Genetics definitions

Question 1

Define genetics

Answer 1

a branch of biology that studies heredity and variation in organisms

Question 2

Define heredity

Answer 2

Passing on traits or characteristics from one generation to the next

Question 3

Define a gene

Answer 3

A unit of heredity/ a segment of DNA that codes for a characteristic/ a section of DNA on a chromosome that codes for a specific trait/protein

Question 4

Define an allele

Answer 4

variation of a gene

Question 5

Define genotype

Answer 5

an individual’s collection of genes

Question 6

Define phenotype

Answer 6

The outward espression of a gene

Question 7

Define Mendel’s law of dominance

Answer 7

Tt 1. When an organism has two different alleles for a trait, one allele dominates.
Tt x tt 2. In a cross of parents that are pure for contrasting traits, only the dominant trait will appear in the phenotype of the offspring.
:3. Recessive alleles will be masked. This is known as complete dominance.

Question 8

Define Mendel’s law of segregation

Answer 8

During gamete formation by a diploid organism, the pair of alleles for a particular trait separate into separate gametes so that each gamete will have a single allele for each characteristic (only 1 copy of a gene)

Question 9

Define a monohybrid cross

Answer 9

A cross between parents with different alleles for a single gene

Question 10

Define a Punnett square

Answer 10

a boxed figure used to determine the probability of genotypes and phenotypes in the offspring of a genetic cross

Question 11

Describe a test cross

Answer 11

If the dominant trait is shown for an organism, in order to determine whether it is heterozygous or homozygous dominant, a test cross is conducted SEVERAL TIMES. A homozygous recessive is crossed with the plant. If all dominant, then it was Homozygous dominant.

Question 12

Define a mutation

Answer 12

A change in the genetic makeup DNA of an organism

Question 13

Define a dominant allele

Answer 13

A variation of a gene of which only one copy is needed to be expressed in the phenotype/ The phenotypic characteristic is present in a heterozygote

Question 14

Define a recessive allele

Answer 14

A variation of the gene of which 2 copied need to be present to be expressed in the phenotype/ It is masked in a heterozygote

Question 15

What is a homozygous genotype?

Answer 15

When two alleles on homologous chromosomes are the same

Question 16

What is a heterozygous genotype?

Answer 16

When two alleles On homologous chromosomes are different.

Question 17

What does CFTR stand for?

Answer 17

Cystic Fibrosis Transmembrane conductance regulator

Question 18

What causes Huntington’s?

Answer 18

A SINGLE DEFECTIVE GENE ON CHR 4

Question 19

What causes sickle cell anemia?

Answer 19

The gene that codes for haemoglobin is mutated (Hb - S)

Question 20

Define polygenic inheritance

Answer 20

The interaction of genes at several loci

Question 21

What are autosomes?

Answer 21

Chromosomes 1-22

Question 22

What are gonosomes?

Answer 22

Chromosomes 23 (1 pair)

Question 23

What is the genotype of a male?

Answer 23

44 XY (can’t use homozygous or heterozygote)

Question 24

What is the genotype of a female?

Answer 24

44 XX (homozygous or heterozygous)

Question 25

What is a pedigree used for?

Answer 25

To analyse the pattern of inheritance of a particular trait throughout a family

Question 26

What is a genetic counsellor?

Answer 26

A health counsellor with specialised graduate degrees and experience in medical genetics and counselling