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GENETICS NOTES OUTLINE
I. CHROMOSOMES
A. Definition:
B. # total chromosomes in humans: ______
Chromosome # is unique to every species
C. Chromosomal problems- aneuploidy
- Too many
Ex: Down’s Syndrome
Klinefelter’s Syndrome
- Too Few
Ex: Turner Syndrome
- Deletions
Ex: Cri Du Chat (chr. 5)
William’s Syndrome (chr. 7)
II. KARYOTYPE
A. Definition:
B. Why used?
III. GENETICS
A. Definition:
B. Gregor Mendel:
Who?
Where?
What?
C. Pea Plants Characteristics
Mendel’s Conclusions:
D DEFINITIONS
DEFINITION
GENES
DOMINANT TRAIT
RECESSIVE TRAIT
PUNNETT SQUARE
HOMOZYGOUS
HETEROZYGOUS
GENOTYPE
PHENOTYPE
ALLELES
TRUE BREEDING
P GENERATION
F1 GENERATION
E. PRINCIPLE OF DOMINANCE
1. Definition:
DOMINANT CHARACTERISTICS GET CAPITAL LETTERS
recessive characteristics get lower case letters
F. PRINCIPLE OF SEGREGATION
a. Definition:
.
IV. PROBABILITY AND PUNNETT SQUARE
A. Why Punnett’s used?
Rule: Dominant letter always capitalized and listed FIRST
Recessive letter always lower case and SECOND
B. Practice:
1. If a homozygous tall person was crossed with a homozygous short person,
what are probably offspring?
2. Cross two heterozygous tall parents.
What is the
genotype ratio?
Tall= T
short= t
3. In dogs, wire hair (W) is dominant to smooth (w). Cross a
homozygous wire haired dog with a smooth-haired dog.
Phenotype?
4. Tongue rolling (T) is dominant to non-tongue rolling (t). Cross a
homozygous tongue-rolling with a heterozygous tongue-rolling.
5. The long-eared allele (L) is dominant to the short-eared allele (l). Cross a
homozygous long ear with a homozygous short-ear. Then cross the F1
generation and give the F2 results.
V. EXPLORING MENDELIAN GENETICS
A. Define Independent Assortment:
1. Example:
B. How to figure out possible gametes in a dihybrid cross:
Just use F.O.I.L.!!
1. Example: TtPp can give gametes: TP, Tp, tP, and tp.
______
______ ______
______
_______
_______
_______
_______
The ratio of a dihybrid heterozygous cross is always: ___________!
VI. BEYOND PURE DOMINANCE
A. Incomplete dominance:
1. Example: Cross a red flower with a white flower, showing incomplete
dominance, where R= red and W= white.
B. Co-dominance:
1. Examples:
C. Multiple Alleles:
1. Examples:
D. Polygenic Traits:
1. Examples:
VII. SEX LINKED TRAITS
A. Sex determination:
B. Thomas Morgan:
C. Remember: The X and Y sex chromosomes are non-homologous. Any allele
on the X chromosome will NOT be masked by a matching allele on the Y
chromosome
D. Why are sex-linked traits more common in males than females?
1. Example of sex-linked Diseases:
2. Other examples:
E. Sex-linked?:
F. Sex-influenced?:
VIII. GENE LINKAGE
A. Scientist who studied gene linkage?
B. What organism did he work with?
C. His major discovery:
Gene map: