Unit 8: Genetics

Question 1

Who discovered the fundamental principles of genetics?

Answer 1

Gregor Mendel

Question 2

True breeding

Answer 2

Varieties for which self fertilization produces offspring identical to the parent

Question 3

P generation

Answer 3

True breeding parental plants

Question 4

F1 generation

Answer 4

Hybrid offspring of P generation

Question 5

F2 generation

Answer 5

The offspring of the F1 generation

Question 6

Monohybrid cross

Answer 6

The mating of two parents that differ in only one trait

Question 7

Allele

Answer 7

Alternative versions of genes

Question 8

Homozygous

Answer 8

2 identical alleles for a gene

Question 9

Heterozygous

Answer 9

2 different alleles for a gene

Question 10

Dominant allele

Answer 10

The allele that determines an organisms characteristics when inheriting 2 different alleles

Question 11

Recessive alleles

Answer 11

The allele that has no noticeable effect on an organisms appearance

Question 12

Law of segregation

Answer 12

A sperm or egg caries only one allele for each inherited character because allele pairs separate from each other during the production of gamates

Question 13

Phenotype vs geneotype

Answer 13

Phenotype: physical traits
Genotype: genetic makeup

Question 14

Alleles of a gene reside of the same…

Answer 14

Locus on homologous chromosomes

Question 15

Dihybrid cross

Answer 15

The result from the mating of parental varieties differing in 2 characteristics

Question 16

Law of independent assortment

Answer 16

Each pair of alleles segregated from the mating of parental varieties during gamate formation

Question 17

Testcross

Answer 17

Crossing an organism with a dominant genotype to a recessive homozygous for a specific phenotype in order to determine dominance/recessiveness or the unknown genotype

Question 18

Independent event

Answer 18

When the outcome of any particular event is unaffected by why happened in previous attempts

Question 19

Compound events

Answer 19

The product of the possibilities of independent events

Question 20

Rule or multiplication

Answer 20

Used for compound events

Question 21

Rule of addition

Answer 21

Used for independent events

Question 22

Most people with recessive orders have normal parents who…

Answer 22

Are both heterozygous and are carriers of the recessive allele for the disorder, but are phenotypically normal

Question 23

What is the most common recessive disorder in the U.S.?

Answer 23

Cystic fibrosis, the excessive secretion of thick mucus from the lungs, pancreas and other organs

Question 24

Dominant disorders are caused by…

Answer 24

Dominant alleles

Question 25

Why are dominant alleles that cause lethal diseases much less common than lethal recessive alleles?

Answer 25

Because the dominant allele cannot be carried by heterozygotes without affecting them. Many lethal dominant alleles can kill the embryo or kill the individual early and the alleles can’t be passed down

Question 26

Achondroplasia

Answer 26

Dominant disorder, form of dwarfism. The homozygous dominant genotype causes death of the embryo and only heterozygotes, individuals with a single copy of the defective allele have the disorder

Question 27

Huntington’s disease

Answer 27

Dominant disorder

A disorder to the nervous system that happens later in life.

Question 28

Amniocentesis

Answer 28

Type of genetic testing between the 14th and 20th weeks of pregnant where a needle is inserted into the uterus, extracting the amniotic fluid, which is tested on

Question 29

Chronic villus screening

Answer 29

Type of genetic testing where a small sample of chorionic villus tissue from the placenta is extracted

Question 30

Complete dominance

Answer 30

When the dominant allele has the same phenotypic effect whether present in one or two copies

Question 31

Incomplete dominance

Answer 31

When the appearance of the F1 hybrids fall between the phenotypes of the two parental varieties

Question 32

Hypercholestemia

Answer 32

Dangerously high blood cholesterol levels

Question 33

ABO blood group

Answer 33

Phenotype in humans that involved three alleles of a single gene

Question 34

Cosominant

Answer 34

Both alleles are expressed in a heterozygous individual (for example, people who have type AB blood)

Question 35

Pleiotropy

Answer 35

When many genes influence many characters

Question 36

How is sickle cell anemia a case of pleiotropy and co-dominance?

Answer 36

Homozygosity for the sickle cell allele causes abnormal hemoglobin and the impact of the abnormal hemoglobin on the shape of red blood cells leads to many symptoms in multiple organs of the body

Question 37

Polygenic inheritance

Answer 37

The additive effects of two or more genes on a single phenotypic character

Question 38

Many physical traits result from a combination of…

Answer 38

Heredity and environment

Question 39

How many genes are found in each chromosome?

Answer 39

Hundreds/thousands

Question 40

What are linked genes?

Answer 40

Genes located close together on the same chromosome that tend to be inherited together
Do not follow Mendel’s law of independent assortment

Question 41

Crossing over recombined linked gene into mixtures of alleles that are not found in…

Answer 41

The parents

Question 42

Recombination frequency

Answer 42

The percent of recombinant gametes

When it is less than 50%, genes are linked

Question 43

Alfred H. Sturtevant hypothesized that the farther apart two genes are on a chromosome…

Answer 43

The higher the probability that a crossover will occur because there will be more points between the, where crossing over could happen

Question 44

Sex linked gene

Answer 44

A gene located on either sex chromosome, but specifically referring to genes on the X chromosome

Question 45

Why do sex linked recessive disorders affect males more than females?

Answer 45

Because men only inherit one sex linked recessive allele which will be expressed, but when women inherit 2 alleles (one from each parent) in order to inherit the trait