Cellular Control and Patterns of Inheritance Key Terms and Processes

Question 1

Define the term :

Genotype

Answer 1

Alleles for a particular characteristic present in the cells of an organism

Question 2

Define the term :

Phenotype

Answer 2

Observed characteristic of an organism

Question 3

Define the term :

Homozygous

Answer 3

Organism with two identical alleles for a particular gene

Question 4

Define the term :

Heterozygous

Answer 4

Organism with two different alleles for a particular gene

Question 5

Define the term :

Dominant

Answer 5

Characteristic that is always expressed in the phenotype in an organism, even in those who are heterozygous

Question 6

Define the term :

Recessive

Answer 6

Characteristic only expressed in the phenotype when there is no dominant allele present

Question 7

Define the term :

Co-Dominant

Answer 7

A characteristic where both alleles contribute to the phenotype

Question 8

Define the term :

Linkage

Answer 8

2 or more genes located on the same chromosomes and are normally inherited together

Question 9

Define the term :

Sex Linkage

Answer 9

Genes with a locus on one of the sex chromosomes (X or Y). Most are on the X chromosome

Question 10

Define the term :

Epistasis

Answer 10

Interaction of genes concerned with the expression of one characteristic, one allele may mask or suppress the expression of another allele

Question 11

Define the term :

Discontinuous Variation

Answer 11

No intermediate categories, phenotypic variation is clearly distinguishable categories, eg; blood group, attached ear lobes, etc

Question 12

Define the term :

Continuous Variation

Answer 12

Phenotypic differences with a wide range of variation with no distinct categories, eg; height weight, etc

Question 13

Define the term :

Allele

Answer 13

Alternative form of a gene found in a specific locus on a specific chromosome

Question 14

Define the term :

Pure Breeding

Answer 14

Homozygous at both alleles, can both be dominant or recessive

Question 15

Define the term :

Multiple Alleles

Answer 15

Characteristic for which there are three or more alleles

Question 16

Define the term :

Dihybrid

Answer 16

Involving two gene loci

Question 17

Define the term :

Monogenic

Answer 17

Determined by a single gene

Question 18

Define the term :

Polygenic

Answer 18

Determined by multiple genes

Question 19

Define the term :

Mutation

Answer 19

A sudden, significant, random change in the sequence of nucleotides in DNA during DNA replication.

Question 20

Define the term :

Mutant

Answer 20

An organism affected by (a) mutations

Question 21

Define the term :

Somatic Mutation

Answer 21

Mutations in non-reproductive cells which cannot be inherited by offspring

Question 22

Define the term :

Germ-Line Mutation

Answer 22

Mutation in gametes, can be inherited by offspring

Question 23

Define the term :

Mutagens

Answer 23

Things like radiation or chemicals (eg in cigarette smoke) that increase the chance of mutations occurring

Question 24

What is a regulatory gene?

Answer 24

• a gene that is present in DNA

- it has a role in the regulating the expression of structural genes

Question 25

Define the term :

Point mutation

Answer 25

A mutation where one base pair is changed

Question 26

Missense mutation

Answer 26

The first base pair of a triplet codon mutates (likely amino acid change)

Question 27

Silent mutation

Answer 27

Mutation that occurs on the second/third base (unlikely amino acid change)

Question 28

Point, Missense and Silent mutations are all types of _________ mutations

Answer 28

Substitution

Question 29

Insertion and deletion is a type of _________ mutation

Answer 29

Frameshift

Question 30

What are neutral mutations?

Answer 30

Mutations that have no effect on the survival of the organism

Question 31

Define the term:

Reproductive Isolation

Answer 31

When two populations of the same species change sufficiently, they fail to interbreed successfully and are said to be reproductively isolated, they have become two separate species, which are genetically isolated

Question 32

Define the term:

Prezygotic

Answer 32

Zygotes do not form because the gametes do not meet

Question 33

Define the term:

Post Zygotic

Answer 33

Zygotes are formed, but they do not produce mature fertile offspring

Question 34

Reasons for Pre-zygotic Isolation Mechanisms

Answer 34

• Geographical Isolation
The populations never meet because they inhabit different areas
• Ecological Isolation
The populations never meet because all though they inhabit the same area, they live in the habitats within that area
• Temporal Isolation
The populations never meet although they inhabit the same area, they love in different habitats within that area

Question 35

Deletion

Answer 35

When part of a chromosome containing genes and regulatory sequences is lost

Question 36

Inversion

Answer 36

When a section of a chromosome may break off, turn through 180° and then rejoin, this results in genes being present but not be too far away from their regulatory sequence to be properly expressed in the phenotype

Question 37

Translocation

Answer 37

A piece of chromosome beams off and attaches to different chromosomes, this can interfere with the regulation of genes on the chromosome with the new DNA

Question 38

Duplication

Answer 38

A piece of chromosome may be copied, this can lead to over expression of genes which can be harmful, as TOL many proteins are produced which can affect the metabolism

Question 39

Non Disjunction

Answer 39

When a pair of chromosomes or chromatids fail to separate in meiosis are lying in a gamete with an extra chromosome, when the gamete is fertilised, the zygote has an extra chromosome
eg - Down syndrome, when individuals have three copies of chromosome 21

Question 40

Define the term:

Operon

Answer 40

A sequence of DNA containing a cluster of genes under the control of a single promoter