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Cells and Genes SF1 > Mendelian and Molecular Genetics > Flashcards

Mendelian and Molecular Genetics Flashcards

1
Q

What are Mendel’s postulates?

A

Unit of genetic inheritance: 1 genes is inherited from each parent
Dominance/ Recessive
Segregation: Alleles are separated randomly in meiosis
Independent assortment: Alleles

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2
Q

what is heritability?

A

how much of a characteristic is due to genetics or the environment: H2 = Genetic variance/ genetic + phenotypic variance.

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3
Q

what is the goal of selective breeding?

A

To improve characteristics/ heritable qualities of the population.

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4
Q

What is the difference between genotype and phenotype?

A

genotype is the assortment of alleles, phenotype is the physical expression of the gene.

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5
Q

describe 3 allelic interactions.

A
  • complete dominance: homozygous and heterozygous phenotypes are the same.
  • Incomplete dominance: Where there is an intermediate phenotype.
  • codominance: when the alleles affect the phenotype in separate distinguishable ways. ex) spotting gene in calico cats + piebalding gene.
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6
Q

what is pleiotropy?

A

when a gene has multiple phenotypic effects.

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7
Q

what is epistasis?

A

when an allele effects the expression of a different allele on a separate locus

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8
Q

what is the male sex genotype

A

heteromorphic XY

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9
Q

what are non sex chromosomes called?

A

Autosomes

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10
Q

what are bird sex chromosomes

A

F: ZW
M: ZZ

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11
Q

What animals have temperature determining sexs

A

Crocodiles - extreme temp = F
Australian Skinks, Australian dragon lizards
Turtles - Cold = M

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12
Q

What is Sry

A

Sex determining region on the Y chromosome (leads to testes production)

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13
Q

descrive XY gene

A

Hemizygous

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14
Q

Describe the gene for Haeomophilia A

A

X linked recessive: Factor VIII is produced, causing impaired blood clotting. a

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15
Q

Describe the gene for Canine Muscular Dystrophy

A

X linked recessive

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16
Q

Describe X chromosome inactivation, give an example where this is show phenotypically.

A

during embryological development an x chromosome will be inactivated by Lyonisation. Meaning only 1 gene in the X chromosome will be expressed (Dosage Compensation).
The inactive X chromosome will become a Barr Body within the cell.

ex) tortoiseshell cats are mainly female due to this.
One allele will code for orange fur, one for black.

17
Q

How are loss of function genes expressed

A

If both alleles are mutated

(gain of function is dominant)

18
Q

what is Heterosis

A

Crossing of homologous strains to form a stronger offspring.
AKA Hyprid vigor.
Used in agriculture

19
Q

Describe Overdominance and give an example

A

when heterozygotes create a superior phenotype to homozygous ex) Sickle Cell. Heterozygous individuals will have a lower degree of sickle cell (1 dom 1 recessive) so are malaria resistant. (erythrocytes will rupture if infected, so parasite cannot reproduce).

20
Q

What is Penetrance

A

how much a gene is expressed throughout a population

21
Q

what is population genetics:

A

the genetic difference within and between populations ex) Dog breeds

22
Q

what is the difference between quantitative genetics and qualitative genetics

A

qualitative is mendelian, individuals groups.
quantitative is on a scale, usually polygenetic

23
Q

describe the 4 processes of population genetics

A

selection
mutation
genetic drift - change in alleles frequency
genetic flow - population seperated

24
Q

Describe Genetic material

A

DNA - double helix running antiparallel, made of nucleotides linked by 5 3 phosphodiester bonds.
Bases are non overlapping.
Degenerate.

25
Q

What is telomere and describe its function

A

the end of a chromosome.
Protects the chromosome from degradation or unnecessary recombination

26
Q

What is a Histone?
what is its function?

A

a protein associated to DNA
helps chromosomes condense

27
Q

What is Chromatin?
What are the different types?

A

the DNA + protein complex
Euchromatin is less condensed, so easily transcribed.
Heterochromatin is highly condensed

28
Q

What is a nucleosome?

A

1.65 turns of of DNA wrapped around 8 histone proteins (histone octamer)

29
Q

How is a chromosome formed?

A

an H1 histon links nucleosomes

30
Q

What is Chromatin Remodelling

A

controlling how DNA is used and condensed.

31
Q

describe ATP dependent remodelling

A

loosens nucleosome to make DNA easier to access

32
Q

name and describe 3 different types of Covalent Histone Modification

A
  • Acetylation: acetyl transferase adds acetyl group to the amino acid to dissociate it with the histone. (DNA becomes positive).
  • Methylation: methyl transferase inactivates chromatin so it binds tighter to the nuclear protein (becomes heterochromatin) so harder for transcription factors to reach.
  • Phosphorylation: Kinase exposes promoter to transcription factor
33
Q

How is the histone modified?

A

Lysine rich N terminals extend out the nucleosome between the DNA. These tails are covalently modified which act as binding sites for regulatory proteins.

34
Q

Which amino acids on the histone are modified by which covalent modification?

A

acetyllation and methylation of lysine
methylation of arginine
phosphorolation of serine.

35
Q

What are Epigenetics ?

A

how environment effects the phenotype. Changes in wether the gene gets switched on or off, so the genotype stays the same.
however is inherited

36
Q

what causes epigenetic effects?

A

modifications after DNA replication
ex) histone methylation, acetylation, phosphorylation, DNA methylation

37
Q

What is metabolic loading

A

when consuming excess calories yet are nutrient deficient.
will cause epigenetic in the foetus

38
Q

what are the epigenetic changes associated with a low protein diet in the mother (in rodents) ?

A

the offsprings pancreatic weight increases, so there are less B cells, less insulin.

39
Q

what is the function of non coding RNA?

A

regulated gene expression at a post translation level. makes up 90% of the genome.

Cells and Genes SF1 (11 decks)

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