Mendelian Inheritance

Question 1

Gregor Mendel

Answer 1

An Austrian monk who conducted breeding experiments with the garden pea. He formulated fundamental laws of heredity in the early 1860s without knowledge of cells or chromosomes and without a microscope.

Question 2

Dominant Characteristics

Answer 2

Traits that are more likely to be inherited because they are expressed in heterozygous or dominant homozygous alleles. (It is written in capitals. In AA or Ab, A is dominant and will be expressed).

Question 3

Recessive Characteristic

Answer 3

Less common traits that are only expressed when an organism has two recessive alleles for that trait. (It is written in lower-case. In Ab, b is recessive and won’t be expressed, but it will be expressed in bb).

Question 4

Homozygous alleles

Answer 4

Inheriting identical version of genes from each parent (e.g., AA or bb)

Question 5

Heterozygous alleles

Answer 5

Inheriting two different versions of the same gene from each parent (e.g., Aa or Bb)

Question 6

Blending

Answer 6

A theory present before Mendel. It stated that parents of contrasting appearance produce offspring with intermediate appearance. (A red and white flower will make a pink flower).

Question 7

Particulate theory of inheritance

Answer 7

Mendel’s theory. Inheritance involves reshuffling genes from generation to generation. Traits are passed down in genes and these genes can be dominant or recessive.

Question 8

monohybrid cross

Answer 8

Breeding two different plants that differ in only one trait. (e.g., breed one tall pea plant and one short pea plant)

Question 9

True-breeding

Answer 9

Breeding plants that are homozygous for a certain trait.

Question 10

P

Answer 10

Parental generation (the first plants that are bred)

Question 11

F1

Answer 11

First filial generation offspring. (The second plants that are bred. They are the offspring of P)

Question 12

F2

Answer 12

Second filial generation of offspring (The third round of plants that are bred. They are offspring of F1)

Question 13

Breakdown of Mendel’s first monohybrid cross

Answer 13

Used two different true-bred plants that different in only one trait, and bred them. He then bred the offspring to get another generation.

Question 14

Law of segregation (4 parts)

Answer 14

1. Each individual has a pair of alleles for each trait
2. The alleles segregate during gamete (sperm and egg) formation
3. Each gamete contains only one allele from each pair
4. Fertilization gives the offspring two factors for each trait.

Question 15

Alleles

Answer 15

A version of the same gene. (e.g., an allele for blue eyes or an allele for green eyes). They occur on the homologous pairs of chromosomes at a particular locus

Question 16

Locus

Answer 16

Location on a chromosome

Question 17

Genotype

Answer 17

Refers to the two alleles an individual has for a specific trait. (e.g., AA or bb)

Question 18

Phenotype

Answer 18

The physical appearance or trait of the individual that is a result of the genotype (e.g., blue eyes)

Question 19

Punnett Square

Answer 19

Table listing all possible genotypes resulting from breeding

Question 20

Dihybrid cross

Answer 20

Uses two different true-breeding plants that differ in two traits. (A tall green pea plant is bred with a short brown pea plant)

Question 21

Law of independent assortment (2 parts)

Answer 21

The pair of alleles for one trait segregate independently of the alleles for other traits. (think of independent assortment in meiosis!!)

All possible combinations of alleles can occur in the gametes.

Question 22

Factors

Answer 22

What Mendel called alleles.

Question 23

The dihybrid cross led to…

Answer 23

the formation of the law of independent assortment

Question 24

The monohybrid cross led to…

Answer 24

the formation of the law of segregation

Question 25

Incomplete Dominance

Answer 25

Heterozygote has phenotype in the the middle of homozygous parents. (red and white flowers make pink flowers)

Question 26

Multiple Allelic Traits

Answer 26

A trait that exists in several allelic forms, but everyone only has 2 alleles. (Aa and Cc both make blue eyes, but you can only have Aa or Cc)

Question 27

"A" blood type

Answer 27

Phenotype is either AA or AO. Expressed with IAIA or IAi genotype

Question 28

"B" blood type

Answer 28

Phenotype is either BB or BO. Expressed with IBIB or IBi genotypes

Question 29

AB blood type

Answer 29

AB phenotype and expressed with only IAIB genotype

Question 30

O blood phenotype

Answer 30

Phenotype is OO and expressed with ii

Question 31

IA blood allele

Answer 31

A antigen on red cells, anti-B antibody in plasma. Dominant allele

Question 32

IB blood allele

Answer 32

B antigen on red cells, anti-A antibody in plasma. It is a dominant allele

Question 33

i blood allele

Answer 33

Neither A or B antigens, and has both antibodies. It is recessive

Question 34

Polygenic Trait

Answer 34

When a trait is governed by two or more genes with different alleles. Each allele has an effect on the phenotype, and each allele adds up to get the final phenotype. (A genotype could be AaBBCcddEe)

Question 35

Bell-shaped/normal curve

Answer 35

The shape of a graph that displays the distribution of polygenic traits

Question 36

Pleiotropy

Answer 36

A gene that affects more than one characteristic. (Sickle-cell trait alters your blood cell shape AND prevents you from malaria)

Question 37

Codominance

Answer 37

More than one allele is fully expressed. (A black cow breeds with a white cow, and they get a black and white striped cow)

Question 38

Epistatis

Answer 38

A gene at one locus interferes with the expression of a gene at a different locus. (if your melanin production gene doesn't work, then it doesn't matter what genes you have for skin color; you will be albino).

Question 39

Himalayan rabbit ice pack experiment

Answer 39

A rabbit had a icepack placed on it's back, and when frozen it's fur turned from black to white. This emphasizes that the environment can effect the phenotypes.