Chapter 11: Review Menden and the Gene Idea Flashcards
(31 cards)
Gene
Specific DNA nucleotide that encodes for a “unit of heredity”
Allele
Different versions of gene
Locus
Physical location on the chromosome
Diploid vs Haploid
2 sets vs 1 set of homologous chromosomes
Genotype vs Phenotype
genetic constitution vs observable characteristics of an organism
Four Possible Allele Combinations
- Homozygous Dominant
2,3. Heterozygous - Homozygous Recessive
Homozygous Dominant
2 copies of same dominant allele (PP)
Heterozygous
1 copy of each of two DIFFERENT alleles (Pp)
Homozygous Recessive
2 copies of same recessive allele (pp)
Phenotypic ratio
Monohybrid: 3:1
Dihybrid: 9:3:3:1
Genotypic ratio
Monohybrid: 1:2:1
Law of Segregation
Two alleles separate (segregate) during gamete formation and end up in different gametes (equal frequency)
(Anaphase I of meiosis)
Law of Independent Assortment
Allele segregation of one gene does not affect the segregation of another gene; allows all combinations of alleles from different genes
Mendel
- Alternate copies of genes exist (alleles) and account for variation in inherited characteristics
- A diploid organism inherits two copies (alleles) for each character, one from each parent
- If the two alleles at a locus differ, the dominant allele will determine the organism’s phenotype; the recessive allele will have no noticeable effect
dominant allele vs recessive allele
allele that fully expressed in the phenotype of a heterozygote (AA, A_) vs allele whose phenotype effect is not observed in a heterozygote (aa)
Monohybrid cross
a cross between two heterozygous for one character
Dihybrid cross
a cross between two heterozygous for two characters (RrYy)
Complete dominance
Dominant allele is completely expressed or have heterozygous (PP, Pp)
Incomplete dominance
Dominant allele is not completely expressed with recessive allele (1:2:1) (C^R C^R, C^R C^W, C^W C^W)
Co-dominance
Both alleles expressed in heterozygotes equally (I^A I^B) (Blood type)
Product Rule
finding probability of both of two events that are independent; multiply chances each event occurs alone (AND)
Sum Rule
finding the probability of either of two events that cannot occur simultaneously; adding their probabilities (OR)
P
The original (parent) set of individual plants that are mated
F1
The offspring of the P generation