Biology: Mendelian Genetics GUHS

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Gregor Mendel
Father of genetics, studied pea plants.
Catholic
trait
Genetically determined variant of a characteristic.
heredity
transmission of characteristics from parents to offspring.
self-pollination
pollination within the same plant
Self-fertilization
cross-pollination
pollination between different plants
dominant
A trait that will always appear if that allele is present.
recessive
A trait that is masked by a dominant trait.
P-generation
true breeding parents
F1-generation
offspring (filial) of P generation parents
homozygous
Is when both alleles of a pair are alike
heterozygous
is when two alleles are different
allele
one of the alternative forms of a gene that governs a characteristic, such as hair color
monohybrid cross
A cross in which one characteristic is tracked
Ex. Br x Br: genotypes: 1:2:1, phenotypes: 3:1
dihybrid cross
A cross in which two characteristics are tracked
BrHr x BrHr
Punnett Square
Graphical method to aid biologists in predicting the probable distribution of inherited traits in the offspring. Developed by Reginald Punnett.
phenotype
an organism's appearance or other characteristic that results from the organism's genotyp
genotype
the combination of genes for one or more specific traits.
law of segregation
Its a separation in the homologous Chromosomes so that there is a pair present in each Gamete
law of independent assortment
states that Chromosomes separate independently of one another during the formation of gametes
test-cross
Crossing an organism with an unknown genotype / with a organism with a known genotype usually a homozygous recessive.
true-breeding
describes organisms or genotypes that are homozygous for a specific trait that always produce offspring that have the same phenotype for that trait
complete dominance
one allele is completely dominant
incomplete dominance
trait is intermediate between the phenotype of the two parents. Example: Red and White produce Pink.
probability
possible future event will occur in any given event. Decimal, percentage, or a fraction
genetics
Scientific study of heredity
gamete
A haploid egg or sperm cell; unite during sexual reproduction to produce a diploid zygote.
gene
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).
genotype
The genetic makeup of an organism.
gene map
Diagram showing the relative locations of each known gene ona particular chromosome
fertilization
The union of haploid gametes to produce a diploid zygote.
true-breeding
Term used to describe organisms that produce offspring identical to themselves if allowed to self-pollinate
trait
Specific characteristics that varies from one individual to another
hybrid
(1) Offspring of two parents that differ in one or more inheritable characteristics. (2) Offspring of two different varieties or of two different species.
allele
An alternative form of a gene.
segregation
Separation of alleles during gamete formation
probability
Likelikhood that a particular event will occur
Punnett square
The checkerboard diagram used for analysis of allele segregation.
phenotype
The physical and physiological traits of an organism.
incomplete dominance
A type of inheritance in which F1 hybrids have an appearance that is intermediate between the phenotypes of the parental varieties.
codominance
A phenotypic situation in which both alleles are expressed in the heterozygote.
multiple alleles
Three or more alleles of the same gene
polygenic traits
Traits controlled by two or more genes
homologous
Term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent
diploid
Term used to refer to a cell that contains both sets of homologous chromosomes
tetrad
Structure containing 4 chromatids that forms during meiosis
meiosis
Process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell
haploid
Term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes.
crossing-over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis
Heredity
Passing of traits from parents to offspring
Offspring
child, baby, new organism born from parent
Gametes
sex cells like sperm and egg with half the number of chromosomes
Zygote
sex cells that have been fertilized resulting in a cell with a full set of chromosomes. Our first cell.
Hybrid
Offspring developed from parents with different forms of a trait
alleles
different forms of forms of a gene, each gene has two alleles: one from MOM and one from DAD.
Dominant trait
trait that is superior over recessive determining the physical appearance
Recessive trait
Inferior trait that is covered up by the dominant trait
Homozygous
Two identical alleles for a trait
Heterozygous
Two different alleles for a trait
Monohybrid Cross
Comparing only one trait of an offspring from two parents
Dihybrid Cross
Comparing two traits of an offspring from two parents