Chapter 14: Mendel and the Gene Idea

Question 0

True-breeding

Answer 0

Breeding where self-fertilizing parents always produce offspring with the parental form of the character

Question 1

Characters

Answer 1

Heritable features

Question 2

Traits

Answer 2

Alternative forms

Question 3

Hybridization

Answer 3

Cross-pollination contrasting true-breeding varieties which allows the next generation to self-pollinate

Question 4

P (parental) generation

Answer 4

True-breeding parental plants

Question 5

F1 (first filial) generation

Answer 5

Offspring of the first cross

Question 6

F2 generation

Answer 6

generation produced by self-cross of F1

Question 7

Alleles

Answer 7

Alternate forms of genes

Question 8

Dominant Allele

Answer 8

Determines the organism’s appearance

Question 9

Recessive Alleles

Answer 9

Has no observable effect on the organism’s appearance

Question 10

Law of Segregation

Answer 10

Two alleles for a heritable character during gamete formation and end up in different gametes

Question 11

Punnett square

Answer 11

Can be used to predict the results of simple genetic crosses

Question 12

Homozygous

Answer 12

Pair of identical alleles

Question 13

Heterozygous

Answer 13

two different alleles

Question 14

Phenotype

Answer 14

expressed traits

Question 15

Genotype

Answer 15

Genetic makeup

Question 16

Monohybrid Cross

Answer 16

Inheritance of a single character is followed through the crossing of monohybrids; cross of parental varieties differing in a single character

Question 17

Monohybrids

Answer 17

F1 offspring that are heterozygous for one character

Question 18

Dihybrid Crosses

Answer 18

Crosses of F1 dihybrids; determine wether the two characters were transmitted independently of each other from the parent plants

Question 19

Dihybrids

Answer 19

Heterozygous for two characters

Question 20

Law of Independent Assortment

Answer 20

States that pairs of alleles for each character segregate independently in the formation of gametes; law applies to genes located on different chromosomes

Question 21

Complete Dominance

Answer 21

The phenotype of the heterozygote is indistinguishable from that of the dominant heterozygote

Question 22

Codominance

Answer 22

Two alleles will affect the phenotype in separate, distinguishable ways; both dominant alleles are expressed in the heterozygote

Question 23

Incomplete Dominance

Answer 23

Alleles have intermediate phenotypes

Question 24

Tay-Sachs Disease

Answer 24

A lethal disorder in which brain cells lack a critical enzyme and are unable to metabolize a type of lipid that then accumulates and damages the brain

Question 25

Pleitropy

Answer 25

The characteristic of a single gene having multiple phenotypic effects in an individual; a single gene impacts more than one characteristic

Question 26

Epistasis

Answer 26

A gene at one locus may affect the expressions of another gene

Question 27

Quantitative Characters

Answer 27

Vary along a continuum in a population (i.e. Height, skin color)

Question 28

Polygenic Inheritance

Answer 28

Two or more genes have an additive effect on one character; Causes phenotypic gradations; polygenic character may result in a normal distribution

Question 29

Norm of Reaction

Answer 29

A phenotypic range within which the environment influences phenotypic expression

Question 30

Multifactorial

Answer 30

A combination of genetic and environmental factors influences phenotype

Question 31

Pedigree

Answer 31

A family tree with the history of a particular trait shown across the generations

Question 32

Carriers

Answer 32

Heterozygotes who are phenotypically normal but may transmit the recessive allele to their offspring

Question 33

Cystic Fibrosis

Answer 33

Most common lethal genetic disease in US; the recessive allele results in defective chloride channels in certain cell membranes; accumulating extracellular chloride leads to the buildup of thickened mucus in various organs and a predisposition to bacterial infections

Question 34

Sickle-cell disease

Answer 34

Most common inherited disease among African Americans; Caused by a single amino acid substitution in the hemoglobin protein, red blood cells deform into a sickle shape when blood-oxygen concentration is low, triggering blood clumping and other pleiotropic events

Question 35

Huntington’s Disease

Answer 35

A degenerative disease of the nervous system that does not develop until later in life

Question 36

Amniocentesis

Answer 36

A procedure that extracts a small amount of amniotic fluid from the sac surrounding the fetus; fluid is analyzed biochemically, and fetal cells present in the fluid are cultured for several weeks and then tested for certain genetic disorders and karyotyped to check for chromosomal defects

Question 37

Chorionic Villus Sampling (CVS)

Answer 37

A technique in which a small amount of fetal tissue is suctioned from the placenta; cells can be karyotyped immediately; procedure may be performed at only 8 to 10 weeks of pregnancy (earlier than amniocentesis)

Question 38

Ultrasound

Answer 38

A simple, noninvasive procedure that can reveal major abnormalities

Question 39

Fetoscopy

Answer 39

The insertion of a needle-thin viewing scope and light into the uterus, allowing the fetus to be checked for anatomical problems