1. Introduction to Genetics
Genes are the stories of the past, the present and the future. What do you think?

2. Where do gametes come from?
Do Now: In 5 minutes, match the definition with the term.
Structure which determines a
phenotype
2. An alternate form of a gene
3. Location where genes are found
4. Contributes only one of the
Homologous chromosomes to offspring
5. Fusion of an oocyte & a spermatocyte
6. Develops from a zygote
7. Known as a sex cell or reproductive
cell
fertilization
gamete
gene
offspring
chromosome
parent
allele
Where do gametes come from?

3. a A
Meet the gametes…

4. Prelab Discussion: 1. c 4. f 7. b 2. g 5. a 3. e 6. d
How are gametes made?
The next slide will summarize in picture form.

5. Meiosis: a type of cell division that produces gametes for sexual reproduction
Originate as a germ cell located in the gonads of the parent. Ovaries and testes are the gonads.
Females produce oocytes and males spermatocytes.
The germ cell starts with pairs of chromosomes. After two rounds of cell division, the new cells contain only one of the pairs of chromosomes. These cells are called gametes.

6. Aa
(homologous
chromosomes)
AAaa
(replicated
chromosomes)
Which of my eggs will get the dominant alleles and which will get the recessive alleles? a a A A
AAaa
(replicated
chromosomes) Aa
(homologous
chromosomes
The children:
What’s our genotype? Let’s
do the lab…
Which of my sperms will get the dominant alleles and which will get the recessive alleles?

7. Congrats! You’re Having A Baby!
A lab about alleles, gametes, fertilization and offspring…

8. Objective #1
Simulate the random passing of alleles from parent to child by using a coin. Coin will be flipped twice to determine the genotype of child.
Observe the genotypes and corresponding phenotypes which result when alleles recombine to again exist as homologous pairs.
Explain how genetic diversity can be achieved in a population

9. Lab Hints… Parents have a heterozygous genotype
Each child receives two alleles which interact to control the phenotype so must flip coin twice
Simple Dominance – coin: head=D; tail=R
Incomplete Dominance – coin: head=D; tail=R
Polygenic Inheritance – coin: head=D; tail=R
Sex Determination – coin: head=X; tail=Y

10. Do Now – You are driving along a country road, you see….
100 Chickens: Black feathered White feathered Black and white feathered
100 Chickens: Black feathered White feathered
Snap Chat #3
Snap Chat #1
100 Chickens:
Black feathered
White feathered
Gray feathered
Which Snap Chat illustrates the least amount of genetic diversity for feather color?
How does the genetic diversity of Snap Chat #2 and #3 compare?
The phenotypes within a population for a given trait is determined by the way in which the alleles can be expressed. Expression requires two alleles; two alleles on the pair of chromosomes.
Snap Chat #2

11. Let’s explore to answer the question…
Objective #2
Observe how allele pairs can interact to determine a phenotype
Describe simple dominance, incomplete dominance, codominance and polygenic inheritance gene interactions
The illustration shows four children . If you observe
the hair structure of each child, you will notice that they
Have curly, wavy or strait hair.
C1C1 = homozygous dominant = phenotype curly
C2C2 = homozygous recessive = phenotype straight
C1C2 = heterozygous = wavy
Is this an example of simple dominance, incomplete
dominance or codominance gene interaction?
Let’s explore to answer the question…

12. Which baby traits followed this pattern?
Simple Dominance is defined as when one allele completely expresses a trait and does not allow the recessive allele to be expressed
Albinism is a disorder in which a person cannot make the pigment, melanin. Persons with “aa” have albinism. The “AA” and the “Aa” genotype produce normal skin pigment. Why?
Which baby traits followed this pattern?

13. Which baby traits followed this pattern?
Incomplete Dominance is when both the dominant and the recessive cannot fully express the trait when inherited together
Snapdragons are flowers.
Note that the dominant “R” allele express red petals. “r” allele expresses white petals. When “R” combines with a recessive “r” allele, notice the petals the petal color which is expressed. Pink! Why?
How is a red flower produced?
How is a white flower produced?
Which baby traits followed this pattern?

14. Did any of the baby traits followed this pattern?
Codominance is defined as when two different alleles fully express the trait when inherited together.
Sickle Cell Anemia is a genetic disorder caused by a gene mutation. Study the genotypes and the phenotypes. State the genotype and describe the phenotype.
Did any of the baby traits followed this pattern?

15. Roan Cattle: What type of gene interaction
Roan Cattle: What type of gene interaction? Write the phenotypes and genotypes that exist
Has a pinkish coat appearance.
Dominant allele expressed red hairs; recessive allele expresses white hairs.
Cows actually have both red and white hairs.

16. Polygenic Inheritance is when many genes participate to
express a trait.
Skin coloration is controlled by three genes: A, B, and C. How forms of each allele are present in skin coloration? 6, because each letter has two forms: a upper and lowercase form.
The white circles represent recessive alleles and black circles represent dominant The more dominant alleles inherited, the darker the skin tone. The fewer dominant alleles inherited, the lighter the skin tone.
Notice the increasing number of possible phenotypes. Genetic diversity is increasing. Why? Think and click to next slide.

17. Synopsis of Congrats! You’re having a baby Lab
Side 1 “Sexual Reproduction”
Side 2 “Gene Interactions”
Inheriting a specific allele is random.
Fertilization is random: do not know which sperm will fertilize the egg.
Probability will explain the chance of passing a specific allele to the offspring.
Alleles work in pairs
The combination of alleles determines the phenotype.
The way in which two alleles interact varies in nature.
More than one gene can control a trait.
Assignment: Must create 3 babies and answer the lab questions