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Section 1: Basic Patterns of Human Inheritance

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1 Section 1: Basic Patterns of Human Inheritance
The inheritance of a trait over several generations can be shown in a pedigree.

2 Essential Questions How can genetic patterns be analyzed to determine dominant or recessive inheritance patterns? What are examples of dominant and recessive disorders? How can human pedigrees be constructed from genetic information? Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

3 Vocabulary Review New genes carrier pedigree
Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

4 Recessive Genetic Disorders
A recessive trait is expressed when the individual is homozygous recessive for the trait. Those with at least one dominant allele will not express the recessive disorder. An individuals who is heterozygous for a recessive disorder is called a carrier. Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

5 Recessive Genetic Disorders in Humans
Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

6 Recessive Genetic Disorders
Cystic fibrosis A disorder that affects the mucous-producing glands, digestive enzymes, and sweat glands. Chloride ions are not properly transported out of cells of a person with cystic fibrosis. Cystic fibrosis causes mucus excretion that clogs ducts in the pancreas, interrupts digestion, and blocks respiratory pathways in the lungs. Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

7 Recessive Genetic Disorders
Cystic fibrosis Occurrence in the US 1 in 3500 Cause The gene that codes for a membrane protein is defective Effect Excessive Mucus production ____________________________ Cure/Treatment No Cure Daily cleaning of mucus from lungs Mucus thinning drugs Pancreatic enzyme supplements Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

8 Recessive Genetic Disorders
Cystic fibrosis Occurrence in the US 1 in 3500 Cause The gene that codes for a membrane protein is defective Effect Excessive Mucus production Digestive and respiratory failure Cure/Treatment No Cure Daily cleaning of mucus from lungs Mucus thinning drugs Pancreatic enzyme supplements Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

9 Recessive Genetic Disorders
Albinism Albinism is caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes. Individuals with albinism have very pale skin, white hair, and pink irises. Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

10 Recessive Genetic Disorders
Albinism Occurrence in the US 1 in 17,000 Cause Genes do not produce normal amounts of the pigment melanin Effect ____________________________ Vision Problems Cure/Treatment No Cure Protect skin from the Sun Visual rehabilitation Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

11 Recessive Genetic Disorders
Albinism Occurrence in the US 1 in 17,000 Cause Genes do not produce normal amounts of the pigment melanin Effect Skin susceptible to UV damage No color in skin, eyes, hair Vision Problems Cure/Treatment No Cure Protect skin from the Sun Visual rehabilitation Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

12 Recessive Genetic Disorders
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. Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

13 Recessive Genetic Disorders
Tay-Sachs disease Occurrence in the US 1 in 2,500 (affects people of Jewish descent) Cause Absence of a necessary enzyme that breaks down fatty substances Effect ____________________________ Mental disabilities Cure/Treatment No Cure or treatment Death by age 5 Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

14 Recessive Genetic Disorders
Tay-Sachs disease Occurrence in the US 1 in 2,500 (affects people of Jewish descent) Cause Absence of a necessary enzyme that breaks down fatty substances Effect Build up of fatty deposites in the brain Mental disabilities Cure/Treatment No Cure or treatment Death by age 5 Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

15 Recessive Genetic Disorders
Galactosemia Recessive genetic disorder characterized by the inability of the body to digest galactose. Inability to digest milk products Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

16 Recessive Genetic Disorders
Galactosemia Occurrence in the US 1 in 50,000 to 70,000 Cause Absence of the gene that codes for the enzyme that breaks down galactose Effect Mental disabilities ____________________________ Cure/Treatment No Cure Restriction of lactose/galactose in the diet Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

17 Recessive Genetic Disorders
Galactosemia Occurrence in the US 1 in 50,000 to 70,000 Cause Absence of the gene that codes for the enzyme that breaks down galactose Effect Mental disabilities Kidney failure Enlarged liver Cure/Treatment No Cure Restriction of lactose/galactose in the diet Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

18 Dominant Genetic Disorders
Huntington’s disease Affects the nervous system, causing gradual loss of brain function Occurs in 1 out of every 10,000 people in the US Achondroplasia Causes small body size and limbs that are comparatively short Caused by an abnormal gene that affects bone growth Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

19 Dominant Genetic Disorders in Humans
Occurrence In US Cause Effect Cure/Treatment Huntington’s disease 1 in 10,000 A gene affecting neurological function is defective ____________________ No cure or treatment Achondroplasia 1 in 25,000 A gene that affects bone growth is abnormal Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

20 Dominant Genetic Disorders in Humans
Occurrence In US Cause Effect Cure/Treatment Huntington’s disease 1 in 10,000 A gene affecting neurological function is defective Ability to move deteriorates Decline of mental and neurological functions No cure or treatment Achondroplasia 1 in 25,000 A gene that affects bone growth is abnormal Short arms and legs Large head Basic Patterns of Human Inheritance Copyright © McGraw-Hill Education

21 Pedigrees A pedigree is a diagram that traces the inheritance of a particular trait through several generations. Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

22 Analyzing Pedigrees Pedigrees can be used to examine both recessive and dominant genetic disorders. Information about an individual’s genotype can be inferred from the phenotype of his/her parents and offspring. Recessive disorder Dominant disorder Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

23 Analyzing Pedigrees Inferring Genotypes Predicting Disorders
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. Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

24 Review Essential Questions Vocabulary
How can genetic patterns be analyzed to determine dominant or recessive inheritance patterns? What are examples of dominant and recessive disorders? How can human pedigrees be constructed from genetic information? Vocabulary carrier pedigree Copyright © McGraw-Hill Education Basic Patterns of Human Inheritance

25 Section 2: Complex Patterns of Inheritance
Complex inheritance of traits does not follow inheritance patterns described by Mendel.

26 Essential Questions (answer after notes)
What are the differences between various complex inheritance patterns? How can sex-linked inheritance patterns be analyzed? How can the environment influence the phenotype of an organism? Copyright © McGraw-Hill Education Complex Patterns of Inheritance

27 Vocabulary Review New gamete incomplete dominance codominance
multiple alleles sex chromosome autosome sex-linked trait polygenic trait Complex Patterns of Inheritance Copyright © McGraw-Hill Education

28 Incomplete Dominance In some organisms, heterozygous individuals will display the dominant phenotype. With incomplete dominance, the heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

29 Codominance In codominance, both the dominant and recessive alleles are expressed in heterozygous individuals. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

30 Codominance Sickle-cell disease Sickle-cell disease and malaria
Changes in hemoglobin cause red blood cells to become sickle shaped. People who are heterozygous for the trait have both normal and sickle- shaped cells. Sickle-cell disease and malaria Those who are heterozygous for the sickle cell trait also have a higher resistance to malaria. The death rate due to malaria is lower where sickle-cell trait is higher, meaning more people live to pass it on to their offspring. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

31 Multiple Alleles Blood groups in humans
Some forms of inheritance are determined by more than two alleles, referred to as multiple alleles. The ABO blood group has three forms of alleles, sometimes called AB markers. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

32 Multiple Alleles 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. The hierarchy of dominance is C > cch > ch >c. The presence of multiple alleles increases the possible number of genotypes and phenotypes. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

33 Sex Determination One pair of chromosomes, sex chromosomes, determine an individual’s gender. XX: female XY: male The other 22 pairs of chromosomes are called autosomes. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

34 Sex-Linked Traits Traits controlled by genes located on the X chromosome are sex-linked traits. Because males have only one copy of the X chromosome, they are more affected by recessive X-linked traits. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

35 Sex-Linked Traits Red-green color blindness Recessive, X-linked trait
Mothers are carriers. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

36 Sex-Linked Traits Hemophilia
Recessive, X-linked trait that causes delayed clotting of blood Copyright © McGraw-Hill Education Complex Patterns of Inheritance

37 Polygenic Traits Polygenic traits arise from the interaction of multiple pairs of genes. Include such traits as skin color, height, and eye color Copyright © McGraw-Hill Education Complex Patterns of Inheritance

38 Environmental Influences
Sunlight and water Without enough sunlight, most plants will not produce flowers. Insufficient water causes plants to drop their leaves. Temperature Most organisms experience phenotypic changes with extreme heat. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

39 Twin Studies Help 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. Copyright © McGraw-Hill Education Complex Patterns of Inheritance

40 Review Essential Questions Vocabulary
What are the differences between various complex inheritance patterns? How can sex-linked inheritance patterns be analyzed? How can the environment influence the phenotype of an organism? Vocabulary incomplete dominance codominance multiple alleles epistasis sex chromosome autosome sex-linked trait polygenic trait Copyright © McGraw-Hill Education Complex Patterns of Inheritance

41 Section 3: Chromosomes and Human Heredity
Chromosomes can be studied using karyotypes.

42 Essential Questions How are karyotypes used to study genetic disorders? What is the role of telomeres? How is nondisjunction related to Down syndrome and other abnormal chromosome numbers? What are the benefits and risks of diagnostic fetal testing? Copyright © McGraw-Hill Education Chromosomes and Human Heredity

43 Vocabulary Review New mitosis karyotype telomere nondisjunction
Chromosomes and Human Heredity Copyright © McGraw-Hill Education

44 Karyotype Studies Scientists study not only genes but entire chromosomes. Images of chromosomes stained during metaphase allow scientists to study sister chromatids and homologous chromosomes. Karyotype – micrograph in which the pairs of homologous chromosomes are arranged in decreasing size. Copyright © McGraw-Hill Education Chromosomes and Human Heredity

45 Nondisjunction Cell division where sister chromatids fail to separate properly is called nondisjunction. Copyright © McGraw-Hill Education Chromosomes and Human Heredity

46 Nondisjunction Down syndrome Result of an extra chromosome 21
Characteristics include distinctive facial features, short stature, heart defects, and mental disability. Copyright © McGraw-Hill Education Chromosomes and Human Heredity

47 Fetal testing Fetal tests can provide information on potential genetic disorders and chromosomal status of developing babies. Copyright © McGraw-Hill Education Chromosomes and Human Heredity

48 Review Essential Questions Vocabulary
How are karyotypes used to study genetic disorders? What is the role of telomeres? How is nondisjunction related to Down syndrome and other abnormal chromosome numbers? What are the benefits and risks of diagnostic fetal testing? Vocabulary karyotype telomere nondisjunction Copyright © McGraw-Hill Education Chromosomes and Human Heredity

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