Module 5

Question 1

Gregor Mendel

Answer 1

A Czech monk (1866) was responsible for the famous pea plant experiments, helping pave the way for our modern-day genetic theories of heredity, especially hybrids.

Question 2

Hybrid

Answer 2

The offspring of individuals differ with regard to certain traits or genetic make-up.

Question 3

Genotype

Answer 3

The genetic make-up of an individual. A genotype is always expressed with two gene alleles.

Question 4

Phenotype

Answer 4

The observable physical characteristics of an individual - the traits that are expressed from genotypes.

Question 5

Principle of Segregation

Answer 5

Gene alleles occur in pairs (because chromosomes occur in pairs) and when gametes are produced the members of each gene allele pair separate (or segregate) randomly so that each gamete contains one member of each pair. It is meiosis ( the cellular division of gametes) that causes the principle of segregation.

Question 6

Dominant Trait

Answer 6

A dominant trait prevents the expression of recessive alleles. When they are present in a genotype, they are always expressed in the resulting phenotype.

Question 7

Recessive Trait

Answer 7

A recessive trait is one that is only expressed when both alleles in the genotype are recessive

Question 8

Punnet Square

Answer 8

A way in which to chart out all the different ways in which alleles can be combined.

Question 9

Principle of Independent Assortment.

Answer 9

gene alleles that code for different traits assort independent of each other when gametes are formed.

Question 10

Sickle Cell Disease

Answer 10

the result of a point mutation. An autosomal recessive disorder that causes a malformation of hemoglobin in the shape of a sickle.

Question 11

Phenylketonuria

Answer 11

An autosomal recessive condition that leads to the accumulation of large quantities of the amino acid phenylalanine, causing mental retardation and other phenotypic abnormalities.

Question 12

Alleles

Answer 12

Alternative versions of a gene. Alleles are distinguished from one another by their different effects on the phenotypic expression of the same gene

Question 13

Heterozygous

Answer 13

Having two different alleles at the loci for a gene on a pair of homologous chromosomes (or autosomes).

Question 14

Homozygous

Answer 14

Having the same allele at the loci for a gene on both members of a pair of homologous chromosomes (or autosomes).

Question 15

Linkage

Answer 15

Genes that are found on the same chromosome are said to be linked. The closer together two genes are on a chromosome, the greater the linkage and the less likely they are to be separated during crossing over.