Mendelian Genetics & Inheritance

Question 1

Character definition

Answer 1

Heritable feature that varies among individuals (ex. Flower color)

Question 2

Trait definition

Answer 2

Each variant of a character (ex. Purple flower color)

Question 3

What kind of plants did Mendel use when working in pea plant varieties?

Answer 3

Hybridized true breeding plants (P generation) he created from PERFECT self-fertilizing plants

produces dihybrids in F1 generation

Question 4

What is a true breeding plant

Answer 4

Plants that have produced ONLY the same variety (homozygous)

Question 5

Law of Segregation

Answer 5

Alleles segregate randomly into gametes

Homologous chromosomes segregate during meiosis

Question 6

Blending Inheritance

Answer 6

The average of parents traits

Question 7

Particulate Inheritance

Answer 7

Traits inherited as genes

Question 8

What are the names of the different generations?

Answer 8

1. Parental Generation produces…
2. F1 (filial) Generation (self-pollinates —> sexual reproduction)
3. F2 Generation

Question 9

Law of Independent Assortment

Answer 9

Each pair is sorted independently from other pairs during meiosis

Non-homologous chromosomes assort independently during meiosis

Question 10

Complete dominance

Answer 10

When phenotype of the heterozygous are identical (dominant allele is expressed)

Question 11

Incomplete dominance

Answer 11

One allele doesn’t fully dominate
50% enzyme activity
(Ex. Red and white flowers produce PINK flowers)

Question 12

Pleitrophy

Answer 12

Genes have multiple phenotypic effects (ex. Hereditary disease like sickle cell disease)

Question 13

Epistasis

Answer 13

Phenotypic traits determined by two or more genes (typical ratio is 9:3:3:1)

Question 14

Polygenic Inheritance

Answer 14

Additive effect of 2 or more genes of a phenotypic trait (ex. Skin pigmentation is determined by 378 genes)

Question 15

Multiple Alleles affecting phenotype:
ABO Blood Groups

Answer 15

-Possible alleles: IA, IB, i
-Possible blood types:
1. A (IA IA/IA i)
2. AB (IA IB)
3. B (IB IB/IB i)
4. O (i i)

Question 16

Family pedigree

Answer 16

Tree describing traits of parents & children across generations

Question 17

Cause of Recessively Inherited Disorders

Answer 17

Alleles codes for a malfunctioning protein or NO protein

Question 18

Which genotype does recessively inherited disorder show up?

Answer 18

Recessive homozygous (aa)
if it’s not expressed, heterozygous (Aa) genotype is a carrier (ex. Ablinism)

Question 19

What increases the chance of a recessively inherited disorder?

Answer 19

Because it is a rare disease allele, it is uncommon that two carriers will meet and mate SO The closer in relation the parents are

Question 20

Dominantly inherited Disorders

Answer 20

Disorders due to dominant alleles (ex. Dwarfism)

Question 21

Lethal dominant allele

Answer 21

Causes death before individual can mature and reproduce so often, the dominant allele is not passed down
-the allele causing disease may show up AFTER reproduction so it is passed down to children (ex. Huntington’s disease appears at 35-45 yrs)

Question 22

Multi factorial Disorders

Answer 22

Genetic component and significant environmental influence (ex. Diabetes, heart disease, cancer, alcoholism, etc.)

the hereditary component of these disorders are polygenic (affected by multiple genes)

Question 23

X-linked genes are passed down to ___ by mothers and passed down to ___ by fathers

Answer 23

1. Daughters and sons (more males than females have x-linked recessive disorders)
2. Daughters only

Question 24

Dominant allele

Answer 24

The allele that is fully expressed in the phenotype of a heterozygote.

Question 25

Recessive allele

Answer 25

The allele whose phenotypic effect is not observed in a heterozygote. You need two copies of it to show it.

Question 26

What is happening during a test cross?

Answer 26

Mendel came up with a special cross to determine the genotype of a dominant phenotype. Cross an individual of unknown genotype with a homozygous recessive one

If the mystery parent is homozygous dominant, you get all hybrid-100% purple.
If the mystery parent is heterozygous, you get 50% hybrid and 50% white (get a 1:1 ratio)

Question 27

A dihybrid cross, a cross between F1 dihybrids, can determine (F2 generation)

Answer 27

whether two characters are transmitted to offspring as a package or independently

Question 28

What is an indicator that there is an x-linked recessive allele?

Answer 28

When the allele skips a generation (parents are normal but offspring are affected)

Question 29

Mothers typically pass x-linked recessive alleles to…

Answer 29

Sons