Key Word Glossary

Question 1

Allele

Answer 1

A possible variant of the gene

Question 2

Codominance

Answer 2

Neither allele is completely dominant to the other, both alleles are shown at the same time in the phenotype

Question 3

Dihybrid Cross

Answer 3

Predicts possible outcomes of characteristics determined by two genes

Question 4

Diploid Organism

Answer 4

Have two copies of their genes, one from each parent, which may or may not be the same allele

Question 5

DNA

Answer 5

A double stranded molecule made up of sequence of pairs of four chemical bases

Question 6

Dominance

Answer 6

Describes a phenotype that is expressed whenever one dominant allele coding for it is present, regardless of other alleles are present

Question 7

Epistatic effects

Answer 7

This is where one gene affects the expression of another gene

Question 8

Gene

Answer 8

A section of DNA that determines the structure of a polypeptide

Question 9

Genotype

Answer 9

Describes all of the genetic information in an organism, some of which is expressed to affect characteristics

Question 10

Heterozygous

Answer 10

Describes a genotype where the two alleles for a gene are different

Question 11

Homozygous

Answer 11

Describes a genotype in which both alleles for a gene are the same

Question 12

Incomplete Dominance

Answer 12

Neither allele is completely dominant to the other. This produces a new phenotype where the heterozygous animal will look different to both homozygous animals

Question 13

Lethal Alleles

Answer 13

These lead to death in the animals that have them. They can be recessive, dominant, or show other interactions

Question 14

Monohybrid Crosses

Answer 14

Predicts possible outcomes of characteristics determined by a single gene

Question 15

Multiple Alleles

Answer 15

This is where three or more alternative alleles of a single gene are possible (but only two are present in an individual organism)

Question 16

Phenotype

Answer 16

Describes the physical and biochemical characteristics of an organism. This will be determined by the genotype, but will also be influenced by environment.

Question 17

Recessive

Answer 17

Describes a phenotype that is only expressed when both alleles (recessive alleles) code for the phenotype

Question 18

Sex Linkage

Answer 18

This is when genes are carried on the sex chromosomes (X or Y)

Question 19

Sex-influenced

Answer 19

The phenotype depends on the gender of the animal even though the gene controlling that characteristic is not on the sex chromosome. It is influenced by sex hormones