Human GeneticsHuman Genetics

I. Mutations = changes in DNAA. Mutations increase the amount of

variation among offspring.

A. Deletion: removal of a chromosomal segmentB. Duplication: repeats a chromosomal segmentC. Inversion: segment reversal in a chromosomeD. Translocation: movement of a chromosomal segment to

another non-homologous chromosome

II. Chromosome Mutations

III. KaryotypesA. Shows chromosomes

paired by size, shape, and appearance in metaphase.

B. Chorionic villi sampling, and amniocentesis can be used to diagnose chromosomal abnormalities.

IV. Changing Chromosome NumberA. Nondisjunction =

failure of chromosomes to separate during meiosis; addition or loss of a chromosome

B. Monosomy missing 1 chromosome (45)

C. Trisomy have an extra chromosome (47)

V. Nondisjunction AbnormalitiesA. Many trisomies and nearly all monosomies are

fatal.B. XYY males (Jacob syndrome)- tall, acne, not

overly aggressiveC. XO females (Turner syndrome)- short, webbed

neck, no puberty.

D. Klinefelter Syndrome = XXY; male, some retardation, low fertility (rare cases (48,XXXY) or (49,XXXXY)

E. Triple X Female (XXX) – no physical abnormalitiesF. Fragile X Syndrome – X chromosome broken; males;

hyperactive or autistic, delayed speechG. Down Syndrome = extra 21st chromosome; mental

retardation, fold of skin above eyes, weak muscles

END NOTES TODAY

VI. Sex DeterminationA. Thomas Hunt Morgan

1. Experiments with Drosophila (fruit fly)

2. Sex Chromosomes Determine Gender

a. Female are XX b. Male are XY

D. Sex chromosomes also carry genes for traits unrelated to gender.

E. Recessive alleles on X expressed in males more often.

F. Carrier: Someone who

is heterozygous for a genetic disease or trait.

G. Example of Sex Link Traits1. Color Blindness

2. Hemophilia – blood doesn’t clot

x x = Healthy x y = Healthy

x x = Healthy x y = hemophilia

X X = hemophilia

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VII. Human Genetic TraitsA. Single Allele Traits

1. Sickle Cell Anemiaa. Sickle shaped red cells

b. Clump & block arteries

c. AA= healthy cell

AA’= both kinds; protected from

malaria

A’A’= sickle cells

B. Other examples 1. Tays-Sacs 2. Cystic Fibrosis

3. Phenylketonuria (PKU)

C. Dominant Allele Diseases 1. Huntington’s Disease

a. Brain cells degenerate; no muscle control;

death

b. Occurs at 30 – 40 years old

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D. Polygenic Traits are traits that have 2 or more genes controlling it.

1.Skin color - 4-7 genes with additive effect of amount of melanin

2. Eye Color – blue (light melanin), brown (lot of melanin)

3. Height

E. Sex Influenced Traits are influenced by sex hormones

1. B = Baldness; dominant in males and recessive in females

2. BB = bald females and males

3. BB” – female will not lose her hair

4. BB” – male will lose hair

End notes Today

VIII. Studying Humans

A. Population Sampling = select a number to represent whole population

B. Twin Studies – environment vs. genetics

C. Pedigree Studies – family chart of traits

D. DNA fingerprinting = study thepatterns of bands obtained from electrophoresis

1. Gel electrophoresis – process to separate DNA fragments by size of charge

E. Pedigrees are charts or “family trees” that track which members of a family have a particular trait.

IF THEY MATED…

Lindsay Lohan and Jared Leto

Nichole Kidman and Keith Urban

Jim Carrey and Jenny McCarthy