Chapter 4: Genetics

Question 1

DNA

Answer 1

Double stranded molecule
Found primarily in the nucleus of cells
Made up of nucleotides
-a purine is always paired with a pyrimidine
A with T
G with C

Question 2

Replication

Answer 2

The process of making two identical DNA molecules from one

When a change in the sequence of a molecule of DNA occurs, it is referred to as Mutation

Question 3

Gene

Answer 3

Submicroscopic functional unit of heredity consisting of a discrete segment of a DNA strand within a chromosome.
Each gene has a promoter region that functions as the on/off switch

Question 4

Chromosome

Answer 4

Single, linear double strand of DNA with associated proteins
Thousands of genes are found in each chromosome
Human cells: DNA organized into 46 chromosomes

Question 5

Polymorphism

Answer 5

Normal variability among individuals

Contribute to uniqueness

Question 6

RNA

Answer 6

Single stranded molecule

Created as a single complementary strand of a DNA template through a process called Transcription

Question 7

Amino Acids

Answer 7

Building blocks of proteins

A sequence of amino acids is called a Polypeptide

Question 8

Karyotype

Answer 8

Visual profile of an individual’s chromosomes

Question 9

Genome

Answer 9

The complete set of instructions for a particular organisms

Question 10

Centromere

Answer 10

Narrowed region of a chromosome
Metacentric- centrally located centromere
Submetacentric- off center centromere
Acrocentric- centromere very close to one end of the chromosome

Question 11

Ideogram

Answer 11

A schematic drawing of a building pattern of a chromosome

Question 12

Mitosis

Answer 12

The process of separating duplicated chromosomes and reconstruction of 2 cell nuclei
Takes place in somatic cells and results in daughter cells that have the same number of chromosomes (46) as the parent cell

Question 13

Cytokinesis

Answer 13

Separation of the cell cytoplasm to form two distinct cells with separate cell membranes

Question 14

Meiosis

Answer 14

Cells undergo one round of DNA replication but two rounds of cell division
Occurs in production of the gametes (sperm, eggs)
Results in 23 chromosomes for sperm cells and ova cells, rather than 46.
Combine to form 46 chromosomes

Question 15

Monosomy

Answer 15

The loss of one copy of a chromosome resulting in the presence of a single copy of a chromosome
Most end in early miscarriage except monosomy X (Turner Syndrome)
Results from failure of meiosis

Question 16

Trisomy

Answer 16

The gain of one extra copy of a chromosome for a total of three chromosomes
Most end in early miscarriage though survival possible for several trisomies.
Results from failure of meiosis

Question 17

Nondisjunction

Answer 17

Abnormal number of chromosomes

Question 18

Deletion

Answer 18

When part of a chromosome becomes separated and lost
Deletions have been reported for all chromosomes
Location of deletion designated by chromosome #, P or Q (short or long arm) and the number of the band where the break occurred

Question 19

Duplications

Answer 19

Rare

Usually associated with malformations, developmental handicaps

Question 20

Translocations

Answer 20

The result of a transfer of genetic material between two or more chromosomes

Question 21

Inversions

Answer 21

Occur when a portion of the chromosomes are turned 180 degrees from its usual rotation

Question 22

FISH

Answer 22

Fluorescence In Situ Hybridization. Procedure involves the use of a nucleic acid probe labeled with a fluorescent dye that localizes a specific DNA segment.

Question 23

Pedigrees

Answer 23

Pictorial representation of family members and their line of descent. Allows important findings to be recorded in a short period of time. 3-4 generations can be described on one page

Question 24

Autosomal Recessive Inheritance

Answer 24

Traits of the phenotype only manifest when the mutation is present in both copies of the gene

Question 25

Autosomal Dominant Inheritance

Answer 25

Traits of the phenotype manifest when mutations are present in either of the two copies of the gene

Question 26

X-Linked Inheritance

Answer 26

Conditions caused by mutations in genes on the X chromosome

Question 27

Y-Linked Inheritance

Answer 27

Conditions caused by mutations in genes on the Y chromosome

Question 28

Multifactorial Inheritance

Answer 28

We don’t know what’s going on

teratogens, etc.

Question 29

Anticipation

Answer 29

some genetic disorders show a tendency to have more severe manifestations or an earlier age of onset with succeeding generations. This is often caused by a CAG repeat that becomes more unstable in the next generation (Huntington’s disease, spinocerebral ataxia, other adult-onset neurodegenerative disorders.) Fragile X is cause by a large expansion of an untranslated CGG repeat.

Question 30

Imprinting

Answer 30

If a gene is maternally imprinted, the allele inherited from the mother is not expressed.