3: Protein Synthesis & Cell Division

Question 1

What are proteins made of?

Answer 1

Proteins are the basic structural molecule of the body. They’re made up of carbon, oxygen, hydrogen and nitrogen. Atoms come together to form molecules called amino acids which create chains that make up proteins

Question 2

What is the structure of proteins?

Answer 2

Proteins have differences in their biochemical structure determined by the amino acid polymer length and the composition and position of amino acids within the chain. This defines the three dimensional shape of a protein

Question 3

How are proteins produced?

Answer 3

Proteins are created by protein synthesis which uses the coding from the DNA

Question 4

What is DNA?

Answer 4

DNA is made of deoxyribose sugar and four nucleotide bases: A-T, and C-G

Question 5

How is DNA involved in protein synthesis?

Answer 5

The amino acid sequence for every protein is held in the DNA within the chromosomes of the nucleus. This piece of DNA is called a gene and holds the code for one protein. Three DNA bases code for each amino acid eg ATC or CGA. The cell will translate the base sequence into a sequence of amino acids that makes up the protein

Question 6

What is a promoter region?

Answer 6

A promoter region is found in every gene and regulates its activity

Question 7

What is transcription?

Answer 7

Transcription is the first part of protein synthesis and means “to make a copy”.

Question 8

What is mRNA?

Answer 8

DNA molecules are too large to go across the nuclear membrane so a ‘go-between’ carries the information from the DNA to the ribosome. This go-between is called messenger RNA (mRNA) add is a copy of the DNA base sequence

Question 9

How does sequencing work in mRNA for protein synthesis?

Answer 9

The bases on the mRNA copy of the DNA are a complimentary match to the DNA code itself, except that “U” substitutes for “T”. The mRNA then exits the nucleus and travels to the ribosome

Question 10

What is a codon?

Answer 10

A codon is a triplet of DNA bases

Question 11

What is cell splicing?

Answer 11

Cell splicing happens before the mRNA copy leaves the nucleus: splicing edits the copy and removes sections (called introns). This has significant regulatory activity in a cell

Question 12

What is translation?

Answer 12

Translation is the second part of protein synthesis

Question 13

What happens in translation?

Answer 13

In translation, a piece of mRNA squeezes into the ribosome until the first of its three bases is in the centre of the ribosome

Question 14

What is tRNA?

Answer 14

TRNA is found in the ribosomes cytoplasm

Question 15

What role does tRNA have in protein synthesis?

Answer 15

During translation, one end of the tRNA molecule binds to one type of amino acid. The other end has a three nucleotide base triplet called an anticodon. The base sequence of the anticodon is a complimentary match to the sequence of each amino acid in mRNA

Question 16

What is an anticodon?

Answer 16

An anticodon is found at one end of tRNA. Its base sequence is a match to the sequence of amino acid in mRNA

Question 17

What are chromosomes?

Answer 17

There are two sets of chromosomes in every cell, making it a diploid. The full set contains 22 pairs of somatic chromosomes and a pair of sex chromosomes (XX/XY)

Question 18

What is mitosis?

Answer 18

Mitosis is a form of continual cell division where the daughter cells are genetically identical to its parent. The daughter cell has a duplicate copy of the parent’s DNA

Question 19

What are chromatids?

Answer 19

In S phase of mitosis, each chromosome creates a duplicate too, called a chromatid. This is passed onto the daughter cell

Question 20

What is meiosis?

Answer 20

Meiosis is a form of cell division that produces sperm and ova, which are genetically different to their parent cell

Question 21

What is the process of meiosis?

Answer 21

Meiosis has four steps:

1. Chromosomes duplicate their DNA to form chromatids ready for division
2. The chromosomes come together to form a tetrad. Crossover occurs where pieces of one chromosome swap with corresponding parts of their partner chromosome
3. The cell divides to form two diploid daughter cells that are genetically different from their parent cell
4. Each daughter cell divides, but the DNA is not duplicated. Each gamete receives one copy of each chromosome

Question 22

What is a gamete?

Answer 22

A gamete is an organism’s reproductive cells. Female cells are called ova or egg cells and male cells are called sperm

Question 23

What is a haploid?

Answer 23

A haploid is a cell with only one chromosomee

Question 24

What is a diploid zygote?

Answer 24

A diploid zygote has characteristics of both parent cells, but isn’t genetically identical to either. It has two chromosomes