Section 1: Basic Patterns of Human Inheritance

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Section 1: Basic Patterns of Human Inheritance

Section 2: Complex Patterns of Inheritance

Section 3: Chromosomes and Human Heredity

Chapter 11 Complex Inheritance and Human Heredity

11.1 Basic Patterns of Human InheritanceComplex Inheritance and Human HeredityChapter 11

Recessive Genetic Disorders

A recessive trait is expressed when the individual is homozygous recessive for the trait.

Complex Inheritance and Human HeredityChapter 11


Complex Inheritance and Human Heredity

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.

11.1 Basic Patterns of Human InheritanceChapter 11


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



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.



Galactosemia Recessive genetic disorder characterized by

the inability of the body to digest galactose.



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.






Pedigrees A diagram that traces the inheritance of a

particular trait through several generations



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.


11.2 Complex Patterns of InheritanceComplex Inheritance and Human Heredity

Incomplete Dominance The heterozygous phenotype is an

intermediate phenotype between the two homozygous phenotypes.

Chapter 11


Codominance

Both alleles are expressed in the heterozygous condition.

11.2 Complex Patterns of InheritanceChapter 11


Sickle-cell Disease 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

Normal red blood cell

7766x



Multiple Alleles Blood groups in

humans ABO blood groups

have three forms of 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.



Coat Color of Rabbits

Light gray

Dark gray Himalayan

Albino

Chinchilla



Epistasis Variety is the result of one allele hiding the

effects of another allele.

No dark pigment present in fur Dark pigment present in fur

eebbeeB_ E_bb E_B_



Sex Determination Sex chromosomes

determine an individual’s gender.



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.

Chromosome inactivation Barr bodies



Sex-Linked Traits Genes located on the X chromosome

Red-green color blindness Hemophilia


Sex-Linked Traits


Polygenic Traits Polygenic traits arise from the interaction of

multiple pairs of genes.



Environmental Influences Environmental factors Diet and exercise Sunlight and water Temperature



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.


Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size.

11.3 Chromosomes and Human HeredityComplex Inheritance and Human Heredity

Karyotype Studies

Images of chromosomes stained during metaphase

Chromosomes are arranged in decreasing size to produce a micrograph.

Chapter 11


Telomeres Telomere caps consist of DNA associated

with proteins. Serves a protective function for the structure

of the chromosome

11.3 Chromosomes and Human HeredityChapter 11


Nondisjunction Cell division during which sister chromatids

fail to separate properly Down syndrome

11.3 Chromosomes and Human HeredityChapter 11





Chapter Resource Menu

Chapter Diagnostic Questions

Formative Test Questions

Chapter Assessment Questions

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Chapter 11

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1. A2. B3. C4. D

CDQ 1

0% 0%0%0%

A. albinismB. cystic fibrosisC. galactosemiaD. Tay-Sachs

Identify the disease characterized by the absence of melanin.



1. A2. B3. C4. D

CDQ 2

0% 0%0%0%



A. excessive mucus production

B. an enlarged liverC. a cherry-red spot on

the back of the eyeD. vision problems

An individual with Tay-Sachs disease would be identified by which symptom?

1. A2. B3. C4. D

CDQ 3

0% 0%0%0%



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.

C. The individual is heterozygous for the trait.

D. There is a mutation in the dominant gene.

1. A2. B3. C4. D

FQ 1

0% 0%0%0%


A. It appears at birth and runs in families.

B. It is linked to an enzyme deficiency.

C. It continues throughout a patient’s life, affecting bones and joints.

D. It is caused by acid excretion and results in black urine.

Which of Dr. Garrod’s observations about alkaptonuria was most critical to his determination that it is a genetic disorder?

11.1 Formative Questions

1. A2. B3. C4. D

FQ 2

0% 0%0%0%


A. DDB. DdC. ddD. dE

Which is the genotype of a person who is a carrier for a recessive genetic disorder?


1. A2. B3. C4. D

FQ 3

0% 0%0%0%



A. at least one parent is a carrier

B. both parents are carriersC. both parents are

homozygous recessiveD. at least one parent is

homozygous dominant

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?

1. A2. B3. C4. D

FQ 4

0% 0%0%0%


A. dosage compensationB. incomplete dominanceC. multiple allelesD. sex-linked

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?


1. A2. B3. C4. D

FQ 5

0% 0%0%0%



A. autosomesB. Barr bodiesC. monosomesD. sex chromosomes

Of the 23 pairs of chromosomes in human cells, one pair is the _______.

1. A2. B3. C4. D

FQ 6

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A. blood typeB. color blindnessC. hemophiliaD. skin color

Which is an example of a polygenic trait?

1. A2. B3. C4. D

FQ 7

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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 pedigree.

What does a karyotype show?


1. A2. B3. C4. D

FQ 8

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A. multiple allelesB. nondisjunctionC. nonsynapsisD. trisomy

What is occurring in this diagram?

1. A2. B3. C4. D

FQ 9

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A. Down syndromeB. Klinefelter’s syndromeC. Tay-Sachs syndromeD. Turner’s syndrome

What condition occurs when a person’s cells have an extra copy of chromosome 21?

1. A2. B3. C4. D

CAQ 1

0% 0%0%0%


A. 1 and 2 are siblingsB. 1 and 2 are parentsC. 1 and 2 are offspringD. 1 and 2 are carriers

Use the figure to describe what the top horizontal line between numbers 1 and 2 indicates.


1. A2. B3. C4. D

CAQ 2

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A. IA B. IO C. IB D. i

Which is not an allele in the ABO blood group?

1. A2. B3. C4. D

CAQ 3

0% 0%0%0%



A. one less chromosome on pair 12

B. one extra chromosome

on pair 21C. one less chromosome

on pair 21D. one extra chromosome

on pair 12

Down Syndrome results from what change in chromosomes?

1. A2. B3. C

STP 1


A. heterozygousB. homozygous dominantC. homozygous recessive

If a genetic disorder is caused by a dominant allele, what is the genotype of those who do not have the disorder?


0% 0%0%

1. A2. B3. C

STP 2



0% 0%0%

A. RRB. RrC. rr

Analyze this pedigree showing the inheritance of a dominant genetic disorder. Which would be the genotype of the first generation father?

1. A2. B3. C4. D

STP 3

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A. codominanceB. dosage compensationC. epistasisD. sex-linked

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?

1. A2. B3. C4. D

STP 4

0% 0%0%0%



A. Males have only one X chromosome.

B. Males have two X chromosomes.

C. Males have only one Y chromosome.

D. The traits are located on the Y chromosomes.

Why are males affected by recessive sex-linked traits more often than are females?

1. A2. B3. C4. D

STP 5

0% 0%0%0%



A. 25%B. 50%C. 75%D. 100%

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?


Glencoe Biology Transparencies


Image Bank

carrierpedigree


Vocabulary

Section 1

incomplete dominance

codominancemultiple allelesepistasissex chromosomeautosome

sex-linked traitpolygenic trait


Vocabulary

Section 2

karyotypetelomerenondisjunction


Vocabulary

Section 3


Animation

Visualizing Nondisjunction


Documents

Section 1: Basic Patterns of Human Inheritance