10 quizzes – 100% (as a test grade) quizzes have similar questions as the test
Overview
1. Mendelian genetics
2. Chromosomes
3. Genomes
4. Structure of DNA
5. Special lab day: extract DNA
6. DNA replication
7. DNA transcription
8. DNA translation
9. Gene regulation Mutation and Cancer
10. Phylogenetics
11. Natural Selection and Evolution
Life is order
- Regulation (rabbit’s ears)
- Energy Flow (food transfer of energy)
- Response to stimuli (rust and oxidation)
- Growth & development (embryos or crystals)
- Evolution (adapts devil’s rocks making round (sculpted))
- Reproduction (viruses)
Life is self-replicating molecule or molecules
Themes of the course:
- Historical perspective
o Gregor Mendel
o James Watson and Francis Crick
o Rosalind Franklin
o Francis Collins
o Kary Mullis “dancing in the mind field” believes in aliens
-
Scientific Methods
o Genes and their behavior
o Discovery of chromosomes
o Discovery of the structure of DNA
o Genetic code (Francis Crick)
o Tree of life (single branch)
-
Modern life
o Genetic disorders
o Pharmaceuticals and agriculture (dogs first GMO)
o Developmental biology
o Criminal justice
o Phylogeny (relationships between different types, sequence)
Historical Background
 Humans have been genetic engineers for less than 10,000 years

Artificial selection
o Ex: Dogs from wolves (humans domesticated wolves) experimental evidence of
evolution
o Ex: Wheat (planting seeds)
o Ex: Corn
2600 year-old Assyrian relief shows selective pollination

1800s
 Selective breeding produces desired traits, but..
 Couldn’t predict what traits would occur in progeny
 Confusing patterns observed
o Ex: Labrador retriever (color sequence)
1859: Trouble for Darwin?
Evolution Review:
 Acquired traits not passed on (e.g., Lamarckism)
 Populations have variables traits
 Traits must be heritable
 Traits that increase survival/reproduction favored & passed across generations
“The laws governing inheritance are quite unknown.” Darwin, 1859
Old Views
 Blended inheritance (red + white = pink)
Pangenesis
 Darwin’s attempt
 Particles (“gemmules”) transferred from somatic cells (body cells)
to gonads
 Lamarckism
Homonculus
 Experiment
Mendel, 1866
 Discuss experimental design of perhaps the most famous experiment in biology
 Discuss Mendel’s laws and principles
 Mendel’s laws explain why two black Labradors could have a litter of black, brown, and
golden puppies.
I.
Mendel’s Peas
a. Set up
1. Exceptional experimentalist
2. Had own garden & plenty of time
3. Used quantitative analyses
4. Settled on perfect model organism
b. Benefits of Pisum sativum
1. Grows well in gardens (large sample size)
2. Self-fertilizing
3. Anatomy of flower allows manipulation
4. Short growing season
5. Clear-cut traits
6. True-breeding lines available
c. The experiment
1. Chose 7 pairs of traits that differ greatly
Ex: yellow vs. green seeds
Ex: round vs. wrinkled
Ex: purple vs. white flower
2. Crossed pure lines that differed in only one trait =
monohybrid crosses
Ex: yellow x green
3. Also did the reciprocal cross
Ex: green x yellow
4. Examined F1 generation (all resemble parents)
5. Examined F2 generation
6. Determined ratios
7. Results falsify the blending hypothesis
8. Results confirm that male and female gamete contribute to
progeny
d. Inferred mode of inheritance
1. Trait in F1 progeny dominant
2. Trait hidden in F2 progeny recessive
3. Progeny inherit one unit of inheritance from both parents
4. Genes = unit of inheritance
5. Alleles = alternate form (pairs) of gene
e. Mendel’s law of segregation (separation)
1. 2 alleles for each trait separate during gamete formation
2. 2 gametes, one from each parent, unite randomly at fertilization
yellow
YY
Green
yy
Yellow
Punnet Square
3:1 (yellow 3,
green 1)
f.
Simple rules of probability apply
1. Product rule = prob. Of 2 independent events occurring together = product pf
their probs.
Ex: coin toss; one heads? = 50%
Two heads? ½ x ½ = ¼ = 25%
Ex: gamete formation
Hybrids = y ½ x Y ½ = ¼ YY, 1.4 Yy, ¼ yY, ¼ yy
2. Sum rule = prob. Of 2 events occurring equal to the sum of their probabilities
Ex: coin toss. Heads 50% Tails 50% prob of either? = 100%
½ + ½ = 2/2 = 1
Ex: likelihood that offspring of Yy hybrid will also be a hybrid?
¼ Y and ¼ y = ½ Yy
Ex: predict yellow and progeny (yy x Yy)
¼ YY + Yy + ¼ yY = ¾ yellow and ¼ green
g. Further crosses verify law of segregation
1. All green F2 peas true breeding
2. 1/3 of yellow F2 peas were pure breeding
3. 2/3 of yellow F2 peas hybrids
h. Definitions of some terms
1. Phenotype = the observable characteristic (yellow or green
seeds)
2. Genotype = the pair of alleles (YY or Yy)
3. Homozygote = having 2 identical alleles (YY or yy)
4. Heterozygote = having two different alleles (Yy)
i. Testcross = cross unknown to a known homozygous recessive
Ex: Yellow peas. Are they YY or Yy?
Unknows denoted Y_ (test question)
Y_
x
unknow Yellow
yy green
100% yellow (given)
YY x yy = Yy Yellow
Common dominant and recessive traits in humans
 Widow’s peak – dominant
 Bent pinky – dominant
 Crossing thumbs – (left over right) – dominant
 Attached earlobe – recessive
 Rolling tongue – dominant
 Cleft chin – dominant
 Dimples – dominant
 Handedness – right handed dominant?
Pedigrees allow study of inheritance in humans
Vertical pattern of inheritance = rare dominant trait; e.g hunting disease (pic)
 Every affected person has at least one affected parent
 Mating between affected and unaffected person effectively a testcross
Horizontal pattern = rare recessive trait; e.g, cystic fibrosis (pic)
 Parents of affected individuals unaffected; heterozygous (carriers) for recessive allele
Rediscovery of Mendel’s work
 Mendel published in 1866, hardly anyone paid attention to his work
 In 1900, 3 scientist independently rediscovered Mendel’s work
Practice Problems (pic)
#1
1) Assign symbols
S = spherical
Ss x Ss
s = dented
2) punnent square
#2
1) Assign symbols
S = spherical
s = dented
2) Punnent square
P SS x ss
F1 SS = Ss x Ss
¾ spherical
¼ dented
#3
1) Assign symbols
S = wire.
s = smooth
S_ SS wire P = SS x ss
ss
genotype = Ss
phenotype 100% wire
#4
1) Assign symbols
H = spherical
H_
H = dented
#5
1) L_ long tail (male) – context clues ll from the mom, so the male is Ll
ll short tail (female)
#6
1) Assigning symbols
B_ brown (2)
Bb x bb >
bb blue (1)
50% chance
Review/Overview
 Mendel’s monohybrid crosses showed 2 main principles
1. Law of segregation
2. Principle of dominance
 Dihybrid crosses demonstrate principle of independent assortment
Flash forward
 Molecular mechanism for round vs. wrinkled peas
 Dominant alleles R
 Recessive allele r
 R allele codes for enzyme SBE-1 (starch branching Enzyme-1)
750 spherical
250 dented




R allele produces faulty SBE-1 enzyme
SBE-1 catalyzes conversion of unbranched to branched starch
Branched starch leads to peas with full, round texture
Unbranched starch leads to peas with wrinkled texture
Dihybrid Crosses reveal the principle of the independent assortment
P
round, yellow
wrinkled, green
x
YYRR
yyrr
F1
round yellow
YyRr
F2
9 round yellow
Parental Recombinants
3 round green
Alleles can be inherited
separately (independently)
3 wrinkled yellow
9:3:3:1
1 wrinkled green
P
RRYY
x
rryy
RY ry
Rr Yy
Rr Yy x Rr Yy
R_ Y_ = round yellow
R_ yy. = round green
rr
Y
rr yy
Ry
ry
Ry
rY
RY
RRYY
RrYy
RRYy
RrYY
ry
RrYy
rryy
Rryy
rrYy
Ry
RRYy
Rryy
RRyy
RrYy
ry
RrYY
rryy
Rryy
rryy
= wrinkled yellow
= wrinkled green
Branching diagram
Gene 1 Yy
Gene 2 Rr
¾ yellow
(pic)
¼ green
Principle of independent assortment: the alleles for two different genes sort independently,
because they are located on different chromosomes.
Testcross dihybrids Y_ R_ x yy rr
YYRR x yy rr
YR x yr
YrRr
YYRr x yy rr
50% yellow round
50% yellow wrinkled
YyRR x yy rr
50% round yellow
50% round green
YyRr x yy rr
¼ round yellow
¼ round green
¼ wrinkled yellow
¼ wrinkled green
Complicated crosses made easy: genotypes
Aa Bb Cc Dd x Aa Bb Cc Dd
What is the probability of getting progeny with the genotype AA bb Cc Dd?
- Aa x Aa = ¼ AA ½ Aa ¼ aa = ¼ AA
- Bb x Bb = ¼ bb
- Cc x Cc = ½ Dd
- ¼ x ¼ x ½ x ½ = 1/64
Complicated crosses made easy: phenotypes
Aa Bb Cc Dd x Aa Bb Cc Dd
How many offspring will show dominant A, recessive b, dominant C and dominant D?
-
A_, bb, C_, D_?
Aa x Aa = ¾ A_
Bb x Bb = ¼ bb
Cc X Cc = ¾ C_
Dd x Dd = ¾ D_
= 27/ 256
Mendelian genetics in humans
- Most traits in humans controlled by more than one gene
- Some single gene traits known
- Humans terrible study organisms:
o Long generation times
o Small number of progeny
o No controlled mating
o No pure-breeding lines