Genetic Inheritance and Pedigrees

Question 1

What is a gene?

Answer 1

Section of a chromosome that is responsible for a characteristic

Question 2

What is an allele?

Answer 2

Alternate forms of a gene at a particular position on a chromosome

Question 3

What is an autosome?

Answer 3

Any chromosome apart from sex chromosomes. The first 22 pairs, 44 chromosomes

Question 4

What is a trait?

Answer 4

Any characteristic that can be passed from parent to offspring

Question 5

What is a sex chromosome?

Answer 5

Sex-determining chromosomes, in humans X and Y. The 23rd pair, 2 chromosomes

Question 6

What is a dominant trait?

Answer 6

A trait which requires only one allele to be present for its expression in a heterozygous (the ‘stronger’ of two alleles); represented with a capital letter

Question 7

What is a recessive trait?

Answer 7

A trait which will only be expressed in the absence of the dominant trait (the ‘weaker’ of two alleles); represented with a lowercase letter

Question 8

What is the genotype?

Answer 8

All genes that are present for a given characteristic (expressed or not)

Question 9

What is the phenotype

Answer 9

Observable properties of the genotype.

Question 10

What is sex linked inheritance?

Answer 10

Characteristics inherited via genes on the sex chromosomes X or Y

Question 11

What is autosomal inheritance

Answer 11

characteristics inherited via genes on the autosomes (not 23rd pair)

Question 12

What is co-dominance?

Answer 12

When two alleles(different versions of the same gene) are expressed to an equal degree within an organism. As a result, traits associated with eachallele are displayed at the same time. Neither allele is dominant

EX: Red + white flower = Red and white spotted flower

Question 13

What is incomplete dominance?

Answer 13

When the heterozygous genotype (2 different alleles for the same gene) appears in the phenotype (observable characteristics) as a blending of the 2 alleles.

EX: Red + white flower = Pink Flower

Question 14

What is a pedigree chart?

Answer 14

• A diagram that shows a family’s
  relationships and how characteristics
  are passed on from one generation to
  the next
• They can be used to study a hereditary
  condition or trait.
• They go from oldest to youngest, left to right.

Question 15

What is autosomal dominant?

Answer 15

A single copy of a mutated gene on an autosome is enough to cause a genetic disorder.

Question 16

What is autosomal recessive?

Answer 16

A child inherits two copies of a mutated gene, one from each parent.