Download Guided Notes-Genetics

I. Genetics & Heredity
a. Genetics - ______________________________________
b. Heredity - _______________________________________
II. Gregor Mendel
a.
______________________________________________________________
______________________________________________________________
b. ______________________________________________________________
______________________________________________________________
c. He began his research with pea plants that were considered ___________________________________.
i. Plants that have the ability to produce offspring identical to themselves, through the use of their
own gametes = “______________________________” = true breeding
d. Most plants reproduce via cross-pollination, ________________________________________________
____________________________________________________________________________________.
e. Mendel DID NOT want to have this extra variable in his research, so he prevented his plants from “selfpollinating” by crossing the pea plants himself.
f. He began his research looking at 7 different pea plant TRAITS.
i. ______________________________________________________________________________
III. Mendel’s Research
a. _____________________________________________________________________________________
b. He cross-pollinated plants with different forms of the same trait (i.e. purple x white) to examine
offspring.
c. Inheritance is determined by GENES.
i. ______________________________________________________________________________
d. Some ALLELES (___________________________________________________________) are considered
Dominant and some are Recessive: ________________________________________________________
i. Dominant ____________________________________________________________________
ii. Recessive  ___________________________________________________________________
e. Mendel conducted __________________________________________ (mating involving only one pair
of traits).
f. He cross-pollinated 2 pea plants with opposing traits
g. _____________________________________________________________________________________
i. Ex  Purple flowering plant & white flowering
plant
h. ______________________________________________
______________________________________________
_____________________________________________,
meaning “first filial.”
i.
Results: _______________________________________
______________________________________________
j.
Mendel’s 2nd Experiment…
i. ______________________________________________________________________________
ii. Results: The ______________________________________ (“second filial”) produced flowers in
a ratio of 3 purple: 1 white
iii. This 3:1 ratio occurred for each of the 7 traits in the F2 Generations!
IV. Mendel’s Conclusions:
a. _________________________________________________________________________________ –
one from each parent.
b. _____________________________________________________________________________ (alleles).
c. When 2 different alleles occur together, ___________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
d. Gametes (sperm and eggs) each carry one allele for a given trait; _______________________________
_____________________________________________________________________________________
V. Basic Terms
a.
b.
c.
d.
__________________________: Segment of DNA that determines a specific trait
__________________________: a characteristic that varies from one organism to another
__________________________: Different forms of a gene
__________________________________: an allele that hides a recessive trait; usually characterized by
a capital letter.
e. __________________________________: an allele that can be “masked” or hidden by a dominant
allele; usually characterized by a lower-case letter
VI. Homozygous vs. Heterozygous
a. Homozygous: _________________________________________________________________________
____________________________________________________________________________________;
also known as “pure-bred”
b. Heterozygous: _______________________________________________________________________;
also known as “hybrid”
VII.
Genotype vs. Phenotype
a. Genotype: the _________________________________________________________________________
(ex: PP, pp, or Pp)
b. Phenotype: _________________________________________________________________________
(ex: blonde h)
VIII. The Law of Segregation
a. _____________________________________________________________________________________
_____________________________________________________________________________________
IX. The Law of Independent Assortment
a. Alleles for different genes separate independently of each other during gamete formation.
b. One trait, like flower color, ____________________________________________________________,
like plant height.
X. Probability
a. Probability = ________________________________________________________________________.
b. _____________________________________________________________________________________
_____________________________________________________________________________________
c. The more trials conducted, the closer the result will come to the EXPECTED ratio.
d. The Punnett square can predict the “probability” of outcomes resulting from a genetic cross.
XI. Punnett Squares
a. Punnett Squares are ___________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
b.
Possible __________________________________ are placed along the _______________ of the
square; possible ________________________________ parent are written on the ______________ of
the square.
c. The genotypes are predicted by combining alleles from each parent.
d.
We can use ratios to express genotypes and phenotypes.
e. ____________________________________ (crosses involving 2 traits) are a little more complex.
f. Possible combinations for the different types of alleles are placed at the top and sides of the square.
g. Example: (Round, Yellow)  (wrinkled, green)
RrYy
rryy
XII.
Beyond Dominant & Recessive Alleles
a. Some traits are ___________________________, meaning that
more than one gene determine the phenotype.
i. Examples  ___________________________________
______________________________________________
____________________________________________
XIII. Incomplete Dominance
a. One form of a trait is NOT dominant or recessive to the
other.___________________________________________
________________________________________________
_____________________________________________.
i. Example Four O’Clocks flower :
Red (RR) X White (WW)  Pink (RW)
XIV. Codominance
a. _________________________________________________________
_________________________________________________________
______________________________________________________
i. ExampleA homozygous red horse mates with a
homozygous white horse to produce a horse with BOTH red
and white hair (called a Roan coat).
XV.
Blood Types
a. ________________________________________ – Genes with 3 or
more possible alleles determining a trait
b. Each individual receives only 2 alleles, but there are more than 2 in
the population
i. Example = Blood Type
1. Blood Phenotypes = ___________________________________
2. Blood Alleles = _______________________________________
3. __________________________________________________________ & i is recessive
XVI. Human Genetics
a. Sex Chromosomes ___________________________________________________________________
_____________________________________________________________________________________
b. Autosomal Chromosomes  The _________________________________________________________
c. Karyotype = __________________________________________________________________________
____________________________________________________________________________________
d. Two types of Disorders:
i. ________________________________________________________
ii. ________________________________________________________
e. Sex-Linked Traits
i. All ____________________ carry an ___________chromosome
ii. _______________________ are XX; ______________________ carry XY
iii. ______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
iv. Males do not carry the backup copy of the X chromosome, so the gene is expressed
XVII.
Sex-Linked Disorders
a. The information/ traits on the sex chromosomes are called sex-linked genes. Because these
chromosomes determine sex, disorders caused by these genes are sex-linked disorders.
_____________________________________________________________________________________
b. Examples
i. ___________________________________________
ii. ___________________________________________
iii. ___________________________________________
XVIII.
Chromosomal Disorders
a. ____________________________________ (failure of homologous chromosomes to separate) occurs
during meiosis. The resulting individual has an abnormal number of chromosomes and that results in a
disorder!
b. Examples:
i. ___________________________________ (Trisomy 21)
ii. __________________________________ (XO) sterile
iii. ___________________________________(XXY)
Karyotype of Trisomy 21