2. Words to know Test cross Genotype F1 generation Phenotype
P generation
Monohybrid cross
Dihybrid cross
Karyotype
Punnett Square
Mendel’s Principles
Incomplete Dominance
Codominance
Multiple Alleles
Genotype
Phenotype
Dominant
Recessive
Homozygous
Heterozygous
Gene
Allele
Gene symbol
Genome

3. Mendel’s 4 Principle’s
Inheritance of biological characteristics is determined by genes
Principle of Dominance
Law of Segregation
Principle of Independent Assortment

4. Mendel’s 4 Principals
Inheritance of biological characteristics is determined by genes
Principal of Independent Assortment
Genes for different traits can segregate independently during the formation of gametes. This principle helps account for many genetic variations in plants, animals and other organisms.
Principle of Dominance
When there are two or more alleles for a gene, some are dominant while others are recessive
Law of Segregation
In sexually reproducing organisms, adult cells have two copies of each gene—one from each parent; these genes segregate when GAMETES are formed

5. Exception to Mendel’s Principles
Incomplete Dominance (blending)
Red flower + white flower= pink flower
Co-Dominance
Chicken with black and white feathers
Multiple Alleles
Many different possible alleles for 1 gene (blood type)
Polygenic traits
Traits controlled by many traits (eye color height)

6. From Peas and fruit flies to humans…
The Human Genome
From Peas and fruit flies to humans…

8. What is a genome???
All the genetic information (genes) that make up an organism

9. What makes us human? Analyze human chromosome… Karotype
Picture of all the chromosomes in an organism
Autosomes
CHROMOSOMES 1-44 (pairs 1-22)
Autosomal chromsomes
Sex chromosomes
Determine a person’s sex (male XY or female XX)
Chromosome 45 and 46 (set 23)

11. 2 events that lead to genetic variation
Crossing over
During prophase 1 of meiosis 1
Segments of homologous chromosomes exchanged
Independent Assortment
In metaphase 1 of meiosis 1
When homologous chromosomes line up in random order along center of the cell in a random fashion

12. CLICK here to see!!

15. Gregor Mendel
1822
Austrian monk
University of Vienna
In charge of the Garden

17. True breeding/Purebred
Parts of the plant
Female part-pistil (egg)
Male part-stamen-pollen (sperm)
Fertilization
Produces new cell which develops into an embryo and is enclosed by a seed
Self-pollinating
Contain male and female parts
Sperm cell in pollen fertilizes egg cells in flower
Offspring inherit all traits of parent
True breeding/Purebred
Genetically identical organisms produced through self-pollination
Allowed to self pollinate
Tall plant
Green seeds
Cross Pollination
Cut off male parts of one plant so it only had eggs
Dusted it with pollen from a different plant

19. Cross Pollination Produces seeds that had two different parents
Mendel could now cross bred plants with different parents

22. Terms
Gene: chemical factors (sections of DNA) that determine specific traits
Trait: a specific characteristic that varies from one individual to another.
Allelle: different forms of a gene, that combined, determine a trait

23. Genotype:
genetic make-up of an organism (the two alleles an organism has inherited from each parent for a trait)
The two alleles carried on an organisms DNA
Phenotype:
physical characteristics or the OBSERVABLE version of the trait; the genotype will determine what phenotype organism has

25. Progeny
Offspring
P1 refers to parent generation
F1 refers to first batch of offspring from original parents
F2 refers to the offspring of the F1 organisms
Dominant
Allele for trait that will be expressed no matter what the other allele is (A)
Recessive
Allele for a trait that can only be expressed if dominant allele is ABSENT (a)
Heterozygous phenotype will be Dominant (or codominant or incomplete dominance)
Organism that has two different alleles for a trait Aa
Homozygous (Dominant or Recessive)
Organism that has two IDENTICAL alleles for a trait
aa or AA

26. Punnett Square Diagram that shows possible genotypes and phenotypes
Probability

27. Test Cross
used to determine whether a plant or animal is homozygous or heterozygous for a particular trait
Organism #1 with a DOMINANT phenotype and an UNKNOWN genotype (A ? ) is crossed with organism #2 who is homozygous recessive (aa)
If #1 is homozygous Dominant (AA) for the trait, all offspring will be dominant for that trait
If #1 is heterozygous dominant (Aa), then some of the offspring will show the recessive phenotype for that trait

39. Punnet Square
Hybrids
Offspring of crossing two parents with different versions of a trait
Ex. Tall with Short; Purple with White
Parents are the “P generation”
Offspring are the “F1 generation/progeny”
When two of the F1 plants are crossed, the offspring are referred to as the “F2 generation/progeny”

40. Ratios What is a ratio? Phenotypic ratios Genotypic ratios
A comparison between multiple objects
Phenotypic ratios
Compares the number of different phenotypes for a cross
# of Dominant Phenotype : # of Recessive Phenotype
Genotypic ratios
Compares the number of different genotypes for a cross
3 possibilities # of DD : # of Dd : # of dd
Homozygous dominant DD
Heterozygous dominant Dd
Homozygous recessive dd

41. What are the phenotypes of the F1 generation?
Probability of having a green pod?
Probability of having a yellow pod?
What are the genotypes for the F1 generation?
What are the phenotypes of the F2 generation?
What are the genotypes for the F2 generation?

42. Probability Def: The likelihood of an event happening
It’s a way to predict the average outcome of a large number of events
CANNOT predict the precise outcome of an event only the LIKELIHOOD of the event
Flip a coin
What is the probability of getting heads?
What is the probability of getting tails?
If you flip a coin 3 times…

43. If you flip a coin two times, does the first flip effect what you are going to get in the second flip?
No…
One event does not effect another event’s probability
If there is a ¼ chance of having a white plant…the chances of having another white plant when crossing the plants again is still ¼
What are the chances of having 2 white plants after two fertilizations?
¼ x ¼ = 1/16

44. Things to keep in mind…
Probability predicts the AVERAGE outcome of a LARGE number of events
Cannot predict a precise outcome
The larger the number of events the closer you will be to getting the expected results

46. Let’s look at Pea shape and pea color
Round (R) vs. wrinkled (r)
Yellow (Y) vs. green (y)
Remember, there are 4 possible gametes
If a parent is homozygous dominant (true-breeding dominant) for both shape and color, what will all possible gametes be?
If a parent is homozygous recessive (true-breeding recessive) for both shape and color, what will all possible gametes be?

47. True breeding Round Yellow Peas Genotype (RRYY)
Make a test cross of:
True breeding Round Yellow Peas
Genotype (RRYY)
True breeding Wrinkled Green peas
Genotype (rryy) ry ry ry ry RY RY RY RY

48. What is the phenotype of the F1 offspring?
What is the genotype of the F1 offspring?

49. What this first cross told us…
All F1 offspring were heterozygous for seed shape (round) and seed color (yellow) RrYy
The F1 plant was made from fusing a gamete carrying RY and a gamete carrying ry
Will the dominant alleles stay together or separate when making the F2 offspring?

50. Now cross these hybrid (RrYy) plants on a new 4X4 Punnett Square

52. What does the F2 cross tell us?
Are there combinations of alleles that we did not see in either of the parents?
This means that the alleles for seed color separated independently than the alleles for seed shape
Genes that segregate separately do NOT influence each other’s inheritance

53. Steps for Dihybrid cross
Make a Key
Trait 1: height
Dominant phenotype: Tall TT or Tt (ways to get it)
Recessive phenotype: Short tt
Trait2: color
Dominant phenotype: Purple PP or Pp
Recessive phenotype: White pp
Write out genotypes for each parent
_ _ _ _ x _ _ _ _
Write Out Gametes for each Parent (use arrows)
4 gametes for each parent (_ _)
Make Punnett Square (16) boxes
Label parent one and write gametes along top
Label Parent 2 and write their gametes on side
Fill in each box (should have 4 letters)
Tally genotypes
Write out 4 possible phenotypic combinations
Dominant trait 1 and dominant for trait 2:______
Dominant trait 1 and recessive trait 2:_______
Recessive trait 1 and Dominant trait 2:_______
Recessive trait 1 and recessive trait 2:________
Tally Phenotypes (should =16)
Write phenotypic ratio
__dd__:__dr__:__rd__:__rr__
Dominant- capital letter D
Recessive- lower case d
Homozygous-
2 of the same size letter
If its two little letters recessive dd
If its 2 big letters it is dominant DD
Heterozygous-
2 different size letters (capital and lowercase) Dd
ALWAYS dominant

54. Principle of Independent Assortment
Genes for different traits can segregate independently during the formation of gametes. This principle helps account for many genetic variations in plants, animals and other organisms.

55. Exception to Mendel’s Principles
Incomplete Dominance (blending)
Red flower + white flower= pink flower
Co-Dominance
Chicken with black and white feathers
Multiple Alleles
Many different possible alleles for 1 gene (blood type)
Polygenic traits
Traits controlled by many traits (eye color height)

56. Incomplete Dominance
When red flowered (CRCR) plants were crossed with white flowered (CWCW) plants they made…pink flowers (CRCW)
Which allele is dominant?
neither
Incomplete dominance:
Case in which one allele is not dominant over another
The heterozygous phenotype is somewhere between the two homozygous phenotypes

58. Codominance Both alleles contribute to the phenotype Chickens
Allele for black feathers is codominant with allele for white feathers
Chicken looks speckled with black and white feathers
Not like the blending of dominant phenotypes…
BOTH dominant phenotypes show up
In humans
Gene for protein that controls cholesterol levels in the blood
People with heterozygous form make both types of protien

60. Multiple Alleles Genes for human blood type
When a gene has more than two alleles
NOT more than 2 alleles for a person but MORE than 2 alleles for the trait exist
Coat color in rabbits
A single gene for coat color
At least 4 different alleles
Simple dominance and make 4 possible coat colors
Genes for human blood type
3 different alleles: IA, IB, I
You can get different genotypes:
IAIA
IAi
IAIB
IBIB
Ibi ii
You can get different Phenotypes:
Type A (dom)
Type B (dom)
Type AB (dom)
Type O (recessive)

65. Polygenic Traits “Poly” many “-genic” genes
Traits controlled by two or more genes
Several genes interact to produce a trait
Wide range of phenotypes
Skin color
Four different genes
Fruit Fly eye color
Three genes make the reddish brown pigment

67. Epistasis
When the expression of one gene effects the expression of another gene
Ex. Fur color in mice…controlled by 2 separate genes
Gene 1
Brown fur pigment (BB or Bb) is dominant over gray fur pigment (bb)
Gene 2
Coat Pigment depositing gene
Dominant gene (CC or Cc) means fur will get pigment and this is determined by gene one
Recessive gene (cc) means that no pigment will be deposited on fur…whether the they have the gene for black or brown fur
The gene for Pigment Deposition is the EPISTATIC gene because it alters the Phenotypic ration Sd