Transcript Welcome AP Super

Welcome AP Super-teachers!
Mendelian Genetics
November 3, 2011
Chapter 14 (in Campbell)
Mendelian Genetics
The Father of Genetics &
Cook for the Abbey
Chapter 14
Objective 1
• TSW: Recognize the differences/similarities
between the terms: Trait, Character, allele,
gene
Character and Trait
Fig: 14.4
One from EACH parent
Sperm AND Egg
Chapter 14
Objective 2
• TSW: Recognize and explain the differences
and “ source” between the following terms:
phenotype and genotype; truebreed and
hybrid
Phenotype vs. Genotype
Physical Trait vs. Gene allele type
Chapter 14
Objective 3
• TSW: Understand and apply Mendel’s laws of
Segregation and Independent assortment
Teach the Skill
• Mendel’s Law of Segregation (Segregate
means “to separate”)
– The genes ON chromosomes can move
independently of one another.
– This is supported by what happens during
Crossover of Prophase I.
Teach the Skill
• Mendel’s Law of Independent ASSORTMENT
(This basically states that VARIATIONS are
possible on chromosomes.) ( Assortment
means “variety exists”)
– This states that chromosomes move
independently of one another.
– This occurs at Anaphase I and II in Meiosis. It also
occurs in Anaphase of Mitosis too.
Chapter 14
Objective 4
• TSW: Be able to calculate probability in
genetic problems using the rule of
multiplication.
• Be able to relate these problems to punnett
squares of genotypes.
• Probability worksheet*
• EXAMPLE: What is the probability that the
following parents will produce the indicated
(DESIRED) offspring?
Assume Independent Assortment of all gene pairs.
•
• Parents Genotypes:
• Male: AABb CC X Mother: Aa Bb cc
• Offspring (Desired) Genotype: AABbCc
•
How to work quickly
•
•
•
•
•
•
•
•
•
•
l
l
MALE:
A A l B b l C C
↓↙ l
X l ↓X↓
FEMALE:
A a l B b l c c
l
l
OFFSPRING: A A l B b l C c
(DESIRED)
l
l
# of Arrows:
2 l
2
l
4
l
l
1/
Fraction:
x 1/2 x
1 = 1/4
2
Probability OR 25% Chance for that DESIRED
genotype outcome
Chapter 14
Objective 5
• TSW: Work with, relate phenotypic ratio
outcomes, and Mendel’s laws associated with
Punnett Squares.
LE 14-7
Dominant phenotype,
unknown genotype:
PP or Pp?
Recessive phenotype,
known genotype:
pp
If Pp,
then 2 offspring purple
and 1 2 offspring white:
If PP,
then all offspring
purple:
p
1
p
P
p
p
P
Pp
Pp
Pp
P
Pp
P
Pp
Pp
pp
pp
Fig: 14.8 (Dihybrid)
Chapter 14 - Objective 6
Teach the Skill
• TSW: Differentiate and give specific examples
related to the following terms: Co.mplete
Dominance, Incomplete Dominance, and
Codominance
Complete
Teach the Skill
Incomplete
Teach the Skill
Codominance
Teach the Skill & Cell Signaling tie-in
Chapter 14
Objective 7
• TSW: Understand, give specific examples, and
relate to Punnett Squares with the concept of
Multiple Alleles
Multiple Alleles
Teach the Skill & Cell Signaling tie-in
Chapter 14
Objective 8
• TSW: Understand and give examples of the
following terms: Pleiotropy, Epistasis,
Polygenic Inheritance, and Multifactorial
Teach the Skill & Tie into Protein
Synthesis and Protein Structure
• Pleiotropy
– This is where one gene affects multiple
Phenotypes. ( “Pleio” means “multiple”)
– Sickle Cell Disease is a great example. (This gene
AFFECTS the red blood cells Shape, Oxygen
carrying ability, Malaria resistance, etc.) The one
gene is affecting multiple phenotypes.
•
Pleiotropy (Sickle Cell)
Teach the Skill
• Epistasis (Fig: 14.11)
– A gene at one locus affects a gene at a second
locus.
– Hair is a great example. (Several genes are
interacting to “create” hair’s phenotypes – These
are: color, shape, thickness, texture, etc.) (“epi”
means “source”; “stasis” means location) The
source is affecting another location.
• Gets a 9:3:4 ratio – This is key.
LE 14-11
BbCc
BbCc
Sperm
1
1
1
1
1
4
BC
1
4
1
bC
4
1
Bc
4
bc
4
BC
BBCC
BbCC
BBCc
BbCc
4
bC
BbCC
bbCC
BbCc
bbCc
4
Bc
BBCc
BbCc
BBcc
Bbcc
4
bc
BbCc
bbCc
Bbcc
bbcc
9
16
3
16
4
16
Teach the Skill
• Polygenic Inheritance (Fig: 14.12)
– This is where there exist many different degrees of phenotypic
outcomes.
– This is due to Quantitative Characters. (Quantity -how many alleles did
you receive from your parents.)
– “poly” means “many”; “ genie” refers to “genes”; “inheritance” from
your parents
– Skin Color is a great example. (We have many different degrees of skin
pigmentation ranging from Albino  Black, Black. It depends on how
many copies of the same gene for making the skin pigment melanin
you inherited from your parents in the sperm and egg.)
– Norm of the Reaction – This refers to where the majority of organisms
fall on the bell curve for that trait.
• Evolution? The norm can tell you about the type of environment organisms
live in. The norm is because some trait is beneficial in that environment.
LE 14-12
AaBbCc
aabbcc
20/64
Fraction of progeny
15/64
6/64
1/64
Aabbcc
AaBbcc
AaBbCc
AaBbCc
AABbCc
AABBCc
AABBCC
Teach the Skill & Tie back into Ecology
• Multifactorial (Fig: 14.13)
– Many ENVIRONMENTAL factors are affecting the
phenotypic display of genes in that organism.
– This gives fuel to the argument over Nature vs.
Nurture in organisms. (The genetics vs. the
environment.)
• While there are equally legitimate arguments for both sides.
The overwhelming evidence supports a 50/50 reality. 50% of
our behavior is innate (in our genetics); after all who teaches
a dog to bark. The other 50% comes from our experiences or
living environment; such as eating good foods affects the
body you “create” over time.
• Height, intelligence, and weight can all be considered
multifactorial.
Multifactorial example
(Acid in soil changes the color)
Chapter 14
Objective 9
• TSW: Be able to read, discuss, and convey
inheritance patterns using pedigrees.
LE 14-14b
First generation
(grandparents)
Second generation
(parents plus aunts
and uncles)
Ff
FF or Ff
Ff
ff
Third
generation
(two sisters)
Attached earlobe
Recessive trait (attached earlobe)
ff
ff
Ff
Ff
ff
FF
or
Ff
Ff
ff
Free earlobe
LE 14-14a
Ww
ww
ww
Ww ww ww Ww
WW
or
Ww
Widow’s peak
Dominant trait (widow’s peak)
Ww
Ww
First generation
(grandparents)
Second generation
(parents plus aunts
and uncles)
ww
Third
generation
(two sisters)
ww
No widow’s peak
Pedigree of Color Blindness
Pedigree 3
• males = square
• females = circle
• 1/2 Shaded =
unaffected carrier
• shaded = affected
• Claim (PoI) =
• Reason =
How do maternal patterns of inheritance relate to mitochondria?
Chapter 14
Objective 10
• TSW: Explain the inheritance of recessive and
dominant disorders.
Human Recessive Disorders
• Cystic Fibrosis (Also referred to as “CF’.)
–
–
–
–
This is the most common lethal genetic disease.
This disorder affects 1 in 2,500 births.
In Caucasians, 1 in 25 people is a carrier for the disorder.
The disorder creates a faulty Chloride ion (Cl-) protein carrier on
cell membranes in the lungs. This causes fluid (water0 to build up
in the lung tissues.
» People drown in their own fluid.
» They are also prone to get multiple infections in the lungs.
– Treatment? Since it is genetic there is NO cure. Patients have to
get the fluid drained from the lungs periodically for their ENTIRE
life. There are medicines to help reduce the number of times this
has to occur.
Recessive
• Tay-Sachs Disease
– This disorder creates a non-functional lysosome in brain cells.
Brain cells need massive amounts of energy to function
properly; therefore, they feed upon lipids primarily. The
lysomomes break them down using beta oxidation for use in
cellular respiration. The lysosomes associated with this
disorder are missing an enzyme to be able to do this; so they
just fill up with lipids. The cells fill with lipids and then die.
– This disorder mainly affects the Jewish Culture because of
marrying within the culture. The Jewish culture has a high
percentage of carriers.
– The children affected, usually die a painful, blind death by age
5.
Recessive
(BE CAREFUL IN DISCUSSING)
• Sickle-cell Disease (Fig: 5.21 Pg. 84)
– This disorder is the most common genetic disorder within the black population. Other
populations can get it too. It is not exclusive.
– It affects 1 in 400 births.
– The 6th Amino Acid is changed (Glutein  Valine) in the PRIMARY sequence of one of
the proteins needed to make red blood cells. (The easy way to remember this is: 666 is
the number of the beast. 6 is the amino acid that changed to create this horrible disease.
It went from good [glutein] to very bad [valine].)
– Sickle- cell trait (“trait” is used to refer to individuals that are carriers.)
» These individuals have resistance to Malaria because of the ONE recessive allele
they possess but mainly have normal red blood cells for carrying oxygen.
» This is referred to as the Heterozygous Advantage. They have an advantage over
individuals that are homozygous dominant or homozygous recessive. Homozygous
dominant are NOT resistant to Malaria. Homozygous recessive are also resistant to
Malaria; BUT they have the disease to contend with.
» Sickle – cell identification of carriers in individuals is important to avoid this
disorder from occurring.
– These sickle shaped cells have reduced oxygen carrying ability. They also are painful
when the points of the cell jab into the walls of the blood vessels.
– Treatment? There is no cure as it is genetic. Some medicines help with the pain or low
oxygen levels.
•
Dominant Human Disorders
• Achondroplasia (Fig: 14.15) (This is referred to as
Genetic Dwarfism.)
– This disorder affects 1 in 10,000 births.
– Most people are homozygous recessive and there for much
taller than these individuals.
Dominant
(BE CAREFUL IN DISCUSSING)
• Huntingdon’s Disease
– This disorder affects 1 in 10,000 births.
– It has a late life onset – usually in the 40-50 age range.
(Usually AFTER children are born.)
– The dominate gene has a locus on tip of Autosome 4.
– Family history is important in diagnosis of this disorder.
(Pedigree can help.)
– It is a slow degenerative disorder affecting the brain that is
almost always fatal.
•
Chapter 15 (in Campbell)
Chromosomal
Inheritance
Chapter 15
Objective 1
• TSW: Be able to understand the difference
between the terms: wild type and mutant
type.
Wild type (red) vs.
Mutant type (white)
Chapter 15
Objective 2
• TSW: Understand and relate to a pedigree, to
incude occurrence rates, the difference
between the terms: linked genes and sexlinked genes.
Autosomes and linked genes
Sex-Linked Male
Teach the Skill
Most common on the AP exam
• Color Blindness
– This is the result of a faulty gene (recessive) on the X
chromosome for making a particular type of color absorbing
protein in cones of the retina of the eye.
• The most common type is Red/Green
Colorblindness. (Red and Green appear gray.)
two
• Duchenne Muscular Dystrophy (“atrophy” means
“break down”)
– This affects about 1 in 3,500 male births.
– These individuals cannot make the muscle protein Dystrophin.
(Thus the name DYStrophy)
– This disorder is a slow weakening of the muscles until around
age 20. They then become confined to a wheelchair until
death soon after.
Three
• Hemophilia (Means “love of bleeding”)
– These individuals cannot make Anti-hemolytic Factor. (AHF for
short.)
– They experience problems with bleeding to death.
– This was a disorder associated with the “Royal Blue-Bloods of
Europe” – They were inbreeding to keep the crown “ In the
Family”.
– Treatment? These individuals have to keep AHF with them at
all times in case they get hurt. If they do get hurt and start to
bleed they will require a shot of AHF to stop the bleeding.
Even a bruise (bleeding under the skin) can possibly lead to
death.
Chapter 15
Objective 3
• TSW: Be able to construct a linkage map using
crossover frequency.
Linkage Map Construction
– He used crossover rates to determine the loci on
chromosomes. (Fig: 15.7)
• The finished product is called a Linkage Map. (Fig. 15.8)
• The smaller the rate; the closer they are to each other
on the same chromosome.
• The higher the rate; the farther apart they are from
each other on the same chromosome.
• The loci are measured in Centimorgans or map units.
LE 15-7
Recombination
frequencies
9%
9.5%
17%
b
Chromosome
cn
vg
Chapter 15
Objective 4
• TSW: Explain and relate the terms: X
inactivation and mosiacism.
Teach the Skill
• X Inactivation (Turning “off” one of the X chromosomes.)
– This ONLY occurs in females because females have two X’s
(Males only have one and it MUST remain active.)
– A Barr body is formed (From condensing one of the X
chromosomes) to inactivate one set of information.
• The Barr body will be located on the nuclear envelope. (Criminal
Forensics? This is how they can tell the sex of the suspect. Males do
not have them on their nuclear envelope.)
– Mosaicism (Fig: 15.11) (A Mosaic is a puzzle.)
• In humans, it is called “Complex Skin”. (Dry spots from mom’s X
chromosome mixed with Sweaty “Greasy” spots from dad’s X
chromosome.)
• Facial products is a Billion Dollar Industry as it only affects females,
who tend to be VERY concerned with their facial appearance and
types of makeup that “Work” on their “skin type”.
Barr Body
Fig: 15.11
Chapter 15
Objective 5
• TSW: Differentiate between, identify, and
recognize terms associated with the following
abnormalities: Chromosomal Number and
Chromosomal Structure.
Number
WHEN IS IMPORTANT & Teach the Skill
Structure & Teach the Skill
Chapter 15
Objective 6
• TSW: Understand and relate the importance
of genomic imprinting.
Uniqueness
• Genomic Imprinting
– Essentially, this is “Erasing” your PARENTS unique
information to create YOUR own unique information.
– “Erasing” genetic information is accomplished by heavy
Methylation.
• Attaching large amounts of methyl (CH4 molecules) to the DNA.
• This acts like a “jacket” covering up the underlying genes.
– The amount varies for each cell that undergoes meiosis.
• If very little occurs – the offspring have a strong resemblance to
the parents.
• If a lot occurs – the offspring have very little resemblance to the
parents.
Chapter 15
Objective 7
• TSW: Understand and relate the importance
of extra-nuclear DNA.
Extranuclear DNA
(This DNA CAN can affect an organism)