Sources of Variation

Question 1

5 Different Sources of Variation

Answer 1

1. Crossing over
2. Independent Assortment
3. Non-Disjunction
4. Random Fertilisation
5. Mutations

Question 2

Crossing Over:
Phase-
_________ chromosomes pair up and ________ occurs at chiasma; recombinant ________ break off and snap.

Answer 2

Crossing Over:
Phase- Prophase I, Meiosis
Homologous chromosomes pair up and synapsis occurs at chiasma; recombinant chromatids break off and snap.

Question 3

Independent Assortment:
Phase-
Two possible combinations for ___________ chromosomes to line up on the ________ ___- 2 to the power of 23.

Answer 3

Independent Assortment:
Phase- Metaphase I, Meiosis
Two possible combinations for homologous chromosomes to line up on the equatorial plate- 2 to the power of 23.

Question 4

Non- Disjunction:
Phase-
Results in _________. Chromosomes or chromatids fail to ________, so one side will have too ____ or too ____ chromosomes.

Answer 4

Non- Disjunction:
Phase- Anaphase I/II, Meiosis
Results in Aneuploidy. Chromosomes or chromatids fail to separate, so one side will have too many or too few chromosomes.

Question 5

Random Fertilisation:

Unique _____, a ______ one fertilizes a ______ ____. Both are ______.

Answer 5

Random Fertilisation:

Unique sperm, a random one fertilizes a random egg. Both are unique.

Question 6

Mutations:
Types- Affects gametes, therefore the mutation is inherited (vs) Affects body cells, therefore the mutation is not inherited.
OR
Types: Changes one gene (vs) changes part/all of the chromosome, therefore multiple genes are affected.

(name the corresponding types)

Answer 6

Mutations:
Types- Germline (vs) Somatic
OR
Types- Gene Mutation (vs) Chromosomal Mutation

Question 7

Gene Mutation
Change:
Type of Mutation: (also name the 2 subcategories)

Answer 7

Gene Mutation
Change: one gene
Type of Mutation: Point Mutation- Frameshift and Non-Frameshift

Question 8

Point Mutation:
Changes:
Frameshift-
Non-frameshift-

Answer 8

Point Mutation:
Changes: one nucleotide base.
Frameshift- insertion, and deletion
Non-frameshift- substitution

Question 9

Chromosomal Mutation
Change:
Types of Mutation: (5 types)

Answer 9

Chromosomal Mutation
Change: part/all of the chromosome, therefore multiple genes are affected.
Types of Mutation: Inversion, Deletion, Duplication, Translocation, Non-Disjunction

Question 10

Inversion: Order of chromosomes ______ during _______.

Answer 10

Inversion: Order of chromosomes inverted during synapsis.

Question 11

Deletion: ____ of a few bases/ large region of a __________

Answer 11

Deletion: Loss of a few bases/ large region of a chromosome

Question 12

Duplication: _________ of a few bases/ large region of a __________

Answer 12

Duplication: Duplication of a few bases/ large region of a chromosome

Question 13

Translocation: ____ of genes between ___-__________ chromosomes

Answer 13

Translocation: Swap of genes between non-homologous chromosomes

Question 14

Non-Disjunction: __________ chromosomes fail to ________, also known as __________.

Answer 14

Non-Disjunction: Homologous chromosomes fail to separate, also known as aneuploidy.

Question 15

Mutations occur due to errors as a result of:
___ R________
C___ D______
E____ of M______

Answer 15

Mutations occur due to errors as a result of:
DNA Replication
Cell Division
Effect of Mutagens

Question 16

DNA Replication
Causes: 
-I\_\_\_\_\_\_\_ of a base
-D\_\_\_\_\_\_ of a base
-S\_\_\_\_\_\_\_\_ of a base
(*side note: i\_\_\_\_\_\_\_ and d\_\_\_\_\_\_ of a base causes f\_\_\_\_\_\_\_, which causes the wrong DNA to be produced in cells)
Types of mutations that result:
-g\_\_\_\_\_\_/s\_\_\_\_\_\_
-g\_\_\_/c\_\_\_\_\_\_\_\_\_\_

Answer 16

DNA Replication
Causes: 
-Insertion of a base
-Deletion of a base
-Substitution of a base
(*side note: insertion and deletion of a base causes frameshift, which causes the wrong DNA to be produced in cells)
Types of mutations that result:
-germline/somatic
-gene/chromosomal

Question 17

Cell Division:
Causes:
-T\_\_\_\_\_\_\_\_\_\_\_
-I\_\_\_\_\_\_\_
-N\_\_-D\_\_\_\_\_\_\_\_
(*gametes affected, faulty chromosome or 1 to many/too few chromosomes) 
Types of mutations that result:
-g\_\_\_\_\_\_
-c\_\_\_\_\_\_\_\_\_\_

Answer 17

Cell Division:
Causes:
-Translocation
-Inversion
-Non-Disjunction
(*gamete- faulty chromosome or 1 to many/too few chromosomes) 
Types of mutations that result:
-germline
-chromosomal

Question 18

Examples:
DNA Replication- S_____-c___ a_____, c___c f_____s, H________’s D_____, c_______s cells
Cell Division- T_____ 2, X__, K_______r s______e, T____r S______e
Mutagen Examples- U Rad_____, m_____d gas, car_______s

Answer 18

Examples:
DNA Replication- Sickle cell anaemia, cystic fibrosis, Huntington’s Disease, cancerous cells
Cell Division- Trisomy 21, XXY, Klinefelter syndrome, Turner Syndrome
Mutagen Examples- UV Radiation, mustard gas, carcinogens

Question 19

Effects of Mutagens
Definition: A b\_\_\_\_\_\_\_ c\_\_\_\_\_\_ and/or physical thing that increases the r\_\_\_ of mutation
-E\_\_\_\_ during DNA R\_\_\_\_\_\_\_\_
-B\_\_\_\_\_ DNA r\_\_\_\_\_\_\_\_
-lengthens or s\_\_\_\_\_\_\_ DNA s\_\_\_\_\_\_\_
-d\_\_\_\_\_\_ DNA structure
-Chemically r\_\_\_\_\_ with DNA/C\_\_\_\_\_\_\_\_\_\_ structure and therefore m\_\_\_\_\_\_ them
Causes:
-G\_\_\_\_\_\_/S\_\_\_\_\_ M\_\_\_\_\_\_
-G\_\_\_/C\_\_\_\_\_\_\_\_\_\_ M\_\_\_\_\_\_

Answer 19

Effects of Mutagens
Definition: A biological chemical and/or physical thing that increases the risk of mutation
-Errors during DNA Replication
-Blocks DNA replication
-lengthens or shortens DNA structure
-damages DNA structure
-Chemically reacts with DNA/Chromosomal structure and therefore modifies them
Causes:
-Germline/Somatic Mutation
-Gene/Chromosomal Mutation