Classical Genetics
Breaking Down the Definitions
1.
2.
3.
4.
5.
6.
7.
Genetics
Heredity
Trait
P generation
Dominant
Recessive
Law of segregation
14. Heterozygous
8. Law of independent 15. Probability
assortment
16. Punnett square
9. Molecular genetics 17. Incomplete
10. Allele
dominance
11. Genotype
18. Codominance
12. Phenotype
13. Homozygous
Genetics—What do you Already Know?
• Write.
• Share with your table.
• Write some more.
Gregor Mendel and his Peas
Mendel’s Results and Conclusions
• DOMINANT means a trait that covers up or dominates
another trait
• RECESSIVE means a trait that does not appear but his hidden
by the dominant trait
• LAW OF SEGREGATION states that a pairs of traits is
segregated (separated) during the formation of gametes
• LAW OF INDEPENDENT ASSORTMENT states that factors
separate independently of one another during gamete
formation (ie the flower color and seed color are completely
separate…one may be dominant and the other recessive)
Mendel to Molecular Genetics
• Mendel’s findings led to modern day
MOLECULAR GENETICS
• On a chromosome there are GENES which occur
in pairs. Mendel’s factors are now called
ALLELES, which are each of the genes in a pair.
• Letters represent alleles, capitalized for
dominant traits, lowercase for recessive traits.
Genetics Review Quiz #1
Genotype
•An organism’s genetic makeup is its
GENOTYPE.
•GENOTYPE = 2 alleles that are inherited
from the parents
•White-Flowering Pea Plant’s genotype is pp
•Purple-Flowering Pea Plant’s genotype is PP
or Pp
Phenotype
•An organism’s appearance is its PHENOTYPE
•The phenotype for a PP or Pp plant is
PURPLE FLOWERS.
•The phenotype for a pp plant is WHITE
FLOWERS
Genetics Review Quiz #2
Alleles
• HOMOZYGOUS happens when both alleles of a pair are alike,
pp or PP
• HETEROZYGOUS happens when the alleles of a pair are
different, Pp.
• PROBABILITY is the likelihood that a specific event will occur.
• Probability- Number of times of an event is expected to
happen/ Number of times an event could happen
• Mendel’s yellow seed color appeared 6022 times, the
recessive green appeared 2001 times.
• Probability of the dominant trait– 6022/8023= .75 or 75%
Probability
• What is the probability of flipping a coin and getting heads??
• Probability Penny Lab
Punnett Squares
•A cross in which only one characteristic
is tracked is called a MONOHYBRID
CROSS
•Biologists use a PUNNETT SQUARE to
predict the traits of the offspring.
Monohybrid Crosses
Bikini Bottom Genetics Part 1
Incomplete Dominance
• Sometimes an organism will have a phenotype in
between that of the parents, this is called INCOMPLETE
DOMINANCE.
Are you a Tongue Roller?
• Scenario:
• Both Parents are tongue rollers, 3 kids are
tongue rollers, 1 kid is not.
• What are the genotypes of the parents? Of the
kids?
More Practice!
Investigating Inherited Traits Lab