Chapter 14 Flashcards
Character
A heritable feature that varies among individuals
True breeding
Varieties that only produce the same variety as the parent plant
Parents will pass down a specific phenotype trait to their offspring
Truebred organisms
Will have a pure genotype and will only produce a certain phenotype
Hybridization
Mating, or crossing, of two true-breeding varieties
P generation
True breeding parents (parental generation)
F1 generation
Hybrid offspring of p generation
First filial generation
F2 generation
Allowing the F1 hybrids to self pollinate produces this generation
(Second filial “son” generation)9
Allele
Alternative versions of a gene
Punnett square
Diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup
Each somatic cell in a diploid organism
Has two sets of chromosomes, one inherited from each parent
Dominant allele
Determines the organism’s appearance
Recessive allele
Has no noticeable effect on the organism’s appearance
First concept of Mendel
Alternative versions of genes account for variations in inherited characters
Second concept of Mendel
For each character, an organism inherits two copies (two alleles) of a gene, one from each parent
Third concept of Mendel
If two alleles at a locus differ, then one, the dominante allele, determines te organism’s appearance, the other, the recessive allele, has no noticeable effect on the organism’s appearance
Law of segregation
The two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes
Homozygous
Pair of identical alleles for a character
Heterozygous
Two different alleles for a gene
Phenotype
Organism’s appearance
Observable traits
Genotype
Genetic makeup
Monohybrid
Heterozygous for the one particular character being following in the cross
Monohybrid cross
Cross between heterozygotes
Dihybrids
Individuals heterozygous for he two characters being followed in the cross
Dihybrid cross
A cross between F1 dihybrids
Can determine which of these two hypotheses is correct
Law of independent assortment
Two or more genes assort independently (each pair of alleles segregated independently of each other pair of alleles) during gamete formation
Law of independent assortment applies to
Genes (allele pairs) locates on different chromosomes (on chromosomes that are not homologous) or to genes that are very far apart on the same chromosomes
Multiplication rule
States that to determine the probability, we multiple the probability of one event by the probability of the other event
Addition rule
The probability that any one of two or more mutually exclusive events will occur is calculated by adding their individual probabilities
Complete dominance
The phenotypes of the heterozygote and the dominant homozygote are indistinguishable
Incomplete dominance
Neither allele is completely dominant
Codominance
Two alleles each affect the phenotype in separate, distinguishable ways
Dominant is
Seen in the phenotype
Not because it subdues a recessive allele
Tay-Sachs disease
Inherited disorder in humans
Quantitative characters
Vary in the population in gradations along a continuum
Quantitative variation usually indicates polygenic inheritance
An additive effect of two or more genes on a single phenotypic character
Pedigree
Information about a family’s history for a particular trait and assembling this information into a family tree describing the traits of parents and children across the generations
Carriers
Heterozygotes may transmit the recessive allele into their offspring and are called
Cystic fibrosis
Lethal genetic disease
Sickle cell disease
Most common inherited disorder among people of African descent
Amniocentesis
Can determine whether the developing fetus has Tay-Sachs disease
Chorionic villis sampling (CVS)
A physician inserts a narrow tube through the cervix into the uterus and suctions out a tiny sample of tissue from the placenta
