Lesson 11 And 12 Flashcards
Heredity
The transmission of traits (inherited features) from one generation to the next
Genetics
The scientific study of heredity. Modern genetics began with the work of Gregor Mendel.
Hybrids
Offspring that results from the mating of individuals from two different species or from two true-breeding varieties of the same species; an offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes.
Cross
A mating of two sexually reproducing individuals; often used to describe a genetics experiment involving a controlled mating (a “genetic cross”)
P generation
The parent individuals from which offspring are derived in studies of inheritance; P stands for parental.
F1 generation
The offspring of two parental (P generation) individuals; F1 stands for first filial.
F2 generation
The offspring of the F1 generation; F2 stands for second filial.
Character
A heritable feature that varies among individuals within a population, such as flower color in pea plants or eye color in humans.
Trait
A variant of a character found within a population, such as purple or white flowers in pea plants.
True breeding
Referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents. The organisms are homozygous for the characters under consideration.
Alleles
An alternative version of a gene
Homozygous
Having two identical alleles for a given gene
Heterozygous
Having two different alleles for a given gene.
Dominant allele
The allele that determines the phenotype of a gene when the individual is heterozygous for that gene.
Recessive allele
An allele that has no noticeable effect on the pheno-type of a gene when the individual is heterozygous for that gene.
Law of segregation
A general rule in inheritance that individuals have two alleles for each gene and that when gametes form y meiosis, the two alleles separated each resulting gamete ending up with only one allele of each gene, also known as Medel’s first law of inheritance.
Punnett square
A diagram used in the study of inheritance to show the results of random fertilization.
Phenotype
The expressed traits of an organism
Genotype
The genetic makeup of an organism
Monohybrid cross
An experimental mating of individuals that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant)
Dihybrid cross
An experimental mating of Individuals that are each heterozygous for both of two characters (or the self-pollination of a plant that is heterozygous for both characters)
Law of independent assortment
A general rule of inheritance (originally formulated by Gregor Mendel) that when gametes form during meiosis, each pair of alleles for a particular character segregates independently of other pairs; also known as Mendel’s second law of inheritance
Testcross
The mating between an individual of unknown genotype for a particular character and an individual that is homozygous recessive for that same character. The testcross can be used to determine the unknown genotype.
Rule of multiplication
A rule stating that the probability of a compound event is the product of the separate probabilities of the independent events.
Rule of addition
A rule stating that the probability that an even can occur in two or more alternative ways is the sum of the separate probabilities of the different ways.
Pedigree
A family genetic tree representing the occurrence of heritable traits in parents and offspring across a number of generations. A pedigree can be used to determine genotypes of matings that have already occurred.
Carrier
An individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder but who may pass on the recessive allele to offspring
Huntingtons disease
A human genetic disease caused by a single dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms
Amniocentesis
A technique for diagnosing genetic defects while a fetus is in the uterus. A sample of amniotic fluid, obtained by a needle inserted into the uterus, is analyzed for telltale chemicals and defective fetal cells
Chronic villus sampling (cvs)
A technique for diagnosing genetic defects while the fetus is in an early development stage within the uterus. A small sample of the fetal portion of the placenta is removed and analyzed.
Complete dominance
A type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
Incomplete dominance
A type of inheritance in which the pheno-type of a heterozygote (Aa) is intermediate between the phenotype of the two types of homozygotes (AA and aa)
ABO blood group
Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The ABO blood group phenotypes, also called blood types, are A, B, AB, and O.
Codominant
Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles.
Pleiotropy
The control of more than one phenotypic character by a single gene
Sickle cell disease
A genetic condition caused by a mutation in the gene for hemoglobin. The mutation causes the protein to crystallize, which deforms red blood cells into a curved shape. Such blood cells produce a cascade of symptoms that can be life threatening.
Polygenic inheritance
The additive effects of two or more gene loci on a single phenotypic character.
Chromosome theory of inheritance
A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.
Linked genes
Genes located near each other on the same chromosome that tend to be inherited together.
