Chapter 3: Mendelian Genetics

Question 1

Mendel suggested that heredity resulted in discontinuous variation

Answer 1

A dominance recessive relationship

Question 2

Darwin and Wallace came up with the theory of continuous variation

Answer 2

Offspring were a blend of parental phenotypes

Question 4

Chromosomal theory of inheritance

Answer 4

–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

Question 5

What does Independent assortment cause/lead to?

Answer 5

Leads to genetic variation

Question 6

Diploid Number (2n)

Answer 6

-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

Question 7

What are Unit factor, and during what stage of meiosis are they in pairs?

Answer 7

A unit factor is another name for a gene. First meiotic prophase

Question 8

Duringwhat phase does SEGREGATION OF ALLELES occur during gamete formation in meiosis

Answer 8

first meiotic anaphase

Question 9

Independent assortment of segregating unit factors

Answer 9

follows many meiotic events

Question 10

Criteria for classifying two chromosomes as homologous pairs

Answer 10

1. both are same size and exhibit the centromere in the same location (not including the X and Y chromosomes)
2. Form pairs or synapse during stages of meiosis
3. Contain identical linear order of gene loci
4. One member of each pair is derived from the maternal parent and the other is derived from the paternal parent

Question 11

Genetic variation is due to…

Answer 11

Non-identical homologous chromosomes

Question 12

Chromosome combination leads to

Answer 12

extensive genetic variation

Question 13

Independent assortment leads to…

Answer 13

Extensive genetic variation

Question 14

Product Law and one example

Answer 14

Calculates the probability outcomes occurring together

Ex. Probabilities of heads or tails of each other at the same time

Question 15

Sum Law and provide an example

Answer 15

Calculates probability of outcomes independent of each other

Ex. Coin toss of penny and nickel and obtaining one head and one tail

Question 16

Chi-Square analysis

Answer 16

Evaluated influence of chance on genetic data

Question 17

Chance deviation

Answer 17

–chance events subject to random fluctuations
–Expected outcome is diminished by larger sample size

Question 18

Two factors in analyzing or predicting genetic outcomes:

Answer 18

1. Independent assortment
2. Sample size

Question 19

Why did Mnendel use Peas as his model organism to study pattern of inheritance?

Answer 19

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

Question 20

How many and describe the features that Mendel used for his model?

Answer 20

-Mendel used seven observable features
-Each feature had two observable forms (aka traits)
-True-breeding strains

Question 21

What is a true-breeding strain?

Answer 21

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.

Question 22

Transmission Genetics or the Transmission of Hereditary Traits

Answer 22

How genes are transmitted form parents to offspring

Question 23

What does a Monohybrod cross reveal and why?

Answer 23

It reveals how one trait is transmitted from generation to generation, because it involved a SINGLE PAIR OF CONTRASTING TRAITS

Question 24

Describe Monohybrid Crosses

Answer 24

• Involves a single pair of contrasting traits

-In Mendel’s experiment, it involved a single pair of contrasting traits

Example: p1 generation

Question 25

What is the P1 generation?

Answer 25

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

Question 26

What is the F1 generation?

Answer 26

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).

Question 29

What are Mendel’s Three Postulates?

Answer 29

1. Unit factors (genes) exist in pairs
2. Dominance/Recessiveness
3. Segregation

Question 30

More info on Mendel’s three postulates: Unit factors existing in pairs

Answer 30

Think of genes on two homologous chromosome pairs.

Genetic characteristics are controlled by unit factorsr

Question 31

Dominance/Recessiveness

Answer 31

In a pair of unit factors, one is dominant, the other is recessive

Question 32

More info on Mendel’s three postulates: Segregation

Answer 32

During gamete formation, unit factors segregate seperately

Question 33

Phenotype

Answer 33

Physical expression of a triat

Question 34

Gene

Answer 34

Unit of inheritance

Question 35

Allele

Answer 35

an alternative form of a single gene

Question 36

Genotype

Answer 36

Genetic makeup of an individual
Written in pairs (DD, Dd, dd)