Inheritence and Mandelian Genetics - Genetics 1 & 2 Flashcards

1
Q

Genetic Diversity

A

Variation in genetic traits within a population.

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2
Q

Why is genetic diversity essential for evolution?

A

In order for traits to be selected for, genetic diversity is needed (different combinations of alleles).

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3
Q

Mutation

A

Change in bases of DNA sequence affecting genetic information - including functional and non-functional genes.

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4
Q

Karyotypic Changes

A

Alterations in chromosome structure or number.

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5
Q

Evolution

A

Process by which species adapt over time.

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6
Q

DNA Replication

A

Process of copying DNA before cell division.

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7
Q

Polymerases

A

Enzymes that synthesize DNA strands.

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8
Q

How is erorr rate reduced in the DNA sequence during replication

A

Proofreading and mismatch repair

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9
Q

Proofreading

A

Error-checking mechanism during DNA synthesis in proofreading domains of polymerases

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10
Q

Mismatch Repair

A

Correction of base-pairing errors in DNA.

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11
Q

Base-Excision Repair

A

Repair mechanism for oxidative DNA damage.

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12
Q

How else can mutations occur apart from random changes to neucleotides?

A

DNA Damage. Agents causing mutatations (mutagens) cause their accumulation

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13
Q

Why do we use harmful chemicals

A

They havn’t been discovered yet as a mutagen/carcinogen

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14
Q

Deleterious

A

Negative, causing harm

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15
Q

Why do organisms have fine-tined mutation rates

A
  • Too many mutations would be deleterious
  • Mutations generate genetic diversity on which evolution acts
    Successful organisms have evolved to repair their DNA efficiently, leaving just enough genetic variability for evolution to continue.
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16
Q

Transition Mutation

E.g. C - T

A

Substitution of one purine for another purine.

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17
Q

Transversion Mutation

E.g T - G

A

Substitution of a purine for a pyrimidine.

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18
Q

3 types of substitution mutations

A
  • Silent
  • Nonsense
  • Missence
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19
Q

Missense Mutation

A

Single base change alters amino acid in protein.

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20
Q

Silent mutation

A

No effect because of the degenerate nature of amino acids

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21
Q

Why are missence mutations sometimes managable

A

R groups of the different amino acid being coded for can have the same charge/polarity (properties) so the 3D structure it folds to is similar enough to carry out its function.

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22
Q

Frameshift Mutation

A

Insertion or deletion alters reading frame of DNA. Every subsequent codon is changed and is are each/most amino acids coded for in the final protein. Protein is unable to bind so unexpressed

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23
Q

Nonsense Mutation

A

Mutation that creates a premature stop codo, producing a truncated protein.

24
Q

Where are frameshift mutations common?

A

In tumor supressor genes

25
Q

Sequence Divergence

A

Variation in DNA sequences among species. Used as a measure of evolutionary relatedness.

26
Q

How is sequence divergence used to measure evolutionary relatedness?

A

Sequences of different organisms are compared for differences, less differences = more closely related

27
Q

Conservation of sequences between different species

A

These sequences have vital fucntions for life. For instance the genes coding for histones which bind to DNA that wraps around, giving histones their shape.

28
Q

Conserved Sequences

A

DNA sequences that remain unchanged across species.

29
Q

Genome Instability

A

Allows frequent mutations leading to genetic diversity that natural selection can act on. It is also a hallmark of cancer

30
Q

Karyotype

A

Visual representation of a person’s chromosomes - can be used to identify oddities in chromosome number/structure.

31
Q

Structural variants of karyotype variation

A

IMAGE

32
Q

Cancer Karyotypes

A

Extreme of genetic diersity - chromosomal variations associated with cancer.

33
Q

Source of genetic diversity that isn’t mutation

A

Chromosomal changes during viral infection and meiosis

34
Q

HIV Resistance

A

Genetic mutation providing immunity to HIV.

35
Q

Natural Selection

A

Process where organisms better adapted survive.

36
Q

SARS-Cov-2 Mutation

A

Genetic changes affecting virus infectivity.

37
Q

Mendel’s pea experiments

A

Only used true breeding plants and studies 7 of the plant’s phenotypes. E.g pea shape and colour, and flower colour and position.

38
Q

What do we assume when doing genetic crossing experiments?

A

Gnetic occurances have direct impact on phenotype - this only occurs when 1 gene impacts a specific phenotype

39
Q

True breeding

A

Phenotypes of offspring are the same as in the parents regardless of how many times they are crossed - nothing new.

40
Q

What did Mendel deduce?

A
  • Traits are controlles by a pair of inherited “factors”
  • One is dominant and one is recessive
  • Pairs segregate randomly during gamete formation - causing different impacts on the phenotyoe
41
Q

Dominant and recessive alleles are contrary to the priginal blending model of genetic inheritence

A

Previously thought that phenotypes olccured due tp blending of parents characteristics (gene)

42
Q

Predict the outcomes of an RR x rr and Rr x rr cross

A
  • RR x rr: 100% Rr
  • R r X rr: 50% rr, 50% Rr
43
Q

Knockout mice

A

Genetically modified lab mice with one or more genes that have been intentionally inactivated

44
Q

You breed 2 heterozygous knockout mice and need homozygous knockout offspring (25%). You notice the litter is smaller than normal and when you run a gel electrophoresis you notice none of the pups are homozygous for the knockout gene. Why?

A

Pups with homozygous knockout are not viable for life so don’t go to full term, hence the smaller litter. Essential genes encoding proteins vital to cellular life were knocked out.

45
Q

Embryonic lethality

A

The death of all organisms in a population during the embryonic period. It is a common phenotype in mice that have genetically engineered mutations.

46
Q

What did Mendel seek to investigate with his usage of dihybrid crosses?

A

Are characteristics of the peas (heritable traits) inherited independently (in an identifiable way from each other) or are they linked.

47
Q

Dihybrid crosses

A

Used to investigate the inheritence of two different traits and how they are combined in the offspring.

48
Q

Mendel’s law of inheritence

A
  1. Law of dominance
  2. Law of segregation
  3. Law of independent segregation
49
Q

Law of segregation

A

When a gamete is formed, the two alleles at a specific location separate, and each gamete has an equal chance of containing either allele.

50
Q

Law of independent segregation

A

During reproduction, two genes independently segregate, each independently determining one aspect of the phenotype

51
Q

Law of dominance

A

When a pair of contrasting characters are present together, only one expresses itself, while the other remains suppressed. (dominance vs recessiveness).

52
Q

Pleiotropy

A

Single gene mutation can cause a range of phenotypes

So, the pheotypes don’t appear the same in 2 patients

53
Q

Gnetic heterogeneity

A

Same penotype can be cause by a range of different genes. As a result, certain symptoms can be difficult to diagnose.

54
Q

Polygenic

A

Traits controlled by more than one gene

55
Q

Examples of polygenic traits

A

Human height, eye, hair and skin colour.
These all have lots of variation within a popualtion.

56
Q

Codominance

A

Two alleles are expressed equally in an organism, resulting in the appearance of both traits/phenotypes.

57
Q

Incomplete dominance

A

Two alleles are blended/mixed rather than both expressed. It’s also known as partial dominance, semi-dominance, or intermediate inheritance.

A white and red flower would prodice a pink flower.