the branch of biology that studies heredity and variation in organisms
A monk and botanist whose experiments in breeding garden peas led to his eventual recognition as the founder of the science of genetics
Law of Segregation
Mendel's first law that says each gene has two alleles. Parents randomly give only one of their two alleles to the offspring. The offspring will have two alleles (one from each parent).
Law of independent Assortment
Mendel's second law that says that genes for different traits are inherited independently of each other. For example, inheriting a random trait for tallness will not affect the trait that the offspring inherits for hair color.
An allele that is always expressed if present
describes an allele that is covered over, or dominated, by another form of that trait and seems to disappear
different forms of genes
sequence of DNA that codes for a protein and thus determines a trait
genetic makeup of an organism
physical characteristics of an organism
having two identical alleles for a trait
having two different alleles for a trait
a chart that shows all the possible combinations of alleles that can result from a genetic cross
creates a blended or mixed phenotype; one allele is not completely dominant over the other. Ex. Red + White = Pink
inheritance pattern in which a heterozygote expresses the distinct traits of both alleles. Ex. Puple + White = white Spots on purple background
two or more genes contribute to the phenotypic expression of a single characteristic. Ex. AaBbCc is a phenotype for skin color
cell division that produces 4 reproductive cells in sexually reproducing organisms
Chromosome pairs of the same length, centromere position, and staining pattern that possess genes. One is inherited from the organism's father, the other from mother.
half a full set of chromosomes (23 in humans), egg and sperm cells are this
a full set of schromosmes (46 in humans), zygote and body cells are this
A fertilized egg.
sperm and ovum are an example of these types of cells.
a threadlike body in the cell nucleus that carries the genes in a linear order
exchange of genetic material between homologous chromosomes during prophase I of meiosis
the physical union of male and female gametes
the first phase of meiosis where homologous chromosomes are separated, and the cell divides for the first time
the second phase of meiosis where sister chromatids are separated, and the cell divides for the second time
one of the two identical parts of a duplicated chromosome in a eukaryotic cell
the 4 letter order of meiosis. This sequence is repeated twice during the phases of meiosis.
a reproductive process that involves only one parent and produces offspring that are identical to the parent
process in which genetic material from two parents combines and produces offspring that differ genetically from either parent
A picture of all the chromosomes in a cell arranged in pairs
chromosome pairs #1-22. These chromosomes include the genetic information for most body cells.
These chromosomes include the genetic information for the sex cells. X and Y are examples of this chromosome type.
is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. Known as Trisomy 21, this syndrome is associated with some impairment of mental and physical ability.
Patau Syndrome-most die within 4 days; people with syndrome can be born with cleft lip or polydactyly.
a chromosomal trisomy in which males have an extra X chromosome resulting in an XXy condition; affected individuals typically have reduced fertility
a diagram that shows the occurrence of a genetic trait in several generations of a family
Disease is dominant allele: phenotype appears every generation, affected individual has at least one affected parent, affects both male and female (ex. huntington's disease)
Trait is recessive: phenotype can skip a generation, affected individual can have unaffected parents, affects both male and female (ex. Sickle Cell Anemia)