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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
H h
H H H
h
h h
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
Hh hh
Hh hh
H h
h
h
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
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
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