Mendelian Genetics

Having two identical alleles for a trait

Having two different alleles for a trait

the different forms of a gene.

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

an allele that is masked when a dominant allele is present

situation in which both alleles of a gene contribute to the phenotype of the organism

Set Fire To The Rain

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

An organism's genetic makeup, or allele combinations.

A condition which creates a blended phenotype; one allele is not completely dominant over the other. The heterozygous phenotype is a mix of the other two possible phenotypes

Father of genetics. Experimented with pea plants and discovered law of dominance, ind. assortment, and segregation.

all offspring show dominant trait

pairs of alleles separate when gametes form

genes for different traits are inherited independently

cross that has one pair of contrasting alleles for a trait (2x2 square)

occurs when certain traits are determined by genes on sex chromosomes. The X chromosome contains many traits not found on the Y chromosome.

two characteristics are tracked (aabb)

A chart that shows all the possible combinations of alleles that can result from a genetic cross

the ratio of genotypes that could appear in offspring

the ratio of phenotypes that could appear in offspring

Ear size

Coat color

An error in meiosis in which homologous chromosomes don't separate; gametes end up with either more or less chromosomes. This is the cause of Trisomy 21(Down's Syndrome)

the loss of all or part of a chromosome. The chromosome will look shorter than normal.

(genetics) a kind of mutation in which the order of the genes in a section of a chromosome is reversed

change to a chromosome in which part of the chromosome is repeated. The chromosome will look longer than normal.

condition in which an individual has three number 21 chromosomes, resulting in Down syndrome

One of our 23 pairs of chromosomes. Contains the x and y chromosomes that determine our physical sex characteristics and other characteristics.

each parent contributes this many chromosomes to their offspring in humans.

Full set of chromosomes in a normal human cell.

a phenotype determined by an allele on an X chromosome. Hemophilia is an example.

area where the chromatids of a chromosome are attached

replicated forms of chromosomes joined together by the centromere and separated during mitosis and meiosis II

chromosomes that have the same sequence of genes, that have the same structured, and that pair during meisosis

form of nuclear and cell division that halves the number of chromosomes when forming specialized reproductive cells (egg and sperm). These cells are haploid.

a cell containing only one set of chromosomes (n). Human haploid cells have 23 chromosomes. Only in sperm and egg cells.

A cell containing both sets of chromosomes (2n). Human diploid cells have 46 chromosomes.

process in which homologous chromosomes exchange portions of their chromatids during meiosis

The first nuclear division of meiosis where homolygous chromsomes are separated, and the cells split in half. The cell has gone from diploid(46) to haploid(23).

The second nuclear division of meiosis, in which sister chromatids are separated from each other. The result is four haploid cells.

BB HH RR TT

bb hh rr tt

Bb Hh Rr Tt

the movement of a segment of DNA from one chromosome to another, which results in a change in the position of the segment

mutation in which a segment of a chromosome is inserted into another chromosome.