DNA, Cell Division And Genetics

Question 1

Chromosomes

Answer 1

Genetic structures that occur in functional pairs in the nucleus of cells (except gametes)

Question 2

Gene

Answer 2

A short section of DNA (chromosome) that codes for a particular characteristic

Question 3

Genome

Answer 3

The entire genetic material found in an organism

Question 4

What shape Is DNA folded into?

Answer 4

A double Helix

Question 5

How are Base Sequences Read?

Answer 5

In sets of 3. Each group of 3 bases is called a Base Triplet. Each Base Triplet codes for a particular Amino Acid. The AA then combine to form Proteins

Question 6

Mitosis

Answer 6

A type of cell division that produces cells genetically identical to the parent cell and to each other

Question 7

Meiosis

Answer 7

A type of cell division that produces cells (gametes) that have half the normal chromosome number

Question 8

Mitosis (key info)

Answer 8

Takes place throughout the body.
Important for growth/repair of cells.
Ensures the new ‘Daughter’ cells have exactly the same chromosome arrangement

Question 9

Meiosis (key info)

Answer 9

Occurs in Sex organs (testes + ovaries)
Produces Gametes
Reduction Division
One cell produces 4 genetically different, haploid cells in 2 divisions

Question 10

Independent Assortment

Answer 10

A process that takes place during meiosis, in which chromosomes are reassorted in the formation of gametes. (Causes variation in Individuals)

Question 11

Allele

Answer 11

A particular form of a gene ( E.g Brown eye or Blue eye )

Question 12

Homozygous

Answer 12

Both alleles of a gene are the same

Question 13

Heterozygous

Answer 13

The 2 alleles of a gene are different

Question 14

Genotype

Answer 14

Paired symbols showing the allele arrangement in an individual . E.g Rr

Question 15

Phenotype

Answer 15

Outward appearance of an individual. E.g Blue eyes

Question 16

What are Punnet Squares used for?

Answer 16

Genetic Crossing

Question 17

Who is Gregor Mendel

Answer 17

The founder of Genetics (monk who carried out monohybrid crosses on peas)

Question 18

Male Sex Chromosomes Vs Female Sex Chromosomes

Answer 18

M = XY , F = XX

Question 19

The Y chromosome in males doesn’t contain?

Answer 19

Any Alleles

Question 20

Genetic Conditions

Answer 20

Are a genetic fault (which can be inherited)

Question 21

Haemophilia (inherited)

Answer 21

Condition caused by a problem with the blood clotting mechanism. Sufferers are at risk of excessive bleeding.

Question 22

Cystic Fibrosis (inherited)

Answer 22

Frequent lung infections and problems with food digestion.

Question 23

Huntingtons Disease (inherited)

Answer 23

Progressive Brain deterioration. Becomes apparent in middle ages. It is fatal and has no cure.

Question 24

Down Syndrome ( mistake during gamete formation - not inherited)

Answer 24

Caused by the presence of an extra chromosome so that affected individuals have 47 chromosomes rather than 46.

Question 25

What can Genetic Screening be used for?

Answer 25

Identifying the presence of genetic conditions (in a foetus)

Question 26

What can Genetic Screening be used for?

Answer 26

Used to testa foetus (or person) for the presence of harmful alleles or other genetic abnormalities

Question 27

How can you test for down syndrome?

Answer 27

Amniocentesis (taking foetal cells and growing them in a laboratory to check how many chromosomes each has).

Question 28

Genetic Engineering

Answer 28

The deliberate modification of the DNA in an organism to introduce desirable characteristics.

Question 29

Bacteria are Genetically engineered to make human insulin. How does this happen?

Answer 29

Special enzymes (restriction enzymes) cut the human gene in such a way as to leave overlapping strands of DNA.the same enzymes cut the bacterial plasmid (DNA) in the same way to leave complementary sticky ends. The sticky ends make it easy for the human and bacterial DNA to join through base pairing.

Question 30

How is Genetically Engineered bacteria formed?

Answer 30

In large Fermenters that provide optimum conditions for growth and reproduction (and producing insulin)

Question 31

Following the production of insulin, what then happens to it? And what is this called?

Answer 31

It is extracted, purified and packaged in a process called downstreaming

Question 32

Advantages of producing insulin by Genetic engineering?

Answer 32

1) Before it, the amount of insulin available was limited (many animals would have needed to be killed)
2) Human insulin is slightly different in Structure (than animals so it would have been less effective)
3) Risk of Spreading Viruses (when transferring insulin from animals)