heredity Flashcards
X-linkage
gene present on the X, but not the Y chromosome
Allele
gene variations that arise by mutation and exist at the same relative locations on homologous chromosomes
ABO blood types
the classification of human blood based on the inherited properties of red blood cells ( erythrocytes) as determined by the presence or absence of the antigens A and B, which are carried on the surface of the red cells.
Autosome
any of the non-sex chromosomes
Carrier
is an individual who carries and is capable of passing on a genetic mutation associated with a disease and may or may not display disease symptoms.
Character
any observable feature, or trait, of an organism, whether acquired or inherited
Cross Over
is the swapping of genetic material that occurs in the germ line
Discontinuous variation
inheritance pattern in which traits are distinct and are transmitted independently of one another
Dominant
trait which confers the same physical appearance whether an individual has two copies of the trait or one copy of the dominant trait and one copy of the recessive trait
Epistasis
antagonistic interaction between genes such that one gene masks or interferes with the expression of another
Dominant Lethal
an allele is lethal both in the
homozygote and the heterozygote
Incomplete Dominance
in a heterozygote, expression of two contrasting alleles such that the individual displays an intermediate phenotype
Essential Gene
are indispensable genes for organisms to grow and reproduce offspring under certain environment.
Chromosome Mapping
Any method used for determining the location of and relative distances between genes on a chromosome.
Chromosomes
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
Discontinous Variation
a variation in which different forms of a CHARACTER fall clearly into a particular grouping without overlapping each other, and are often controlled by a small number of major genes.
Essential Gene
are indispensable genes for organisms to grow and reproduce offspring under certain environment.
Blending theory
The discredited theory that inheritance of traits from two parents produces offspring with characteristics that are intermediate between those of the parents.
Lethality
A single copy of the wild-type allele is not always
sufficient for normal functioning or even survival
Quanititiative Trait
are phenotypic traits that are determined, jointly with the environment, by many genes of small effect.
Linkage
phenomenon in which alleles that are located in close proximity to each other on the same chromosome are more likely to be inherited together
Codominance
is a relationship between two versions of a gene. Individuals receive one version of a gene, called an allele, from each parent
Chromosome mapping
is a technique used in autosomal DNA testing which allows the testee to determine which segments of DNA came from which ancestor.
P-generation
the first set or first generation in the study of inheritance
Homozygous
having two identical alleles for a given gene on the homologous chromosome
Heterozygous
having two different alleles for a given gene on the homologous chromosome
Hemizygous
presence of only one allele for a characteristic, as in X-linkage; hemizygosity makes descriptions of dominance and recessiveness irrelevant
Law of Segregation
paired unit factors (i.e., genes) segregate equally into gametes such that offspring have an equal likelihood of inheriting any combination of factors
Phenotype
physical
appearance or observable
characteristic of the alleles
Genotype
underlying genetic makeup, consisting of both physically visible and non-expressed alleles, of an organism
Genes
a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
Polygenic inheritance
as the quantitative inheritance of multiple independent genes having an additive or cumulative effect on a single quantitative trait.
Essential Gene
are indispensable genes for organisms to grow and reproduce offspring under certain environment
Dihybrid Cross
result of a cross between two true-breeding parents that express different traits for two characteristics
F2 Generation
second filial generation produced when F1 individuals are self-crossed or fertilized with each other
F1 Generation
first filial generation in a cross; the offspring of the parental generation
Gregor Mendel
Augustinian monk and botanist who formulated the laws of heredity based on his careful breeding experiments on garden pea plants.
Phenotypic ratio
the number of times a specific combination of alleles appears in the predicted phenotypes of any offspring.
3:1
Genotypic ratio
the number of times a characteristic of an organism will be seen in the offspring when genes for certain traits are crossed
1:2:1
Nonfunctional Allele
the cell will continue to grow and divide, regardless of the signals it receives
Huntington’s Disease
a hereditary disease marked by degeneration of the brain cells and causing chorea and progressive dementia.
Law of Independent Assortment
genes do not influence each other with regard to sorting of alleles into gametes; every possible combination of alleles is equally likely to occur
Locus
is the specific physical location of a gene or other DNA sequence on a chromosome, like a genetic street address
Monohybrid cross
result of a cross between two true-breeding parents that express different traits for only one characteristic
Punnett Square
visual representation of a cross between two individuals in which the gametes of each individual are denoted along the top and side of a grid, respectively, and the possible zygotic genotypes are recombined at each box in the grid
Quantitative Traits
are phenotypic traits that are determined, jointly with the environment, by many genes of small effect.
Recessive
trait that appears “latent” or non-expressed when the individual also carries a dominant trait for that same characteristic; when present as two identical copies, the recessive trait is expressed
Recessive disease
A condition that appears only in individuals who have received two copies of a mutant gene, one copy from each parent.
Recessive lethal
as a mutation that results mainly in the premature death of homozygous individuals, sickle cell anemia is a recessive lethal condition.
Recombinantion chromosomes
are formed when there is shuffling of genetic material between the homologous chromosomes.
Segregate
the separation of paired alleles during meiosis so that members of each pair of alleles appear in different gametes genetic science , genetics - the branch of biology that studies heredity and variation in organisms
Self-fertilization
the fertilization of plants and some invertebrate animals by their own pollen or sperm rather than that of another individual.
Sex linkage
any gene on a sex chromosome
Sex chromosome
are one pair of non-homologous chromosomes.
Testcross
cross between a dominant expressing individual with an unknown genotype and a homozygous recessive individual; the offspring phenotypes indicate whether the unknown parent is heterozygous or homozygous for the dominant trait
Trait
a variant of a character
True-breeding
offspring produced by self-fertilization all
look like a parent, over multiple generations.
wild type
a phenotype, genotype, or gene that predominates in a natural population of organisms or strain of organisms in contrast to that of natural or laboratory mutant forms
