Download Genetics Powerpoint 2/7/17

Genetics
The study of heredity
polydactyly
Heredity
• The passing on of traits (characteristics) from
parents to offspring
China McClain & sisters (Ant Farm)
Examples of Traits
Hair color
Eye color
Ability to roll your tongue
Height
Intelligence
Mid-digital hair
Attachment of ear lobe
Ability to taste bitter
• Traits are controlled by genes
…. so then what are genes?
– Gene
• Controls how an organism develops
• It is a specific segment of DNA located on a chromosome
• Each trait has two alleles
…. so then what are alleles?
– Allele
• Different forms of the same gene
• How are genes passed on? By your parents in reprododo
Alleles
• Dominant allele
– Produces a trait that is observed in the offspring
whenever present
– Represented with an uppercase letter
• Recessive allele
– produces a trait that is observed in the offspring only
if both alleles are recessive.
– Otherwise, the trait disappears
– Represented with a lowercase letter
--The separation of alleles during meiosis to form
gametes. ( Sex cells: egg/sperm)
• The law of independent assortment states
that genes for different traits can segregate
or switch independently during the formation
of gamates.
For example:
• Eye Color
– Dominant Color: Brown = B
– Recessive Color : Blue = b
• One allele from each parent because two
alleles form a trait, therefore…
BB
bb
Bb
Brown
Blue
Brown
• Phenotype
– The way an organism looks (physical)
For example:
BB
Phenotype: Brown
bb
Bb
Blue
Brown
• Genotype
– The gene combination of an organism (genes)
1.Homozygous (same)
• If the two alleles of a trait are the same (BB or bb)
2.Heterozygous (one of each)
• If the two alleles for a trait are different (Bb)
For example:
BB
Genotype: Homozygous
Dominant
bb
Bb
Homozygous
recessive
Heterozygous
How did we figure this stuff out?!
• Gregor Mendel was a monk from Austria born in 1822
• He made observations of his father’s orchard and
decided he could predict the kinds of flowers a plant
could produce…if he knew something about the parent
plants.
• After 8 years of carefully carrying out the scientific
method, Mendel wrote a paper about inheritance in
pea plants.
Traits of Pea Plants
Punnett Square
Diagram used to predict genetic crosses.
Individuals with identical alleles are called homozygous.
Individuals with different alleles are called heterozygous.
Phenotype-physical characteristics
Genotype-genetic makeup
How to use a Punnett Square
-choose a letter to represent the alleles
in the cross
-write the genotypes of the parents
-determine the possible gametes
(reproductive cells)that the parents can
Produce.
-enter the possible gametes at the
top and side of the Punnett Square
b
b
b
b