1. Why do we show the traits we do?
Genetics
Why do we show the traits we do?
Went in text through monohybrid cross (plus incomplete dominance and codominance)

2. Mendelian Genetics Father of genetics, but mostly a monk!
Published research on inheritance in pea plants
Inheritance = heredity
Pea plants could be easily cross-pollinated by hand
Used data to make inferences about how traits were inherited
Chose pea plants because they are true breeders – consistent produce off spring with only one form of a trait

3. Features of Pea Plants Vocabulary
Characters – physical features that are inherited
Flower color in peas is a character
Trait – one of several possible forms of a character
The flower colors of purple or white are traits
Hybrid – offspring of a cross between parents with different traits
If a purple flowered peas crosses with a white flowered pea, its offspring would be a hybrid

4. Pea Plant Characters – Mendel observed 7 characters
Height of plant’s stem (tall or short)
Position of flower on stem (mid-stem or end of stem)
Pod Color (green or yellow)
Pod Appearance (smooth or bumpy)
Seed Texture (round or wrinkled)
Seed Color (green or yellow)
Flower Color (purple or white)

5. Pollination – Mendel manually took pollen from an anther (male) & transferred it to the stigma (female).
Self-Pollination: a flower will pollinate itself or another flower on the same plant
Cross Pollination: a flower will pollinate a flower on a different plant
**Mendel uses both forms of pollination in his experiments.
Stopped here!

6. III. Mendel’s Experiment
Mendel first used true-breeding plants.
True-Breeding – a plant that is pure for a trait; when self-pollinated, its offspring will always have that same trait
A true-breeding purple flowered plant will always produce purple flowered plants!
Mendel formed 14 strains that were true-breeding.
These true-breeding plants were labeled the P1 generation since they were the original parents.

7. Two P1 generation plants of contrasting traits were cross-pollinated
Two P1 generation plants of contrasting traits were cross-pollinated. Their offspring were labeled the F1 generation.
An F1 generation plant was allowed to self-pollinate. Its offspring were labeled the F2 generation.

8. An Example of Mendel’s Results
P1 = True-Breeding Purple X True-Breeding White
F1 = 100% were Purple Flowers
F2 = 75% Purple flowers & 25% White flowers
* = 3 Purple : 1 White Ratio

9. **Mendel crossed all 14 traits and always received
a 3:1 ratio in the F2 generation

10. Inheritance of Traits Original cross between Parent (P) generation
Offspring = F1 generation
Offspring of F1 generation = F2 generation
Cross of yellow and green seeds
F1 – all yellow seeds
F2 – 3:1 ratio of yellow to green…how?
Must be two forms of the seed trait in plants
These different forms are called alleles
Explain Mendel and his cross of the green and yellow peas. Use board!

11. Dominance (Vocabulary)
Must be two forms of the seed trait in plants
These different forms are called alleles
Allele – an alternative form of a single gene passed on from generation to generation
Dominant allele (Y) – appeared in F1 generation
Recessive allele (y) – masked in F1 generation
We receive one allele from each parent
So which would be dominant and recessive?
What does it mean to be masked? Why are they in pairs? Phenotype is outward appearance

12. Dominance (Vocabulary)
Phenotype – green or yellow (color)
Genotype – allele pairs (YY, Yy, or yy)
Homozygous – two of the same allele
YY or yy
Heterozygous (hybrids) – two different alleles Yy

13. Law of Segregation
Two alleles join during fertilization and separate during meiosis
What do I mean by fertilization?

14. Punnett Squares Start here for day 2!
Don’t forget to talk about the ratios!

16. Types of Dominance
Incomplete dominance – heterozygous phenotype is an intermediate between the two homozygous phenotypes
Snapdragons – red, pink, white flowers
Codominance – both alleles are expressed in the heterozygous condition
Both are expressed!
Now let’s practice!
Red and white flowers

17. Stop here!!!
Incomplete
Dominance
Codominance

18. Law of Independent Assortment
Genes on separate chromosomes sort independently during meiosis
Color and Round v. Wrinkled
Example: four allele combinations each equally as likely to occur (YR, Yr, yR, yr) in Heterozygous dihybrid
Math in Biology – FOIL!
Results in a new phenotypic ratio
Probability – the more offspring, the closer we get to these “magic” ratios
Draw figure 11 for independent assortment!

19. Dihybrid Crosses How can we look at more than one trait at once?
Round (R - dominant) v. Wrinkled (r) seeds
How can we add this to our monohybrid?
Yellow/Round x Green/Wrinkled
YYRR x yyrr
F1 is YyRr but what about F2?
Click one more time!
8th period stopped here, give 6th period time to finish their sleeping around.

20. Gene Linkage
Genes that are located close to each other on the same chromosome travel together during meiosis
Exception to Mendel’s law (not independent)
Studied in fruit flies
Crossing over
Can separate once close genes; bring far apart genes closer
More likely to occur in genes farther apart
Remember – many genes makeup a chromosome!

21. Polyploidy
Most species have diploid cells, but some have polyploid cells (more than 2n)
Triploid – 3n
In humans it is lethal but…
In plants they increase vigor and size!
As many as 8n – sugar cane

22. Sickle Cell and Malaria
Caused by just one DNA base change
Disease that affects a blood cell’s ability to transport oxygen
Block circulation in small blood vessels
Heterozygous – normal and sickle cells
Sickle cells are also malaria resistant!
These people are okay because “normal” blood cells compensate!
This is why the disease continues to persist! Evolution - but we’ll move on from that for now.

23. DihyBrid Crosses – Sleeping Around!
With a partner, pick two of the traits from the list below and run two dihybrid crosses for your “offspring.”
Assume complete dominance
If dominant, flip a coin
Heads = homozygous dominant, Tails = heterozygous
Traits
Widow’s Peak (W) v. Continuous hairline (w)
Freckles (F) v. no freckles (f)
Attached earlobes (A) v. unattached (a)
PTC paper taste (P) v. no taste (p)
Can roll tongue (T) v. can’t (t)
Dimples (D) v. not (d)
Hand clasping left (L) v. not (l)
Repeat two more times with different partners!
Write the names of the pair above each cross.