Lesson 11 And 12

Question 1

Heredity

Answer 1

The transmission of traits (inherited features) from one generation to the next

Question 2

Genetics

Answer 2

The scientific study of heredity. Modern genetics began with the work of Gregor Mendel.

Question 3

Hybrids

Answer 3

Offspring that results from the mating of individuals from two different species or from two true-breeding varieties of the same species; an offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes.

Question 4

Cross

Answer 4

A mating of two sexually reproducing individuals; often used to describe a genetics experiment involving a controlled mating (a “genetic cross”)

Question 5

P generation

Answer 5

The parent individuals from which offspring are derived in studies of inheritance; P stands for parental.

Question 6

F1 generation

Answer 6

The offspring of two parental (P generation) individuals; F1 stands for first filial.

Question 7

F2 generation

Answer 7

The offspring of the F1 generation; F2 stands for second filial.

Question 8

Character

Answer 8

A heritable feature that varies among individuals within a population, such as flower color in pea plants or eye color in humans.

Question 9

Trait

Answer 9

A variant of a character found within a population, such as purple or white flowers in pea plants.

Question 10

True breeding

Answer 10

Referring to organisms for which sexual reproduction produces offspring with inherited traits identical to those of the parents. The organisms are homozygous for the characters under consideration.

Question 11

Alleles

Answer 11

An alternative version of a gene

Question 12

Homozygous

Answer 12

Having two identical alleles for a given gene

Question 13

Heterozygous

Answer 13

Having two different alleles for a given gene.

Question 14

Dominant allele

Answer 14

The allele that determines the phenotype of a gene when the individual is heterozygous for that gene.

Question 15

Recessive allele

Answer 15

An allele that has no noticeable effect on the pheno-type of a gene when the individual is heterozygous for that gene.

Question 16

Law of segregation

Answer 16

A general rule in inheritance that individuals have two alleles for each gene and that when gametes form y meiosis, the two alleles separated each resulting gamete ending up with only one allele of each gene, also known as Medel’s first law of inheritance.

Question 17

Punnett square

Answer 17

A diagram used in the study of inheritance to show the results of random fertilization.

Question 18

Phenotype

Answer 18

The expressed traits of an organism

Question 19

Genotype

Answer 19

The genetic makeup of an organism

Question 20

Monohybrid cross

Answer 20

An experimental mating of individuals that are heterozygous for the character being followed (or the self-pollination of a heterozygous plant)

Question 21

Dihybrid cross

Answer 21

An experimental mating of Individuals that are each heterozygous for both of two characters (or the self-pollination of a plant that is heterozygous for both characters)

Question 22

Law of independent assortment

Answer 22

A general rule of inheritance (originally formulated by Gregor Mendel) that when gametes form during meiosis, each pair of alleles for a particular character segregates independently of other pairs; also known as Mendel’s second law of inheritance

Question 23

Testcross

Answer 23

The mating between an individual of unknown genotype for a particular character and an individual that is homozygous recessive for that same character. The testcross can be used to determine the unknown genotype.

Question 24

Rule of multiplication

Answer 24

A rule stating that the probability of a compound event is the product of the separate probabilities of the independent events.

Question 25

Rule of addition

Answer 25

A rule stating that the probability that an even can occur in two or more alternative ways is the sum of the separate probabilities of the different ways.

Question 26

Pedigree

Answer 26

A family genetic tree representing the occurrence of heritable traits in parents and offspring across a number of generations. A pedigree can be used to determine genotypes of matings that have already occurred.

Question 27

Carrier

Answer 27

An individual who is heterozygous for a recessively inherited disorder and who therefore does not show symptoms of that disorder but who may pass on the recessive allele to offspring

Question 28

Huntingtons disease

Answer 28

A human genetic disease caused by a single dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms

Question 29

Amniocentesis

Answer 29

A technique for diagnosing genetic defects while a fetus is in the uterus. A sample of amniotic fluid, obtained by a needle inserted into the uterus, is analyzed for telltale chemicals and defective fetal cells

Question 30

Chronic villus sampling (cvs)

Answer 30

A technique for diagnosing genetic defects while the fetus is in an early development stage within the uterus. A small sample of the fetal portion of the placenta is removed and analyzed.

Question 31

Complete dominance

Answer 31

A type of inheritance in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable.

Question 32

Incomplete dominance

Answer 32

A type of inheritance in which the pheno-type of a heterozygote (Aa) is intermediate between the phenotype of the two types of homozygotes (AA and aa)

Question 33

ABO blood group

Answer 33

Genetically determined classes of human blood that are based on the presence or absence of carbohydrates A and B on the surface of red blood cells. The ABO blood group phenotypes, also called blood types, are A, B, AB, and O.

Question 34

Codominant

Answer 34

Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles.

Question 35

Pleiotropy

Answer 35

The control of more than one phenotypic character by a single gene

Question 36

Sickle cell disease

Answer 36

A genetic condition caused by a mutation in the gene for hemoglobin. The mutation causes the protein to crystallize, which deforms red blood cells into a curved shape. Such blood cells produce a cascade of symptoms that can be life threatening.

Question 37

Polygenic inheritance

Answer 37

The additive effects of two or more gene loci on a single phenotypic character.

Question 38

Chromosome theory of inheritance

Answer 38

A basic principle in biology stating that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

Question 39

Linked genes

Answer 39

Genes located near each other on the same chromosome that tend to be inherited together.