Download Genetics Chapter 5 outline

Chapter 5
Beyond Mendel’s Laws
I. A New View of Mendelian Genetics
A. Rarely is a trait controlled by a single gene.
1. Genes interact with each other and the environment.
2. Mendel’s laws are still in effect.
II. When Gene Expression Appears to Alter Mendelian Ratios
A. Gene Expression
1. The __________ change when some traits show different
_________ to different degrees
2. The _______________ stay the same
B. Lethal Genes
1. organism dies before it _________________
2. Gene cannot be passed on
3. Lethal genotypes
a. can be AA or aa (must be __________________)
b. depending on the disorder
c. ________________ lethal alleles cause 25% of miscarriages
d. Give an example.
C.
Multiple Alleles
1. more than _________ gene contributes to the trait
2. Gives variation to the ____________________
3. The more _____________ that contribute =, the more variety to the
phenotype
4. The _______ of the disorder will help the parents know what to
expect
5. PKU
a. disorder that all babies are tested for
b. build up of ______________________ in brain
c. causes _____________________
d. babies are put on a low phenylalanine diet to save the brain
e. 300 different ____ that contribute to this to form 4 types of
PKU
1. Classic PKU - _____________________________
2. Moderate PKU - ____________________________
3. Mild PKU
4. release of Phenylalanine in the urine
6. Cystic Fibrosis
a.
D.
___% of cases - controlled by 1 gene; typical textbook
disorder
b. ____% of cases - controlled by multiple alleles; has degrees
of severity
7. Every disorder controlled by __________________________ has
degrees of severity.
Different Dominant Relationship
1. Incomplete Dominance
a. 3 traits appear
b. Give an example; write out the genotypes and
phenotypes.
2.
Codominance
a. both traits expressed at the same time
b. Brown x White --> Roan
c. List the genotypes of the 4 Blood Types
3.
E.
F.
Epistasis
a. when one gene affects the __________________ of another
gene
1. ABO blood type dictates blood type by coating the
membrane in a sugar/carbohydrate
a. the H gene allows the sugar to stick to the cell,
so if the person is hh no sugar will stick, so the
person can’t be A or B even if they carry the
genes for that trait.
Penetrance and Expressivity
1.
Completely Penetrant
a. you will always show ___________________
2. Incompletely Penetrant
a. inherit it but show ______________________
3. What 2 things influence an expressed gene?
Pleiotrophy
1. A gene that controls many functions or has more than one effect.
2.
3.
A ______________ affects different parts of the body or can
participate in more than one relation.
Describe the effects of Marfan Syndrome.
G.
Genetic Heterogeneity
1. Mutations in different genes that cause the same phenotype.
a. affecting proteins and enzymes
b. Osteogenesis imperfecta has abnormally low _______________
causing bones to break easily.
H. Phenocopy
1. something in the _______________ or a virus causes a trait to
appear
2. The __________________ appears to be genetic but was really
caused by the environment.
3. Illnesses ________________ a genetic disorder
III. Mitochondrial DNA
A. Maternal DNA
1. 37 genes in the mitochondria
2. not from the father at all
3. Most of the genes effect the production of _______ and proteins.
These are found in cells with a lot of mitochondria.
Which part of one’s anatomy would be affected most by this?
4. Name 3 symptoms:
5. Pedigrees will show traits from mother to child.
6. Diseases are rare.
7. Most diseases don’t show until adulthood when the majority of
one’s cells contain affected mitochondria.
8. If a disorder is homozygous _______________ a miscarriage will occur
so, most disorders are heterozygous.
9. How is mitochondrial DNA used?
IV. Linkage
A. When 2 genes are on the same chromosome.
1. They do not go through independent assortment or segregation; they do
not follow __________________ Law. Do not have predicted ratios.
2.
3. The closer the 2 genes are on a chromosome the ________ likely they
will ___________________ or separate, due to physical distance.
4. The further apart the 2 genes are on a chromosome the
________________ likely they will crossover or separate, due to
_______________ _____________.
B. Linkage Maps
1. To make the map show the ____________ of the genes and the
_____________________ between each gene.
2. Subtraction or addition is all that is required to figure
out the distance between chromosomes
3. What does 1 map unit equal?