What is Heredity?
Genetics -1 – Mendelian Genetics
??What is a trait??
A characteristic caused by a gene
??What traits do you share with your mother? father??
???????
??Does a trait always have to be physical??
All traits have some physical basis, even behavior.
??What can we say about the traits of a population of organisms
that reproduce sexually?? Why?
They have genetic variation due to meiosis
Genetics – study of how hereditary information is passed from
generation to generation.
??What material is the study of heredity and genetics??
DNA – Deoxyribonucleic Acid
BUT NOT IN MENDELIAN GENETICS!!!
Gregor Mendel – Austrian monk that conducted pea
experiments to study genetics
Studied Pea Plants:
-Easy to grow -Sharply Contrasting Traits
-Mature quickly
(tall/short, yellow/green)
Traits – the characteristic that results from a gene
Hybrid – an organism that has two different traits from
parents with identical traits. Only one of the traits is
shown/expressed.
Also known as heterozygous
Law of Dominance
Dominant – the trait that is shown/expressed
Recessive – the trait that is hidden
Gene Chromosome Theory
Mendel didn’t know much about chromosomes, but it later became
known that the __genes__ are located on the _chromosomes__.
Genotype - the genetic make-up of an organism
Phenotype – the physical traits of an organism
What happens during crossing-over?
P = Parents
F1 = 1st generation
F2 = 2nd generation
Possible combinations:
Punnett Squares – shows the possibilities of genetic crosses
(It is also going to help us understand these terms!!!)
Co-Dominance – two traits are displayed at the same time
Ex. Roan coat in cattle
Incomplete Dominance – Type of heredity which the hybrid is
in between dominant and recessive
Ex. Japanese 4 O’clock plant
White + Red = Pink