Genetics I

An Introduction

Key Vocabulary:

genetics Heredity

Genetic traits vs. acquired characteristics

(nature) vs. (nurture)

(raw talent) (specific skills)

Key VOCAB:

Review homologs gene alleles

Key VOCAB: (New)

genotype phenotype heterozygous homozygous Law of Dominance dominant Recessive environment

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

All BIO 151 Students have three possible genotypes

w respect to eye color:B B

║B b

║b b

║Genotype

Phenotype

All BIO 151 Students have three possible genotypes

w respect to eye color:B B

║B b

║b b

║Genotype Homozygous

Dominant

Phenotype

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

All BIO 151 Students have three possible genotypes

w respect to eye color:B B

║B b

║b b

║Genotype Homozygous

DominantHeterozygous

Phenotype Brown eyes Brown eyes

All BIO 151 Students have three possible genotypes

w respect to eye color:B B

║B b

║b b

║Genotype Homozygous

DominantHeterozygous Homozygous

recessive

Phenotype Brown eyes Brown eyes

All BIO 151 Students have three possible genotypes

w respect to eye color:B B

║B b

║b b

║Genotype Homozygous

DominantHeterozygous Homozygous

recessive

Phenotype Brown eyes 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) BB 2) Bb

3) BbFF 4) BbMm

5) FfDdmm 6) MM

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

Ova

b

Sample Punnet Box:

Possible sperm:

↓B b Possible

Ova

b Bb b b

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

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?