Genetics: the study of heredity
Genes: control an organism’s traits
Alleles: different forms of a trait a gene may have

Every trait is controlled by TWO alleles (one from mom and one from dad)
Gregor Mendel : father of genetics

Studied how traits were passed in PEA PLANTS

Used probability to explain heredity
Dominant Allele : trait that covers up another form of that trait (CAPITAL LETTER)
Recessive Allele : trait that is covered up by another form of that trait (LOWER CASE LETTER)
Genotype : genetic makeup
Phenotype : physical appearance (what it looks like)
Example: T = tall, t = short

Homozygous dominant : two dominant alleles (TT) - tall

Homozygous recessive : two recessive alleles (tt) – short

Heterozygous : a dominant and recessive allele (Tt) - tall
Punnett Squares : shows possible gene combinations of offspring between two parents
Example: N = Freckles, n = no freckles
Genotype percentages:
50% heterozygous
50% homozygous recessive
Phenotype percentages:
50% freckles
50% no freckles
Sex determination
Sex chromosomes:

Females: XX
 Males: XY

All eggs have X

Sperm cells have either X or Y
Pedigree Charts: visual tool to follow a trait through generations
1.
Which person has the recessive trait in generation 2? Individual 1
2.
The mother in 1 st
generation is normal. Which of her children are carriers?
Individuals 2, 3 and 4
3.
If the mother in 1 st generation is a carrier, which of her children are carriers? Individuals 2, 3 and 4

Genetic engineering : when humans alter the genetic makeup of an organism

Recombinant DNA: combination of DNA from two different organsims
Example: when combine human gene and bacterial DNA

make recombinant
DNA which is inserted into a bacterial cell

bacteria start producing the substance

reproduce by
mitosis / asexual repro (used to produce insulin, growth hormone, clotting factor)

Selective breeding : when humans decide what animals should cross to produce offspring
- Hybridization: cross 2 organisms with different traits

make offspring with
combination of those traits
- Inbreeding : cross 2 organisms with same trait  make offspring that maintain that trait

Cloning : produce offspring that are genetically identical to original organism o Use the SOMATIC CELL of the organisms to be cloned and an EGG CELL WITH NO
NUCLEUS o The embryo produced is inserted into a uterus

develops into an organism