Complex Inheritance and Human Heredity Section 1: Basic Patterns of Human Inheritance Section 2: Complex Patterns of Inheritance Section 3: Chromosomes and Human Heredity

Recessive Genetic Disorders Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Recessive Genetic Disorders A recessive trait is expressed when the individual is homozygous recessive for the trait.

Section 1 Complex Inheritance and Human Heredity

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Cystic Fibrosis Affects the mucus-producing glands, digestive enzymes, and sweat glands Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat. Without sufficient chloride ions in the cells, a thick mucus is secreted.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Albinism Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes White hair Very pale skin Pink pupils

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Tay-Sachs Disease Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration.

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Galactosemia Recessive genetic disorder characterized by the inability of the body to digest galactose.

Dominant Genetic Disorders Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Dominant Genetic Disorders Huntington’s disease affects the nervous system. Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short.

Basic Patterns of Human Inheritance Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance

Section 1 Complex Inheritance and Human Heredity

Section 1 Complex Inheritance and Human Heredity Basic Patterns of Human Inheritance Pedigrees A diagram that traces the inheritance of a particular trait through several generations

Section 1 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.

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Incomplete Dominance The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.

Both alleles are expressed in the heterozygous condition. Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Codominance Both alleles are expressed in the heterozygous condition. Sickle-cell disease is one example.

Section 2 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 7766x

ABO blood groups have three forms of alleles. Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Multiple Alleles Blood groups in humans ABO blood groups have three forms of alleles.

Multiple alleles can demonstrate a hierarchy of dominance. Section 2 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, ch, and c. Option 2 (continued on the next slide)

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Epistasis Variety is the result of one allele hiding the effects of another allele.

Sex chromosomes determine an individual’s gender. Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sex Determination Sex chromosomes determine an individual’s gender.

Section 2 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.

Genes located on the X chromosome Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Sex-Linked Traits Genes located on the X chromosome Red-green color blindness Hemophilia Sex-Linked Traits

Section 2 Complex Inheritance and Human Heredity Complex Patterns of Inheritance Polygenic Traits Polygenic traits arise from the interaction of multiple pairs of genes.

Environmental Influences Section 2 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

Section 2 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.

Images of chromosomes stained during metaphase Section 3 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.

Telomere caps consist of DNA associated with proteins. Section 3 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

Cell division during which sister chromatids fail to separate properly Section 3 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

Section 3 Complex Inheritance and Human Heredity

Section 3 Complex Inheritance and Human Heredity

Identify the disease characterized by the absence of melanin. Chapter Complex Inheritance and Human Heredity Chapter Diagnostic Questions Identify the disease characterized by the absence of melanin. albinism cystic fibrosis galactosemia Tay-Sachs A B C D CDQ 1

An individual with Tay-Sachs disease would be Chapter Complex Inheritance and Human Heredity Chapter Diagnostic Questions An individual with Tay-Sachs disease would be identified by which symptom? excessive mucus production an enlarged liver a cherry-red spot on the back of the eye vision problems A B C D CDQ 2

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

Which is the genotype of a person who is 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? DD Dd dd dE A B C D FQ 2

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? at least one parent is a carrier both parents are carriers both parents are homozygous recessive at least one parent is homozygous dominant A B C D FQ 3

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? dosage compensation incomplete dominance multiple alleles sex-linked A B C D FQ 4

Of the 23 pairs of chromosomes in human Chapter Complex Inheritance and Human Heredity Section 2 Formative Questions Of the 23 pairs of chromosomes in human cells, one pair is the _______. autosomes Barr bodies monosomes sex chromosomes A B C D FQ 5

What does a karyotype show? Chapter Complex Inheritance and Human Heredity Section 3 Formative Questions What does a karyotype show? The blood type of an individual. The locations of genes on a chromosome. The cell’s chromosomes arranged in order. The phenotype of individuals in a pedigree. A B C D FQ 7

What is occurring in this diagram? Chapter Complex Inheritance and Human Heredity Section 3 Formative Questions What is occurring in this diagram? multiple alleles nondisjunction nonsynapsis trisomy A B C D FQ 8

What condition occurs when a person’s cells 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? Down syndrome Klinefelter’s syndrome Tay-Sachs syndrome Turner’s syndrome A B C D FQ 9

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

Down Syndrome results from what change in chromosomes? Chapter Complex Inheritance and Human Heredity Chapter Assessment Questions Down Syndrome results from what change in chromosomes? one less chromosome on pair 12 one extra chromosome on pair 21 one less chromosome on pair 21 one extra chromosome on pair 12 A B C D CAQ 3

If a genetic disorder is caused by a dominant 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? heterozygous homozygous dominant homozygous recessive A B C STP 1

RR Rr rr Standardized Test Practice 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 B C RR Rr rr STP 2

Standardized Test Practice 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 B C D codominance dosage compensation epistasis sex-linked STP 3

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

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? 25% 50% 75% 100% A B C D STP 5

Section 1 Vocabulary carrier pedigree Section 1 Complex Inheritance and Human Heredity Vocabulary Section 1 carrier pedigree

Section 2 Vocabulary incomplete dominance codominance multiple alleles Complex Inheritance and Human Heredity Vocabulary Section 2 incomplete dominance codominance multiple alleles epistasis sex chromosome autosome sex-linked trait polygenic trait

Section 3 Vocabulary karyotype telomere nondisjunction Section 3 Complex Inheritance and Human Heredity Vocabulary Section 3 karyotype telomere nondisjunction