Mendel and Gene Idea

Question 1

Character

Answer 1

An observable heritable feature that may vary among individuals

Question 2

Trait

Answer 2

One specific variation of a heritable character (such as brown eyes for the character eye colour)

Question 3

True-Breeding

Answer 3

Organisms that produce offspring of the same variety over many generations of self-pollination

Question 4

Hybridisation

Answer 4

• The interbreeding of individuals from different varieties, subspecies, or species to produce hybrid offspring

Question 5

P generation

Answer 5

The true-breeding (homozygous) parent individuals from which the F₁ hybrid offspring are derived in studies of inheritance; P stands for Parental.

Question 6

F₁ Generation

Answer 6

First filial hybrid (heterozygous) offspring arising from a parental (P generation) cross

Question 7

F₂ Generation

Answer 7

The offspring resulting from interbreeding (or self-pollination) of the hybrid F₁ generation

Question 8

Allele

Answer 8

Any of the alternative versions of a gene that may produce distinguishable phenotypic effects

Question 9

Dominant Allele

Answer 9

An allele that is fully expressed in the phenotype of a heterozygote

Question 10

Recessive Allele

Answer 10

Allele whose phenotypic effect is not observed in a heterozygote. Only when that allele is present in homozygotes

Question 11

Law of Segregation

Answer 11

Mendel’s first law. States that the 2 alleles in a pair segregate into different gametes during gamete formation

Question 12

Punnett Square

Answer 12

A diagram used to predict genotypic results of random fertilization in genetic crosses between individuals of known genotype

Question 13

Homozygous

Answer 13

Having 2 identical alleles for a given gene

Question 14

Heterozygous

Answer 14

Has 2 different alleles for a given gene

Question 15

Phenotype

Answer 15

Observable physical and physiological traits of an organism which are determined by its genetic makeup

Question 16

Genotype

Answer 16

Genetic makeup

Question 17

Testcross

Answer 17

Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The Ratio of phenotypes in the offspring reveals the unknown genotype

Question 18

Monohybrids

Answer 18

Organism that is heterozygous with respect to a single gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. (Parents of genotype AA and aa produce a monohybrid of Aa)

Question 19

Monohybrid Cross

Answer 19

A cross between 2 organisms that are heterozygous for the character being followed (or self-pollination of a heterozygous plant)

Question 20

Dihybrid

Answer 20

Organism that is heterozygous with respect to 2 genes of interest. All the offspring from a cross between parents double homozygous for different alleles are dihybrids. (Parents of genotype AABB and aabb produce dihybrid of genotype AaBb

Question 21

Dihybrid Cross

Answer 21

Cross between 2 organisms that are each heterozygous for both of the chaacters being followed (or self-pollination of a plant that is heterozygous for both characters)

Question 22

Law of Independent Assortment

Answer 22

Each pair of alleles segregates independently of each other pair of alleles during gamete formation

Question 23

Multiplication Rule

Answer 23

A rule of probability stating that the probability of two or more independent events occurring together can be determined by multiplying their individual probabilities

Question 24

Addition Rule

Answer 24

A rule of probability stating that the probability of any one of 2 or more mutually exclusive events occurring can be determined by adding their individual properties

Question 25

Complete Dominance

Answer 25

Situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable

Question 26

Incomplete Dominance

Answer 26

Situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele

Question 27

Codominance

Answer 27

Situation in which the phenotypes of both alleles are exhibited in the heterozygotes because both alleles affect the phenotype in separate and distinguishable ways

Question 28

Tay-Sachs Disease

Answer 28

Human genetic disease caused by a recessive allele for a dysfunctional enzyme; leading to accumulation of certain lipids in the brain. Seizures

Question 29

Multiple alleles

Answer 29

Genes that have more than two alleles

Question 30

Pleiotropy

Answer 30

Ability of a single gene to have multiple effects

Question 31

Epistasis

Answer 31

Where expression of one gene alters expression of another independently inherited gene

Question 32

Quantitative Characters

Answer 32

Heritable feature that varies continuously over a range rather than in an either-or fashion

Question 33

Polygenic Inheritance

Answer 33

An additive effect of 2 or more genes on a single phenotypic character

Question 34

Norm of Reaction

Answer 34

Range of phenotypes produced by a single genotype due to environmental influence

Question 35

Multifactorial

Answer 35

Many factors( both genetic and environmental) influence a phenotype

Question 36

Pedigree

Answer 36

Diagram of a family tree with conventional symbols showing the occurrence of heritable characters in parents and offspring over multiple generations

Question 37

Carriers

Answer 37

An individual who is heterozygous at a given genetic locus for a recessively inherited disorder. The heterozygote is generally phenotypically normal for the disorder but can pass on the recessive allele to offspring

Question 38

Cystic Fibrosis

Answer 38

Human genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consequent vulnerability to infection; fatal if untreated.

Question 39

Sickle-Cell Disease

Answer 39

Recessively inherited human blood disorder. Changes red blood cell shape and causes multiple symptoms in afflicted individuals

Question 40

Huntington's Disease

Answer 40

Genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10-20 years after onset of symptoms

Question 41

Amniocentesis

Answer 41

Technique associated with prenatal diagnosis. Amniotic fluid is obtained from fetal cells and analyzed

Question 42

Chorionic Villus Sampling

Answer 42

Prenatal diagnosis technique. Small sample of fetal portion of placenta is removed and analyzed

Question 43

Name environmental impacts on phenotype and genotype

Answer 43

diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens

Question 44

What can pedigrees be used for?

Answer 44

Can be used to deduce the possible genotypes of individuals and make predictions about future offspring. Predictions are statistical probabilities rather than certainties

Question 45

How can lethal dominant alleles be eliminated from a population? How can non lethal and lethal dominant alleles that strike later in life be inherited?

Answer 45

Lethal dominant alleles can be eliminated from the population if affected people die before reproducing. Non Lethal and lethal dominant alleles can be inherited in a mendelian way