10a Flashcards
Incomplete dominance
Mode of inheritance in which a heterozygote’s phenotype is intermediate between the phenotypes of the two homozygotes. (snapdragon color)
Codominance
Mode of inheritance in which two alleles are fully expressed in the heterozygote (blood type)
Mendel’s Law of segregation (2)
Diploid cells have pairs of genes on pairs of homologous chromosomes. The two genes are separated during meiosis and end up in different gametes.
Mendel’s 2nd law
A gene is distributed into a gamete independently of how other genes are distributed.
linkage group
Group of genes that tend to be inherited together because they are on the same chromosome
Linked genes
genes on the same chromosome
linkage map
diagram of gene order and spacing on a chromosome, based on crossover frequencies
Product rule
States that the chance that two independent events will occur equals the product of the individual chances that each event will occur.
True breeding
Always producing offspring identical to the parent for one or more traits (homozygous)
Locus
The physical locatioin of a gene on a chromosome
Allele
One of the alternative forms of a specific gene
Hybrid
Producing a mix of offspring for one or more traits (heterozygous)
Mutant
A phenotype, genotype or allele resulting from a mutation in a gene
Dominant allele
An allele that exerts its effects whenever it is present
Recessive Allele
An allele whose effect is masked if a dominant allele is also present
Test cross
A mating between and individual of unknown genotype and a homozygous recessive individual. The genotype of the unknown parent can be deduced from the phenotype ratio of the offspring.
Polygenic
Phenotype reflects the activity of more than one gene. (i.e. eye color)
Homozygous
Possessing two identical alleles for a gene
Heterozygous
Possessing two different alleles for a gene
Autosomnal Dominant
Inheritance pattern of a dominant allele on a chromosome. Expressed in heterzygotes, One or both parents must also have the disorder. (Huntington’s)
Autosomnal Recessive
Inheritance pattern of a recessive allele on a chromosome - requires that a recessive allele by passed down by both parents. (albinism)
X-inactivation
Turning off all but one X chromosome in each cell of a mammal (usually female) in early development.
X-linked
Describes traits controlled by genes of the X chromosome
Pleiotropy
One gene has multiple effects on the phenotype. (i.e. one protein is used or affects
many parts of the body. (Marfan/connective tissue)
Epistasis
One gene masks another gene’s expression (i.e. baldness hides the effects of a widow’s peak)
Phenotype
Observable characteristic of an organism
Genotype
An individual’s combination of alleles for a particular gene
What is P, F1, F2
The P generation is the parental or starting generation. F1 and F2 (filial) refer to the first and second generations, respectively.
What is a monohybrid cross, and what are the genotypic and phenotypic ratios expected in the offspring of the cross?
A monohybrid cross is a mating between two individuals that are each heterozygous for one gene. The genotypic ratio expected in a monohybrid cross is 1:2:1 (homozygous dominant : heterozygous : homozygous recessive); the phenotypic ratio is 3:1 (dominant:recessive).
What is a dihybrid cross, and what is the phenotypic ratio expected in the offspring of the cross?
In a dihybrid cross, two individuals that are each heterozygous for two genes are mated. The phenotypic ratio that is expected is 9:3:3:1 (dominant for both genes: dominant for one gene and recessive for the other: recessive for one gene and dominant for the other: recessive for both genes).
Punnett square use?
Punnett squares show the genotypes of each parent as well as the genotypes of potential offspring. Phenotypic and genotypic ratios of offspring can be predicted from the data in Punnett squares.
X-linked dominant disorders
hairy, rickets, retinis pigmentosa
X-linked recessive disorders
RG colorblindness, hemophilia, Duchenne
Centromeres divide in?
Mitosis/anaphase and Meiosis 2/Anaphase 2
Describe and differentiate between Diploid vs. Haploid
A diploid cell (2n) has two full sets of chromosomes, with one set coming from each parent. A haploid cell (n) has only one set of chromosomes.
Non-mendelian inheritance
Codominance, incomplete dominance, pleiotropy, epistasis
