Studied by 2 people
cross fertilization
a hybridization of offspring of two varieties
self fertilization
the fusion of sex cells produced by the same individual (offspring of one variety)
flower
reproductive organ, can be male or female, can make sperm or egg cells
character
a heritable feature that varies among individuals
trait
varient or alternate form for a character
allele
an alternate version of a gene usually represented by capital or lowercase letter
homozygous
having two identical alleles for the given genes
heterozygous
having two different alleles for the given genes
gene
a segment of DNA that codes for a polypeptide
phenotype
genetics distinguished between its physical form
genotype
genetic makeup
punnet square
a diagram used in the study of inheritance to show the results of random fertilization
true breed
sexual reproduction produce offspring with inherited traits identical to those of the parents
cross
a mating of two sexually reproducing individuals
P generation
true-breeding parents
F1 generation
true-breeding offspring
F2 generation
F1 plants self-fertilize offspring
Mendel’s experiments
Mendel produced individuals that are pure for a particular trait (true breed or strain) by self-pollinating a plant repeatedly to obtain that one trait a number of times and only that trait is observed through multiple generations and self-pollinations.
Mendel then crossed two pure plants for a particular trait, a purple flower and a white flower. 'The pure/strain/true breed parents are called the P generation (parental) and their offspring/hybrids are called the F1 generation (filial).
The next generation is obtained by self-fertilizing/pollinating the F1 generation to get the F2 generation.
Mendel’s observations
There are alternative versions of genes that account for variations in inherited characteristics.
For each character, an organism inherits two alleles, one from each parent.
If the two alleles of an inherited pair differ, then one determines the organism’s appearance and is called the dominant allele. The other has no effect on the appearance and is called the recessive allele.
A sperm or egg only carries only one allele for each inherited character because allele pairs separate from each other during the production of gametes.
The Law of Segregation
when sperm and egg unite at fertilization, each contributes its allele, restoring the paired condition in the offspring. a pair of alleles segregate during gamete formation
dominant allele
a pair of alleles that determines the organism’s appearance
recessive allele
a pair of alleles with no effect on the organism’s appearance
Principle of Independent Assortment
He concluded that seed color was independent of seed shape during gamete formation. He further reasoned that each pair of alleles (seed shape and seed color) segregates independently, Principal of Independent Assortment. In other words, the different characters (pea color and pea shape) are inherited independently from each other.
gene locus
the location of a gene on a chromosome
dihybrid cross
a mating of parental varieties differing in two characters
incomplete dominance
a single gene locus trait of inheritance in which the phenotype of a heterozygote is intermediate between the phenotypes of the two types of homozygotes
multiple allele traits
a single gene locus trait in which genes are found in populations in more than two versions
ex. ABO blood group in humans involve 3 alleles of a single gene → A, B, AB, and O
codominance
a single gene locus heritable trait in which both alleles are expressed in heterozygous individuals who have type AB blood
plietrophy
one gene that influences multiple characteristics
ex. sickle cell disease is one amino acid that is different than a normal chain and causes many issues
polygenic inheritance
the additive effects of two or more genes on a single phenotypic character (more than one gene location)
ex. hair, skin color, nose shape
linked genes
genes located close together on the same chromosome tend to be inherited together
ex. sweet pea genes for flower color and pollen shape are located on the same chromosome
sex-linked gene
a gene located on either sex chromosome
ex. male phenotype relies entirely on his single x-linked gene
crossing over
the exchange of genetic material between homologous chromosomes
recombination frequency
equivalent to the crossing over frequencies for genes on the same chromosome. The recombination/crossing over frequencies or % of unexpected outcomes/ combinations is equivalent to a map unit. Map unit is equal to the % of crossing over
ex. fruit flies have a 17% frequency of a recombination
monohybrid cross
an experimental mating of individuals that are heterozygous for the character being followed
test cross
a mating between an individual of unknown genotype and a homozygous recessive individual
rule of multiplication
a probability of an event is the product of the separate probabilities of the independent events
rule of addition
the probability of an event can occur in two or more alternative ways is the sum of the separate probabilities of the different ways
chromosome theory of inheritance
a theory that states genes have specific loci on chromosomes that involve different chromosome behavior like linkage, segregation, and independent assortment
the X-Y system
a sex determination system in which the sex of an individual is determined by the male chromosomes
ex. humans
the X-O system
a sex determination system in which the Y chromosome is absent yet the sex of an individual is determined by the male
ex. grasshoppers
the Z-W system
a sex determination system in which the sex is determined by the female chromosomes
ex. birds and plants
the chromosome number system
a sex determination system in which the sex of an organism is determined by their chromosomal number
ex. bees and ants
hermaphroditic
individuals that produce both sperm and egg
monoecious
plants that produce sperm and egg
pedigree
a family genetic tree representing the occurence of heritable traits in parents and offspring accross a number of generations
Note 
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