Heredity

Question 1

What is a gene?

Answer 1

A gene represents the genetic material on a chromosome that contains the instructions for creating a particular trait.

Question 2

What is an allele?

Answer 2

It is one of several varieties of a gene.

Question 3

What is a locus?

Answer 3

This refers to the location on a chromosome where a gene is located. Every gene has a unique locus on a particular chromosome.

Question 4

What term describes the expression of an allele?

Answer 4

Phenotype

Question 5

What term represents the actual alleles?

Answer 5

Genotype

Question 6

Who is credited with the discovery of LAWS of SEGREGATION and INDEPENDENT ASSORTMENT?

Answer 6

Gregory Mendel

Question 7

Describe the Law of Segregation

Answer 7

Separation of alleles and chromosomes to individual gametes (meiosis)

Question 8

What is independent assortment?

Answer 8

The independent assortment of homologs in metaphase I as they are separated into opposite poles. This assortment is independent because the migration of homologues within one pair of homologous chromosomes does not influence the migration of other homologues.

Question 9

When do you utilize a monohybrid cross?

Answer 9

Investigation of ONE trait

Question 10

When do you utilize a dihybrid cross?

Answer 10

Ingestivation of TWO traits.

Question 11

Inheritance pattern in which one allele is expressed as dominant to a second allele.

Answer 11

Complete (or full) dominance

Question 12

Describe the genotypic frequencies resulting from the cross (TT x tt)

Answer 12

4/4 Tt

Question 13

Describe the genotypic frequencies resulting from a monohybrid cross of two heterozygotes.

Answer 13

(Tt x Tt), we see 1/4 TT + 1/2 Tt + 1/4 tt

Question 14

In a dihybrid cross of homozygous dominant and homozygous recessive plants with two traits, what are the genotypes of F1 generation? (YYRR x yyrr)

Answer 14

16/16 heterozygous YyRr

Question 15

Describe the genotypic frequencies of the F2 generation (F1: YyRr)

Answer 15

1: YYRR
2: YYRr
2: YyRR
4: YyRr

1: yyRR
2: yyRr

1: YYrr
2: YyRr

1: yyrr

Question 16

Describe the phenotypic frequencies of the F2 generation (F1: YyRr)

Answer 16

9
1:2:2:4

3
1:2

3
1:2

1
1

Question 17

Imagine a continuum of inheritance patterns. Identify each extreme and one in between.

Answer 17

Complete dominance would be one extreme in which one allele is expressed. At the other extreme is Codominance, in which both alleles are expressed. In between is Incomplete dominance in which there is a blending of two alleles producing an intermediate phenotype.

Question 18

How many possible genotypes/genotypes for blood types?

Answer 18

6 genotypes, 4 genotypes

Question 19

The expression of both kinds of proteins in blood AB is an example of which inheritance pattern?

Answer 19

Codominance

Question 20

The heights of humans are displayed as a _______ _________ from very short to very tall. This is usually a result of ________ __________.

Answer 20

Continuous Variation; Polygenic Inheritance

Question 21

What is polygenic inheritance?

Answer 21

The interaction of many genes to shape a single phenotype

Question 22

What are linked genes?

Answer 22

Genes that reside on the same chromosome and cannot segregate independently because they are physically connected. They do not obey the law of independent assortment and are usually inherited together.

Question 23

Describe the function of SRY

Answer 23

Sex-determining region of Y regulates gene activities on other chromosomes which stimulate the development of male characteristics….resulting in traits that are sex-limited

Question 24

Failure of one or more chromosome pairs of chromatids to separate and move to opposite poles during meiosis or mitosis

Answer 24

Nondisjunction

Question 25

How does nondisjunction occur in meiosis?

Answer 25

Failure of homologues to separate in anaphase I and failure of chromosomes to separate into chromatids in anaphase II

Question 26

How does nondisjunction occur in mitosis?

Answer 26

Same way in anaphase II

Question 27

How does mosaicism occur?

Answer 27

During embryonic development, nondisjunction results in cells with extra or missing chromosome - cells that have descended from a cell where nondisjunction occured

Question 28

What happens if all chromosomes undergo meiotic nondisjunction?

Answer 28

Polyploidy. A polyploidy zygote can result from two polyploidy parents. This is common in plants.

Question 29

When a single nucleotide in the DNA of a gene is incorrect, this is referred to as __________

Answer 29

Point mutation

Question 30

What causes sickle-cell disease?

Answer 30

nucleotide substitution resulting in production of defective hemoglobin that become sickle-shaped when low-oxygen conditions occur.

Question 31

What happens in an individual homozygous for the allele for (sickle-cell disease)?

Answer 31

They suffer inadequate oxygen supply which can lead to organ damage, bone abnormalities, and impaired mental functioning

Question 32

Describe symptoms of individuals with sickle-cell trait

Answer 32

Generally asymptomatic as the normal allele is sufficient to produce adequate amounts of normal hemoglobin

Question 33

What causes Tay-Sachs disease?

Answer 33

Usually caused by a nucleotide insertion - which results in lysosomes lacking the enzymes needed to metabolize glycolipids. As a result, these fats accumulate in nerve cells of the brain - causing them to die - causing early childhood death

Question 34

What is Turner syndrome?

Answer 34

XO - occurs in females as a result of nondisjunction of sex chromosomes. ("Turner was my ex ho")

Question 35

What is Klinefelter syndrome?

Answer 35

XXY - males have an extra X chromosome as a result of nondisjunction of sex chromosomes from parents. (3 syllables, like 3 chromosomes)

Question 36

What causes Huntington's disease? | Hint: Hunting-T-O-N

Answer 36

("Three Oligodendrocytes Nondisjunction") Insertion of multiple repeats of 3 nucleotides. This mutant gene codes for a defective enzyme, which results in the death of nerve cells in the brain.

Question 37

Describe chromosomal aberrations

Answer 37

changes in chromosome segments: (e.g. Inversions (Paracentric vs Pericentric), Translocations, Duplications)