Genetics

Allele

The different forms of a gene

Dominant Allele

An allele whose trait always shows up in the organism when the allele is present

Recessive Allele

An allele that is masked when a dominant allele is present

Homozygous

Having two identical alleles for a trait

Heterozygous

Having two different alleles for a trait

Genotype

An organisms genetic makeup, or allele combinations

Phenotype

The physical traits that appear in an individual as a result of its genotype

Chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins. Most cells in your body have 46.

Trait

A describable feature of an organism.

e.g. ability to roll tongue

Punnett Square

diagram that can be used to predict the genotype and phenotype combinations of a genetic cross

Carrier

A person who has one recessive allele for a trait, but does not have the trait.

Gene

A segment of DNA on a chromosome that codes for a specific trait

maternal

of or like a mother

paternal

of or like a father

Hybrid

An organism that has two different alleles for a trait

Purebred

An organism in which both alleles for a trait are the same

Heredity

Passing of traits from parents to offspring

mutation

a random error in gene replication that leads to a change

Mendelian Genetics

The pattern of inheriting characteristics that follows the laws formulated by Gregor Mendel

Gregor Mendel

Father of genetics

Angiosperms

flowering plants that bear fruits and flowers

self-fertilization

When pollen from an anther fertilizes the eggs on the same flower.

cross-fertilization

When the pollen is transferred to the stigma of an entirely different plant

genetics

The scientific study of heredity

pollination

The transfer of pollen from male reproductive structures to female reproductive structures in plants

Law of independent assortment

Mendel's second law, stating that allele pairs separate from one another during gamete formation

Law of Segregation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

incomplete dominance

Situation in which one allele is not completely dominant over another allele

Codominance

A condition in which neither of two alleles of a gene is dominant or recessive.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

autosomal recessive

two copies of an abnormal gene must be present in order for the disease or trait to develop

autosomal dominant

Name the pattern of genetic transmission characterized thus: both M and F are affected; M may transmit to M; each generation has at least one affected parent; and one mutant allele may produce the disease.

sex-linked traits

Traits controlled by genes located on sex chromosomes.

In a pedigree, a horizontal line represents?

marriage

In a pedigree a vertical line represents?

offspring

In a pedigree - diagonal line through symbol

deceased

In a pedigree, a shaded circle represents?

affected female

In a pedigree, a shaded square represents?

affected male

Genome

the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes

monohybrid cross

A cross between individuals that involves one pair of contrasting traits

dihybrid cross

A cross between individuals that have different alleles for the same gene

P generation

Parental generation, the first two individuals that mate in a genetic cross

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms

F2 generation

offspring of the F1 generation

polygenetic characteristics

personal traits or physical properties that are influenced by many genes working in combination

Number of years Mr. McNeeley has been teaching

40