Transcript Genetics - My CCSD

Human Genetics
Human Genetics
I. Mutations = changes in DNA
A. Mutations increase the amount of
variation among offspring.
II. Chromosome Mutations
A.
B.
C.
D.
Deletion: removal of a chromosomal segment
Duplication: repeats a chromosomal segment
Inversion: segment reversal in a chromosome
Translocation: movement of a chromosomal segment to
another non-homologous chromosome
III. Karyotypes
A. 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 Number
A. 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 Abnormalities
A. Many trisomies and nearly all monosomies are
fatal.
B. XYY males (Jacob syndrome)- tall, acne, not
overly aggressive
C. 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 abnormalities
F. Fragile X Syndrome – X chromosome broken; males;
hyperactive or autistic, delayed speech
G. Down Syndrome = extra 21st chromosome; mental
retardation, fold of skin above eyes, weak muscles
END NOTES TODAY
VI. Sex Determination
A. 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 Traits
1. Color Blindness
2. Hemophilia – blood doesn’t clot
x H xH = Healthy
xH y = Healthy
h
H
h
x x = Healthy
x y = hemophilia
h h
X X = hemophilia
VII. Human Genetic Traits
A. Single Allele Traits
1. Sickle Cell Anemia
a. 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
H
h
h
h
Hh
hh
Hh
hh
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 the
patterns 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