Intro to
Genetics
Human Traits
 How
do we get our traits? Why are we tall, short,
blonde? What makes us…us?
Genetics
 Every
living thing – plant or animal, microbe or human being –
has a set of characteristics inherited from its parent or
parents.
 Since
the beginning of recorded history, people have wanted
to understand how inheritance is passed from generation to
generation
What is Genetics?
 Genetics Heredity Traits-
branch of biology that studies heredity
passing of traits from parents to offspring
Characteristics that are inherited through DNA
Gregor Mendel
 Gregor
Mendel - an Austrian monk, “Father of Modern
Genetics”
 Mendel
 He
was born in 1822 in what is now the Czech republic
studied to be a priest and spent several years studying
science and math
Gregor Mendel
 Mendel
spent many years of his life
working in the local monastery and
teaching high school.
 While
there, Mendel was in charge
of the garden and spent much of
his time tending to and studying
the plants around him.
Observations
 Mendel
observed seven traits in pea plants that only
occurred in two forms. (Shape, color, size…)
Why these traits?
 Were
 How
these genetic or environmental factors?
did pea plants pass their traits?
Pea Plants
 Pea
plants reproduce sexually. (Require both male and
female sex cells)
 Gamete

half of the chromosomes
 Somatic

= sex cell.
Cell = the “regular” cells in your body.
full set of chromosomes
Experiments
 Mendel
forced pea plants with different traits to pollinate each
 Wanted
to see how offspring compared to parents.
other.
 The
experiments are called genetic crosses
Genetic Portraits
Genetic Portraits
Offspring
 Mendel
noticed that many times the second
generation plants showed different traits from the
parents
Genetic Vocabulary
 Phenotype=
the physical characteristics of an
organism. (Purple flowers or white flowers)
 Genotype=
the gene combination of an organism
that determines its phenotype.
Alleles
 Allele
= the specific form of a trait/gene. We have two alleles
for each trait in our DNA.

(Ex: Brown eye or blue eye gene / purple or white flower)
 Dominant
Allele = observable trait requiring only one allele to
be expressed.

(Written as a capital letter)
 Recessive
Allele = allele that is not observed when a
dominant allele is present in the genes. Can be hidden.

(Written as a lower case letter)
Allele Pairing
 Homozygous

= two alleles for a trait are the same.
(Ex: BB or bb )
 Heterozygous


= two alleles for a trait are not the same.
(Ex: Bb)
Dominant trait will be observed.
Science Show - Gregor Mendel
100 Greatest Discoveries Mendel (First section)
Chromosome – Gene – Allele – Protein – Trait