1. NOTE:
This presentation was not made for public use. Please do not use this presentation without my permission and the permission of each of the authors of the photographs, quotes, and other materials that they contain.
Thank you,
Vicki Hughes

2. Alleles = different forms of a gene
Chromosome
Gene
Allele
Genes come in “versions”
Alleles = different forms of a gene
Ex. brown vs. blue eye color (let’s pretend there are only two possible eye colors)
Alleles are inherited separately =
each parent gives one allele
(either a brown or a blue)
Some alleles mask others
brown eye color masks blue

3. True-breeding = self-pollinate to produce identical offspring.
self-pollination

4. OK, who took all the yellows?
true-breeding green
Parent
true-breeding yellow
Parent
All green F1!
F1= First Generation
OK, who took all the yellows?

5. Bb bb Dominant alleles mask recessive alleles.
The capital letters represent the dominant trait…
And the lowercase letters represent the recessive trait.
Phenotype =
traits you see
Genotype = actual genes Bb bb
Dominant alleles mask recessive alleles.
Why does the blue man have all brown eyes?

6. aa Bb rr Ss Ww Tt Aa Yy BB RR bb Ee Homo = same Hetero = different
Homozygous dominant =
Homozygous recessive =
Heterozygous = AA
Homo = same
Hetero = different aa Aa aa Bb rr Ss Ww Tt Aa Yy BB RR bb Ee

7. Bb x Bb Punnett Squares = used to predict genetic outcomes. X
Probability = mathematical chance some event will occur.
What is the probability that this couple will have a blue-eyed baby? X
male
female
_______ _______
_________%
_______ _______
What would be the F1 generation?

8. There is always a 50% chance for either gender!
XY XX
Males have XY alleles.
The Y makes it a boy!
Females have XX alleles.
What is the chance that this couple will have a baby BOY? X
male
_______ _______
female
_________%
There is always a 50% chance for either gender!
_______ _______

9. Let’s put it all together.Bb Bb
Let’s put it all together.
What is the chance that this couple will have a baby BOY with BLUE eyes?
Do we need to put the X’s and Y’s? NO
Why not? Because there is always a 50% chance of either gender. X
male
female
_______ _______
_________%
_______ _______
Human Genetic Traits 2:02

10. How do we predict two traits at one time?
We use a Dihybrid Cross (mating of two individuals involving two traits).
Both Bob and Sue are heterozygous for both height and eye color.
Height: Tall = T; short = t
Eye color: Brown = B; blue = b
________ ________ X
How many different gametes could be produced?

11. TtBb Done for you…Figuring out gamete pairs.
Dihybrid Cross (mating of two individuals involving two traits).
Both Bob and Sue are heterozygous for both height and eye color.
Height: Tall = T; short = t
Eye color: Brown = B; blue = b
TtBb
TtBb
________ ________ X
How many different gametes could be produced? TB Tb tB tb TB Tb tB tb
TtBb

12. Law of Independent Assortment
Alleles will sort out independently when gametes are formed.
How many different gametes can we make?
TtBb
TtBb
________ ________ X TB Tb tB tb TB Tb tB tb

13. Heterozygous Dihybrid Cross
T = tall
t = short
B = brown hair
b = blonde hair
Parents: TtBb x TtBb
Heterozygous Dihybrid Cross
9:3:3:1
Tall/Brown
Tall/blonde
Short/Brown
Short/blonde

14. Meiosis and Genetic Variation
Meiosis = process of making gametes
Gametes = sex cells (egg & sperm or pollen & ovule)
Variation = all the different possible individuals

15. 46 23 23 MEIOSIS MEIOSIS Not Good! 46 + 46 = 92!
“Sweet Mama”
“Big Daddy”
Everyone knows it takes two to make babies.
That’s how we get variation!
BUT HOW?
= 92!
Not Good!
How can we get the right number of chromosomes in the babies?
46 chromosomes
46 chromosomes
3.bp.blogspot.com
1.bp.blogspot.com
MEIOSIS
MEIOSIS
spanishdict.com
hihi11.seesaa.net
meandvinnie.blogspot.com
babyinsane.com
durtbagz.wordpress.com
Mutant Baby! 46
metropolitician.blogs.com 23 23
OK, you can only work with what you’ve got.

16. Somatic Cell = has 2 copies of each chromosomes (2n)
Diploid = 2n (has two copies of each chromosome) Haploid = 1n (has only one copies of each chromosome)
Homologous Chromosomes = matching chromosomes
“Sweet Mama”
46 chromosomes 2n 2n
3.bp.blogspot.com 1n 1n
MEIOSIS
metropolitician.blogs.com 23

17. Genetic Recombination = mixing up chromosomes during meiosis
MEIOSIS (meiosis divides twice!) Done for you:
Cytokinesis!
Parent 2n
Telophase I
Prophase I
Metaphase I
Anaphase I
Cytokinesis! 1n
Telophase II
Anaphase II
Metaphase II
End with four
haploid gametes
Genetic Recombination = mixing up chromosomes during meiosis

18. Variation = differences in genetic makeup
Crossing-Over =
chromosomes literally cross ends and swap genes.
Genetic Recombination = mixing up chromosomes with Meiosis

19. Variation = differences in genetic makeup
Mutations = change in DNA
Can you spot the mutation in the DNA below?
Hint 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 7 8 9 10 11 12 13 14 15 16

20. Patterns of Inheritance
Incomplete dominance = dominant gene does not completely mask recessive gene
Hybrid = mix of two true-breeding individuals
Hybrids have “in-between” appearance
RR = red flowers
rr = white flowers
Rr = pink flowers

21. Codominance x = Equal dominance Chickens
Codominance = dominant and recessive genes are expressed. (expressed = are visible as a trait)
Codominance
Equal dominance
Chickens
A black-feathered chicken is crossed with a white-feathered chicken.
All of the babies are white with black speckling.
Both white and black show up equally. x =

22. Multiple Alleles = more than one allele available
PHENOTYPES for Blood are A, B, AB, or O.
Alleles to make these types include IA, IB and i.
IA and IB are codominant.
i is recessive
So…
Type A = IA IA or IA i
Type B = IB IB or IB i
Type AB = IA IB
Type O = ii

23. XHY HH XHXh Hh x XH Y XHXH XHXH XHY XHY XH Xh XHXh XHXh XhY XhY
Sex-linked = trait is carried on X chromosome.
XHY HH
XHXh Hh
2 normal parents,
but mother is carrier x XH Y
XHXH
XHXH
XHY
XHY XH Xh
XHXh
XHXh
XhY
XhY

24. Human skin color Polygenic = “many genes” AaBbCc x AaBbCc
range of shades
most children = intermediate skin color
some can be very light & very dark

25. Linked Genes = genes found on the same chromosome

26. Phenotype is a result of both genetics and environment.
Cold Environment
Siamese cats that grow up in a cold environment are darker…
…than those that grow up in a warmer environment.
Warm Environment

27. You got questions? ASK THE TEACHER!
ACT L34