Ch 7 Extending Mendelian Genetics Section 7 1

Ch. 7 Extending Mendelian Genetics Section 7. 1: Chromosomes and Phenotipe Section 7. 2: Complex Patterns of Inheritance Section 7. 3: Chromosomes and Human Heredity Click on a lesson name to select.

Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Pedigrees § A diagram that traces the inheritance of a particular trait through several generations

Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Inferring Genotypes § Knowing physical traits can determine what genes an individual is most likely to have. Predicting Disorders § Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Incomplete Dominance § The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Codominance § Both alleles are expressed in the heterozygous condition. § Sickle-cell disease is one example.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sickle-cell Disease Normal red blood cell § Changes in hemoglobin cause red blood cells to change to a sickle shape. § People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell 7766 x

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Multiple Alleles § Blood groups in humans § ABO blood groups have three forms of alleles.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Coat Color of Rabbits § Multiple alleles can demonstrate a hierarchy of dominance. § In rabbits, four alleles code for coat color: C, cch, and c.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Epistasis § Variety is the result of one allele hiding the effects of another allele.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sex Determination § Sex chromosomes determine an individual’s gender.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Dosage Compensation § The X chromosome carries a variety of genes that are necessary for the development of both females and males. § The Y chromosome mainly has genes that relate to the development of male characteristics. § In females, one X chromosome is inactivated in each cell. The inactivated X chromosome is visible in stained cells as a Barr body.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sex-Linked Traits § Genes located on the X chromosome § Red-green color blindness § Hemophilia

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Polygenic Traits § Polygenic traits arise from the interaction of multiple pairs of genes.

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Environmental Influences § Environmental factors influence an organism’s phenotype § Diet and exercise § Sunlight and water § Temperature

Complex Inheritance and Human Heredity Complex Patterns of Inheritance Twin Studies § Helps scientists separate genetic contributions from environmental contributions § Traits that appear frequently in identical twins are at least partially controlled by heredity. § Traits expressed differently in identical twins are strongly influenced by environment.

Complex Inheritance and Human Heredity Chromosomes and Human Heredity Karyotype Studies § Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size. § Images of chromosomes stained during metaphase § Chromosomes are arranged in decreasing size to produce a micrograph.

Complex Inheritance and Human Heredity Chromosomes and Human Heredity Telomeres § Telomere caps consist of DNA associated with proteins. § Serves a protective function for the structure of the chromosome

Complex Inheritance and Human Heredity Chromosomes and Human Heredity Nondisjunction § Cell division during which sister chromatids fail to separate properly § Down syndrome, also called trisomy 21

Chapter Complex Inheritance and Human Heredity Chapter Diagnostic Questions Under what circumstances will a recessive trait be expressed? A. A recessive allele is passed on by both parents. B. One parent passes on the recessive allele. 1. trait. A C. The individual is heterozygous for the D. There is a mutation in the dominant 2. B 3. C gene. 4. D

Chapter Complex Inheritance and Human Heredity Section 1 Formative Questions Which is the genotype of a person who is a carrier for a recessive genetic disorder? A. DD B. Dd C. dd D. d. E 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Section 1 Formative Questions Albinism is a recessive condition. If an albino squirrel is born to parents that both have normal fur color, what can you conclude about the genotype of the parents? A. at least one parent is a carrier 1. A B. both parents are carriers 2. B 3. C C. both parents are homozygous recessive 4. D D. at least one parent is homozygous dominant

Chapter Complex Inheritance and Human Heredity Section 2 Formative Questions When a homozygous male animal with black fur is crossed with a homozygous female with white fur, they have offspring with gray fur. What type of inheritance does this represent? A. dosage compensation B. incomplete dominance C. multiple alleles D. sex-linked 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Section 2 Formative Questions Of the 23 pairs of chromosomes in human cells, one pair is the _______. A. autosomes B. Barr bodies C. monosomes D. sex chromosomes 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Section 2 Formative Questions Which is an example of a polygenic trait? A. blood type B. color blindness C. hemophilia D. skin color 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Section 3 Formative Questions What does a karyotype show? A. The blood type of an individual. B. The locations of genes on a chromosome. C. The cell’s chromosomes arranged in order. D. The phenotype of individuals in a 1. A 2. B pedigree. 3. C 4. D

Chapter Complex Inheritance and Human Heredity Section 3 Formative Questions What is occurring in this diagram? A. multiple alleles B. nondisjunction C. nonsynapsis D. trisomy 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Section 3 Formative Questions What condition occurs when a person’s cells have an extra copy of chromosome 21? A. Down syndrome B. Klinefelter’s syndrome C. Tay-Sachs syndrome D. Turner’s syndrome 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Chapter Assessment Questions What does the top horizontal line between numbers 1 and 2 in the figure indicates? A. 1 and 2 are siblings B. 1 and 2 are parents C. 1 and 2 are offspring D. 1 and 2 are carriers 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Chapter Assessment Questions Which is not an allele in the ABO blood group? A. IA B. IO C. IB D. i 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Chapter Assessment Questions Down Syndrome results from what change in chromosomes? A. one less chromosome on pair 12 B. one extra chromosome on pair 21 C. one less chromosome on pair 21 1. 2. D. one extra chromosome on pair 123. 4. A B C D

Chapter Complex Inheritance and Human Heredity Standardized Test Practice If a genetic disorder is caused by a dominant allele, what is the genotype of those who do not have the disorder? A. heterozygous B. homozygous dominant C. homozygous recessive 1. 2. 3. A B C

Chapter Complex Inheritance and Human Heredity Standardized Test Practice Analyze this pedigree showing the inheritance of a dominant genetic disorder. Which would be the genotype of the first generation father? A. RR B. Rr C. rr 1. 2. 3. A B C

Chapter Complex Inheritance and Human Heredity Standardized Test Practice Shorthorn cattle have an allele for both red and white hair. When a red-haired cow is crossed with a white-haired bull, their calf has both red and white hairs scattered over its body. What type of inheritance does this represent? A. codominance B. dosage compensation C. epistasis D. sex-linked 1. 2. 3. 4. A B C D

Chapter Complex Inheritance and Human Heredity Standardized Test Practice Why are males affected by recessive sex-linked traits more often than are females? A. Males have only one X chromosome. B. Males have two X chromosomes. 1. A C. Males have only one Y chromosome. 2. B D. The traits are located on the Y 3. C 4. D chromosomes.

Chapter Complex Inheritance and Human Heredity Standardized Test Practice A carrier of hemophilia and her husband, who is unaffected by the condition, are expecting a son. What is the probability that their son will have hemophilia? A. 25% B. 50% C. 75% D. 100% 1. 2. 3. 4. A B C D