodile va barramundi

A

Humans: depends on what SRY gene does
Crocodiles: sex switch depends on incubation temperature during critical period during embryo development
Baramundi: start as males will remain as males if temperature drops, rainwater lowers salinity, food is scarce as wouldn’t be able toput energy into developing eggs. If conditions are right > become female

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17
Q

Baramundi and crocodile sex determination vs humans (switch)

A

In the animals there is a switch which is a response to environmental change
In humans chromosomal sex determination the switch for sex can’t be turned off

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18
Q

Theoretical chromosomes duplicate in S phase in interphase

A
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19
Q

Early prophase

A

Chromatin anchors to nuclear membrane and starts condensing

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20
Q

Late prograde

A

Nuclear membrane starts breaking down

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21
Q

Prometaphase

A

Spindle fibres attach to centromere

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22
Q

Metaphase

A

Tension of spindle fibres draws chromosomes into metaphase plate

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23
Q

Anaphase

A

Tension high enough- causes kinetic bores to break, sister chromatids forms and travel to opposite sides of the cell

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24
Q

Teloohase

A

Nuclear membrane begins to form. Two daughter cells begin to form

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25
Interphase
Cell begins duplicating theoretical chromosomes
26
Micotic cell division
No. Chroms is the same No. Chromatids per chromosome decreases from 2->1 Interphase will duplicate info -> 2 chromatids again so it can split
27
Meiosis
Change in no. Chroms 2 parents therefore the amount of nuclear material going into the gamete must halve
28
Meiosis interphase
Pair of homologous chromosomes in diploid parent cell DUPLICATE into 2 sister chromatids per chromosome (2 chroms in the cell)
29
Prophase 1
1. Chromosome pairs with its homolog, crossing over (RECOMBINATION) occurs at CHIASMA DNA molecules of nonsister chromatids are broken by proteins and rejoined together 2. Spindle fibres attach to the kinetocores (ONE AT THE CENTROMERE OF EACH HOMOLOG) 3. Homologous pairs moved toward metaphase plate
30
Metaphase 1
Aligned along metaphase plate
31
Anaphase 1
Homologs move toward opposite ends of cell (NOT BROKEN APART)
32
Telophase 1
2 daughter cells with 2 chromatids per chromosome NEED TO HALVE THIS
33
Meiosis 11
Like mitosis -> serves to half number of chromatids per chromosome to 1
34
Define recombination
The process of exchanging genetic information between chromosomes Genes same but versions of genes different
35
What is the difference with meiosis 2
2 spindle fibres attach to the kinetocores in anaphase 2 causing the kinetocores to break In meiosis 1 the kinetocores didn’t break, the bivalents were separated
36
consequences of meisos - gametes - recombination
forms haploid gametes increases genetic diversity and resistance to environmental change through genetic recombination and chiasma formation
37
mitosis __ the number of chromatids that make up a chromosome meisosis ___ the number of chromatids that make up a chrom
maintaines halves
38
where n is the number of chroms the number of possible combinations of chrom phenotype is
2^n for every crossover that occurs you can double 2^ number
39
5 factors of mendelian inheritance
1. the phenotype is determined by heritage factors (genes) 2. alternate forms of genes are responsible for variation in inherited characteristics 3. for each character an organism inherits 2 copies of a gene one from each parent 4. if 2 different alleles are present, one is fully expressed and the other is recessive 5. the two alleles for each trait segregate during gamete production
40
incomplete dominance
heterozygote has a different phenotype from either homozygote
41
codomiance
the phenotype of both alleles is expressed
42
autosomal inheritance
transformation of genetic information on non-sex chromosomes, affecting males and females equally
43
example: R dominant -> red r recessive -> white what would incomplete and codominance look like?
incomplete dominance: heterozygote: Rr is not red nor white, it is pink. 3rd phenotype therefore incomplete dominance codomiance: RR and rr both exist simultaneously causing pink colour. FOR THE FLOWER EXAMPLE: THE EXPRESSED PHENOTYPE INFLUENCES POLLINATION AND THUS PASSING DOWN OF GENES THEREFORE IT IS INCOMPLETE DOMINANCE
44
What does the persistence of genes in a population depend on
the ecological interactions for which the genes are responsible for
45
mendelian genetics phenotypic and genotypic ratios for recessive + dominant system
phenotype 3:1 genotype 1:2:1
46
population
localised group of freely interbreeding organisms that belong yo the same species
47
geneflow
movement of genes between populations as a result of migration/gamete dispersal if gene flow is 0 -> speciation
48
gene pool
sum of total of all genes and their alleles present in a population
49
two alleles of the same gene will not stay in the same gamete meiosis 1: separate chrom pairs meiosis 2: breaks chrom apart
50
to find the proportion (relative frequency) of alleles you must
times the total genotypes by 2
51
In HW equilibrium:
genotype frequency: p^2 + 2pq+q^2 = 1 the allelic frequencies remain constant
52
5 conditions of HW equilibrium
1. no gene flow, population is closed 2. population is large 3. random mating by phenotype 4. no natural selection 5. no mutations
53
what is evolution (genetics answer)
change in the frequencies of alleles in a population over time
54
genetic drift
change in frequency of an existing gene variant due to random chance. occurs to a greater extent in smaller populations ---> decreases genetic diversity, high chance of losing recessive allele
55
genetic drift + decreasing population size
genetic drift will stabilise on homozygosity and decrease heterozygosity
56
genetic bottlenecks
populations size is drastically reduced in time --> change in allelic frequencies, loss of genetic diversity
57
founder effects
spatial version of a bottleneck. constriction of a population in space not entire genetic variation represented when species migrate, loss of genetic diversity
58
stabilising selection is what advantage
heterozygote advantage. stabilising selection requires pressure against both homozygotes
59
example of heterozygote advantage
sickle cell anemia and malaria resistance. having sickle cell recessive trait means resistant to malaria, overall net benefit despite still getting a little sick from sickle cell
60
diversifying selection
selection against the heterozygote, homozygote favoured
61
directional selection
one allele is selected for
62
Assume that genes A and B are 50 map units apart on the same chromosome. An animal heterozygous at both loci is crossed with one that is homozygous recessive at both loci. What percentage of the offspring will show recombinant phenotypes resulting from crossovers? Without knowing these genes are on the same chromosome, how would you interpret the results of this cross?
If they are 50 units apart, this means the recombination frequency is 50%, therefore, 50% of the offspring will show recombinant phenotypes resulting from crossovers. This is a high percentage of recombination and is similar to what would be expected from genes not on the same chromosome. Therefore, the high recombination frequency would lead to the interpretation that the genes are not on the same chromosome or that they are unlinked.
63
Q: Why are specific alleles of two distant genes more likely to show recombination than those of two closer genes?
Crossing over is a random occurrence, and the more distance there is between two genes, the more chances there are for crossing over to occur, leading to new allele combinations.
64
trisomony defintion and example
one extra copy of that chromosome (2n+1) causes down syndrome
65
why are inversions and reciprocal translocations less likely to be lethal than aneuploidy, duplications, deletions and nonreciprocal translocations?
In inversions and reciprocal translocations, the same genetic material is present, just rearranged differently. Deletions, duplications, aneuploidy and nonreciprocal translocations cause changes to the chromosome structure via removing a section, duplication of a section, changing chromosome number, and moving sections to another chromosome, respectively. Therefore, the balance of genetic material is upset. This can disrupt gene function and lead to adverse phenotypic effects.
66
67
Banana plants, which are triploid, are seedless and therefore sterile. Thinking about meiosis, propose a possible explanation.
As they are triploid, chromosomes cannot be paired up evenly during meiosis. this results in imbalanced chromosomes in the gametes, making them sterile
68

Biology (5 decks)

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