Module 5: Genetic Variation Flashcards

(37 cards)

1
Q

What is genetics?

A

Genetics is the field of study that examines genes and inheritance.

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2
Q

What is genotype?

A

The information contained in your DNA for each gene.

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3
Q

What is phenotype?

A

The observed physical expression of your genes.

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4
Q

What does it mean when something is “homozygous” for a trait?

A

Both letters in the genotype are the same.

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5
Q

What does it mean when something is “heterozygous” for a trait?

A

The letters in the genotype are different.

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6
Q

How is the probability of offspring genotype predicted?

A

Using punnett squares.

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7
Q

Who discovered the basics of genetics?

A

Gregor Mendel.

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8
Q

What is complete dominance?

A

The phenotype of heterozygotes cannot be distinguished from homozygous dominants.

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9
Q

What is an example of comlete dominance?

A

Purple and white flowers in Gregor Mendel’s pea plants.

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10
Q

What is incomplete dominance?

A

The phenotype of heterozygotes appears as a blend of the phenotypes of either type of homozygotes.

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11
Q

What is an example of incomplete dominance?

A

The breeding of red and white snapdragons creates pink snapdragons.

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12
Q

What is codominance?

A

The phenotype of heterozygotes involves both alleles being expressed, with neither dominant over the other.

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13
Q

What is an example of codominance?

A

When brown and white cattle are bred, the result is a roan coat, featuring brown and white hairs together.

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14
Q

What signals incomplete dominance in sickle cell disease?

A

When looking at the phenotype of a heterozygote, they appear to have an intermediate condition of the two homozygous phenotypes.

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15
Q

What signals codominance in sickle cell disease?

A

At a molecular level the heterozygote is expressing both alleles, creating both normal and abnormal haemoglobin.

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16
Q

What are some advantages of models?

A

They help us see things we can’t normally see, help us understand scientific phenomena, and help us notice patterns.

17
Q

What are some limitations of models?

A

They can be oversimplified, they cannot possibly account for every detail in scientific phenomena, and as a result can be innaccurate.

18
Q

What is the purpose of scientific models?

A

Models help us see and understand things that we cannot directly observe, such as very large or very small phenomena.

19
Q

What are 2 examples of things models can show?

A

The solar system and a cell.

20
Q

What are the benefits of using models?

A

They help us understand complex phenomena and notice patterns.

21
Q

Why are models never fully accurate?

A

They are oversimplified and cannot explain every detail of complex concepts.

22
Q

Why do scientists use models to study meiosis?

A

Because meiosis involves complex microscopic processes that are difficult to directly observe.

23
Q

What is crossing over?

A

The exchange of genetic material between homologous chromosomes during meiosis.

24
Q

During which phase of meiosis does crossing over occur?

25
What is the importance of crossing over?
It increases genetic variation by shuffling alleles and creating unique combinations in gametes.
26
What is the result of fertilising gametes that underwent crossing over?
Zygotes with novel genotypes, leading to phenotypic diversity.
27
What is another name for crossing over?
Genetic recombination
28
Between which chromatids does crossing over occur?
Non-sister chromatids of homologous chromosomes.
29
What structure do homologous chromosomes form during crossing over?
A tetrad (four chromatids).
30
What are mutations?
Alterations in genes caused by external factors such as chemicals or radiation.
31
How do mutations contribute to genotypic variation?
They introduce new genes or alter existing ones, leading to new genotypes.
32
How can mutations affect gene expression?
The can silence certain genes, changing or eliminating traits.
33
What are most genetic disorders in humans caused by?
Recessive alleles that only show in the phenotype when someone is homozygous for the disorder.
34
Why can genetic disorders be carried through families unnoticed for generations?
Because carriers (heterozygous individuals) do not show the disorder phenotype
35
What can pedigrees be used for?
Understanding inheritance patterns and determining whether a gene is dominant, recessive, autosomal, or sex-linked.
36
What is a defining feature of an autosomal dominant trait in a pedigree?
An affected individual always has at least one affected parent.
37
Can two affected parents have an unaffected child in an autosomal dominant condition?
Yes