Stem Test: Heredity

Alleles

Different forms of genes for a single trait

Dominant Allele

One whose trait always shows up in the organism when the allele is present; always expressed

Recessive allele

One whose trait is hidden whenever the other allele is present; only expressed in the homozygous state

Heterozygous

Genotypes made of two different alleles

Homozygous

Genotypes made of the same alleles

Heredity

The passing of physical characteristics from parent to offspring

Genetics

The scientific study of heredity

Trait

Each specific characteristic, such as stem hight or seed

Gene

Used to describe the factors that control a trait, section of DNA molecule that contains information to code for one specific protein

Purebred

An offspring of many generations that have the same form of a trait

Hybrid

An organism that has two different alleles for a trait

Fertilization

The process in which a new organism begins to form when egg and sperm cells join together.

Genotype

An organism’s genetic makeup, or alleles: Ex: R,R R,r

Phenotype

An organism’s physical appearance, or visible trait; how a trait looks or is expressed

Punnett Square

a chart that shows all of the possible ways that alleles can combine in a genetic cross

Probablility

A number that describes how likely an event is to happen

Incomplete dominance

Occurs when both alleles are partially dominant

Example of incomplete

Codominance

Occurs when both alleles for a gene are expressed equally

Example of codominance

Multiple alleles

Three or more possible alleles that determine the trait

Example of multiple alleles

Eye Color

Polygenic inheritance

Occurs when one or more gene affects a trait

Example of polygenic inheritance

Height

Meiosis

The process by which the process of chromosomes is reduced by half as sex cells form; the chromosome pairs separate into two different cells; the sex cells that form later have only half as many chromosomes as the other cells in the organism

Nitrogen bases

Adenine, Thymine, Cytosine, Guanine

How nitrogen bases mix

(AT) (TA) (CG) (GC)

What does DNA stand for

Deoxyribonucleic acid

DNA replication

The process in which an identical copy of a DNA strand is formed for a new cell; because of the way nitrogen bases pair up, the order of the bases in each new DNA strand exactly matches up the order in the original DNA strand

Order of Structures (smallest to biggest)

Nitrogen bases, DNA, chromosome, cell

Good path of cell division

Makes an identical copy

Bad path of cell division

Has mutations (can lead to cancer)

Mutation

A change in the DNA of a gene or chromosome, can cause a cell to produce an incorrect protein during protein synthesis which may cause an organisms trait to be different from what it normally would

What did Mendel observe?

The offspring in the F1 generation always had the dominant alleles trait, while the offspring of the F2 generation often had ¼ of the recessive trait

Significance of Mendel’s observations

Showed that the offspring traits are determined by individual, separate alleles inherited by each parent

What is a chromosome made of

Substitution

Wrong base is matched

Insertion

A base is added in

Deletion

A base is removed

How is cancer caused

Many mutations in a cell