Vocab Flashcards
Dominant allele
If the alleles of an inherited pair differ, then one determines the organism’s appearance and is called the dominant allele.
Recessive allele
The other has no noticeable effect on the organism’s appearance and is called the recessive allele.
Phenotype
appearance or expression of a trait.
Genotype
genetic makeup of a trait.
Law of Segregation
A sperm or egg carries only one allele for each inherited character because allele pairs separate (segregate) from each other during the production of gametes. This statement is called the law of segregation.
Punnette square
shows the four possible combinations of alleles that could occur when these gametes combine.
Locus
is the specific location of a gene along a chromosome.
Dehybrid
is a mating of parental varieties that differ in two characters
Law of independent assortment
suggested that the inheritance of one character has no
effect on the inheritance of another, and suggested that the dihybrid cross is the equivalent to two monohybrid crosses.
Test cross
the mating between an individual of unknown genotype and a homozygous recessive individual.
Rule of multiplication
the probability is the product of the probabilities for each event.
Rule of addition
The probability that an event can occur in two or more alternative ways is the sum of the separate probabilities
Wild type traits
those prevailing in nature, are not necessarily specified by dominant allel
Pedigree
shows the inheritance of a trait in a family through
multiple generations,
– demonstrates dominant or recessive inheritance, and
– can also be used to deduce genotypes of family members.
Recessive inheritance
– two recessive alleles are needed to show disease,
– heterozygous parents are carriers of the disease-causing allele, and
– the probability of inheritance increases with inbreeding, mating between close relatives.
Inbreeding
mating between close relatives.
Dominant inheritance
one dominant allele is needed to show disease and
– dominant lethal alleles are usually eliminated from the population.
cystic fibrosis
The most common fatal genetic disease in the United States. resulting in excessive thick mucus secretions.
Achondroplasia
resulting in dwarfism,
Hunningtons
degenerative disorder of the nervous system.
Complete dominance
Mendel’s pea crosses always looked like one of the parental varieties
Incomplete dominance
When for some characters, the appearance of F1 hybrids falls between the phenotypes of the two parental varieties.
neither allele is dominant over the other and
– expression of both alleles occurs.
hypercholesterolemia
dangerously high levels of cholesterol occur in the blood and
– heterozygotes have intermediately high cholesterol levels.
Con dominance
The A and B alleles are both expressed in heterozygous individuals neither allele is dominant over the other and
– expression of both alleles is observed as a distinct phenotype in the heterozygous individual.
– AB blood type is an example of codominance.
Pleiotropy
when one gene influences many characteristics.
Polygenic inheritance
in which a single phenotypic character results from the additive effects of two or more genes.
chromosome theory of inheritance
genes occupy specific loci (positions) on chromosomes
and
– chromosomes undergo segregation and independent assortment during meiosis.
linked genes,
are located close together on the same chromosome and
– tend to be inherited together.
recombination frequency.
Linked alleles can be separated by crossing over, forming recombinant gametes.
sex chromosomes,
designated X and Y,
– that determine an individual’s sex.
Sex-linked genes
are located on either of the sex chromosomes.
Alleles
Are alternative versions of genes that account for variations in inherited characters.
Homozygous
Genotype has identical alleles.
Heterozygous
Genotype has two different alleles.
Monohybrid Cross
A cross between two individuals differing in a single character.
Character
A heritable feature that varies among individuals like flower color.
Trait
Each variant for a character such as purple or white.
Hybrid
The offspring of two different variates.
