Mendelian genetics chap14

Question 1

How are traits transmitted from parents to offspring?

Answer 1

Each parent cell has two alleles for each character. The two alleles segregate during gamete formation. Offspring inherit one allele from each parent.

Question 2

DOMINANT V recessive

Answer 2

DOMINANT exerts its effects whenever present. recessive has no effect if a dominant allele is present.

Question 3

Genotype and phenotype

Answer 3

Genotype is an organism’s genetic information.
Homozygous, 2 identical alleles for the same gene (YY or yy) Heterozygous, 2 different alleles for the same gene (Yy). Phenotype is the set of observable physical traits.

Question 4

Mendel’s experiments

Answer 4

Mendel used self fertilization and cross-ferilization.

Question 5

Generations of Mendel’s experiments

Answer 5

Mendel standardized the naming system of generations to track inheritance patterns:
Parental Generation (P): the original (parent) set of individuals that are mated.
First Filial (F1): the offspring of the P generation (filial = child)
Second Filial (F2): the offspring of the F1 generation.

Question 6

3 laws

Answer 6

Law of Dominance, Law of Independent assortment, and Law of segregation.

Question 7

Law of segregation

Answer 7

During gamete formation, 2 alleles of the same gene separate and end up in different gametes. (gametes are haploid and receive only one copy of a gene/allele)

Question 8

Law of independent assortment

Answer 8

Allele segregation of one gene does not affect the segregation of another gene. Allows gametes with all combination of alleles from different genes. Mendel monitored inheritance of multiple genes to make this discovery using dihybrid crosses.

Question 9

Genotypic vs. Phenotypic Ratio

Answer 9

Genotypic Ratio: the ratio of different genotypes observed in the offspring
The characteristic genotypic ratio from a monohybrid cross is 1:2:1 (homozygous dominant: heterozygous: homozygous recessive)
Phenotypic Ratio: the ratio of different phenotypes observed in the offspring
The characteristic phenotypic ratio from a monohybrid cross is 3:1 (dominant phenotype: recessive phenotype)

Question 10

Test crosses

Answer 10

Phenotypes do NOT always reveal the genotype, scientists use test crosses to test/identify the genotype of an unknown parent.

Question 11

Steps to Performing a Test Cross

Answer 11

Cross the mystery parent (unknown genotype) with a homozygous recessive parent
Analyze the offspring (F1) phenotypes
Make a conclusion about mystery parent’s genotype based on results
All dominant offspring: mystery genotype = homozygous dominant
Mixed offspring: mystery genotype = heterozygous

Question 12

Dihybrid cross

Answer 12

USE FOIL (first outside inside last)

Question 13

Dihybrid crosses

Answer 13

Dihybrid, organism that is heterozygous for 2 specific genes (RrYy). Dihybrid cross: cross fertilization between two dihybrid organisms. The characteristic phenotypic ratio from a dihybrid cross is 9:3:3:1 (dominant/dominant: dominant/recessive: recessive/dominant: recessive/recessive)

Question 14

Incomplete dominance

Answer 14

Heterozygotes show a blended phenotype that is an intermediate of the phenotypes from the two alleles. Ex incomplete dominance between a red and white flower results in a pink flower.

Question 15

Codominance

Answer 15

Heterozygotes equally express both phenotypes from each allele in “patches”. Ex codominance in a white chicken and a black chicken results in dotted or spotted white and black chickens.

Question 16

Blood typing

Answer 16

Blood typing is an example of codominance in humans, Blood type is determined by combinations of 3 possible alleles: A, B, or O. A and B alleles are codominant, where as O allele is recessive.

Question 17

Sex linked genes

Answer 17

Genes also exist on sex chromosomes, this leads to differences between XX and XY individuals and a special way to work on punnet squares.

Question 18

Pedigrees

Answer 18

Pedigrees show how traits are passed through generations. They can also be used to determine how a trait is inherited. (DOMINANT, recessive, sex linked, codominance, incomplete dominance).