1. DNA Deoxyribonucleic Acid
A code that is stored in a cell’s heredity material in the nucleus
Contains information for an organism’s growth and function

3. What part of your cells contain your genetic instructions?
Your genetic instructions are located in the nucleus of every cell, stored within chromosomes.

4. Chromosomes: How many? Where are they?
A human body cell contains 46 chromosomes, which are stored inside every cell’s nucleus.
Human sex cells contain 23 chromosomes each.

5. DNA Structure Two chains of molecules in a spiral form
Each molecule consists of the sugar called deoxyribose
The rungs of the ladder are made of nitrogen bases

6. DNA Model Four kinds of nitrogen bases are found in DNA Adenine
Guanine
Cytosine
Thymine

7. DNA Model Bases occur as pairs in DNA
Adenine always pairs with Thymine
Guanine always pairs with Cytosine

8. Heredity: The passing of traits from parent to offspring.
Genetics: The study of how traits are inherited through the interactions of alleles

9. How will your traits be passed on to your future children?
Fathers pass genetic instructions to offspring through sperm cells.
Mothers pass genetic instructions to offspring through egg cells.

10. Gregor Mendel
An experiment with pea plants helped scientists understand why your eyes are the color they are.

11. Gregor Mendel He was known as the “FATHER OF GENETICS”
He discovered how traits were inherited

12. Alleles Genes on chromosomes control an organism’s form and function
Allele: different forms of a trait
Most cells in your body have two alleles for every trait
Every sex cell has one allele for each trait

13. Genotype vs. Phenotype Genotype: Genetic makeup
Phenotype: the way an organism looks and behaves as a result of its genotype

14. Dominant vs. Recessive
Dominant: a trait that covers up, or dominates another form of that trait
Represented by uppercase letter

15. Dominant vs. Recessive
Recessive: a trait that is covered over, or dominated by another form of that trait and seems to disappear
Represented by lowercase letter

16. Homozygous vs. Heterozygous
Homozygous: an organism with two alleles that are the same (RR)
Purbred
Heterozygous: an organism that has different alleles for a trait (Rr)
Hybrid

17. Dominant traits are represented by a capital letter.
Yellow seeds are dominant…….. Y

18. Recessive genes (for the same trait) are represented by a lower case letter.
Green seeds are recessive………. y
Dominant (yellow) = Y
Recessive (green) = y

19. In pea plants, tall is dominant over short
In pea plants, tall is dominant over short. The letter used to represent the tall gene is T.
The short gene is represented by t.
Tall =T
Short = t

20. In humans, brown eyes are dominant over blue.
Brown = B
Blue = b

21. Why must all blue eyed people be PUREBRED for that trait?

22. Incomplete Dominance
Production of a phenotype that is intermediate between the two homozygous parents

23. Incomplete Dominance
Because neither curly or straight hair is recessive, no lower case letters are used.
CC = curly hair
CS = wavy hair
SS = straight hair

24. Codominance
Codominance: occurs when both alleles for gene are expressed equally + =

25. Mutations Occurs when DNA is not copied exactly right
Without correct proteins an organism can’t grow, repair, or maintain itself

26. Down Syndrome
Results when three copies of chromosome 21 are produced in the fertilized human egg

27. Recessive Genetic Disorders
Many human genetic disorders are caused by recessive genes.
A heterozygous individual doesn’t show any signs.
Child will show symptoms if both parents pass down a recessive gene