Genetics
Vocabulary (Chapter 14): character, trait, true-breeding, homozygous, heterozygous, hybridization, Law of Segregation, alleles, dominant, recessive, Punnett square, phenotype, genotype, testcross, monohybrid cross, dihybrid cross, Law of Independent Assortment, complete dominance, incomplete dominance, codominance, Tay-Sachs disease, pleiotropy, epistasis, multiple alleles, polygenic inheritance, quantitative characters, multifactorial characters, pedigree, carriers, albinism, cystic fibrosis, sickle-cell disease, Huntington's disease, achondroplasia, amniocentesis, chorionic villus sampling (CVS)
Objectives:
After attending lectures and studying the chapter, the student should be able to:
1. Define diploid and state which cells in your body are diploid.
2. State the number of chromosomes in your diploid cells and state how many of those
chromosomes came from your father and how many came from your mother.
3. Distinguish between autosomes and sex chromosomes, state how many of each are in
your diploid cells, and state the sex-chromosome combinations that are in human males
and human females.
4. Describe an individual's karyotype.
5. Explain the relationship between genes and chromosomes.
6. Explain the relationship between genes and alleles.
7. Describe linked genes.
8. State the number of alleles you have for each gene in your diploid cells and state how
many of those alleles came from your father and how many came from your mother.
9. Distinguish between an individual's phenotype and genotype.
10. Distinguish between autosomal traits and sex-linked traits.
11. Distinguish between complete dominance, incomplete dominance, and codominance.
12. Describe the multiple allele inheritance pattern of the human ABO blood type.
13. Describe and give an example of polygenic inheritance.
14. Describe and give an example of epistasis.
15. Describe and give an example of pleiotropy.
16. Describe a pedigree and use a pedigree chart to determine patterns of inheritance.
17. List the 4 steps used in genetics problems to determine offspring possibilities.
18. Use the 4-step genetics-problem-solving process to work single-gene cross and 2-gene
cross genetics problems, including monohybrid and dihybrid crosses.
19. Give examples of and work genetics problems relating to each of the following human
single-gene traits:
a. autosomal and sex-linked traits(chapter 15);
b. normal traits and genetic disorders;
c. traits with multiple alleles in the population;
d. recessively-inherited and dominantly-inherited traits; and,
e. traits with complete dominance, incomplete dominance, and codominance.
Vocabulary (chapter 15): sex-linked genes, duchene muscular dystrophy, hemophilia, Barr body, linked genes, nondisjunction, aneuploidy, monosomic, trisomic, polyploidy, deletion, duplication, inversion, translocation, Down syndrome, Turner syndrome, Klinefelter syndrome
20. Describe meiotic nondisjunction and explain how this can lead to human chromosomal
abnormalities.
21. Describe the human chromosomal abnormalities that lead to Down syndrome, Turner
syndrome, and Klinefelter syndrome.
22. Describe genomic imprinting and how it affects phenotypic expression of genes.
23. Understand linked genes and why they do not show the same pattern of inheritance as genes located on different chromosomes.
Terms : Hide Images
| 1248476016 | Concept 14.1 Mendel used the scientific approach to identify two laws of Inheritance | The Law of Segregation The Law of Independent Assortment | 1 | |
| 1248476017 | Character | An observable heritable feature that may vary among individuals. |  | 2 |
| 1248476018 | Trait | One of two or more detectable variants in a genetic character. | 3 | |
| 1248476019 | True-Breeding | Referring to organisms that produce offspring of the same variety over many generations of self-pollination. | 4 | |
| 1248476020 | hybridization | In genetics, the mating, or crossing, of two true-breeding varieties. | 5 | |
| 1248476021 | P Generation | The true-breeding (homozygous) parent individuals from which F1 hybrid offspring are derived in studies of inheritance; P stands for "parental." | 6 | |
| 1248476022 | F1 generation | The first filial, hybrid (heterozygous) offspring arising from a parental (P generation) cross. | 7 | |
| 1248476023 | F2 generation | The offspring resulting from interbreeding (or self-pollination) of the hybrid FF1 generation. | 8 | |
| 1248476024 | The Law of segregation | Mendel's first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation. |  | 9 |
| 1248476025 | Allele | Any of the alternative versions of a gene that may produce distinguishable phenotypic effects. |  | 10 |
| 1248476026 | Dominant Allele | An allele that is fully expressed in the phenotype of a heterozygote. | 11 | |
| 1248476027 | Recessive Allele | An allele whose phenotypic effect is not observed in a heterozygote. | 12 | |
| 1248476028 | Genotype | The genetic makeup, or set of alleles, of an organism. |  | 13 |
| 1248476029 | Phenotype | The EXPRESSED/observable physical and physiological traits of an organism, which are determined by its genetic makeup. | | 14 |
| 1248476030 | The Law of Segregation | Mendel's first law, stating that the two alleles in a pair segregate (separate from each other) into different gametes during gamete formation. | 15 | |
| 1248476031 | Punnett Square | A diagram used in the study of inheritance to show the predicted genotypic results of random fertilization in genetic crosses between individuals of known genotype. |  | 16 |
| 1248476032 | Homozygous | Having two identical alleles for a given gene. |  | 17 |
| 1248476033 | Heterozygous | Having two different alleles for a given gene. |  | 18 |
| 1248476034 | Phenotype | Expressed. The observable physical and physiological traits of an organism, which are determined by its genetic makeup. |  | 19 |
| 1248476035 | Genotype | The genetic makeup, or set of alleles, of an organism. |  | 20 |
| 1248476036 | Testcross | Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring reveals the unknown genotype. |  | 21 |
| 1248476037 | The Law of Independent Assortment | Mendel's second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes. | 22 | |
| 1248476038 | Monohybrids | An organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. For example, parents of genotypes AA and aa produce a monohybrid of genotype Aa. |  | 23 |
| 1248476039 | Monohybrid Cross | A cross between two organisms that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant). |  | 24 |
| 1248476040 | Dihybrids | An organism that is heterozygous with respect to two genes of interest. All the offspring from a cross between parents doubly homozygous for different alleles are dihybrids. For example, parents of genotypes AABB and aabb produce a dihybrid of genotype AaBb. |  | 25 |
| 1248476041 | Dihybrid Cross | A cross between two organisms that are each heterozygous for both of the characters being followed (or the self-pollination of a plant that is heterozygous for both characters). |  | 26 |
| 1248476042 | What is Mendel's Second Law? | The Law of Independent Assortment. Mendel's second law, stating that each pair of alleles segregates, or assorts, independently of each other pair during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes. |  | 27 |
| 1248476043 | Concept Check 14.1 Draw It. Pea Plants heterozygous for flower position and stem length (AaTt) are allowed to self pollinate, and 400 of the resulting seeds are planted. Draw a Punnett square for this cross. How many offspring would be predicted to have terminal flowers and be dwarf? (See Table 14.1) | refer to diagram | 28 | |
| 1248476044 | Concept Check 14.1 What if? List all gametes that could be made by a pea plant heterozygous for seed color, seed shape, and pod shape (YyRrIi; see Table 14.1). How large a Punnett square would you need to draw to predict the offspring of a self-pollination of this trihybrid? | See table | 29 | |
| 1248476045 | Concept Check 14.1 Make Connections. In some pea plant crosses, the plants are self-pollinated. Refer back to Concept 13.1 (pp. 248-249) and explain whether self-pollination is considered asexual or sexual reproduction. | Asexual | 30 | |
| 1248476046 | Which choice below is a basic difference between Mendel's particulate hypothesis and the hypothesis of blending inheritance? (eText Concept 14.1) The blending inheritance hypothesis, but not the particulate hypothesis, maintained that mutation is the major source of new gene combinations. The blending inheritance hypothesis, but not the particulate hypothesis, maintained that the two alleles at any given locus are always different. The blending inheritance hypothesis, but not the particulate hypothesis, maintained that the traits governed by genes in the egg are different from the traits governed by genes in the sperm. The blending inheritance hypothesis, but not the particulate hypothesis, maintained that after a mating, the genetic material provided by each of the two parents is mixed in the offspring, losing its individual identity. All of the listed responses are correct. | The blending inheritance hypothesis, but not the particulate hypothesis, maintained that after a mating, the genetic material provided by each of the two parents is mixed in the offspring, losing its individual identity. The blending hypothesis maintained that the genetic material contributed by the two parents mixes in a manner analogous to the way blue and yellow paints blend to make green. | 31 | |
| 1248476047 | If a plant variety is true-breeding for a dominant trait, then _____. (eText Concept 14.1) if the plant were allowed to self-pollinate, the dominant and recessive traits would consistently appear in a 3:1 ratio among the progeny the plant is heterozygous for the trait if the plant were crossed with a heterozygote, one-half of the progeny would show the dominant trait, and one-half would show the recessive trait if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait the variety is unable to mutate | if the plant were allowed to self-pollinate, all of the progeny would have the dominant trait | 32 | |
| 1248476048 | A = big apples; R = red apples; a = small apples; r = yellow apples. You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half of the new trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents? (eText Concept 14.1) AArr and aaRr Aarr and aaRr AARr and Aarr AaRr and AaRr AaRr and aarr | AArr and aaRr | 33 | |
| 1248476049 | Assume tall (T) is completely dominant to dwarf (t) in a certain species of plant. If a homozygous dominant individual is crossed with a homozygous dwarf, the offspring will _____. (eText Concept 14.1) all be intermediate in height all be tall be 1/2 tall and 1/2 dwarf be 3/4 tall and 1/4 dwarf all be short | all be tall | 34 | |
| 1248476050 | The F1 generation differed from the F2 in Mendel's experiments in that _____. (eText Concept 14.1) all of the F1 showed the dominant phenotype, whereas only half of the F2 did all of the F1 showed the dominant phenotype, but only three-fourths of the F2 did all of the F1 showed the dominant phenotype, and all of the F2 showed the recessive phenotype one-half of the F1 showed the dominant phenotype, and three-fourths of the F2 did none of the F1 showed the dominant phenotype, but one-half of the F2 did | all of the F1 showed the dominant phenotype, but only three-fourths of the F2 did | 35 | |
| 1248476051 | Physically, what are different alleles? (eText Concept 14.1) Different alleles are different DNA sequences found at the same locus on sister chromatids. Different alleles are different particles found in gametes. Different alleles are different phenotypes for a particular character. Different alleles are different DNA sequences found at the same locus on homologous chromosomes. None of the listed responses is correct. | Different alleles are different DNA sequences found at the same locus on homologous chromosomes. | 36 | |
| 1248476052 | In a certain plant, the alleles A, B, and C are completely dominant to the alleles a, b, and c. A plant with the genotype AABbcc will have the same phenotype as a plant with the genotype _____. (eText Concept 14.1) Aabbcc aabbcc AaBBcc AABBCc None of the listed responses is correct. | AaBBcc | 37 | |
| 1248476053 | Pea plants are tall if they have the genotype TT or Tt, and they are short if they have genotype tt. A tall plant is mated with a short plant. Which outcome below would indicate that the tall parent plant was heterozygous? (eText Concept 14.1) All of the offspring are short. All of the offspring are tall. The ratio of tall offspring to short offspring is 3:1. The ratio of tall offspring to short offspring is 1:1. There is not enough information to answer the question. | The ratio of tall offspring to short offspring is 1:1. | 38 | |
| 1248476054 | What is indicated when a single-character testcross yields offspring that all have the dominant phenotype? (eText Concept 14.1) The parent with the dominant phenotype was homozygous. The parent with the dominant phenotype was heterozygous. Epistasis has occurred. The alleles are codominant. Both parents are heterozygous. | The parent with the dominant phenotype was homozygous. | 39 | |
| 1248476055 | If an organism that is homozygous dominant is crossed with a heterozygote for that trait, the offspring will be _____. (eText Concept 14.1) all of the dominant phenotype 1/4 of the recessive phenotype all homozygous dominant all homozygous recessive present in a 9:3:3:1 ratio | All of the dominant phenotype | 40 | |
| 1248476056 | In Mendel's monohybrid cross of purple-flowered and white-flowered peas, all members of the F1 generation had the _____ phenotype because their genotype was _____ at the flower-color locus. (eText Concept 14.1) white-flowered ... homozygous recessive white-flowered ... heterozygous purple-flowered ... homozygous recessive purple-flowered ... homozygous dominant purple-flowered ... heterozygous | purple-flowered ... heterozygous | 41 | |
| 1248476057 | If the two traits that Mendel looked at in his dihybrid cross of smooth yellow peas with wrinkled green peas had been controlled by genes that were located near each other on the same chromosome, then the F2 generation _____. (eText Concept 14.1) would have contained four phenotypes in a 9:3:3:1 ratio would have contained only individuals that were heterozygous at both loci would have deviated from the 9:3:3:1 phenotypic ratio that is predicted by the law of independent assortment would have contained no individuals that were heterozygous at both loci None of the listed responses is correct. | Would have deviated from the 9:3:3:1 phenotypic ratio that is predicted by the law of independent assortment If the two characters are located on the same chromosome, they will not segregate independently. | 42 | |
| 1248476058 | In carrying out his breeding studies, Mendel examined characters that had which of the following properties? (eText Concept 14.1) They were controlled by loci that were (or behaved as if they were) on different chromosomes. It was possible to isolate true-breeding varieties for each trait. The traits varied in an either-or fashion. The characters each were controlled by a single gene. All of the listed responses are correct. | All of the listed responses are correct. | 43 | |
| 1248476059 | The law of independent assortment _____. (eText Concept 14.1) states that the alleles at different loci segregate independently from one another during a dihybrid cross can account for a 9:3:3:1 ratio seen in the F2 generation applies only to genes that are present on different chromosomes (or behave as if they were) The first and second answers are correct. The first, second, and third answers are correct. | The first, second, and third answers are correct. | 44 | |
| 1248476060 | Homologous pairs of chromosomes often _____. (eText Concept 14.1) carry different genes for different traits differ in length contain different alleles are not both present in diploid somatic cells are paired up in the G2 phase of the cell cycle | contain different alleles | 45 | |
| 1248476061 | Concept 14.2 The laws of probability govern Mendelian Inheritance | ... | 46 | |
| 1248476062 | The multiplication rule | A rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities. | 47 | |
| 1248476063 | The addition rule | A rule of probability stating that the probability of any one of two or more mutually exclusive events occurring can be determined by adding their individual probabilities. | 48 | |
| 1248476064 | Concept 14.3 Inheritance Patterns are often more complex than predicted by simple Mendelian Genetics | ... | 49 | |
| 1248476065 | Complete dominance | The situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable. | 50 | |
| 1248476066 | Incomplete dominance | The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele. |  | 51 |
| 1248476067 | Codominance | The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways. | 52 | |
| 1248476068 | Tay-Sachs Disease | A human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and mental performance usually become manifest a few months after birth, followed by death within a few years. | 53 | |
| 1248476069 | Pleiotropy | The ability of a single gene to have multiple effects. | 54 | |
| 1248476070 | Epistasis | A type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene. | 55 | |
| 1248476071 | Quantitative Characters | A heritable feature that varies continuously over a range rather than in an either-or fashion. | 56 | |
| 1248476072 | Polygenic Inheritance | An additive effect of two or more genes on a single phenotypic character. | 57 | |
| 1248476073 | Norm of Reaction | The range of phenotypes produced by a single genotype, due to environmental influences. | 58 | |
| 1248476074 | Multifactorial | Referring to a phenotypic character that is influenced by multiple genes and environmental factors | 59 | |
| 1248476075 | Concept 14.4 Many Human Traits Follow Mendelian Patterns of Inheritance | ... | 60 | |
| 1248476076 | Pedigree | A diagram of a family tree with conventional symbols, showing the occurrence of heritable characters in parents and offspring over multiple generations. | 61 | |
| 1248476077 | Carriers | In genetics, an individual who is heterozygous at a given genetic locus for a recessively inherited disorder. The heterozygote is generally phenotypically normal for the disorder but can pass on the recessive allele to offspring. | 62 | |
| 1248476078 | Cystic Fibrosis | A human genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated. | 63 | |
| 1248476079 | Sickle Cell Disease | A recessively inherited human blood disorder in which a single nucleotide change in the β-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms in afflicted individuals. | 64 | |
| 1248476080 | Huntington's Disease | A human genetic disease caused by a dominant allele, characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms. | 65 | |
| 1248476081 | Amniocentesis | A technique associated with prenatal diagnosis in which amniotic fluid is obtained by aspiration from a needle inserted into the uterus. The fluid and the fetal cells it contains are analyzed to detect certain genetic and congenital defects in the fetus. |  | 66 |
| 1248476082 | Chorionic Villus Sampling (CVS) | A technique associated with prenatal diagnosis in which a small sample of the fetal portion of the placenta is removed for analysis to detect certain genetic and congenital defects in the fetus. |  | 67 |
| 1248476083 | Concept 15.1 Mendelian Inheritance has its physical basis in the behavior of chromosomes | ... | 68 | |
| 1248476084 | Chromosome Theory of Inheritance | A basic principle in biology stating that genes are located at specific positions (loci) on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns. | 69 | |
| 1248476085 | Wild Type | The phenotype most commonly observed in natural populations; also refers to the individual with that phenotype. | 70 | |
| 1248476086 | Concept 15.2 Sex-Linked Genes Exhibit Unique Patterns of Inheritance | ... | 71 | |
| 1248476087 | Sex-Linked Gene | A gene located on either sex chromosome. Most sex-linked genes are on the X chromosome and show distinctive patterns of inheritance; there are very few genes on the Y chromosome. | 72 | |
| 1248476088 | X-Linked Genes | A gene located on the X chromosome; such genes show a distinctive pattern of inheritance. | 73 | |
| 1248476089 | Duchenne Muscular Dystrophy | A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue. | 74 | |
| 1248476090 | Hemophilia | A human genetic disease caused by a sex-linked recessive allele resulting in the absence of one or more blood-clotting proteins; characterized by excessive bleeding following injury. | 75 | |
| 1248476091 | Barr Body | A dense object lying along the inside of the nuclear envelope in cells of female mammals, representing a highly condensed, inactivated X chromosome. | 76 | |
| 1248476092 | Concept 15.3 Linked Genes Tend to be Inherited Together because they are Located near Each Other on the Same Chromosome. | ... | 77 | |
| 1248476093 | Genetic Recombination | General term for the production of offspring with combinations of traits that differ from those found in either parent. | 78 | |
| 1248476094 | Parental Types | An offsprring with a phenotyp that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotype itself. | 79 | |
| 1248476095 | Recombinant Types/Recombinants | An offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself. | 80 | |
| 1248476096 | Crossing Over | The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis. | 81 | |
| 1248476097 | Genetic Map | An ordered list of genetic loci (genes or other genetic markers) along a chromosome. | 82 | |
| 1248476098 | Linkage map | A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes. | 83 | |
| 1248476099 | Map Units | A unit of measurement of the distance between genes. One map unit is equivalent to a 1% recombination frequency. | 84 | |
| 1248476100 | Concept 15.4 Alterations of Chromosome Number or Structure Cause Some Genetic Disorders | ... | 85 | |
| 1248476101 | Nondisjunction | An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other. | 86 | |
| 1248476102 | Aneuploidy | A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number. | 87 | |
| 1248476103 | Monosomic | Referring to a diploid cell that has only one copy of a particular chromosome instead of the normal two. | 88 | |
| 1248476104 | Trisomic | Referring to a diploid cell that has three copies of a particular chromosome instead of the normal two. | 89 | |
| 1248476105 | Polyploidy | A chromosomal alteration in which the organism possesses more than two complete chromosome sets. It is the result of an accident of cell division. | 90 | |
| 1248476106 | Deletion | (1) A deficiency in a chromosome resulting from the loss of a fragment through breakage. (2) A mutational loss of one or more nucleotide pairs from a gene. | 91 | |
| 1248476107 | Duplication | An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such taht a portion of a chromosome is duplicated. | 92 | |
| 1248476108 | Inversion | An aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated. | 93 | |
| 1248476109 | Translocation | (1) An aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome. (2) During protein synthesis, the third stage in the elongation cycle, when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome. (3) The transport of organic nutrients in the phloem of vascular plants. | 94 | |
| 1248476110 | Down Syndrome | A humaan genetic disease usually caused by the presence of an extra chromosome 21; characterized by developmental delays and heart and other defects that are generally treatable or non-life threatening. | 95 | |
| 1248476111 | Concept 15.5 Some Inheritance Patterns are exceptions to Standard Mendelian Inheritance | ... | 96 | |
| 1248476112 | Genomic Imprinting | A phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent. | 97 |
