Exam 4: Genetics and Meiosis Flashcards

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1
Q

Genetics

A

The scientific study of heredity and variation. We don’t inherit traits, but rather genes.

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2
Q

Mitosis

A

Asexual reproduction resulting in genetically identical offspring

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3
Q

Meiosis

A

Sexual reproduction forming gametes. The process by which those gametes become haploid instead of diploid.

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4
Q

Genes

A

Segments of DNA on chromosomes.
One set of chromosomes is inherited from each parent.

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5
Q

Gametes

A

Reproductive cells. They are haploid, there are 23, and contain chromosomes 1-22 and a single sex chromosome. Eggs: sex chromosome is X. Sperm: sex chromosome is X or Y. They are the only types of human cells produced by meiosis.

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6
Q

Fertilization

A

The fusion of two gametes forms a diploid zygote.

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7
Q

Somatic cell

A

Body cell. Anything in humans that is not a gamete.

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8
Q

Important elements of meiosis

A

In the first cell division (meiosis I), homologous chromosomes separate, resulting in two haploid daughter cells with replicated chromosomes. In the second cell division (meiosis II), sister chromatids separate, resulting in four haploid daughter cells with replicated chromosomes.

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9
Q

Variation in a population

A

Prerequisite for evolution. Sexual reproduction contributes to this.

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10
Q

Natural selection

A

Accumulation of genetic variations favored by the environment

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11
Q

Mutation

A

Change in the nucleotide sequence of DNA, which creates alternative alleles of a gene.

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12
Q

Genotype

A

Which alleles an individual has: homozygous (2 of the same alleles), or heterozygous (2 different alleles)

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13
Q

Phenotype

A

The physical characteristics of an organism

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14
Q

Dominant vs recessive alleles

A

Dominant designated by capital letter, recessive by lowercase. Otherwise explanation is in the name itself. Saying an allele is dominant doesn’t mean it’s common. It means it masks a recessive allele in heterozygotes.

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15
Q

Law of segregation

A

Mendel’s reasoning that patterns of inheritance included: individuals have two alleles. And those separate from one another during gamete formation.

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16
Q

Homozygous

A

Both alleles are the same. Must specify homozygous dominant vs recessive.

17
Q

Carrier

A

Individuals who are heterozygous for a particular gene of interest and thus can pass on the recessive allele without showing any of its effects.

18
Q

Complications to Mendelian patterns of inheritance—why

A

-not all traits have only two possibilities
-not all traits are controlled by a single gene
-not all alleles are clearly dominant or recessive

19
Q

Mendelian traits

A

When phenotypes of the heterozygote and dominant homozygous are identical

20
Q

Incomplete dominance

A

The phenotype of the heyerozygote is intermediate

21
Q

Codominance

A

Both phenotypes are expressed by the heterozygote

22
Q

Pleiotropy

A

One gene with many phenotypic effects. Example is albinism.

23
Q

Polygenic traits

A

A single trait whose phenotype is determined by the interaction between alleles of more than one gene

24
Q

Sex-linked genes

A

Genes located on either sex chromosome. Usually the X. Examples: color blindness, hemophilia