HMB265H1 Study Guide - Fall 2018, Comprehensive Midterm Notes - Zygosity, Wild Type, Single-Nucleotide Polymorphism
12 Oct 2018
School
Department
Course
Professor
HMB265H1
MIDTERM EXAM
STUDY GUIDE
Fall 2018
1
HMB265
Lecture 1
Genetics = science of inheritance
Medical genetics = identify genetic cause of disease to cure, diagnose & prevent disease, gene therapy (CRISPR),
pharmacogenomics/how genes affect your response to drug treatment
Agricultural genetics = use of GMOs as food source
Conservational genetics = use genetics to restore biodiversity
Conditions are not always purely genetic – also have environmental factors
<~~~GENETIC ~~~~~~~~~~~~~~ ENVIRONMENTAL~~~>
Down’s syndrome (genetic), heart disease (both!), diabetes (both!), TB, scurvy (env!)
Lecture 2
Pre-Mendelian: used breeding w/ livestock, had some understanding that traits are passed in families
Q’s: Siblings? New characteristics? Skipping generations? Uni or biparental? Pass traits acquired over lifetime?
Mendel
• Looked at traits individually, not at whole organism
• Good model organism
o Fast growth, short generation, selfing (cut anthers & transfer pollen), many offspring
• Performed controlled experiments
Discrete/simple inheritance: either/or trait
• antagonistic pairs: mutually exclusive traits (discrete, either/or)
Continuous/complex inheritance: seems to blend, though not the case
Reciprocal cross: traits coming from opposite parent, Mendel used this to disprove uniparental inheritance
Monohybrid cross: Aa x Aa
• reappearance of recessive trait disproves blending, disproves uniparental inheritance
• P → F1 → F2
• Dominant/recessive
• law of segregation
Dihybrid cross: AABB x aabb
• law of independent assortment
Probability
Product rule: probability of (A) AND (B) happening → probability of (A) X probability of (B)
Sum rule: probability of (A) OR (B) happening → probability of (A) + probability of (B)
Probability it’s at least one person’s birthday = 1 – probability it’s nobody’s birthday
Pat least 1 person’s birthday = 1 – (364/365)people
P (A HAPPENING) + P (A NOT HAPPENING) = 1
P (A HAPPENING) = 1 – P (A NOT HAPPENING)
find more resources at oneclass.com
find more resources at oneclass.com
2
Dominant/recessive
P AA x aa
F1 all Aa (dominant allele)
F2 3:1 (dominant:recessive)
F3 aa x aa (recessive from F1 purebreeding = 100% recessive)
Aa x Aa (3:1)
AA x AA (dominant from F2 purebreeding = 100% dominant)
Test cross F3 dominant with recessive to distinguish between Aa and AA
If Aa → 1:1 dominant:recessive
If AA → 100% dominant
Dihybrid cross
P AABB x aabb
F1 Linked assortment → Independent assortment → all AaBb
F2 Linked assortment → 1:1 (A-B- aabb) Independent assortment → 9:3:3:1 (A-B- A-bb aaB- aabb)
Multihybrid cross
AaBbCc x AaBbCc
2 possible phenotypes for A/a, B/b, C/c → (2)(2)(2) = 8 possible phenotypes
Complementation: two pure-breeding recessive lines → re-appearance of dominant phenotype
Continue to F2, 9/16 blue, 7/16 white (3 b/c A missing, 3 b/c B missing, 1 b/c both missing)
Due to protein pathways
• Two genes involved, step-wise pathway, could be regulatory gene, precursor
• Stop protein A, protein B not formed, no phenotype
• Stop protein B, no phenotype
• Need at least one dominant at both genes
Sex linkage: X-chromosome carries traits as well as determining sex
Males: always get Y from dad
Cannot mask sex-linked disorder, have only one X chromosome
Females: X from dad, X from mom
X-linked recessive
➔ Males pass to all daughters, not to sons
➔ Daughters will be heterozygous carriers
➔ Trait oft skips generation
Autosomal inheritance
• 22 pairs of autosomal chromosomes in humans
• Autosomal dominant
o If affected parent + unaffected parent → some kids affected
o If affected + affected = unaffected, parents both heterozygous
o Does NOT skip a generation
o Males and females equally affected
• Autosomal recessive
o If unaffected + unaffected → affected kids, must be recessive disease
o Can skip a generation
o Males and females equally affected
Recessive disease RARE → assume unaffected are AA
Dominant disease RARE → assume affected Aa
Disease RARE → inheritance with FEWEST people affected/carrying most probable
e.g. very rare and showing up, probably sex-linked
find more resources at oneclass.com
find more resources at oneclass.com
25
HMB265H1 Full Course Notes
Verified Note
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Document Summary
Medical genetics = identify genetic cause of disease to cure, diagnose & prevent disease, gene therapy (crispr), pharmacogenomics/how genes affect your response to drug treatment. Agricultural genetics = use of gmos as food source. Conservational genetics = use genetics to restore biodiversity. Conditions are not always purely genetic also have environmental factors. Pre-mendelian: used breeding w/ livestock, had some understanding that traits are passed in families. Mendel: looked at traits individually, not at whole organism, good model organism, fast growth, short generation, selfing (cut anthers & transfer pollen), many offspring, performed controlled experiments. Discrete/simple inheritance: either/or trait antagonistic pairs: mutually exclusive traits (discrete, either/or) Continuous/complex inheritance: seems to blend, though not the case. Reciprocal cross: traits coming from opposite parent, mendel used this to disprove uniparental inheritance. Monohybrid cross: aa x aa reappearance of recessive trait disproves blending, disproves uniparental inheritance: p f1 f2, dominant/recessive law of segregation. Dihybrid cross: aabb x aabb law of independent assortment.
