Chapter 15

Question 1

Genes are located on chromosomes, and these chromosomes are passed down through generations, carrying inherited traits. This theory explains how genetic traits are connected to the physical structure of chromosomes and how they move during reproduction.

Answer 1

Chromosome Theory of Inheritance

Question 2

A pioneering geneticist who discovered the role of chromosomes in heredity by studying fruit flies. His work confirmed that genes are on chromosomes, supporting the chromosome theory of inheritance.

Answer 2

Thomas Hunt Morgan

Question 3

Chromosomes that determine an organism’s sex; in humans, these are X and Y chromosomes. They differ from autosomes in their role in sex determination and often carry genes linked to sex-specific traits.

Answer 3

Sex Chromosomes

Question 4

A condition where cells have an abnormal number of chromosomes, such as trisomy (an extra chromosome) or monosomy (missing a chromosome). Examples include Down syndrome (trisomy 21) and Turner syndrome (monosomy X).

Answer 4

Aneuploidy

Question 5

Changes that occur when chromosomes have extra or missing copies or structural changes, like deletions or duplications, which can impact gene function and lead to various genetic disorders.

Answer 5

Alternations of Chromosome Number or Structure

Question 6

Each parent has two alleles for a trait, but only one is passed to the offspring. This law explains why offspring inherit one version of each gene from each parent.

Answer 6

Law of Segregation

Question 7

Genes for different traits are distributed to offspring independently, meaning the inheritance of one trait doesn’t affect the inheritance of another—assuming they are on different chromosomes.

Answer 7

Law of Independent Assortment

Question 8

The typical or most common version of a gene found in nature, usually considered the “standard” against which mutant forms are compared.

Answer 8

Wild Type

Question 9

Any form of a gene that deviates from the wild type, often due to a mutation. Mutant types can lead to new traits or characteristics.

Answer 9

Mutant Type

Question 10

Genes located on sex chromosomes (X or Y) that are often involved in sex-specific traits. They follow unique inheritance patterns, especially in males and females.

Answer 10

Sex-Linked Genes

Question 11

Genes on the X chromosome, which show distinctive inheritance patterns, especially in organisms where males have only one X chromosome, like in humans.

Answer 11

X-Linked Genes

Question 12

A severe genetic disorder caused by mutations in the dystrophin gene on the X chromosome, leading to muscle degeneration and weakness, primarily affecting boys.

Answer 12

Duchenne Muscular Dystrophy

Question 13

A genetic disorder where blood doesn’t clot properly due to a mutation on the X chromosome, often affecting males more severely than females.

Answer 13

Hemophilia

Question 14

In female mammals, one X chromosome in each cell becomes inactive to balance gene expression. The XIST gene helps silence one X chromosome, forming a Barr body.

Answer 14

X Inactivation in Female Mammals and XIST

Question 15

A condensed, inactive X chromosome found in female cells, which helps balance the number of active X-linked genes between males and females.

Answer 15

Barr Body

Question 16

Genes located close to each other on the same chromosome that tend to be inherited together, as they are less likely to be separated during crossing over.

Answer 16

Linked Genes

Question 17

The process by which offspring inherit a new combination of genes different from the parent, often due to crossing over between chromosomes during meiosis.

Answer 17

Genetic Recombination

Question 18

Offspring that inherit genetic combinations identical to those of one of the parents, typically without recombination between linked genes.

Answer 18

Parental Types

Question 19

Offspring that inherit genetic combinations identical to those of one of the parents, typically without recombination between linked genes.

Answer 19

Recombinant Types or Recombinants

Question 20

A process during meiosis where homologous chromosomes exchange genetic material, creating new gene combinations in offspring.

Answer 20

Crossing Over

Question 21

A visual representation showing the positions of genes on a chromosome based on recombination frequency, helping to predict inheritance patterns.

Answer 21

Genetic Map

Question 22

A type of genetic map that shows the relative positions of genes on a chromosome based on how often they recombine.

Answer 22

Linkage Map

Question 23

A measure of genetic distance between genes, indicating the likelihood of recombination, with one unit roughly equivalent to a 1% chance of recombination.

Answer 23

Map Units

Question 24

When cells have extra or missing chromosomes, leading to developmental issues or genetic disorders, like trisomy (extra) or monosomy (missing a chromosome).

Answer 24

Abnormal Chromosome Number and Results

Question 25

An error during cell division where chromosomes fail to separate properly, leading to an abnormal number of chromosomes in the resulting cells.

Answer 25

Nondisjunction

Question 26

A condition where a cell has an abnormal number of chromosomes, such as an extra chromosome in trisomy or a missing one in monosomy.

Answer 26

Aneuploidy

Question 27

A condition in which a cell has only one copy of a chromosome instead of two, often resulting in developmental abnormalities.

Answer 27

Monosomic

Question 28

A condition where a cell has three copies of a chromosome instead of the usual two, which can lead to genetic disorders like Down syndrome.

Answer 28

Trisomic

Question 29

A state where cells have more than two complete sets of chromosomes, often seen in plants, leading to increased size or vigor.

Answer 29

Polyploidy

Question 30

A type of chromosomal alteration where a portion of a chromosome is missing, often resulting in a loss of important genetic information.

Answer 30

Deletion

Question 31

An error where a segment of a chromosome is duplicated, leading to multiple copies of certain genes, which can disrupt normal development.

Answer 31

Duplication

Question 32

A chromosomal rearrangement where a section of the chromosome is reversed, potentially altering gene expression or function.

Answer 32

Inversion

Question 33

A genetic event where a segment of one chromosome attaches to a different chromosome, which can disrupt gene function and cause disorders.

Answer 33

Translocation

Question 34

A group of related symptoms or traits that often appear together and indicate a specific genetic or medical condition.

Answer 34

Syndrome

Question 35

A genetic disorder caused by an extra copy of chromosome 21, leading to developmental delays and characteristic physical features.

Answer 35

Down Syndrome

Question 36

A genetic condition in males where they have an extra X chromosome (XXY), affecting physical and cognitive development.

Answer 36

Klinefelter Syndrome

Question 37

A genetic phenomenon where certain genes are expressed based on whether they’re inherited from the mother or father, affecting traits in unique ways.

Answer 37

Genomic Imprinting

Question 38

Genes located in organelles like mitochondria or chloroplasts are inherited only from the mother in most species, following non-Mendelian inheritance.

Answer 38

Inheritance of Organelle Genes