Transcript Genetic I - University of Dayton

Genetics I
An Introduction
Key Vocabulary:
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genetics
Heredity
Genetic traits vs. acquired characteristics
(nature)
vs. (nurture)
(raw talent)
(specific skills)
Key VOCAB:
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Review
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homologs
gene
alleles
Key VOCAB: (New)
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genotype
phenotype
heterozygous
homozygous
Law of Dominance
dominant
Recessive
environment
Some human examples
read “=“ as “codes for”
B= brown eyes
D = dimples
F = freckles
M = migraines
G = near-sighted
b = blue eyes
d = no dimples
f = no freckles
m = no migraines
g = normal vision
All BIO 151 Students
have three possible genotypes w respect to eye color:
BB
Bb
bb
║ ║ ║
Genotype
Phenotype
All BIO 151 Students
have three possible genotypes w respect to eye color:
Genotype
Phenotype
BB
Bb
║
║ ║
Homozygous
Dominant
bb
All BIO 151 Students
have three possible genotypes w respect to eye color:
BB
Bb
║
║ ║
Genotype
Homozygous
Dominant
Phenotype
Brown eyes
bb
All BIO 151 Students
have three possible genotypes w respect to eye color:
BB
Bb
bb
║
║
║
Genotype
Homozygous
Dominant
Heterozygous
Phenotype
Brown eyes
Brown eyes
All BIO 151 Students
have three possible genotypes w respect to eye color:
BB
Bb
bb
║
║
║
Genotype
Homozygous
Dominant
Phenotype
Brown eyes
Heterozygous Homozygous
recessive
Brown eyes
All BIO 151 Students
have three possible genotypes w respect to eye color:
BB
Bb
bb
║
║
║
Genotype
Homozygous
Dominant
Phenotype
Brown eyes
Heterozygous Homozygous
recessive
Brown eyes
Blue eyes
Question:
What does meiosis have to do with
genetics??
Remember: Homologs (matching
chromosomes) separate into different
gametes…….
Matching genes (alleles) separate into
different gametes during meiosis!
Problem: Find all possible gametes for
individuals w the following genotypes:
1)
2)
3)
4)
5)
6)
BB 
Bb 
BbFF 
BbMm 
FfDdmm 
MM 
How do you predict the genotypes of the
offsprng of any two individuals??
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(What do you do when it’s fourth down & 40?)
Guide for Solving Genetic Problems:
1)
Record genotypes of both parents
2)
Record all possible gametes.
(Don’t SKIP this step!!)
3)
Construct a Punnet Box
4)
ANSWER the question asked!
Sample Punnet Box:
Possible
sperm:
↓
b
B
b
 Possible
Ova
Sample Punnet Box:
Possible
sperm:
↓
b
B
Bb
b
bb
 Possible
Ova
Possible

Zygotes
Practice Problem #1:
Bill is heterozygous for eye color. Jeannie has
blue eyes. What is the probability that their
daughter has blue eyes?
Practice Problem #2
Fred is homozygous dominant for eye color and
heterozygous for dimples. Wilma has blue
eyes and no dimples. What is the probability
that Pebbles is both blue-eyed & dimpled.
(Show all work)
Practice Problem #3
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Rachel is heterozygous for freckles and has
blue eyes. Ross has no freckles and is
heterozygous for eye color. What is the
probability that their baby will be both blueeyed and freckled?