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Biology > 10.2 Inheritance > Flashcards

10.2 Inheritance Flashcards

1
Q

How do unlinked genes segregate as a result of meiosis?

A

Unlinked genes segregate independently as a result of meiosis

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2
Q

What is segregation?

A

The separation of the two alleles of every gene that occurs during meiosis

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3
Q

What is independent assortment?

A

The observation that the alleles of one gene segregate independently of the alleles of other genes

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4
Q

Where can unlinked genes be found?

A

On different chromosomes

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5
Q

How do unlinked genes segregate?

A

Independently as a result of meiosis

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6
Q

Where can linked genes be found?

A

On the same chromosome

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7
Q

How do linked genes segregate?

A

They do not segregate independently

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8
Q

What is the exception for linked genes to be segregated independently?

A

If they are far apart on the chromosome

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9
Q

What does it mean when two gene loci are further apart on a chromosome?

A

There is a greater chance of recmobinant gametes forming

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10
Q

When are gene loci said to be linked?

A

If they are on the same chromosome

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11
Q

What is a locus of a gene?

A

A particular gene that is found in a specific position on one chromosome type

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12
Q

What does it mean when two chromosomes are homologous?

A

They have the same sequence of genes

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13
Q

How are homologous chromosomes not usually identitical to each other?

A

Because, for at least some of the genes on them, the alleles will be different

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14
Q

What are autosomes?

A

Chromosomes that are common to males and females
* In males there is an X and another is a Y chromosome.
* In female two of them are X chromosomes
* The other 6 chromosomes are common to both male and females <- they are called autosomes

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15
Q

What are autosomes?

A

Chromosomes that are common to males and females
* In males there is an X and another is a Y chromosome.
* In female two of them are X chromosomes
* The other 6 chromosomes are common to both male and females <- they are called autosomes

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16
Q

What are the two types of linkage?

A
  • Autosomal gene linkage
  • Sex linkage
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17
Q

What is autosomal linkage?

A

When the genes are on the same autosome
* gene loci present on the same autosome (non-sex chromosome) that are often inherited together

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18
Q

What is sex linkage?

A

When the genes are located on the X chromosome

19
Q

What can variation be? (2)

A

Discrete or continuous

20
Q

What is referred to as variation?

A

The differences between individual organisms

21
Q

Is blood type discrete or continuous variation?

A

Discrete because while there are several blood types, there are no in-between categories

22
Q

Is blood type discrete or continuous variation?

A

Discrete because while there are several blood types, there are no in-between categories

23
Q

What type of variation do the phenotypes of polygenic characteristics tend to show?

A

Continuous variation

24
Q

What is an example of continuous variation?

A

Height

25
Q

What does a normal distrubution curve look like?

A

A bell-shaped curve

26
Q

What are 4 characteristics of a normal distribution?

A
  • The mean, mode and median are the same
  • The distribution has a characteristic bell shape which is symmetrical about the mean
  • 50% of the values are less than the mean and 50% are greater than the mean
  • Most values lie close to the mean value - the number of individuals at the extremes are low
27
Q

What are polygenic traits?

A

Traits that are controlled by two or more than two genes (usually by many different genes) at different loci on different chromosomes
* These genes are described as polygenes

28
Q

What is polygenic inheritance?

A

Polygenic inheritance refers to a single characteristic that is controlled by more than two genes (also called multifactorial inheritance) Polygenic inheritance patterns normally follow a normal (bell-shaped) distribution curve - it shows continuous variation.

29
Q

What are the two causes of variation?

A

Genetic and environmental

30
Q

What are 3 causes of genetic variation?

A
  • Mutations - changes to the DNA sequence that lead to new alleles
  • Meiosis - independent assortment and crossing over
  • Sexual reproduction - random fusion of gametes from two unrelated individuals
31
Q

What are characteristics that exhibit discontinuous variation usually determined by?

A

the alleles of a single gene locus - they are monogenic

32
Q

What is meant by monogenic?

A

Characteristics that exhibit discontinuous variation that are determined by the alles of a single gene locus
* One gene = monogenic

33
Q

What is meant by polygenic?

A

When many genes are involved in determining such characteristics

34
Q

What does it mean when the alleles have an additive effect on the phenotype?

A

The alleles of each gene may contribute a small amount to the phenotype, therefore the alleles have an additive effect on the phenotype

35
Q

How does polygenic characteristics show continuous variation?

A

As a result of the additive effect on the phenotype, the phenotypic categories vary in a quantitive way.
* The greater number of gene loci contributing to the determination of the characteristic, the more continuous the variation (the greater the range)

36
Q

Contintious vs discontinous variation (discrete)

A
37
Q

How can the number and frequency of variants be predicted?

A

Using alternative rows of Pascal’s triangle

38
Q

What may polygenic traits also be influenced by besides by multiple genes?

A

Environmental factors

39
Q

What is variation due to polygenic inheritance tend to be?

A

continuous

40
Q

What is an example of continious variation in humans?

A

Skin color
* Due to the influence of several genes
* Partially due to the environment - sunlight stimulates the production of the black pigment melanin in the skin

41
Q

How is skin color an example of polygenic inheritance?

A

It is due to the influence of several genes

42
Q

What is recombination?

A

The formation of a chromosome or DNA with a new combination of alleles

43
Q

What is a recombinant?

A

An individual that has this recombinant chromosome and therefore has a different combination of characters from either of the original parents is called a recombinant

Biology (57 decks)

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