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25 Cards in this Set
- Front
- Back
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What is an allele?
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Each of the two copies of a gene.
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What is heredity?
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Passing characteristics from parents to offspring.
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What are single-gene traits?
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Traits that are determined by the instruction a person carries on just one gene.
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How many traits are single-gene traits?
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Over 9000!
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What did Gregor Mendel contribute to genetics?
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He helped us understand how traits are inherited using methodical experimentation and hypothesis testing.
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What is true-breeding?
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Always producing offspring with the same variant of the trait as the parents.
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What does it mean when a genotype is said to be homozygous?
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An individual inherited the same two alleles for a gene.
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What does it mean when a genotype is said to be heterozygous?
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A different allele was inherited from each parent.
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What is Mendel's Law of Segregation?
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One one of two alleles for a gene from each parent is put into a gamete.
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What is a phenotype?
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The outward appearance: visible features. Also includes chemicals produced and behaviors.
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What is a genotype?
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The genetic composition usually in reference to a trait.
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If both parents of a child are heterozygous for Tay-Sachs, what is the chance the baby will inherit Tay-Sachs?
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.5 * .5 = .25 = 25%
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What does a test-cross allow us to determine?
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Which alleles an individual carries, by crossing an individual exhibiting a dominant trait with an individual that is homozygous recessive. The phenotypes of the offspring will reveal the unknown genotype.
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What is a pedigree?
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A type of family tree that gathers information from as many related individuals as possible across multiple generations.
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What are sex-linked traits?
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Traits controlled by genes on the sex chromosomes.
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What is a carrier?
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An individual who does not exhibit a trait but carries one allele for a recessive trait that their offspring can inherit.
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What does incomplete dominance mean?
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A heterozygote appears to be intermediate between the two homozygotes.
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What is codominance?
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A heterozygote displays characteristics of both homozygotes. (Sickle-Cell Disease)
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What is multiple allelism?
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A single gene having more than two alleles. Blood type is an example. O, A, B, AB.
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Why are people with type O blood type considered universal donors?
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They have neither A nor B antigens on their red blood cells, and produce antibodies that attack A and B antigens.
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What does it mean for a trait to be polygenic?
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The trait is influenced by many different genes. E.g., skin color, eye color, height.
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What is pleiotropy? Is it common?
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One gene influences multiple unrelated traits. Most, if not all genes are like this.
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How often does trait inheritance depend on sex?
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When a trait is coded for by a gene on a sex chromosome (color vision), the pattern of expression differs for males and females. Otherwiese, it usually does not differ.
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What is the law of independent assortment?
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All traits are inherited separate from each other, neither trait influences the inheritance pattern for the other.
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What are linked genes?
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When trait influencing genes are close together on the same chromosome and often express themselves together.
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