Ch. 12 Biology Inheritance Patterns And Human Genetics

Front 1

sex chromosomes

Back 1

X, Y; contain genes that determine the sex, (gender), of an individual

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autosomes

Back 2

remaining chromosomes that do not determine sex of an individual

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SRY sex determining region Y

Back 3

a gene on the Y chromosome that codes for a protein that causes an embryo's gonads to develop as testes

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sex-linked trait

Back 4

a trait that is coded for by an allele on a sex chromosome
(because the X chromosome is much larger than the Y chromosome, there are many more X-linked traits than Y-linked traits)

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linked genes, linkage group

Back 5

pairs of genes that tend to be inherited together; set of linked genes

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crossing-over

Back 6

occurs during the first division of meiosis; it is the exchange of DNA between homologous chromosomes leading to a rearrangement of allele combinations (it does not create new genes or delete old ones)

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chromosome map

Back 7

diagram that shows the linear order of genes on a chromosome

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the percentage of crossing-over for two traits is proportional to....

Back 8

the distance between them on a chromosome

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map unit

Back 9

a frequency of crossing-over of 1%

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germ-cell mutations

Back 10

change in the nucleotide-base sequence of a gene or DNA molecule in an organism's gamete; these can be inherited

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Somatic-cell mutations

Back 11

change in the nucleotide-base sequence of a gene or a DNA molecule that take place in an organism's body cells and can affect the organism (these can not be inherited)

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lethal mutations

Back 12

change in the nucleotide-base sequence of a gene or DNA molecule that can cause death (not all mutations are deadly, some give an evolutionary advantage)

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deletion

Back 13

loss of piece of a chromosome due to breakage

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inversion

Back 14

a chromosomal segment breaks off, flips around backward, and reattaches

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translocation

Back 15

piece of one chromosome breaks off and reattaches to a nonhomologous chromosome

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nondisjunction

Back 16

chromosome fails to separate from its homologue during meiosis; therefore, one gamete redeives an extra chromosome, and another gamete receives no copies
(example: Down's Slyndrome, Trisomy 21)

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point mutation

Back 17

the substitution, addition, or removal of a single nucleotide; a change that occurs within a single gene or other segment of DNA on a chromosome

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substitution

Back 18

one nucleotide replaces another, if it occcurs in a codon, the amino acid can be changed

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frameshift mutation

Back 19

occurs when a deletion mutation or an insertion mutation causes incorrect grouping of the remaining codons as all amino acids downstream change

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pedigree

Back 20

diagram that shows how a trait is inherited over several generations

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carriers

Back 21

organisms that have one copy of a recessive allele but do not have the disease, but can pass it to their offspring

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Genetic disorders

Back 22

diseases or disabling conditions that have a genetic basis

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polygenic

Back 23

human characteristics that are influenced by several genes
(skin color, eye color, height, hair color)

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complex characters

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conditions that are influenced strongly both by the environment and by genes

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multiple alleles

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genes with more than three alleles (ex: blood types)

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incomplete dominance

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occurs when an individual displays a trait that is intermediate between the two parents

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x-linked traits

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pedigree shows many affected males and no affected females
(colorblindness)

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sex-influenced traits

Back 28

usually autosomal, occurs when males and females show different phenotypes even when they share the same genotype (allele for pattern baldness- dominant in males, and recessive in females)

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Single allele traits

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occurs when a single allele of a gene controls a single-allele trait in a dominant fashion (ex: Huntington's Disease onset of mental deteriation in ages 30-40; there is direct DNA testing)

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Genetic screening

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the use of pedigrees, karotypes, blood tests for certain proteins, direct test of DNA, amniocentesis, chorionic villus sampling

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gene therapy

Back 31

technique that places a healthy copy of a gene into the cells of a person whose copy of the gene is defective; includes both somatic cell, and germ cell therapy)