Download Genetics Unit 2 – Transmission Genetics

Genetics Unit 2 – Transmission Genetics
Chapter 4 – Pages 69-86
Mendel’s Experiments – Why were pea plants a good choice?
1. Easy to _________
2. Takes little space
3. ________________
4. Self- and cross-fertilization are possible
5. Traits are easy to _______________
6. They reproduce quickly and have many offspring.
***This was a large experiment (______________ plants)
Monohybrid Cross – involves ___ trait (___ genes)
P1 x P1 = ___
- P1 (parent generation) are _________________
- always breed ________ (all offspring same)
- dominant traits prevent others from _________________
F1 x F1 = ____
- some traits in ____ are not present in F1
- recessive traits are expressed _____
Alleles – different forms of the same ___________
If smooth peas are dominant over wrinkled, then:
Genotype – genetic makeup (gene pair)
Dominant SS (purebred or ___________________)
- alleles are ____________
Ss (hybrid or _____________________)
- alleles are _______________
Recessive ss (purebred or homozygous)
- alleles are identical
Phenotype = ____________________________
SS or Ss = _________________ peas
ss = __________________ peas
Wild Type – most _________________ phenotype in a population
Dihybrid Cross – involves _______ traits (_____ genes)
Law of Segregation - ___________ of gene pairs occurs during _____________
(SsYy = S or s and Y or y) because a parent can only pass on ____ of their
genes.
Law of Independent Assortment - The _____________________ of one gene of
each pair into gametes (SsYy = _________________________)
Mendel’s Results
1. Organisms inherit ____________________, one from each parent.
2. Some traits are _______________ and some are ________________.
3. Recessive traits show only when no ____________________ are present.
Autosomal Recessive Traits
- more ___________ phenotypically
- may show common _______________
- caused by the loss of normal _______________ production or function
_____________________ – means “shared blood” or interbreeding
- better chance of having genes _____________________
- makes ___________ recessives show
- _______________________________ affected
- heterozygotes have ____ children affected
Albinism
Cystic Fibrosis
Galactosemia
Sickle Cell Anemia
Phenylketonuria (PKU)
Xeroderma pigmentosum
Autosomal Dominant Traits
- heterozygotes have ___ children affected
- ____________________________ affected
- can cause a “______________________” as an abnormal protein
interferes with a normal one
- heterozygotes usually show a _______________ of the trait than
homozygotes
Achondroplasia
Familial Hypercholesterolemia
Huntington Disease
Marfan Syndrome
Neurofibromatosis
Polydactyly
Porphyria
Proteus Syndrome
Retinoblastoma
Uses of a Pedigree
Determines:
- If a disease (defect) is ________________
- The __________________ of family members
- The ______________________________ involved
- The ___________________________ on the trait
Probability
1. ____________Rule – the chance that two independent events will
occur equals the _____________ of the chance either event will occur
on its own.
Ex.- What is the risk of you being infected with a flesh eating bacteria
(1/170,000) __________ having your car stolen (1/145)?
1/170,000 x 1/145 = 1/24,650,000
2. ___________ Rule – the chance that one of two independent events
will occur equals the __________ of the chance either event will occur
on its own.
Ex.- What is the risk of you being infected with a flesh eating bacteria
(1/170,000) _______ having your car stolen (1/145)?
1/170,000 + 1/145 ~ 6.9/1000
Chapter 5 – Pages 93-107
Exceptions to Mendel’s Laws
1. Multiple alleles – forms through a gene mutation causing multiple alleles in
a ___________________, not in an __________________.
A) ABO Blood Groups
B) _________ – over 300 alleles
C) _________ – over 1500 alleles (70% F508 gene)
2. Incomplete Dominance – both alleles are expressed causing a
___________________ trait.
A) Sickle Cell Anemia
B) Familial Hypercholesterolemia
3. _______________________ – both alleles are expressed
A) AB blood type
4. Epistasis – one _______________ or affects the expression of a different
gene.
A) Bombay phenotype – some people have Type ___ blood, but not
genotype ___ due to __ and __ antigens not able to attach to RBCs.
5. Variation in traits – Marfan Syndrome, Porphyria
A) __________________ - % of those who carry a given gene, and
show expression of it.
- complete vs. incomplete penetrance
B) Expressivity – _______________ of phenotypic expression that is
present (________________).
C) ________________ – disorder with many apparently unrelated
symptoms.
- ______________ produce these affects due to controlling
several functions
- Gene SCN9A – People feel ___ pain and have no sense of
________________
6. Phenocopy – an environmentally caused trait that ________ an inherited
trait.
- thalidomide effects vs. phocomelia
7. Genetic Heterogeneity – different genes can produce the same __________.
- 132 forms of autosomal recessive ____________, but a child must
inherit _____ genes on the ______ chromosome to be affected.
8. M-linked inheritance (_______________ inheritance)
- passed from ______________ to all children
- contains 37 genes affecting __________ synthesis (skeletal muscle), and
____________ production causing fatigue and vision problems
- heteroplasmy occurs in which a mutation is present in ______ mitochondria.
- mutations tend to ________________ with each mitotic division, causing the
defect to ______________ with age.
- has two ___________________ regions that are unique to each family used for
mtDNA studies
9. Linkage – certain genes are ___________________ because of how close they
are to each other on the same chromosome.
- the farther apart the genes are, the more likely a ____________ will occur
between them, and they ______________ inherited together.
- do not ___________ themselves independently
- used to produce linkage maps (____________) by comparing crossover
____________ with the _____________ between genes
10. Amplified Repeats
- _____________________ sequences repeated with each generation
- odds of defect increases with each ______________________
- number of repeats may affect __________________________
Ex.- __________________ = #1 form of inherited mental retardation
- CGG repeat