Bio 156 Human Genetics Chapter 21
Terms
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- units of information about inherited traits that can be passed from one generation to the next
- genes
- different forms of a gene
- alleles
- two chromosomes of each pair in a diploid cell that are alike in length, shape and genes
- homologous chromosomes
- when homologous chromosomes exchange corresponding segments
- crossing over
- name for combinations of alleles in gametes, then in offspring, that were not present in a parent
- genetic recombination
- pairs of chromosomes that are the same in males and females
- autosomes
- pairs of chromosomes that govenr a new individual's gender
- sex chromosomes
- a diagram that can help answer questions about a person's chromosomes.
- karyotype
- chemical that arrests mitosis at metaphase during a karyotype
- colchicine
- most or all of the genes on one of a female's x chromosomes are "switched off" soon after the first cleavages of the zygote
- x inactivation
- condition occurring in females in whom mutated gene that blocks the formation of sweat glands
- anhidrotic ectodermal dysplasia
- genetic family history
- pedigree chart
- deviation from the average
- abnormality
- causes mild to severe medical problems
- disorder
- a set of symptoms that characterize a disorder
- syndrome
- condition resulting from abnormal buildup of the amino acid phynylalanine
- phynylketonuria (PKU)
- condition in which an individual lacks hexosaminidase A, the enzyme required for the metahbolism of sphingolipids that are espciall y abundant in the plasma membrane of cells in nerves and the brain, causes loss of motor functions, deabness blindness , m
- Tay-Sachs disease
- diesase in which the basal nuclei of the brain degenerate, homozygootes die as embryos
- Huntington disease
- condition results in weakened connective tissues in many body structures including aorta, often results in death due to a blood vessel rupture before age 50
- Marfan syndrome
- condition in which cartilage elementos of bones do not form properly, hymozygoutes are usually stillborn, adults are usually under 4'4" tall
- achondroplasia
- condition in which dangerously elevated blood cholesterol
- familial hypercholesterolemia
- gene sequences that are repeated
- duplications
- part of one chromosome exchanges places with a corresponding part of another chromosome that is not its homologous partner
- translocation
- loss of a gene that may be caused spontaneously, or by a virus or by irradiation or some other environmental factor including but not limited to chemical assaults
- deletion
- disorder in which the deletion of human chromosome 5 leads to mental retardation and an abnormally shaped larynx resulting in a cat cry
- cri-du-chat
- a change in one or more of the nucleotides that make up a particular gene
- mutation
- condition in which the embryo doesn't have an exact multiple of the normal haploid set of 23 chromosomes
- aneuploidy
- a ______ embryo has three, four or more sets of the normal haploid set of 23 chromosomes. All but 1 % die before birth and the rare newborns die soon afterward
- polyploid
- one or more pairs of chromosomes fail to separate during mitosis or meiosis, resulting in too many or too few crhomosomes
- nondisjunction
- when fertilization brings together a geamete with an extra chromosome resulting in 3 of one type of chromosome
- trisomy
- when fertilzation results in the agamete missing a chromosome the the result is ______
- monosomy
- When a nondisjunction has reduced the chromosome number to 45, resulting in individuals who are missing an x chromosome
- Turner syndrome
- How do X and Y chromosomes differ?
- X chromosomes are female and Y chromosomes are male
- What do we mean when we say someone is a carrier of a genetic trait
- they have the ability to pass on the trait as they carry the recessive allele, but due to they are not affected by it.
- What evidence indicates that a trait is coded by a dominant allele on an autosome?
- the trait usually appears in each generation
- Explain the difference in an X-linked trait and a sex influenced trait
- X-linked genetic disorders occurwhen the mutated gene is on the X chromosome, typically affecting males who inherit only one X chromosome, Sex-influenced traits appear more frequently in one sex.
- Give two examples of phenotypes that can result from nondisjunction
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Turner Syndrome
XXX females
Klinfelter syndrome
xyy condition -
Genetic disorders can be caused by _____.
A gene mutations
B. changes in chromosome structure
C. changes in chromosome number
D. all of the above - D
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______ segregate during _____.
A Homologues; mitosis
B. Genes on one chromosome; meiosis
C. Homologues; meiosis
D. Genes on one chromosome; mitosis - C
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The alleles of a gene on homologous chromosomes end up in separate _____.
A. body cells
B. gametes
C. nonhomologous chromosomes
D. offspring
E. both B and D are possible - E
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Genes on the same chromosome tend to remain together during _____ and end up in the same _____.
A. mitosis; body cell
B. mitosis; gamete
C. meiosis; body cell
D. meiosis; gamete
E. both A and D - E
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The probability of a crossover occurring between two genes on the same chromosome is _____.
A. unrelated to the distance between them
B. increased if they are closer together on the chromosome
C. increased if they are farther apart on the - C
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A chromosome's structure can be altered by _____.
A. deletions
B. duplications
C. translocations
D. all of the above - D
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Nondisjunction can be caused by _____.
A. crossing over in meiosis
B. segregation in meiosis
C. failure of chromosomes to separate during meiosis
D. multiple independent assortments - C
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A gamete affected by nondisjunction could have _____.
A. a change from the normal chromosome number
B. one extra or one missing chromosome
C. the potential for a genetic disorder
D. all of the above. - D
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A person who is a carrier for a genetic trait _____.
A. is heterozygous for a dominant trait
B. is heterozygous for a recessive trait
C. is homozygous for a recessive trait
D. could be either A or B but not C. - D