1. The study of inheritance of characteristics
Genetics
The study of inheritance of characteristics

3. I. Mendel’s experiment 1. used garden pea plants because:
easy to self-pollinate or cross- pollinate, mature quickly, produce many offspring, traits are easy to see

4. Mendel’s 1st experiment
2. Gamete- sex cell
- both gametes need to be present (in same flower in peas)
male = pollen (in anther)
female = ovule (in pistil)

5. 3. Pollination- transfer of pollen to pistil
4. Fertilization- unification of male & female gametes

6. 5. monohybrid parents have different forms of only one trait
(P1) 1st let peas self-pollinate for several generations ensuring
true-breeding for a trait
(F1) First generation cross- 1 true- breeding white x 1 true-breeding purple
Results=
all offspring were 1 color

7. (F2) 2nd generation cross= 1st generation (F1) self pollinate
Results=
Produced 3 purple, 1 white
-repeated w/1000 plants = same results

8. 6. Rule of unit factors- 2 factors control every trait located on chromosomes
7. Alleles- different forms of the same trait - 1 inherited from each parent (ex. Brown or blue eyes)

9. 8. Mendel’s Law #1: Law of Dominance - only one form of the traits is seen at a time
9. Dominant- the allele that is expressed whenever present
How is this written?
As a capital letter, 1st in pair
10. Recessive- allele not expressed when dominant allele is present
lower case letter, 2nd in the pair

10. 12. What is the only way for the recessive allele to be expressed?
11. Whenever the dominant allele is present (either 1 or 2) the dominant trait will be expressed.
ex: TT = tall, or Tt = tall
12. What is the only way for the recessive allele to be expressed?
Both alleles must be recessive
ex: tt = short
13. Is the dominant trait always the most common trait in a population? No
Ex: polydactyly, Huntington’s disease

11. 14. Mendel’s Law #2: Law of segregation - 2 alleles for each trait must separate when gametes are formed

12. 15. phenotype -the way an organism looks and behaves – its physical characteristics
examples: brown eyes, wrinkled seed, tall plant
16. genotype -gene or allele combination of an organism – a formula
examples: BB, rr, Tt

13. Kinds of genotypes 17. Homozygous- both alleles are the same
(sometimes called a purebred)
TT= homozygous dominant
tt= homozygous recessive
18. Heterozygous- alleles are different
Tt = heterozygous (hybrid)

14. Try p. 3 – identify if heterozygous or homozygous and use pink sheet to determine phenotype

15. Mono and dihybrid punnett squares

16. III. Patterns of Heredity
1. Pedigree- a graphic representation of genetic inheritance
Affected w/ trait
death
= female
= male
Known heterozygote (carrier)
Parents (mating) 1 2
Generation= Roman numeral (top is oldest)
Individual = Arabic number
siblings 1 2

17. Autosomal or Sex-linked
2. autosomes - 22 pairs of matching homologous chromosomes not carrying information about gender.
*3. If gene is autosomal, it will appear in both sexes equally.

18. 4. Sex chromosomes- Female XX, Male XY
5. sex-linked traits discovered by Thomas Hunt Morgan with fruit flies.
6. If gene is sex-linked, its effects are usually seen in 1 sex.
7. on X chromosome and are recessive.
8. Passed from mother to son.
9. examples: hemophilia, red-green color blindness, Duchenne muscular dystrophy

19. Hemophilia- an example of a x-linked disease

20. Dominant or Recessive
9. If gene is autosomal dominant, each individual with the condition has a parent with the condition.
-shows up every generation
10. If recessive- 1, both, or neither parents may exhibit the condition
-may skip generations

21. Heterozygous or Homozygous
11. If homozygous dominant or heterozygous what will their phenotype show? Tt or TT
dominant trait
12. If individual is homozygous recessive, what will their phenotype show? tt
recessive trait
13. Can 2 parents that don’t express a condition have a child that expresses the condition?
Yes, if both heterozygous
***show with a punnett square

22. IV.Complex patterns of heredity
Polygenic inheritance-
Inheritance pattern of a trait controlled by 2 or more genes.
Makes a bell-shaped curve
Ex: skin color, height

23. 2. Incomplete dominance-
Phenotype of heterozygote is between the homozygous dominant & recessive phenotypes
Ex: snapdragon flowers
Red = RR, white = R’R’
R R
R’ R’
RR’
RR’
RR’ = pink!
RR’
RR’

24. Causes phenotypes to express BOTH alleles equally
3. Codominance-
Causes phenotypes to express BOTH alleles equally
Ex: chickens Black= BB, White= WW
B B
W W BW BW BW BW
BW= black & white checkered!

25. Ex: blood type- 3 alleles: IA, IB, i = 4 blood types
4. Multiple alleles- traits controlled by more than 2 alleles- caused by mutations
Ex: blood type- 3 alleles: IA, IB, i = 4 blood types
Type A: IAIA, or IAi = surface protein A
Type B: IBIB or IBi = surface protein B
Type AB: IAIB = surface proteins A & B
Type O: ii = no surface proteins
Fill in table on board

26. 5. What environmental factors can influence phenotype?
Sunlight, chemicals, nutrition, temperature, hormones, etc.
Age & gender can affect gene function

27. Sources for pictures

28. Sources for pictures

29. Sources for pictures