Genetics I

1
Genetics I

• An Introduction

2
Key Vocabulary

• genetics
• Heredity
• Genetic traits vs. acquired characteristics
• (nature) vs. (nurture)
• (raw talent) (specific skills)

3
Key VOCAB

• Review
• homologs
• gene
• alleles

4
Key VOCAB (New)

• genotype
• phenotype
• heterozygous
• homozygous
• Law of Dominance
• dominant
• Recessive
• environment

5
Some human examples

• read as codes for
• B brown eyes b blue eyes
• D dimples d no dimples
• F freckles f no freckles
• M migraines m no migraines
• G near-sighted g normal vision

6
All BIO 151 Students have three possible
genotypes w respect to eye color
B B B b b b
Genotype
Phenotype
7
All BIO 151 Students have three possible
genotypes w respect to eye color
B B B b b b
Genotype Homozygous Dominant
Phenotype
8
All BIO 151 Students have three possible
genotypes w respect to eye color
B B B b b b
Genotype Homozygous Dominant
Phenotype Brown eyes
9
All BIO 151 Students have three possible
genotypes w respect to eye color
B B B b b b
Genotype Homozygous Dominant Heterozygous
Phenotype Brown eyes Brown eyes
10
All BIO 151 Students have three possible
genotypes w respect to eye color
B B B b b b
Genotype Homozygous Dominant Heterozygous Homozygous recessive
Phenotype Brown eyes Brown eyes
11
All BIO 151 Students have three possible
genotypes w respect to eye color
B B B b b b
Genotype Homozygous Dominant Heterozygous Homozygous recessive
Phenotype Brown eyes Brown eyes Blue eyes
12
Question

• What does meiosis have to do with genetics??
• Remember Homologs (matching chromosomes)
  separate into different gametes.

13
Matching genes (alleles) separate into different
gametes during meiosis!
14
Problem Find all possible gametes for
individuals w the following genotypes

1. BB ?
2. Bb ?
3. BbFF ?
4. BbMm ?
5. FfDdmm ?
6. MM ?

15
How do you predict the genotypes of the offsprng
of any two individuals??

• (What do you do when its fourth down 40?)

16
Guide for Solving Genetic Problems

1. Record genotypes of both parents
2. Record all possible gametes.(Dont SKIP this
   step!!)
3. Construct a Punnet Box
4. ANSWER the question asked!

17
Sample Punnet Box
Possible sperm? B b ? Possible Ova
b
18
Sample Punnet Box
Possible sperm? B b ? Possible Ova
b Bb b b Possible ? Zygotes
19
Practice Problem 1

• Bill is heterozygous for eye color. Jeannie has
  blue eyes. What is the probability that their
  daughter has blue eyes?

20
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)

21
Practice Problem 3

• 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 blue-eyed and freckled?