Chapter 3: Mendelian Genetics Flashcards
Mendel suggested that heredity resulted in discontinuous variation
A dominance recessive relationship
Darwin and Wallace came up with the theory of continuous variation
Offspring were a blend of parental phenotypes
Chromosomal theory of inheritance
–genetic material living in living organism containing chromosomes
–Separation of chromosomes during meiosis served as a basis for Mendel’s principles of segregation and independent assortment
What does Independent assortment cause/lead to?
Leads to genetic variation
Diploid Number (2n)
-The specific number of chromosomes in each somatic cell nucleus of a diploid species
-During the formation of gametes via meiosis
-The chromosome number is precisely halved into haploid cells (n)
-When two gametes combine during fertilization, diploid number is reestablished
What are Unit factor, and during what stage of meiosis are they in pairs?
A unit factor is another name for a gene. First meiotic prophase
Duringwhat phase does SEGREGATION OF ALLELES occur during gamete formation in meiosis
first meiotic anaphase
Independent assortment of segregating unit factors
follows many meiotic events
Criteria for classifying two chromosomes as homologous pairs
- both are same size and exhibit the centromere in the same location (not including the X and Y chromosomes)
- Form pairs or synapse during stages of meiosis
- Contain identical linear order of gene loci
- One member of each pair is derived from the maternal parent and the other is derived from the paternal parent
Genetic variation is due to…
Non-identical homologous chromosomes
Chromosome combination leads to
extensive genetic variation
Independent assortment leads to…
Extensive genetic variation
Product Law and one example
Calculates the probability outcomes occurring together
Ex. Probabilities of heads or tails of each other at the same time
Sum Law and provide an example
Calculates probability of outcomes independent of each other
Ex. Coin toss of penny and nickel and obtaining one head and one tail
Chi-Square analysis
Evaluated influence of chance on genetic data
Chance deviation
–chance events subject to random fluctuations
–Expected outcome is diminished by larger sample size
Two factors in analyzing or predicting genetic outcomes:
- Independent assortment
- Sample size
Why did Mnendel use Peas as his model organism to study pattern of inheritance?
Because peas are:
1. Easy to grow
2.Peas are true breeding [strains], meaning that they always pass the same exact genotypic and phenotypic traits down to their offspring.
3. He could control the matings through: self-fertilization and cross-fertilization
4. The peas can grow to maturity in one season
5. The peas have observable characteristics with two distinct forms
How many and describe the features that Mendel used for his model?
-Mendel used seven observable features
-Each feature had two observable forms (aka traits)
-True-breeding strains
What is a true-breeding strain?
In plants, a true-breeding strain is formed when the parents are homozygous for every trait, resulting in offspring that would carry the same exact phenotype and genotype as their parents.
Transmission Genetics or the Transmission of Hereditary Traits
How genes are transmitted form parents to offspring
What does a Monohybrod cross reveal and why?
It reveals how one trait is transmitted from generation to generation, because it involved a SINGLE PAIR OF CONTRASTING TRAITS
Describe Monohybrid Crosses
- Involves a single pair of contrasting traits
-In Mendel’s experiment, it involved a single pair of contrasting traits
Example: p1 generation
What is the P1 generation?
It is the original (or the first) set of parents
Also known as the Parental Generation
This generation has one that has a genotype of both recessive alleles and the other of both dominant alleles
What is the F1 generation?
It is the (first set of) offspring from the P1 generation
Known as the first Filial generation
Filial means any generation resulting from a genetically controlled mating following parental generation (it usually results from parents that are “pure” genotypes).
What are Mendel’s Three Postulates?
- Unit factors (genes) exist in pairs
- Dominance/Recessiveness
- Segregation
More info on Mendel’s three postulates: Unit factors existing in pairs
Think of genes on two homologous chromosome pairs.
Genetic characteristics are controlled by unit factorsr
Dominance/Recessiveness
In a pair of unit factors, one is dominant, the other is recessive
More info on Mendel’s three postulates: Segregation
During gamete formation, unit factors segregate seperately
Phenotype
Physical expression of a triat
Gene
Unit of inheritance
Allele
an alternative form of a single gene
Genotype
Genetic makeup of an individual
Written in pairs (DD, Dd, dd)
