Genetics Review

•Physical characteristics studied in genetics are called ?

Traits•For example: height, color, dimples, etc.

•The different forms of a gene are called?

Alleles•You get one from each parent.•Maybe a dominant from Mom and recessive from Dad

•A hidden or masked trait in a gene combination is called?

recessive•You only ‘see’ the recessive trait if there are two of them•Homozygous recessive, ee

•Show a heterozygous gene combination using the letter G

Gg•Heterozygous gene combinations have two different genes, one dominant and one recessive

•How many genes for each trait does an offspring receive from each parent?

One•You get one gene from each parent.

•What does a Punnett square show?

Probability of Genotypes

•The probability of the genotypes of the offspring.•75% chance of being tall•25% chance of being short

•In genetics a capital letter represents a __________ trait.

Dominant•All dominant traits are represented with a capital letter.

•In genetics a lower case letter represents a ___________ trait.

recessive•Recessive traits are represented with a lower case letter, you must have two of them in order to ‘see’ that trait.

If G=green and g= blue

What would be the probability of the offspring being blue?

25%

If G=green and g=blue

What word describes the genotypes of the parents?

Heterozygous or Hybrid

If G=green and g=blue

What words describe the genotype of the blue offspring?

homozygous recessive or purebred

recessive

•An organism’s expressed physical trait, such as seed color or shape, is called its ______________.

Phenotype•A phenotype is an organism’s physical appearance.

•If purple flowers are dominant to white flowers, what would be the phenotypes of the offspring of a purple homozygous flower with a white homozygous flower?

PurplePP x pp means all offspring will be Pp,so they will all be purple.

Pp

Pp

Pp Pp

•Which nitrogen pairs bond with each other?•(hint: A,C,G,T)

A – T and C – G •Adenine always bonds with Thymine•Cytosine always bonds with Guanine

•What word describes an organism that has two identical alleles for a trait?

Homozygous•The prefix ‘homo’ means ‘same’

List the levels of organization from largest to smallest.

•Use these terms: •DNA, chromosome, gene, nucleus, cell

Cell – nucleus – chromosome- gene- DNA

•What is the function of DNA?

DNA carries all of the genetic information of

the organism.•DNA is the code for how to build and maintain and organism (like you).

•How do you get a genetic disorder?

Passed from the genes of a parent

•A genetic disorder is passed from parent to child through the genes, it cannot be ‘caught’ like the flu or the measles.

•If an offspring has two parents and is a unique individual is it a product of asexual or sexual reproduction?

Sexual Reproduction

G = green and g = blue

•Genotype of homozygous dominant

GG

G = green and g = blue

•Genotype for hybrid

Gg

G = green and g = blue

•Phenotype of homozygous recessive

blue

G = green and g = blue

•Phenotype of heterozygous

Green

G = green and g = blue

•Phenotype of homozygous dominant

Green

G = green and g = blue

•Show the genotypic cross between a purebred blue and a hybrid

gg x Gg

G = green and g = blue

•Show a Punnett square for a cross between two heterozygous parents

G g

GG Gg

gg