Module 02.01 Prenatal Development

Question 1

zygote

Answer 1

the new cell formed by the process of fertilization

Question 2

genes

Answer 2

the basic unit of genetic understanding

Question 3

DNA molecules

Answer 3

the substance that genes are composed of that determines the nature of every cell in the body and how it will function

Question 4

chromosomes

Answer 4

rod-shaped portions of the DNA that are organized into 23 pairs

Question 5

gametes

Answer 5

(sex cells: ova and sperm) are formed in the adult body via meiosis

Question 6

monozygotic twins

Answer 6

twins who are genetically identical

Question 7

dizygotic twins

Answer 7

twins who are produced when two separate ova are fertilized by two separate sperm at roughly the same time

Question 8

dominant trait

Answer 8

the one trait that is expressed when two competing traits are present

Question 9

recessive trait

Answer 9

a trait within an organism that is present but not expressed

Question 10

genotype

Answer 10

the underlying combination of genetic material present (but not outwardly visible) in an organism

Question 11

phenotype

Answer 11

an observable trait; the trait that is actually seen

Question 12

allele

Answer 12

genes governing traits that may take alternate forms (e.g. hair or eye color)

Question 13

homozygous

Answer 13

inheriting similar genes for a given trait from both parents

Question 14

heterozygous

Answer 14

inheriting different forms of a gene for a given trait from each parent

Question 15

phenylketonuria (PKU)

Answer 15

an inherited disorder in which a child is unable to make use of phenylalanine, an essential amino acid present in proteins found in milk and other foods

Question 16

polygenic inheritance

Answer 16

inheritance in which a combination of multiple pairs of genes is responsible for the production of a particular trait

Question 17

reaction range

Answer 17

the potential degree of variability in the expression of a trait as a result of environmental conditions

Question 18

X-linked genes

Answer 18

genes that are considered recessive and located only on the X chromosome (e.g. hemophilia, and red-green color blindness) [thereby affecting males more than females]

Question 19

behavioral genetics

Answer 19

the study of the effects of heredity on behavior

Question 20

Down syndrome

Answer 20

(previously mongolism) a disorder produced by the presence of an extra chromosome on the 21st pair

Question 21

fragile X syndrome

Answer 21

a disorder produced by injury to a gene on the X chromosome, producing mild to moderate intellectual disability

Question 22

sickle-cell anemia

Answer 22

a blood disorder that gets its name from the shape of the red blood cells

Question 23

Tay-Sachs disease

Answer 23

a disorder that produces blindness and muscle degeneration before death; there is no treatment

Question 24

Klinefelter’s syndrome

Answer 24

a disorder resulting from the presence of an extra X chromosome that produces underdeveloped genitals, extreme height, and enlarged breasts

Question 25

Turner’s syndrome

Answer 25

a genetic disorder characterized by a missing or partially missing second X chromosome

Question 26

genetic counseling

Answer 26

the discipline that focuses on helping people deal with issues relating to inherited disorders

Question 27

karyotype

Answer 27

a chart containing enlarged photos of each of the chromosomes

Question 28

ultrasound sonography

Answer 28

a process in which high-frequency sound waves scan the mother’s womb to produce an image of the unborn baby, who size and shape can then be assessed

Question 29

amniocentesis

Answer 29

the process of identifying genetic defects by examining a small sample of fetal cells drawn by a needle inserted into the amniotic fluid surrounding the unborn fetus

Question 30

chorionic villus sampling (CVS)

Answer 30

a test used to find genetic defects that involves taking samples of hairlike material that surrounds the embryo

Question 31

germ line therapy

Answer 31

cells with defective genes are taken from an embryo, repaired, and replaced