1. Do Now:
True or False?
1. Certain acquired characteristics, such as mechanical or mathematical skill may be inherited.
2. Color blindness is more common in males than in females
3. A person may transmit characteristics to offspring which he/she does not show.
4. Certain inherited traits may be altered by the stars, planets or moon early in development.
5. The total number of male births exceeds female births each year.
6. There is such a thing called “Werewolf syndrome” that could be linked to genes.

2. Hypertrichosis (“werewolf syndrome”)
Stephen Bibrowski as “Lionel the Lion-faced Man”

3. Patterns of Heredity Genetics
Chapter 4

4. Objectives: To distinguish between heredity and inheritance
To describe Mendel’s experiments in heredity
To compare heterozygous vs. homozygous and dominant vs. recessive.

5. Genetics = the study of heredity by which traits are passed from parents to offspring

6. Heredity The passing of genes/traits from parents to offspring.
Many of your traits, including eye color, shape of your eyes, texture of your hair, height, weight, resemble those of you parents!
Inheritance -passing of traits by heredity

7. What is a gene?
segment of DNA on a chromosome that codes for a particular protein
genes occur in pairs

8. Thanks Mom and Dad! We inherit genes from our parents
Those genes code for the traits we express
Most traits are coded by more than 1 gene!

9. Recall….
A pair of chromosomes are called homologous (homo meaning same)
Homologous chromosomes have the same size, structure, and genetic information.

10. What are alleles? T = tall t = short Alternative forms of a gene.
Dominant capital letter (shields recessive trait)
Recessive Lowercase letter (usually hidden)
T = tall
t = short

11. (Ex. Blue Eyes, or Brown Eyes)
Phenotype vs. Genotype
Genotype: Genetic makeup of an organism (genes).
(internal information. Ex: BB, Bb, bb)
Phenotype: the physical characteristics of an organism.
(Ex. Blue Eyes, or Brown Eyes)

13. Example of Genotype and Phenotype
Tall TT
genotype
phenotype

14. Homozygous – when both alleles of a pair are the same
dominant TT
homozygous
recessive tt

15. Heterozygous – when both alleles of a pair are not the same
(tall) Tt

17. Recessive vs. Dominant
Recessive: Need two recessive alleles in order to express it. (bb)
Dominant: The expressed form of the trait when present (even if it is just 1 allele) (Bb or BB)

18. In dogs, black fur is dominant over white fur color.
B = black fur b = white fur
WOOF WOOF! bb
BB or Bb

19. Think – Pair - Share If Joseph Gordon-Levitt is heterozygous
(H=Black, h=blonde)
1. What is JGL’s genotype?
2. What is JGL’s phenotype?
Beyonce is BB. (B= brown eyes, b=blue eyes)
1. What is her genotype?
2. What is her phenotype?
3. Is her heterozygous or homozygous?
Explain.

20. Punnett Square
A diagram that predicts the outcome of a genetic cross by considering all possible combinations of gametes in the cross.

21. Probability
Probability calculations can predict the results of genetic crosses. It is the likelihood that a specific event will occur.
= number of one kind of possible outcome
Total number of all possible outcomes
Example: If you flip a coin, you will have 1 outcome, but two possible outcomes. Your answer would be ½.

22. Question 1
A jar contains 3 red marbles, 7 green marbles, and 10 white marbles. If a marble is drawn at random, what is the probability that this marble is white?

23. Question 2
Suppose you toss a coin and roll a dice. What is the probability that you toss heads and roll a four?

24. Question 3
Two dice are rolled, find the probability that the sum is equal to 5.

25. How do you write a ratio?
When flipping a coin and it lands on tails  ½ or 1:2
Genotypic ratio: What is genetically written
Phenotypic ratio: what physical traits you would see
Phenotypic Ratio
3:1
3 Black : 1 White

26. Punnett Square Rules! Assign symbols Determine parents genotype
Draw punnett square
Place gametes on left + top of square
Fill in punnett square
Analyze + answer questions

27. Practice Punnett Squares: Monohybrid Cross
Phenotypic Ratio and %:
Genotypic Ratio :
T: Tall plants
t: Short plants

28. Monohybrid Cross R= Can roll your tongue r= Can’t roll your tongue
Genotype Ratio:
Phenotype Ratio: R r

29. Lets Try a Monohybrid together!
Daffy Duck is heterozygous for black feathers. Daisy Duck is homozygous for yellow feathers. Set up a punnett square and determine probabilities of their potential offspring. (Both genotype and phenotype ratios!)
B = Black b = yellow

30. What is a dihybrid Cross?
A dihybrid cross allows us to predict possible outcomes of offspring that will have 2 traits simultaneously.
Ex: what would you get if you crossed a Brown-haired brown-eyed male with a blonde-haired blue-eyed female? How many of the children would have brown hair and brown eyes? Brown hair and blue eyes? Blonde hair and brown eyes? Blonde hair and blue eyes?

31. Example

32. Setting up Dihybrid Crosses
1. Determine parent genotypes
2. Determine alleles to be passed down
3. Set up punnet square
4. Determine outcome
Phenotype Ratio
Genotype Ratio

33. Dihybrid Crosses Looking at two different traits
Ex. Hair color and eye color
B=brown eyes
b=blue eyes
R=Brown hair
r=blonde hair
Mother is heterozygous for both traits
Father is heterozygous for eye color and homozygous dominant for hair color
What could the phenotypes and genotypes be of their children?

34. More Practice
Mickey Mouse is heterozygous for Round ears and homozygous for Black eyes.
Minnie Mouse also is homozygous for Floppy ears and heterozygous for Black eyes.
Determine genotype and phenotype ratios. (B=black, b=brown, R=round, r= floppy.)

35. Do Now
What would you get if you crossed a tall brown eyed person who’s mother was short with blue eyes, and a person who is short and a hybrid for brown eyes?
Tall=T
Short=t
Brown=B
Blue=b

36. Test cross – an individual with unknown genotype is crossed with a homozygous recessive individual
Used to determine the genotype of any
individual whose phenotype is
dominant
Ex: A yellow pea is yellow, but can be YY or Yy.
To find out if the yellow pea is homozygous or heterozygous, you cross it with a recessive pea and the outcome will tell you depending on the ratio.

37. Lets Try a Test Cross
Spongebob squarepants doesn’t know whether or not he is Homozygous Dominant or Heterozygous for his yellow color. The recessive trait is a white sponge. Let’s say that we perform a “test cross” on spongebob (spongebob + a white female sponge) and all of the baby sponges are yellow. What would spongebob’s genotype be?

38. And Another…
In fruit flies, red eyes are dominant over sepia eyes. While working in your lab late one night, a red eyed fruit fly came in for a crash landing on your apple. Wanting to know more about your new friend, you decide to run a test cross on your little buddy.
If all of the offspring turn out to be red-eyed ( all 347 of them!!) what would be the genotypes of the flies used in your test cross? (Use R and r)
__________x __________
Genotypic Ratio:
Phenotypic Ratio:

39. Just one more….
You are a mink farmer. In minks, black fur is dominant over white fur. The market for black mink fur cots is higher than white fur. You decide only to raise black mink. However, the guy you bought your minks from seems a little strange. You want to make sure these minks are true breeds so you run a test cross.
Give the phenotypes of the minks in your test cross:
_________x________
In the first run, 30 out of 60 offspring are black, and the rest are white! What are the actual genotypes of the minks in your test cross?
________x_________
Was the black furred mink a pure breed? What is his genotype?

40. The history of Gregor Mendel- 1866
Austrian Monk – Czech
Father of Genetics!
Bred different varieties of garden pea plants.
First to develop rules that accurately predict patterns of heredity.
Discovered how traits were inherited in a population

41. Pollination – transfer of pollen from anthers to stigma in flowers
1) self pollination occurs within the same flower or same plant
2) cross pollination occurs between different plants

42. Pea plants = great subject to study heredity
Several traits exist in two clear different forms.
Ex: Flower color was either purple OR white
The male and female reproductive parts are enclosed within the same flower. It is easy to control mating by allowing a flower to fertilize itself (self fertilization), or you can transfer pollen to another flower (cross pollination).
The garden peas are:
Small
Grow easily
Mature quickly
Produce many offspring.
**Results can be obtained quickly with many offspring.

43. Steps in Mendel’s research…
Allowed each garden pea to self-pollinate for several generations to ensure “true-breeding” for that particular trait.
P Generation = parental generation
Mendel then cross-pollinated two P generation plants that had different forms of the trait (purple and white flower). The offspring from that were called the F1 generation.
F1 generation- Filial Generation
Allowed the F1 generation to self-pollinate and those offspring are called the F2 generation.
F2 Generation - Filial Generation

44. Mendel’s Crosses with Pea Plants
Pure tall
plants
Pure short
plants P1
parental
generation X
Cross Pollination
first filial
generation F1
All Tall plants
Self Pollination
787 tall plants, 277 short plants
second filial
generation F2
3 to ratio

47. Mendel’s 3 Laws of Inheritance
1. Law of Dominance-Each trait is controlled by 2 factors, one factor (dominant ) may mask the other factor (recessive ) preventing it from having an effect.

48. Mendel’s 3 Laws of Inheritance
2. Law of Segregation-Each allele a person has separates into different gametes
Ex. Ww – one W goes in one sperm and the other w goes into another sperm Ww W w

49. Mendel’s 3 Laws of Inheritance
3. Law of Independent Assortment- Gene pairs (homologous) will separate randomly into gametes (metaphase I of meiosis)
(Why? Random orientation of homologous pairs at the metaphase plate)

50. Mendel Video

51. Do Now Hope you had a wonderful weekend!!
Please Grab the worksheet off my desk to review.

52. Inheritance of Traits
Pedigree – a family history that shows how a trait is inherited over several generations.

53. In a pedigree… You can see how a genetic disorder runs in a family.
Carriers are individuals who are heterozygous for an inherited disorder but do not show symptoms.
Carriers can pass the allele for the disorder to their offspring

55. Figure out each genotype!

56. How many generations are there?
How many marriages are shown?
How many people are male?
Which person is the daughter in-law?
Who is she married too?
How many children do they have?
Who is the oldest?

57. DO NOW Fill in the genotypes for the following pedigree B=brown eyes
b = blue eyes

58. Do Now Please take out your homework, and put it on your desk.
Then answer:
What do you think incomplete dominance and codominance mean? Try to give an example using black and white as your colors.
Hint: Think about monohybrid crosses and think about what it means for an allele to be dominant!

59. 11.2 Incomplete Dominance:
Heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.
Two alleles are blended
Ex) Four O’clock Flowers
Red + White = Pink

60. For each phenotype below: Identify the genotype.
Lets Practice!
In snapdragons, flower color is controlled by incomplete dominance. The allele for Red is R and the allele for white is W.
Knowing this trait is incompletely dominant, what would be the phenotype for the heterozygous condition (RW)?_______________
For each phenotype below: Identify the genotype.
Red____________ White ____________

61. A pink flowered snap dragon is crossed with a white flowered snapdragon.
Make a Punnett Square and:
Give the expected probabilities for each genotype and phenotype
Give the ratios for the genotypes and phenotypes.

62. Lets try another example quick.
Coat color in mice is incompletely dominant. Yellow white white-colored mice are homozygous, while cream-colored mice are heterozygous.
If two cream-colored mice mate, what phenotypic ratio can we expect of their offspring?
Show the Punnett Square.
(Use Y and W)

63. Codominance
Neither trait is dominant instead, both traits are expressed (No Blending)
Ex) Roan Cows.
white hair (HW) is codominant with red hair (HR)
horses with genotype (HRHW) have coats with a mixture of red and white hairs (roan)

64. Examples:
What offspring are expected from mating a roan bull and a roan cow?
What about a roan bull crossed with a red cow? What would be the phenotypes of their offspring.
Give phenotypic ratio for both

65. Sickle Cell Disease
Affects red blood cells and ability to transport oxygen.
Homozygous recessive alleles=
Heterozygous=
Homozygous dominant alleles=

66. Sickle Cell and Malaria
People who are heterozygous for sickle cell, have a higher resistance to malaria.

67. Multiple alleles – 3 or more alleles that control a trait
Example – blood type (IA,IB,io)
GENOTYPES IAIA
IAio
RESULTING PHENOTYPES Type A Type A
IBIB IBio
Type B Type B
IAIB
Type AB
ioio
Type O

68. Do Now
In humans, hair type is determined by incomplete dominance. Some people have curly hair (CC), some people have straight hair (SS), and heterozygotes have wavy hair (CS). What would occur if a person with wavy hair had a baby with a person with straight hair?
Draw the Punnett square and identify the genotypes and phenotypes of their offspring.
Cat fur color is determined by codominance. The allele for tan fur (FTFT) and the allele for black fur (FBFB) are codominant. The heterozygous condition (FTFB) results in a cat with tan and black spots, called a tabby cat.
What would be the chances of receiving a cat with black fur if two tabby cats were crossed? What about Tan fur?

69. Universal Donor?

70. Sample Problem
Determine the possible offspring of the following crosses
1. AB and O
2. AA and BO
3. AB and AB

71. Coat Color of Rabbits Rabbits have a hierarchy of coat color
4 alleles (C, cch, ch, and c)
Dominant C > cch> ch > c Recessive
C Full color
cch Chinchilla
ch Himalayan
c albino

72. Coat Color of Rabbits
Chinchilla
Albino
Option 2
Full Color
Himalayan

73. Let’s try a sample problem
cc x Ccch
Genotype and phenotype ratios

74. Do Now What blood type is shown to the left? Explain how you know!
(Anti-D = Anti-Rh)
Explain how you know!

75. What do you see?

76. What do you see?

78. Autosomal vs. Sex-Linked
Autosomal – it will appear in both sexes equally
Sex-Linked - trait whose allele is located on the X or Y chromosome. Most are recessive.
X linked: gene is located on the X chromosomes
Y linked: gene is located on the Y chromosome
Because males carry only one X chromosome, a male who carries a recessive allele on the X or Y will exhibit the sex linked condition.
A female who carries a recessive allele on one X chromosome will not exhibit the condition if there is a dominant allele on her other X chromosome. Needs 2 recessive X to show condition!

79. What are the chances of having a girl?
How would you go about solving it?

80. Sex Chromosomes We have 23 pairs of chromosomes
1 pair are known as the sex chromosomes, which determines the sex of the offspring
Males = XY
Females = XX

81. Sex-Linked Traits
A man who is color blind marries a woman that is heterozygous for color blindness.
What is the chance of having a color blind boy?

82. Polygenic Traits – Interaction of multiple pairs of genes
A wide range of variability! Genes can be located on different chromosomes

84. Traits can be influenced by the environment!
Hydranga Flowers:
When in acidic soil, they bloom blue flowers
When in basic soil, they will bloom pink flowers
Arctic Fox – Enzymes will make pigments during a certain time of the year.

85. Treating Genetic Disorders
Most genetic disorders cannot be cured, although progress is being made.
Families who have a history of genetic disorders are recommended to undergo counseling before having a child. They can find out how it could affect their offspring.
Some genetic disorders can be treated if diagnosed early enough, such as PKU (lacking a certain enzyme).
If known, that child can be put on a certain diet and medicine routine.

86. Genetic Disorders Sickle Cell Anemia Cystic Fibrosis (CF) Hemophilia
Albinism
Tay-Sachs
Huntingtons Disease
Hypercholesterolemia

87. Do Now
The gene for colorblindness is carried on the X chromosome and is recessive. A man, whose father was colorblind, has a colorblind daughter.
a) Is this man colorblind? How do you know?
b) Where did he get his gene for colorblindness?