Chapter 11 Flashcards
Locus
The specific location of a gene, DNA sequence, or position on a chromosome
Genes
The basic physical unit of heredity
-a linear sequence of nucleotides along a segment of DNA that provides the coded instructions for synthesis of rna, which when translated into protein leads the expression of heredity character
Allele
An alternative form of a gene
Homozygous
An organisms that has two identical alleles for a gene for a given character
- YY = homozygous dominant
- yy = homozygous recessive
Heterozygous
An organism that has differing alleles for a trait
-Yy
Genotype
The genetic makeup of an organism with reference to a single trait, set of traits, or an entire complex of traits
-ex) if yellow is dominant, the organism can be YY or Yy
Phenotype
A physiological feature, bodily characteristic, or behavior of an organism
- ie a plant’s visible characteristics
- ex) purple flowers, white flowers, yellow seeds, green seeds
P
Shorthand for the parental generation in experiments
F1
The offspring of the parental generation
- the first filial generation
- filial indicates a daughter or son
F2
The second filial generation
-Fx is used for any succeeding generation
Monohybrid cross
A genetic cross made to examine the distribution of one specific set of alleles in the resulting offspring
-ex) seed color
Punnett square method
A simple graphical way of discovering all of the potential combinations of genotype a that can occur in children, given the genotype of their parents
-also shows us the odds of each of the offspring genotype a occurring
Test cross
A cross between an individual exhibiting the dominant phenotype of a trait and an individual that is homozygous recessive for that trait in order to determine he genotype of the dominant individual
Law of segregation
- differing characteristics in organisms result from two genetic elements (alleles) that separate in gamete formation, such that each gamete gets only one of the two alleles
- mendels first law
- the separation of homologous chromosomes during meiosis
Dihybrid cross
A breeding experiment between P generation organisms that differ in two traits
- ex) green pod color and yellow seed color
- expressed in the format GgYy
Law of independent assortment
During gamete formation, gene pairs assort independently of one another
- traits are transmitted to offspring independently of one another
- mendels second law
Incomplete dominance
A genetic condition in which the heterozygous phenotype is intermediate between either of the homozygous phenotypes
- ex) snapdragons are pink as heterozygotes instead of red or white because neither the red nor white alleles are completely dominant
- *neither allele is expressed fully
Codominance
A condition in which two alleles of a given gene have different phenotypic effects, with both effects manifesting in organisms that are heterozygous for the gene
- *both alleles are expressed fully
- ex) AB
Continuous variation
Variation in phenotypic traits such as body weight or height I which a series of types are distributed on a continuum rather than grouped into discrete categories
-ex) 6.21, 6.22, 6.23, 6.24
What blood types are expressed by each gene combination?
- A= AA or AO
- B= BB or BO
- AB= AB
- OO= O
