Transcript MENDEL Fundamentals of Genetics _1_

Fundamentals of Genetics
Gregor Mendel: Genetics Pioneer
•Genetics = study of __________.
genes
•Gregor Mendel – Australian Monk
•Identified 7 pairs of contrasting characteristics
pea __________.
plants
in _______
Mendel’s Experiment
•Developed pure strains for each of the 14 characteristics by
self pollination (pollen from anther to stigma of same flower or
plant)
•Then, cross pollinated
•Parent plants = P1 generation
•First generation of offspring = F1 generation
F2 generation
•Second generation of offspring = ____
Mendel’s Results
P1: green pods x yellow pods ---------> all green pods (F1)
F1: green pods x green pods -------> ¾ green pods, ¼ yellow pods
•Mendel got the same ¾ to ¼ ratio or each
____ pair of pure traits he tested
Genes and Appearance
Genotype: gene combination present
Example: TT, Tt, tt
Phenotype: Physical
_______ appearance
__________ due to gene action
Example: tall, tall, short
Homozygous: both gene of pair Chromosomes
______________
(same)
Example: TT, tt
Heterozygous: genes of pair _____________
Chromosomes
(different)
Example: Tt
Also called a hybrid
Alleles: contrasting traits for the same characteristic
Example: tallness and shortness
Multiple Alleles: traits with more than two alleles
Example: blood type (A, B, O)
2 (two)
How many of these possible different genes can you inherit? __________________
Mendel’s Conclusions
Principles of Dominance and Recessiveness
expression
= one factor in a pair may mask the other, preventing its ______________.
Law of Segregation
= a pair of factors is segregated, or separated during the formation of gametes
Law of Independent Assortment
= factors are distributed to gametes separate of other factors
*Later found to be untrue where gene linkage is present
Modern Look at Mendel’s Work
genes
• Mendel’s factors = _______.
• Letters used to represent gene pairs:
– Capital letters for dominant genes
– Lower case letters for recessive
_________ genes
Example: Tallness vs. Shortness
T = tall gene
t = short gene
Tall
TT = _____
Tall
Tt = _____
tt =Short
____