Genetics

Question 1

Gregor Mendel

Answer 1

Studied inheritance of pea plants

Cross-pollination and true-breeding

Discovered basic laws of heredity

Question 2

Mendel’s Hypothesis

Answer 2

Alternative versions of genes - alleles

Organisms inherit one allele from each parent

If alleles are not homozygous, the dominant allele determines appearance

Law of segregation- alleles separate during meiosis so they end up in different gametes

Question 3

Dominant Allele

Answer 3

Trait displayed

Question 4

Recessive Allele

Answer 4

Trait only displayed if homozygous

Question 5

Punnet Square

Answer 5

Determines probability of inheriting a trait

Question 6

Phenotype

Answer 6

Trait displayed

Question 7

Genotype

Answer 7

Pair of alleles

Question 8

Homozygous

Answer 8

Dominant or recessive

Same gene

Question 9

Heterozygous

Answer 9

Different genes

Dominant trait displayed

Question 10

Co-dominance

Answer 10

Two dominant alleles

Both affect phenotype

Example: Blood Types, animal fur

Question 11

Incomplete dominance

Answer 11

Neither allele is fully dominant

Heterozygotes show a hybrid trait

Question 12

Test Cross

Answer 12

Determines genotype if dominant phenotype but unknown genotype

Crosses it with a homozygous recessive

Will only get recessive phenotype if it is heterozygous

Question 13

Dihybrid Cross

Answer 13

Shows inheritance of two characters

Produces four genotypes

Each allele is separate

Question 14

Pleiotropy

Answer 14

When a gene has multiple phenotypic effects

Example: Sickle Cell Anemia- many different characteristics because of one trait

Question 15

Polygenic Trait

Answer 15

Determined by two or more gene

Example: Skin colour

Question 16

Recessive Disorders

Answer 16

Most disorders

Only show up in homozygous recessive

Question 17

Carrier

Answer 17

Heterozygotes for a recessive disease

Don’t have the disease themselves, phenotypically normal

Question 18

Pedigree

Answer 18

Family tree

Traces inheritance patterns

Question 19

Sex Linked Disorders

Answer 19

Genes on X chromosome

More common in males because they only need one X

Most are recessive

Example: Colour blindness, hemophilia, baldness