Terms + Punnett Squares

Question 1

Trait

Answer 1

a particular version of an inherited characteristic (ex. person’s eye colour, shape of a leaf, blood type)

Question 2

True-breeding organism

Answer 2

an organism that produces offspring that are genetically identical for one or more traits when self-pollinated or when crossed with another true-breeding organism for the same traits

Question 3

Hybrid

Answer 3

the offspring of two different true-breeding plants

Question 4

Cross

Answer 4

the successful mating of two organisms from distinct genetic lines

Question 5

P generation

Answer 5

Parental generation, the first two individuals that mate in a genetic cross

Question 6

F1 generation (first filial generation)

Answer 6

offspring of a P-generation cross

Question 7

Monohybrid cross

Answer 7

a cross designed to study the inheritance of only one trait

Question 8

Monohybrid

Answer 8

the offspring of two different true-breeding plants that differ in only one characteristic

Question 9

F2 generation

Answer 9

offspring of an F1-generation cross

Question 10

Law of segregration

Answer 10

scientific law stating that:

1. organisms inherit 2 copies of genes, one from each parent
2. organisms donate only one copy of each gene to their gametes because the genes separate during genetic formation

Question 11

Homozygous

Answer 11

decribes an individual that carries two of the same alleles for a given characteristic

Question 12

Heterozygous

Answer 12

decribes an individual that carries two different alleles for a given characteristic

Question 13

Recessive allele

Answer 13

the allele that is not expressed if a dominant allele is present

Question 13

Genotype

Answer 13

the genetic makeup of an individual

Question 14

Phenotype

Answer 14

an individual’s observable characteristics

Question 15

Dominant allele

Answer 15

the allele that, if present, is always expressed

Question 16

Punnett Square

Answer 16

a diagram that summarizes every possible combination of each allele from each parent; a tool for determining the probability of a single offspring having a particular genotype

Question 17

Incomplete dominance

Answer 17

describes a condition in which neither of the two alleles for the same gene can’t completely conceal the presence of the other

Question 18

Codominance

Answer 18

a situation in which both alleles for a gene are fully expressed

Question 19

Multiple alleles

Answer 19

-occurs when there are more than 2 possible alleles for a given gene (ex. eye colour, blood type)

-results in a larger number of possible genotype combinations & a greater variety of phenotypes

Question 20

Pedigree

Answer 20

a flowchart that uses symbols to show the inheritance patterns of traits in a family over generations

Question 20

X-Linked recessive traits

Answer 20

-most sex-linked traits are X-linked recessive traits

-males only need to inherit one allele for the disorder to be present, while females need to inherit both alleles

-therefore, they affect more males than females

-ex. hemophilia

Question 21

Autosomal inheritance

Answer 21

-inheritance of a genetic trait not on a sex chromosome (chromosomes 1-22)

-can be dominant or recessive

Question 22

Autosomal dominant

Answer 22

-expressed when individuals have one copy of the allele

-half of the children of an affected parent are expected to be affected

-the trait is transmitted only by affected individuals (does not skip generations)

-males & females are affected in equal numbers

-ex. huntington disease

Question 23

Autosomal recessive

Answer 23

-expressed when an individual has 2 copies of the allele

-both parents of an affected individual must be heterozygous

-affected individuals may not appear in every generation

-when only one copy of the allele is present, the individual is a carrier

-ex. cystic fibrosis

Question 24

X-linked recessive

Answer 24

-no father-son transmission

-trait can skip generations

-predominately males affected