Genetics Notes
Genetics - the study of how traits are
inherited.
Heredity - the passing of traits from
parent to offspring. These traits are
controlled by genes.
What are genes?????
Genes - segments of DNA and found on
chromosomes. Genes control specific
traits.
Gregor Mendel
The father of genetics

Studied science and math, but
eventually became a monk.
He was in charge of the gardens at
the monastery.
He began experimenting with pea
plants.
Dominant - the form of a trait that
appears to dominate or hide another
form of the same trait.
Recessive - the form of a trait that
appears to disappear behind the
dominant form of that trait.
Behind the scenes, the genes control
the flower color. The genes come in
pairs (because chromosomes come in
pairs). One from Mom and one from
Dad.
Alleles - Different forms a gene may
take (for example: pink allele, white
allele). Dominant and recessive alleles
are represented by letters. A capital
letter stands for a dominant allele and a
small letter stands for a recessive allele.
Always use the letter for the dominant
allele.
A tool that shows how a parent's genes
can combine. It is used to predict the
characteristics of the offspring.
1. Which color is dominant?
Recessive?
2. What letter would you pick to
represent an allele for pod color?
3. How would you write letter for the
dominant pod color allele?
4. How would you write the letter for
the recessive pod color allele?
5. What two alleles could a yellow pea
pod have?
___ ___
6. What two of alleles could a green
pea pod have?
___ ___ & ___ ___
7. Complete the Punnett square.
8. A smooth pea is dominant over a
wrinkled pea. What type of pea would
have the following:
Ss -
SS ss 8. Create a Punnett Square for Ss x
Ss.
Genotype - the genetic make-up of a
particular trait. Example: PP, Pp, pp
Phenotype - the physical trait of a gene.
Example: pink flower, white flower
Homozygous - when the two alleles of a
gene are exactly the same. Example:
PP, pp. Also called purebred.
Heterozygous - when the two alleles of
a gene are different. Example: Pp.
Also called hybrid.