1. INTRODUCTION TO GENETICS

2. TRAITS
Traits are the different forms of a characteristic that you may exhibit
Ex: Blue or Brown Eyes
Traits are inherited from our parents – mother and father
Therefore, when we talk about genetics, we are talking about sexual reproduction

3. Chromosomes
Every cell in a human body has 23 pairs of chromosomes – half from our mother, half from our father
Genes are found on chromosomes
We have about 20,000-25,000 genes
Each gene holds a code that tells our body to make
a certain protein
The protein that is made determines a
Specific trait.  
Ex:  Blue eye pigment or Brown eye pigment

4. Alleles The different forms of a gene that can exist
Ex:  Curly hair gene or straight hair gene
Dominant – ‘Strongest Allele’ – If it is present, you will have that trait.  We use upper case letters for dominant alleles
Recessive – ‘Weakest Allele’ – This won’t show up unless there are two of them.  We use lower case letters for recessive alleles

6. Human cells contain ____ chromosomes23 46 12 2

7. DNA contains a code that tells your body to make _____________
fat
carbohydrate
protein

8. ______________ traits won’t show up unless you have two copies of the gene.
Recessive
Dominant
Generic
Terrific

9. Genotype The actual alleles you have for a trait
Ex:  For eye color, you inherit B from dad and b from Mom
Your genotype is Bb
If there is a dominant allele, the genotype is written with the upper case first.  (Never write bB)
Always use the same letter for both alleles
Your genotype is the genes you have

10. Genotype (cont’d)
If you have two copies of the same allele for a trait (BB or bb), then you are HOMOZYGOUS for that trait.
If you have two different alleles for a trait (Bb), then you are HETEROZYGOUS for that trait

11. Phenotype How the genes actually show up, or how they are expressed
So, if your genotype is Bb,
Where B is brown
And      b is blue
The phenotype would be Brown eyes
Phenotype is the physical appearance

12. BB
Heterozygous
Homozygous

13. Rr
Heterozygous
Homozygous

14. Freckles No freckles Ff FF
You inherit the gene for freckles (F) from your mother, and the gene for no freckles (f) from your father. What is your genotype?
Freckles
No freckles Ff FF

15. Freckles No freckles Ff FF
You inherit the gene for freckles (F) from your mother, and the gene for no freckles (f) from your father. What is your phenotype?
Freckles
No freckles Ff FF

16. Blue is dominant to white
Blue is dominant to white. What would the genotype be for a white flower? BB Bb bb

17. Blue is dominant to white
Blue is dominant to white. What would the genotype be for a heterozygous blue flower? BB Bb

18. Karyotype – Normal/Male
A picture of the chromosomes found in an individual.  Used to determine abnormalities.

19. Karyotype – Abnormal/Female
There are three copies of chromosome 21 – there should only be two copies.  This is  a karyotpe of a female with Down’s Syndrome.