Term
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Definition
| THe failure of one or more chromosome pairs of a single chromosome to properly separate (segregate) during cell division (meiosis or mitosis). |
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Term
| What is a sex-linked gene and why is it so important? |
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Definition
| A sex-linked genes are genes that reside primarily on the X, or sex, chromosome. A male needs only to inherit one copy of a defective allele for a mutation/disorder to occur. |
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Term
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Definition
| Linked genes are genes on the same chromosome and therefore cannot segregate independently. They are usually inherited together. |
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Term
| What is polygenic inheritance? Give an example. |
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Definition
| The interaction of many genes to shape a single phenotype. Skin color, height, etc. |
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Term
| What is pleiotropy? Give an example. |
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Definition
| Occurs when a single gene has more than one phenotypic expression. Sickle-cell anemia, in that there is "a general breakdown throughout the entire body." |
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Term
| What is epistasis? Give and example. |
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Definition
| Occurs when one gene affects the phenotypic expression of a second gene. Pigmentation or skin color. |
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Term
| What does multiple alleles refer to? Give an example. |
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Definition
| More than one allele can be expressed in an individual, such as in blood type (A, B, or O). |
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Term
| What is codominance? Give an example. |
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Definition
| An inheritance pattern in which a heterozygote expresses the distinct trait of both alleles. The blood type AB. |
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Term
| How does incomplete dominance differ from complete dominance? |
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Definition
| Incomplete dominance is the combined expression of two different alleles. This condition produces a blending of the individual expressions of the two alleles. |
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Term
| What is a test cross and what is needed for it? |
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Definition
| A test cross is a mechanism to determine genotype. This involves a mating of an unknown genotypic individual with one that is homozygous recessive for the trait. |
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Term
| What are homologous chromosomes? |
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Definition
| A pair of chromosomes that contain the same genetic information (genes), one from each parent. |
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Term
| What are sister chomatids? |
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Definition
| Contain identical copies of the DNA molecule (duplicated chromosomes). |
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Term
| How does an allele differ from a gene? |
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Definition
| An allele is one of several varieties of genes, whereas a gene is simply the general genetic material on a chromosome. |
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Term
| What does the "law of segregation" mean? |
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Definition
| The segregation (separation) of alleles and their chromosomes to individual gametes. |
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Term
| What does the "law of independent assortment" mean? |
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Definition
| The independent assortment of alleles and their chromosomes. |
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Term
| What are the three ways eukaryotes can increase their genetic variation? |
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Definition
| crossing over, random alignment of homologous chromosomes (independent orientation/assortment), and random fertilization |
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Term
| What are the three ways prokaryotes can increase their genetic variation? |
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Definition
| transduction, transformation, and conjugation |
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Term
| When are the "rules of multiplication" for genetics applicable? |
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Definition
| If a compound event is the product of the separate probabilities of the independent events. (AND) |
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Term
| When are the "rules of addition" for genetics applicable? |
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Definition
| An event can occur in two or more alternative ways is the sum of the separate probabilities of the different ways. (OR) |
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Term
| What is a mutation? Can it cause evolutionary adaptation? |
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Definition
| Any change in the nucleotide sequence of an organism's DNA and is the ultimate source of genetic diversity. However, natural selection is the only mechanism that causes evolutionary adaptation. |
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