Genetics

Question 1

What is a gene?

Answer 1

• Biological set of instructions which tells a cell how to develop, hence determines the characteristics of an organism
• And is located on chromosomes

Question 2

What are chromosomes?

Answer 2

• Contains protein and DNA
• Like pieces of wound up string
• Exist in pairs, members in each pair is the same shape and size

Question 3

Is an organism more complex if they have more chromosomes?

Answer 3

-No, characteristics are determined by the genes inside chromosomes, not the amount of chromosomes there are

Question 4

How many chromosomes are inherited from the father and the mother?

Answer 4

23 from the father and 23 from the mother.

Question 5

How many homologous pairs do we have?

Answer 5

22

Question 6

What are chromosomes arranged according to?

Answer 6

The chromosomes are numbered and arranged to their size, 1 being the largest

Question 7

What type of cell are most cells in our body?

Answer 7

Diploid cells, as they contain 2 of each type of chromosomes

Question 8

What type of cells are sex cells?

Answer 8

Sperm or ova are haploid cells as they have only one chromosome of each type

Question 9

What are sex chromosomes in mammals called?

Answer 9

X and Y chromosomes

Question 10

What defines the gender of the offspring?

Answer 10

Whether the chromosome is an x or Y chromosome

Question 11

What does a sperm cell contain?

Answer 11

Either an X or Y chromosome with 22 other chromsosomes

Question 12

What does an ova contain?

Answer 12

Contain an X chromosome and 22 other chromosomes

Question 13

What is the difference between Y and X chromosomes?

Answer 13

Y chromosomes is smaller than X and contains fewer genes

Question 14

Why is cell division necessary?

Answer 14

necessary for growth, repair and reproduction

Question 15

What happens in mitosis and where does it occur?

Answer 15

• Type of cell division
• Occurs in every cell except sex cells
• Produces two diploid cell for every one parent cell
• Daughter cells are identical to parent cells

Question 16

Where does meiosis occur?

Answer 16

Only in sex cells, hence occurs in testes to produce sperm and ovaries to produce eggs.

Question 17

What happens in meiosis?

Answer 17

• Four daughter cells are produced
• Daughter cells are haploid and non- identical
• Daughter cell contain one of each type of chromosome

Question 18

What is a gamete?

Answer 18

Daughter cell produced by meiosis and one gamete contain only of each type of chromosome.

Question 19

What is a zygote?

Answer 19

Produced by when a sperm fertilises an egg, has a total of 46 chromosomes

Question 20

What does DNA stand for?

Answer 20

deoxyribonucleic acid

Question 21

What is the composition of DNA?

Answer 21

• Composed of 2 bases and strands
• Strands are made out of sugar and phosphate
• Double stranded with each base on one strand being weakly bonded to its base pair on the opposite strand
• Bonding make the two strands to bridge together to for a double helix

Question 22

What are characteristics of an organism determined by?

Answer 22

The genes included within the DNA strand

Question 23

What are bases and what are they made up of?

Answer 23

• 4 bases include: adenine, thymine, cytosine, guanine

- And are made up of nitrogen

Question 24

Why does only A bond with T, and C with G?

Answer 24

due to their chemical structure

Question 25

Why are organisms different?

Answer 25

As the proteins which make up their cells are different

Question 26

What tells the body what type of protein to make?

Answer 26

A gene consists of a section of DNA

Question 27

What is the difference between one gene and another?

Answer 27

Order of the bases

Question 28

Why are proteins important?

Answer 28

Proteins are responsible for cell structure and function

Question 29

How is a protein molecule made?

Answer 29

Any three bases, code a triple code aka codon, with one codon coding for one amino acid, to make up a part of protein molecule

Question 30

How many codons are possible?

Answer 30

64

Question 31

Why does amino acids have various codons to produce it?

Answer 31

as there are only 20 amino acis

Question 32

What is the START and STOP codons responsible for?

Answer 32

Indicate where the amino acid should start as well as the end of the chain.

Question 33

What is replication? What happens in replication for it to occur?

Answer 33

• When the DNA in the chromosome copies itself
  1) Weak bonds between the base pairs break
  2) DNA untwists and unzips
  3) Spare bases in the chromosome match up with it complementary base on the unzipped strand
  4) A new strand begins to build on each of the old strand
  5) One of each section is copied, the old and new strand are zipped together to form an identical copy of the original DNA