1. Topic 4 – Wearing your Genes
Biological Diversity

2. To Ponder….
Questions:
Why do some people have blue eyes and others have brown eyes?
What makes some people red heads and others brunettes?
Are some people born great musicians or do their talents develop with practice?
Why is one sibling a great athlete when the other is not?

3. Genetics
Heredity is the passing on of characteristics from parents to their offspring
A characteristic is also called a trait
The study of heredity is called genetics

4. Two kinds of inherited Variation
1. Continuous Variation
Any trait that has a range of possibilities
Anything that deals with measurement or weight and color
EXAMPLES: Hair Color, Skin Color, Height, Weight

5. 2. Discrete Variation
Any trait that has a limited number or possibilities
Either _________ or __________.
Example: Tongue roller, earlobe (attached or detached), left or right handed

6. QUESTIONS  Would hair color be a discrete or continuous variation?
hair color would be continuous because there are many different options

7. List all the blood types possible
List all the blood types possible. Would blood type be a discrete or continuous variation?
Blood Types would be discrete because it is a limited number of options. You are either A or B or AB or O (+/-)

8. GREGOR MENDEL First known geneticist and “father of genetics”
Was an Austrian monk and was born in 1822
Did most of his genetic studies on pea plants

9. Gregor Mendel: Mendels Laws of Heredity
1. Each trait is controlled by two factors-genes (one from each parent)
2. Each gene has two forms (alleles) – dominant or recessive
3. For each trait an organism could inherit either:
Two dominant alleles
Two recessive alleles
One dominant and one recessive allele
4. The distribution of dominant and recessive genes from the parents to the offspring was determined by chance

10. Mom
Dad
Dominant and Dominant
Recessive and Dominant
Dominant and Recessive
Recessive and Recessive

11. Dominant Traits
A dominant trait is a trait that takes charge over any other allele. It will mask the recessive trait
It will show up in the offspring if they get that trait
EXAMPLE: ‘E’ is the symbol representing the dominant trait for detached earlobes.
‘EE’ or ‘Ee” will have the dominant trait showing up.

12. Recessive Traits
A recessive trait is a trait that will only show up in the offspring if you have two of the recessive alleles.
It allows the dominant trait to control it
EXAMPLE: ‘e’ is the symbol representing the recessive trait for attached ear lobes
‘ee’ is needed for the recessive trait to show up.

13. Eye Color (Dominant to Recessive)
Eyecolor—Brown color is dominant and blue is recessive.
A person can have a brown allele and a blue allele but still have brown eyes because the brown allele is dominant and “hides” the blue allele.
Dark brown, Light brown, Light Gray, Blue, Green.

14. Facts: We are all made of cells
Cells have a nucleus which contains 46 chromosomes for humans
These chromosomes are made up of genes
Genes have 2 forms called alleles (dominant and recessive)
Phenotype is the outward appearance of alleles
It is what you see (earlobes for example)

15. Genotype is the genetic combination of alleles (the genetic make-up)
EE or Ee or ee
Homozygous is when the genotype has both the same alleles
Two dominant alleles would show the dominant trait
Two recessive alleles would show the recessive trait
Heterozygous is when the genotype has one of each type of allele

16. Punnett Square
The punnett Square can be used to see the genotype possibilities of offspring traits
Used to help predict Mendelian genetics

17. Example: R= dominant r = recessive
Generally, dominant alleles are represented with a capital letter, and recessive alleles are represented with a lower case letter.
Example: R= dominant r = recessive

18. “Purebred” species have two alleles of the same trait
Represented by two of the same letters. This is called homozygous. For instance: BB or bb.
Species with two different alleles or two different forms of the gene would be “hybrid”
Represented by two different “letters” and by called “heterozygous”. For instance: Bb

19. Steps for using the Punnett square:
Steps for using the Punnett square:
One parent’s alleles (genotype) go along the top
The other parent’s alleles go down the side.
You fill in the squares like doing the communicative property of multiplication.
B b B BB Bb b Bb bb

20. Steps for using the Punnett square:
Let’s say the parents are Bb and Bb (the same genotype).
What would be their phenotype?
Brown Eyes
B b
So you would predict:
¼ offspring to be BB, or Brown Eyes
2/4 or 1/2 to be Bb, or Brown Eyes
and ¼ to be bb or Blue eyes B BB Bb b Bb bb

21. M/F R M/F r M/F R r M/F R r HOMOZYGOUS DOMINANT PARENTS
HOMOZYGOUS RECESSIVE
PARENTS
M/F R
M/F r
___recessive trait ___dominant trait
___recessive trait ___dominant trait
HOMOZYGOUS DOMINANT AND HETEROZYGOUS PARENTS
TWO HETEROZYGOUS PARENTS
M/F R r
M/F R r
___recessive trait ___dominant trait
___recessive trait ___dominant trait

22. Sex Linked Traits
Sex linked traits are connected to the X or Y chromosome
(X-chromosome is larger)
EXAMPLES:
color blindness (red-green--mostly males)
voice (masculine, etc.)

23. -

24. Traits Incomplete Dominance is when traits blend to make a third trait
Example: White and red flowers reproduce to make pink flowers
Quantitative Inheritance is when not all traits are controlled by one pair of genes
Example: hair color – this is VERY hard to study

25. Nature (genetics) vs. Nurture (environment)
Are all characteristics inherited?
A persons weight can be altered by genetics, diet and activity level
Some people think that genetics are the cause of everything about a person
EXAMPLE: Likes and dislikes
Some people think that the environment can mould and shape a person
Example: Identical Twins

26. Nature is a persons genetics
What you are born with
Nurture is the environmental affects on a person
Abilities, skills, scars, cosmetic surgery, injuries

27. Changing our Genetic Material
Changes to DNA are called Mutations
Mutations cause changes in the structure of organisms
Mutagens are things that cause mutations
X rays, ultraviolet rays, cosmic rays, some chemicals

28. In some cases, mutations in individual cells cause cancer
Cancerous cells go through rapid cell divisions and do not develop in the same way healthy cells do
Mutations in DNA can be passed on in the genetic material to offspring