1. Genetics…
it’s all about
YOU!

2. physical characteristics
Have you ever heard someone say…
“You have your father’s eyes.” or
“You’ve got your mother’s smile.” or
“You look just like your grandfather.”
physical characteristics
We all know that we get certain traits from our parents or grandparents.
But have you ever wondered HOW it happens?
How you got your dad’s eyes or your mom’s smile?
The answer to “How does it happen?” is…
GENETICS!

3. An Austrian priest and science teacher named
the passing of traits from parents to offspring.
Heredity is
Genetics is
the study of heredity.
Traits are
physical characteristics, like eye color, hair color, freckles, or blood-type.
Who was the first person to study genetics?
An Austrian priest and science teacher named
Gregor Mendel

4. Some Human Traits
Dimples
mid-digit hair
cleft chin
Tongue-roller

5. Mendel was an Austrian monk and science teacher who was also responsible for the monastery’s garden.
During the years , he conducted experiments with over 28,000 pea plants.
His experiments were the first large-scale, long-term scientific study of heredity ever done.
Mendel
His work, published in 1865, was ignored at the time, because other scientists did not understand its importance.
However, Mendel’s experiments with pea plants were rediscovered in He is now known as the “Father of Genetics” for his discoveries of inheritance patterns in pea plants.

6. Photos of Brno monastery in Austria
flower bed
staircase & flower bed
Photos of Brno monastery in Austria
Photos of Brno monastery in Austria
northern wall of the monastery’s garden
beehives and apiary

7. 2. They have many simple, either-or traits
Mendel’s choice of pea plants for his experiments was a good choice, for 2 reasons:
1. They reproduce quickly & have many offspring
2. They have many simple, either-or traits
Mendel tested 7 pea plant traits:
 seed shape
seed color
 flower color
 flower position
pod color
 pod shape
 stem height
Short
Side
End
Inflated
Pinched

8. Pea Plants

9. In order to control which plants pollinated which plants, Mendel had to hand-pollinate every flower in the pea plants he was experimenting on.

10. purebred
purebred means that all the offspring have the same trait as the parents.
Short
Short X X
Short
Short
Short

11. Mendel’s first experiment
In his first experiment, Mendel crossed (mated) a purebred tall pea plant with a purebred short pea plant.
Short X
What do you think happened?
You would predict that half the offspring would be tall and half would be short, wouldn’t you?
Or maybe you would predict that the offspring would all be medium height.
Mendel’s first experiment
Both predictions are WRONG!!!

12. So what happened to the “short” trait? Did it disappear?
In every single experiment, Mendel found that ALL the offspring were… tall!!!
Short
P generation (parents) X
purebred tall
purebred short
F1 generation (children)
offspring are all tall
So what happened to the “short” trait? Did it disappear?

13. Mendel’s second experiment
Here’s where Mendel showed true genius!
What he did next was… he crossed (mated) the tall offspring from the first experiment with each other. X
He was trying to find out if the “short” trait had really disappeared, or if it was still present in the tall pea plants, but was covered up somehow.
Mendel’s second experiment
The results from his second cross were truly amazing. What do you think happened?

14. In EVERY SINGLE EXPERIMENT, the offspring in the second cross were:
offspring of first cross (F1 generation) X
Short
offspring of second cross (F2 generation)
3/4 (75%) tall
&
1/4 (25%) short

15. Here’s a summary of Mendel’s experiments
P1 generation “Parents” (purebred plants) X
Here’s a summary of Mendel’s experiments
F1 generation “Children” X
(hybrid tall plants) F2
generation “Grandchildren”
75% tall 25% short

16. The F1 generation plants were always 100% the dominant trait.
Mendel tested his experiment again and again, and got the same results every time.
Then he tested 6 other traits in the same way, and he got the exact same results with those traits.
“Parents” P
The F1 generation plants were always 100% the dominant trait.
“Children” F1
“Grand-children”
The F2 generation plants were always 75% the dominant trait, and 25% the recessive trait. F2

17. Mendel’s actual experimental results

18. Mendel drew several conclusions:
So, what’s going on here?
Mendel drew several conclusions:
1. The inheritance of each trait is determined by "factors" (now called genes) that are passed on from parents to offspring unchanged.
2. An organism inherits two factors, one from each parent, for each trait.
3. One factor can “mask” or cover up another factor.
4. A trait may not show up in an individual but can still be passed on to the next generation.

19. Genes
Mendel realized that one factor in a pair was masking, or hiding, the other factor. For instance, in his first experiment, when he crossed a purebred tall plant with a purebred short plant, all offspring were tall. Although the F1 offspring all had both tall and short factors, they only displayed the tall factor. He concluded that the tallness factor masked, or “covered up”, the shortness factor.
Today, scientists refer to the “factors” that control traits as genes.

20. Genes
A gene is a section of a chromosome, which contains the instructions for a trait (Examples: plant height or flower color in pea plants, or hair color and blood type in humans)

21. Genes
All chromosomes come in pairs that are the same size, and have the same genes in the same locations. This is because an organism inherits 2 sets of chromosomes, one from the father and one from the mother.
Since the chromosomes come in pairs, the genes come in pairs too. Every organism has 2 of every gene in their chromosomes. These genes are called gene pairs.

22. Alleles different forms of a gene For example: Chr. Blue allele
If the gene is for tail color in critters, the 2 alleles would be “blue tail” or “orange tail”.
If the gene is for flower color in pea plants, the 2 alleles would be “purple” or “white”.
Chr.
Gene for flower color
Gene for tail color
Blue allele
Orange allele

23. Alleles different forms of a particular gene
What are some possible alleles for:
~ handedness?
~ hair color?
~ eye color?
~ hair texture?
~ dimples?

24. Dominant and Recessive Alleles
Dominant: Alleles that cover up or hide recessive alleles.
Recessive: alleles that are hidden or covered up by a dominant allele.
Which of the 2 tail color alleles in critters was dominant?

25. Homozygous and Heterozygous
 homozygous: has 2 identical alleles for a trait (purebred)
 heterozygous: has 2 different alleles for a trait (hybrid)

26. Homozygous or Heterozygous?
T T
b b
R r
S S
G g
t t
Y Y

27. Homozygous or Heterozygous?
Alleles A a b B c c d D e e F F G G H h I I

28. Genetic Notation
Geneticists assign a letter to each allele for a trait. They use the first letter in the dominant trait. So, for the trait stem height, since tall is dominant, the letter “T” would be used. The dominant allele (tall) is abbreviated “T” and the recessive allele (short) is abbreviated “t”.
A purebred tall plant would be TT, and a purebred short plant would be tt.
A hybrid pea plant (like the tall plants in the F1 generation) would be Tt, because it has one dominant tall allele, and one recessive short allele.

29. Genetic Notation

30. Genotype and Phenotype
 An organism’s genotype is its genetic make-up. (Examples: TT, Tt, tt)
 An organism’s phenotype is its physical appearance. (Examples: tall plant, round seed, purple flower)
Genotype
Phenotype TT
tall plant Tt
tall plant tt
short plant

31. What would be the phenotype for the following genotypes?pp Pp PP Yy RR rr SS
green pod
yellow pod
green pod
white flower
purple flower
purple flower
yellow seed
round seed
wrinkled seed
side flower

32. What are the possible genotypes for the following phenotypes?
end flower
side flower
green seed
yellow seed
round seed
wrinkled seed
tall plant
short plant ss
SS, Ss yy
YY, Yy
RR, Rr rr
TT, Tt tt

33. Probability… is expressed as a percentage or fraction.
is the likelihood (chance) that an event will happen.
is expressed as a percentage or fraction.
Everyday examples of probability:
weather! Lots of times we hear predictions like “80% chance of rain,” or “20% chance of snow.”
the lottery “There’s a 1 in 10 million chance your ticket will be a winner.”
genetics is all about probability

34. Calculating Probability
Probability is calculated using this formula:
Actual outcomes x 100 = Probability % Possible outcomes
Example A: If I flip a coin, the probability that it will show heads is 1 out of 2, or 50%.
Example B: If I roll a die, the probability that I will roll a 3 is 1 out of 6, or 16.7%.
Example C: If I roll a die, the probability that I will roll an even number is 3 out of 6, or 50%.

35. Multiple Probabilities
In multiple probabilities (likelihood of 2 or more events happening at the same time), you multiply the probability of one event times the probability of the second event.
Prob of Event 1 x Prob. of Event 2 = Multiple Probability
For example: the probability of flipping two coins and getting 2 heads is:
1 x 1 = 1
or 25%

36. Probability Practice
1. What is the probability that, if I roll a pair of dice, I will get 2 sixes?
1 out of 36, or 2.8%
2. What is the probability that, if I flip a penny 10 times, I will get heads all 10 times?
1 ÷ 210, or 1/1024
3. If I’m a pea plant, and my father is hybrid tall, what is the probability that I got a t gene from him?
1/2
4. If I’m a pea plant, and my mother is hybrid tall, what is the probability that I got a t gene from her?
1/2
5. If I’m a pea plant, and both my parents are hybrid tall, what is the probability that I will get a t gene from both of them?
1/2 x 1/2 = 1/4, or 25%

37. Probability H-H H-T T-H T-T
When flipping 2 pennies, there are 4 possible outcomes:
H-H
H-T
T-H
T-T
Same thing
Probability 1/4 or 25%
Probability 1/4 or 25%
Probability 1/4 or 25%
Probability 1/4 or 25%
25% + 25% = 50%
How does this relate to genetics?
In hybrid (heterozygous) crosses, the probabilities are the same as when flipping pennies!

38. Two purebred tall plants can only have purebred tall offspring.
Punnett Squares
Punnett squares are diagrams that show the probability that offspring will inherit a certain trait.
For example: this is a Punnett square for a cross between two purebred (homozygous) tall pea plants.
Genotype of offspring:
100% TT T T T T T T T T T T T T
Phenotype of offspring:
100% tall
Two purebred tall plants can only have purebred tall offspring.

39. How To Make Punnett Squares

40. How about a cross between two purebred short pea plants?
Genotype of offspring:
100% tt t t t t t t t
Short t t t t t
Phenotype of offspring:
100% short
Two purebred short plants can only have purebred short offspring.

41. How about a cross between a purebred tall and a purebred short pea plant?Tt Tt
Genotype: 100% Tt
Phenotype: 100% tall Tt Tt t
This is a Punnett square of Mendel’s first experiment. The result is all hybrid tall offspring.

42. Cross between 2 Hybrid (Heterozygous) tall plants
Genotype:
TT 25%
Tt 50%
tt 25 % T
T T
T t t
T t
t t
Phenotype:
Tall 75%
Short 25%
Look familiar? This is Mendel’s second cross…

43. How about a cross between a purebred short and a hybrid tall plant?
Okay…how about a cross between a purebred tall and a hybrid tall plant? T T
Genotype:
50% TT, 50% Tt T T T T T t T t T t
Phenotype:
100% tall
How about a cross between a purebred short and a hybrid tall plant?
Genotype:
50% Tt, 50% tt t t T T t T t
Phenotype:
50% tall, 50% short t t t t t

44. Punnett Square for Albinism in Humans
In the cross Nn x Nn, where N is a dominant allele for Normal pigmentation and n is a recessive allele for no pigmentation (albinism), there is a¾_ probability the offspring will be normal pigmentation and ¼_ probability they will be albino. N n N NN Nn n Nn nn
Albino child, Tanzania
Albino child, USA

45. Dirk brings his family tree to class

46. Family Tree

47. Exploring a Pedigree
Pedigree: diagram that shows the presence of a trait in a family.
A carrier is a person who does not have the recessive trait, but does have the recessive gene. (They’re hybrid)

48. Pedigree of Queen Victoria of England
for the trait of hemophilia
How many children did Victoria and Albert have?
How many were daughters, and how many were sons?
How many of Victoria’s daughters were carriers of the hemophilia gene?
How many of Victoria’s sons were hemophiliacs?
How many of her grandsons were hemophiliacs? How many of her great-grandsons?

49. Mermaid Tails

50. Pedigree Analysis is a Key Tool in Human Genetics
Analyzing a pedigree is like puzzle-building – you try things (assigning potential genotypes) until the pieces fit, and you’re as certain as you can be about genotypes and inheritance patterns (autosomal vs. X-linked; dominant vs. recessive; complete, incomplete or co-dominance).
Pedigree Analysis

51. Shea Family Pedigree-Blue/non-blue eyes

52. Shea Family Pedigree-ADD/non-ADD

53. A Pedigree of a Dominant Human Trait

54. A Pedigree of a Recessive Human Trait
Note that the trait can appear in offspring of parents without the trait.
Heterozygotes (hybrids) who do not show the trait are termed carriers.
How many possible carriers are there on this pedigree? 7

55. Co-Dominance
One exception to the dominant / recessive pattern is co-dominance. In this pattern, both alleles are dominant, and both traits are expressed.
A capital letter represents one of the co-dominant alleles.
A different capital letter represents the other co-dominant allele.
In cattle, red and white coats are co-dominant. The hybrid offspring is called roan; it has both red and white hairs in its coat.
RR red
WW white X
RW roan
roan steer

56. Co-Dominance
In horses, gray horses (GG) are codominant to white horses (WW).  The heterozygous horse (GW) is an appaloosa horse (a white horse with gray spots). X
White (WW)
Gray (GG)
Appaloosa (GW)

57. BLOOD TYPE: an example of co-dominance in humans
There are 4 blood types: A, B, AB, O
 Blood type is determined by 2 factors in the blood: factors A and B.
•If factor A is present, you are Type A.
•If factor B is present, you are Type B.
•If A and B factors are present, you are Type AB.
•If neither factor is present, you are Type O.
• The A and B factors are co-dominant; when both are present, both are expressed.
• Type O is recessive (needs two O genes to be present).

58. Blood Type Genotypes & Phenotypes
Phenotype Genotype
Type A blood
Type B blood
Type AB blood
Type O blood
AA or AO
BB or BO AB OO
1) What are the genotype and phenotype probabilities for the children of a man with Type A blood (homozygous) and a woman with type B blood (homozygous)?
2) What are the genotype and phenotype probabilities for the children of a man with Type O blood and a woman with Type AB blood?

59. 1) What are the genotype and phenotype probabilities for the children of a man with Type A blood (homozygous) and a woman with Type B blood (homozygous)?
2) What are the genotype and phenotype probabilities for the children of a man with Type O blood and a woman with Type AB blood?

60. Incomplete Dominance
One thing Mendel didn’t realize was that there are some exceptions to the dominant / recessive pattern of inheritance that he observed in his pea plants.
One exception is: incomplete dominance. In this pattern, one allele/trait does not completely dominate the other allele/trait. The result: the traits are blended.
F1 generation: offspring of red and white flowers are all pink (a blend of the 2 parents’ colors).
F2 generation: offspring of pink plants are 25% red, 25% white, and 50% pink
Incomplete dominance

61. Pink crossed with pink makes:
Incomplete Dominance
Here’s what’s happening: R R
Red crossed with white makes pink offspring. RW RW W RW RW W R W
Pink crossed with pink makes:
25% red
25% white
50% pink R RR RW W RW WW

62. is incompletely dominant to straight hair (H1H1).
Incomplete Dominance
A capital letter (P) represents one of the incompletely dominant alleles.
 The same capital letter prime (P1) represents the other incompletely dominant allele, so that the two do not get mixed up.
In humans, curly hair (HH)
is incompletely dominant to straight hair (H1H1).
Cross a person with curly hair with a person who has wavy hair.
A heterozygous human has wavy hair (HH1).

63. Polygenic Inheritance
When a single trait is determined by more than one gene, we say that it is polygenic.
Height is a polygenic trait
Also:
eye color
hair color
blood type

64. Multiple Alleles Eye color is determined by more than one gene
Thus eye color appears to vary on an almost continuous scale from brown to green to gray to blue
Eye color is determined by three genes: one controls texture of the iris which refracts light to make blue, and a second which determines the amount of pigment, called melanin. When a small amount of melanin is present, blue or green eyes result, while brown & black eyes result from increasing amounts of melanin

65. Eye Color
Eye colors can range from the most common color, brown, to the least common, green. Rare genetic specialties can even lead to unusual eye colors: black, red, and violet. Eye color is an inherited trait influenced by more than one gene (polygenic).
There are 3 genes that control eye color. One gene has Brown (B) and blue (b) alleles (Brown is dominant over blue). The 2nd gene also has 2 alleles: Green / hazel (G) and lighter color (g). Green is dominant over the lighter-color allele.
Heterochromia (eyes that are different colors)
Eye Color Calculator activity

66. Hair color Hair color is determined by more than one gene
Thus hair color appears to vary on an almost continuous scale from black to brown to blond to red
The brown and black pigment is melanin
The red pigment is an iron- containing molecule

67. It is thought that hair color is controlled by two genes.
               
Black hair
           
Dark brown hair
                  
Brown hair
            
Auburn hair
Red hair
Blonde hair
Grey (gray) hair
             
White hair
One gene has 2 alleles: Brown (B) and blonde (b). The 2nd gene has 2 alleles: Non-red (N) and red (n). The combination of these two genes, plus environmental factors (and age), contributes to the many different shades of hair color in humans.

68. Skin Color
Skin color is determined by the amount and type of melanin, the pigment in the skin. Skin color is determined by 6 different genes, which accounts for the vast range of different skin colors in human beings.
link

69. Chromosomes, Genes and DNA
The structure and an actual picture of a chromosome.
Human chromosome set from a skin cell.
Chromosomes are long strands of DNA, wrapped around proteins. Humans have 46 chromosomes in every cell.
Genes are sections of chromosomes. Humans have 20, ,000 genes in every cell.

70. karyotype
Karyotype: a picture of all 46 of a person’s chromosomes, arranged in 23 pairs.
Note that 22 of the 23 pairs of chromosomes are the same size, and have the same banding patterns.
The first 22 pairs of chromosomes are called “autosomal.”
However, the 23rd pair of chromosomes do not look alike at all.
The 23rd pair of chromosomes are called the “sex” chromosomes, or “X and Y” chromosomes.
Make a karyotype
How scientists read chromosomes

71. Human Chromosome 1
False-color photograph shows human chromosomes, with the Chromosome 1 pair highlighted in blue.
Chromosome 1 contains nearly twice as many genes as the average chromosome and makes up eight percent of the human genetic code. It is packed with 3,141 genes and linked to 350 illnesses including cancer, Alzheimer’s, Parkinson’s disease, and a gene for a common form of cleft lip and palate. 

72. X and Y Chromosomes
The 23rd pair of chromosomes in humans determines a person’s gender.
A female has two X chromosomes;
a male has 1 X and 1 Y chromosome.
Female: XX
Male: XY
X chromosome is much larger than the Y chromosome.

73. Which of these karyotypes shows a male, and which shows a female?B
Which of these karyotypes shows a male, and which shows a female? A

74. Gender Determination
egg
girl X X
boy Y

75. Genetic abnormalities of the XY Chromosomes
Klinefelter Syndrome
Triple X syndrome
Turner Syndrome
XYY syndrome

76. Fragile X Syndrome Fragile X Syndrome
Fragile X syndrome is caused by a mutation in the FMR1 gene, located on the X chromosome. The mutated gene cannot produce enough of a protein that is needed by the body's cells, especially brain cells, to develop and function normally.
There are a variety of symptoms, including: Mental retardation, Hyperactivity, Short attention span, and Autism.
Click here to learn more about FXS

77. Down Syndrome
Down Syndrome, or Trisomy 21, occurs when a person has 3 copies of Chromosome 21, instead of the normal 2 copies.
Other Genetic Abnormalities

78. Who’s Got the Most Chromosomes?
Plants
Animals
Apple 34
Dog 78
Peas 14
Frog 26
Onion 16
Goldfish 94
Horse 66
Potato 48
Housefly 12
Rice 24
Human 46
Tomato 24
Mosquito 6
Corn 20 40
Click here to find out how many chromosomes other species have.
Mouse
Chicken 78

79. GENES BY THE NUMBERS GENES BY THE NUMBERS
Even though all the cells in the body contain the exact same genes, the genes that are “turned on” in each cell vary depending on the cell’s function. These are the numbers of working genes in different parts of the body.
Brain
White blood cell 2164
Liver
Heart
Pancreas 1094
Bone
Colon
Skeletal muscle 735
Kidney
Skin
Thyroid Gland
Eye
Small Intestine
Smooth muscle 127
Esophagus
Red blood cell

80. Some Genetics Numbers
Some Genetics Numbers
3 billion base pairs
1 billion codons
in one human cell there are…
25, 000 genes
46 chromosomes
6.5 feet of DNA
Number of people on Earth: 7 billion
Number of people with exactly your DNA
….1
YOU !!!

81. Asexual Reproduction Asexual Reproduction
organism divides and produces an exact replica (clone) of itself.
Examples: bacteria, amoeba, yeast, algae
• no genetic material (DNA) is exchanged.
• no genetic diversity in the species (except for mutations)
paramecium
algae
amoeba
hydra (budding)

82. Sexual Reproduction Sexual Reproduction
 involves the mixing of DNA, usually from the union of an egg cell and a sperm cell.
Examples: humans, flowers, fish, frogs, birds, snakes
 half the genetic material comes from the mother, and half from the father.
 offspring is unique (no other organism on Earth has exactly the same DNA it has)
 there is genetic diversity in the species, which helps ensure that a species will survive a widespread disease or environmental disaster.
hoverflies
frogs
sperm fertilizing egg
paramecia

83. Twins and Multiple Births
There are two types of twins, and they occur in two different ways…
Identical twins
Fraternal twins
• identical
• not identical
Click here to learn more about twins
• formed when one fertilized egg divides
• two eggs are fertilized at the same time
Chances of multiple births
Twins: 1 in 90
Triplets: 1 in 8100
Quadruplets: 1 in 729,000

84. Multiple Births Multiple Births
first set of octuplets born alive, in Houston TX, in 1998
identical quadruplets
triplets
van Tol quintuplets
McCaughey septuplets
Gosselin twins & sextuplets
news on multiple births

85. Homologous chromosomes
Two chromosomes which contain the same genes but may contain different alleles*
*Alleles are different forms of the same gene.
For example: the gene for eye color has many alleles: blue, green, brown, hazel, black, gray, etc.

86. What’s Where? What’s Where? cell nucleus chromosome gene
Chromosomes are made out of… DNA.