Text Chapter 7: Patterns / Chromosomal Basis of Inheritance Flashcards Preview

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Flashcards in Text Chapter 7: Patterns / Chromosomal Basis of Inheritance Deck (25):
1

Principle of Genetic Segregation

in the formation of gametes, the members of a pair of alleles separate (or segregate) cleanly from each other so that only one member is included in each gamete- each gamete has an equal probability of containing either member of the allele pair

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Principle of Independent Assortment

when gametes are formed, the alleles of one gene segregate independently of the alleles of another gene producing equal proportions of all possible gamete types

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Allele

alternate form of a gene

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Gene

sequence of DNA that codes for a protein, gives rise to a physical trait

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Dominant

masks recessive alleles, homozygous dominant, heterozygous

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Recessive

masked by dominant, homozygous recessive

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Genotype

alleles carried by an individual

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Phenotype

physical characteristic or appearance of an individual

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F1

first generation

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F2

second generation

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Heterozygous

cells contain two different alleles at a gene

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Homozygous

cells contain two of the same allele at a gene

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Autosome

any chromosome that is not a sex chromosome

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Sex Chromosome

homologous chromosomes that differ in genetic composition between males and females

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Incomplete Dominance

neither allele masks the other and both are observed as blending in the heterozygote

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Codominance

neither allele masks the other so that effects of both alleles are observed in heterozygotes without blending

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Complete Dominance

the dominant allele completely masks the recessive allele in a heterozygous condition

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Locus

area on the chromosome where gene is located

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Multiple Alleles

three or more alleles exist for one trait

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Peiotropic Effects

one gene effects many traits

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Polygenic Inheritance

many genes affect one trait

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How Gender is Determined

Gender is determined by the sperm- females donate one X chromosome and males donate either an X or a Y chromosome which determines the sex of the child

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Pattern of Inheritance for Sex-Linked Traits

Males carry only one copy of genes on the X chromosome but females carry two copies, therefore their sex-linked traits have a greater influence on male children

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How Human Chromosomal Abnormalities Arise

Nondisjunction

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Nondisjunction

the failure of homologues or chromatids to separate during meiosis