Transcript Genetics

Genetics
The study of genes and the
inheritance of traits
Characteristics
 These are features you
exhibit physically
( your looks)
Example: Eye color green
Traits
 The different versions
of a characteristic
 Example: blue, green,
and brown eyes
Genes
 Bits of information
passed down from
parent to child.
 Made of chemicals
called DNA.
Reproduction
 Sexual – Sperm
fertilizes an egg to
produce offspring
 Asexual – occurs
when 1 organism
copies itself to produce
offspring
Genotype
 A combination of
alleles
Example: TT, Tt, or tt
*We flipped coins to determine the
genotype of our critters and
puppies.
Genotype
 How the genes code for a specific trait.
 If the trait is dominant it uses a capital
letter
– Example – Tall (T)
 If the trait is recessive it uses the same
letter but lower case
– Example – short (t)
 Genotypes always have two letters – one
for dad and one for mom
Types
of
genotype
 Purebred (homozygous) dominant – the genes
only have the dominant trait in its code.
– Example – Dominant Tall -- TT
 Purebred (homozygous) recessive –
the genes only have the recessive
trait in its code.
– Example – Recessive short – tt
 Hybrid (heterozygous) – the genes
are mixed code for that trait.
– Example – hybrid Tall -- Tt
Alleles
 T – is considered a
dominant allele
 t – is considered a
recessive allele
TT – is dominant
Tt or tT – is
dominant
tt - is recessive
Punnett Square
 Uses mom and dad’s
genotypes to
determine the possible
traits of their offspring.
 4 offspring
Phenotype
 They are the traits
determined by reading
the genotype.
 Example : FF = black
fur
 Black fur is the
phenotype or trait
Phenotype
The outward appearance of
the trait.
How an organism looks
How an organism acts
How an organism feels
Tricks to remembering the
difference between Genotype and
Phenotype
Genotype – deals
with GENE CODE.
Phenotype – deals
with looks you can
take a PHOTO with.
Review Words
 Characteristics – are the category of a trait –
– Example – eye color, height, likes/dislikes
 Traits – the physical, social, and emotional qualities of an
organism
– Example – blue eyes, tall, hates carrots
 Dominant Trait – when a majority of an organism shows
the trait.
– Example – most pea plants show as tall
 Recessive Trait – when a minority of an organism shows
the trait.
– Example – few pea plants show as short
 Alleles – all the possible choices for a characteristic
– Example – eye color – blue, brown, gray, green