I. (Mendelian Genetics, Dominance Relationships, Multiple Allelism, Lethal Alleles, Modifier Genes)

Question 1

Who is the Father of Genetics?

Answer 1

Gregor Mendel

Question 2

What serves as the basis of the study of inheritance?

Answer 2

Gregor Mendel’s Experiment on Pisum sativum, the garden pea.
He had a good choice of which experimental organism to use because garden peas are easy to grow and only need 1 season. He used true-breeding (homozygous) plants and chose varieties that differed in only one trait (monohybrid cross).

Question 3

___ is the fundamental physical and functional unit of heredity that carries information from generation to generation. It is a segment of DNA that makes possible transcriptions.

Answer 3

Gene

Question 4

The existence of a gene can be confirmed by ____ ____ and it occupies a specific ____ ____.

Answer 4

allelic variants; chromosomal locus

Question 5

What is another term for Gene?

Answer 5

Mendelian Factor

Question 6

In molecular terms, a gene is a nucleotide sequence in DNA that specifies a ____ or ____.

Answer 6

polypeptide; RNA

Question 7

What gives rise to species and individual variation?

Answer 7

Alterations in a gene’s sequence.

Question 8

____ is the basic unit of biological information; a specific segment of DNA in a discrete region of a chromosome that serves as a unit of function by encoding a particular RNA or protein.

Answer 8

Gene

Question 9

____ is a position on a chromosome where a gene is located.

Answer 9

Locus

Question 10

An ____ is any 2 or more related genes of a trait.

Answer 10

Allele or Allelemorph

Question 11

A ____ ____ expresses its effect over another allele; it masks the recessive allele in the heterozygous organism.

Answer 11

Dominant Allele

Question 12

A ____ ____ is masked in a heterozygous individual by the presence of a dominant allele.

Answer 12

Recessive Allele

Question 13

____ is the visible appearance.

Answer 13

Phenotype

Question 14

____ is the genetic constitution.

Answer 14

Genotype

Question 15

_____ _____ are crossing a male with one trait with a female having the other trait (from a pair of contrasting traits).

Answer 15

Reciprocal Crosses

Question 16

____ is also referred to as self-pollination. It is the crossing of individuals from the same generation.

Answer 16

Selfing

Question 17

____ is the observable heritable feature.

Answer 17

Character

Question 18

____ is a variant for a character.

Answer 18

Trait

Question 19

The ____ is the parental generation; where the 1st individuals crossed.

Answer 19

P

Question 20

The ____ generation is the 1st filial generation offspring; the offspring of P.

Answer 20

F1

Question 21

____ generation is the 2nd filial generation offspring; the offspring of F1.

Answer 21

F2

Question 22

The ____ states that an individual organism possesses two alleles encoding a trait and that these two alleles separate in equal proportions when gametes are formed.

Answer 22

Law of Segregation

Question 23

____ is a cross between 2 individuals involving 1 character.

Answer 23

Monohybrid Cross

Question 24

A ____ _____ is used to present the gametes of the parents and the genotypes and phenotypes of the offspring.

Answer 24

Punnett Square

Question 25

The _____ states that the genes encoding different characters assort independently when gametes are formed.

Answer 25

Law of Independent Assortment

Question 26

Differentiate the Law of Segregation from the Law of Independent Assortment.

Answer 26

Law of Segregation - Allele pairs separate and each goes into a different gamete. Law of Independent Assortment - Alleles from one locus segregate into gametes independently of those from another locus.

Question 27

____ is a cross between 2 individuals involving 2 characters (e.g. seed shape and seed color).

Answer 27

Dihybrid Cross

Question 28

____ is a genetic cross between a homozygous recessive individual and a corresponding suspected heterozygote to determine the genotype of the latter.

Answer 28

Test Cross

Question 29

A ____ is a cross or a breeding experiment between two organisms that differ in one characteristic or trait.

Answer 29

Monohybrid Test Cross

Question 30

A ____ is a genetic cross between two individuals that differ or are hybrid in two traits or characters.

Answer 30

Dihybrid Test Cross

Question 31

The ____ or ____ can also be used as a more orderly way of showing the gametes that a particular genotype can generate.

Answer 31

Forked-Line Method; Branch Diagram

Question 32

What formula should be used to determine the number of gamete types formed by an individual?

Answer 32

2n, where n represents the number of heterozygous characters.

Question 33

In _____, for a specific character, there is a dominant allele that when present, the dominant trait is always expressed.

Answer 33

Complete Dominance

Question 34

In _____, one copy of the gene is enough for the individual to be affected; both males and females are affected with equal frequency.

Answer 34

Autosomal Dominant Inheritance

Question 35

What are some examples of conditions inherited in this manner (autosomal dominance)? (4)

Answer 35

1. Huntington's Disease 2. Achondroplasia (Short-limbed Dwarfism) 3. Polycystic Kidney Disease 4. Polydactyly

Question 36

In ____, it takes 2 copies of the gene for the trait to be expressed, both males and females are affected with equal frequency.

Answer 36

Autosomal Recessive Inheritance

Question 37

What are some examples of conditions inherited in this manner (autosomal recessive)? (4)

Answer 37

1. Cystic Fibrosis 2. Tay-Sachs 3. Hemochromatosis 4. Phenylketonuria (PKU)

Question 38

In ____, there is a dominant allele and a recessive allele but the dominant one cannot completely mask the effect of the recessive allele such that heterozygotes come out with a blended phenotype. Both parental phenotypes are not seen. Instead, there is a new phenotype that results from the mixing of the parental genes.

Answer 38

Incomplete Dominance or Partial Dominance

Question 39

In ____, both alleles involved are equally dominant. Both parental phenotypes can be seen simultaneously expressed in the same offspring.

Answer 39

Codominance

Question 40

If the coat color of the parents is blended, it can represent _____.

Answer 40

Incomplete/Partial Dominance

Question 41

If the individual coat colors of the parents are both visible, it is _____.

Answer 41

Codominance

Question 42

In ____, the heterozygote has a more extreme phenotype than that of either of his parents.

Answer 42

Overdominance

Question 43

Why is overdominance also referred to as heterozygote advantage?

Answer 43

The heterozygous individuals have a higher fitness than the homozygous individuals.

Question 44

What is it called when a character is controlled by three or more alleles for a gene?

Answer 44

Multiple Allelism

Question 45

A ____ is a rare blood type that lacks A, B, and H antigens in the red cells and has anti-H antibodies in the serum.

Answer 45

Bombay Phenotype Blood

Question 46

A Bombay phenotype often results from ____.

Answer 46

Consanguineous Mating; parents are blood relatives (e.g. first cousins).

Question 47

Whenever inbreeding occurs, the proportion of rare homozygotes ____ in frequency.

Answer 47

increases

Question 48

____ are alleles that cause an organism to die only when present in homozygous condition, where the gene involved must have been an essential gene.

Answer 48

Lethal Alleles

Question 49

____ is the case where no individual of a certain genotype attains the age of reproduction.

Answer 49

Complete Lethality

Question 50

Such lethal genes that handicap but do not destroy their possessor are called ____.

Answer 50

Subvital/Sublethal/Semi-lethal Genes

Question 51

Instead of mutations altering the phenotypes of the organisms, a ____ could cause death.

Answer 51

Mutant Allele

Question 52

When an essential gene is mutated, it can result in a ____.

Answer 52

Lethal Phenotype

Question 53

Are most lethal genes dominant or recessive?

Answer 53

Recessive

Question 54

In humans, recessive lethal genes are present in individuals with ___, ____, and ____. (3)

Answer 54

Tay-Sachs, Cystic Fibrosis, and Sickle Cell Anemia

Question 55

____ is due to the deficiency of hexosaminidase A, resulting in the inability to break down specific membrane lipids. It progressively destroys nerve cells (neurons) in the brain and spinal cord.

Answer 55

Tay-Sachs Disease

Question 56

What are some of the symptoms of Tay-Sachs?

Answer 56

Infants: slow development, weak muscles, lost motor skills (e.g. turning over, sitting, crawling), developed an exaggerated startled reaction to loud noises. Children: experience seizures, vision and hearing loss, intellectual disability, paralysis, and cherry-red spot (eye abnormality).

Question 57

____ refers to the cause of the sickling of all red blood cells.

Answer 57

Sickle Cell Anemia

Question 58

____ refers to if the mutation is caused by a dominant lethal allele, the heterozygote for the allele will then show the lethal phenotype; whose lethal effects occur in heterozygous individuals.

Answer 58

Dominant Lethal Genes

Question 59

____ is a dominant progressive disorder that affects the brain's basal ganglia (includes voluntary and involuntary motor control, procedural learning, eye movements, and cognitive, emotional functions).

Answer 59

Huntington's Disease

Question 60

____ are those whose effects are exerted only under certain environmental conditions; can be expressed due to specific circumstances (e.g. temperature).

Answer 60

Conditional Lethal Genes

Question 61

____ is a sex-linked, inherited condition that results from a deficiency in an enzyme called glucose-6-phosphate dehydrogenase (G6PD).

Answer 61

Favism

Question 62

____ are genes that kill some individuals in a population, but not all of them; environmental factors and other genes may help prevent the detrimental effects of these genes.

Answer 62

Semi-lethal/Sublethal Genes

Question 63

____ is a hereditary disease caused by deficiencies in clotting factors, which results in impaired blood clotting and coagulation.

Answer 63

Hemophilia

Question 64

____ are genes that do not mask the effects of another gene. Instead, they can modify the expression of a second gene.

Answer 64

Modifier Genes

Question 65

When two genotypes produce the same phenotype due to different environments, each one is called the _____ of the other, because they differ genotypically.

Answer 65

Phenocopy