Transcript r - LT AP BIO

Genetics
Yeah-ya!
PRACTICE
E = Free ear lobes
e = attached ear lobes
Cross a heterozygous free-eared male with
a woman with attached ear lobes
e
e
E
Ee
Ee
E
Ee
e
ee
ee
e
ee
e
Genotypic Ratio : 2:2 Phenotypic Ratio : 2:2
EE – 0
Free – 2 (50%)
Ee – 2 (50%)
Attached – 2 (50%)
Ee – 2 (50%)
Draw the other possible crosses for
this gene
Use other possible genotypes
Punnett Square Trends
What process is a punnett square
showing (predicting)?
Independent vs. Dependent
Assortment
It’s all about Probability
Old School Thinking
Mendel
Why Peas?
•Chosen for its 7
easily
distinguishable
characteristics
•Short life span
•Small
•Large number
of offspring
•Easy to self or
cross fertilize
Mendel’s Process
4 Key Findings
Characters (traits) are influenced by
alleles (different forms of the same gene)
Each organism inherits 2 “factors” (alleles)
for each trait – one from each parent
One allele will dominate over the recessive
one
Alleles segregate during gamete
production
CHROMOSOMES
LETTERS are ALLELES
SEED SHAPE
SEED COLOR
THREE DIFFERENT POSSIBILITIES FOR A GENE
HOMOZYGOUS
DOMINANT
HOMOZYGOUS
RECESSIVE
HETEROZYGOUS
DOMINANT
MEIOSIS
4 CELLS WITH ‘R’ ALLELE FOR THIS GENE
How did Mendel find true-breeding
plants?
Any ideas
Testcross
What does it mean to be dominant?
Different types of inheritance
Complete Dominance
– 50 copies of the
functional protein
gives the same effect
as 100 copies
(haplosufficiency)
– PKU (genetic disorder
where phenylalanine
cannot be broken
down – missing
enzyme)
Can cause mental
retardation if untreated
Incomplete Dominance – 50 copies is not
sufficient (Flower color in snapdragons)
– FF – produces 100 red pigment molecules
(very dense) – seen as red
– Ff – produces 50 red pigment molecules (less
dense) – seen as pink
– ff – produces no red pigment molecules –
seen as white
Codominance – 2 different proteins can be
made by a single gene (A&B blood types)
– When the A allele is present – A antigens are
made and seen on the RBC surface
– When the B allele is present – B antigens are
made and seen on the RBC surface
– When neither are present – no antigens are
present
– When both alleles are present – both antigens
are seen on the surface of the RBC’s
Multiple Alleles – more than 2
possible alleles for a gene
Rh Factor – normal autosomal
inheritance
Blood Types and Personality
According to the Japanese...
Type OYou want to be a leader, and when you see
something you want, you keep striving until you achieve
your goal. You are a trendsetter, loyal, passionate, and
self-confident. Your weaknesses include vanity and
jealously and a tendency to be too competitive.
Type AYou like harmony, peace and organization. You
work well with others, and are sensitive, patient and
affectionate. Among your weaknesses are stubbornness
and an inability to relax.
Type BYou're a rugged individualist, who's straight
forward and likes to do things your own way. Creative
and flexible, you adapt easily to any situation. But your
insistence on being independent can sometimes go too
far and become a weakness.
Type ABCool and controlled, you're generally well-liked
and always put people at ease. You're a natural
entertainer who's tactful and fair. But you're standoffish,
blunt, and have difficulty making decisions.
Genes on the Male Sex Chromosomes
XH
DOMINANT
RECESSIVE
Xh
XH
XH XH XH Xh
Y
XH Y
XhY
IV.
Sex-linked Inheritance
A. Color Blindness – recessive, linked to the X
chromosome
1. Cannot distinguish between colors like red
and green
2. Genotypes:
a. XCXC – normal female, non carrier
b. XCXc’ – normal female, carrier (may pass
recessive allele on to sons and/or
daughters)
c. Xc’Xc’ – colorblind female (will pass
recessive allele to all children
d. XCY – normal male
e. Xc’Y – colorblind male (will pass recessive
allele to daughters only)