Nuclei Acid And Protein Synthesis

Question 1

DNA nucleotides

Answer 1

Deoxyribose (a pentose sugar)
A phosphate group
A nitrogenous base (adenine, cytosine, guanine or thymine)

Question 2

RNA nucleotides

Answer 2

Ribose (a pentose sugar)
A phosphate group
A nitrogenous base (uracil, adenine, cytosine and guanine)

Question 3

ATP structure

Answer 3

Ribose bonded with adenine and three phosphate groups

Question 4

Differences between RNA and DNA

Answer 4

RNA has ribose, DNA has deoxyribose as it’s pentose sugar.
DNA molecules are made of two polynucleotide chains, RNA is made of one
RNA has uracil as a nitrogenous base DNA has thymine

Question 5

Purines

Answer 5

Have a double ring structure

Adenine, guanine

Question 6

Pyrimidine

Answer 6

Have a single ring structure

Thymine, uracil and cytosine

Question 7

Complementary base pairing

Answer 7

Adenine always pairs with thymine and cytosine always pairs with guanine

Question 8

DNA molecule structure

Answer 8

Two polynucleotide strands running anti parallel to each other. The strands are held together by hydrogen bonds between the bases. It is in a double helix. The phosphate and sugar groups are held together by covalent bonds

Question 9

Antiparallel

Answer 9

The strands running in opposite directions to each other.

Question 10

What carbon groups are linked to each other

Answer 10

The covalent sugar phosphate bond links the 5- carbon of one sugar molecule and the 3 carbon of the next. The polynucleotide strand is said to have 3’ and 5’ ends.

Question 11

Polynucleotide

Answer 11

Many nucleotides are linked together in a long chain. This takes place in the nucleus during interphase

Question 12

RNA structure

Answer 12

A single strand of polynucleotides

Question 13

DNA replication

Answer 13

• The double helix unwinds and the hydrogen bonds between the bases break by DNA helicase.
• In the nucleus there are nucleotides and two extra phosphates are added, this activated the nucleotide.
• Each of the bases of the activated nucleotide pairs up with its complimentary base on the old DNA strand. DNA polymerase links the sugar and phosphate groups together. The two extra phosphates are broken off and released into the nucleus

Question 14

Semi conservative

Answer 14

Each new molecule contains one old strand and one new strand.

Question 15

Gene

Answer 15

A sequence of nucleotides that’s forms part of a DNA molecule which codes for a polypeptide

Question 16

Gene mutation

Answer 16

A change in the sequence of nucleotides in a gene which may result in an altered polypeptide

Question 17

Sickle cell anaemia

Answer 17

In people who have sickle cell anaemia the gene which codes for the beta polypeptide is different. They have the HB^s allele instead of the HB^a allele. The base sequence CTT is replaced with CAT and valine is produced instead of glutamic acid. This type of mutation is called substitution

Question 18

protein synthesis transcription formation of mRNA

Answer 18

Part of the DNA molecule unwinds and the hydrogen bonds break by the enzyme DNA helicase. Free activated RNA nucleotides pair up with the exposed bases according to complimentary base airing. The RNA nucleotides have their sugar phosphate group bonded by the RNA polymerase. The mRNA molecule leaves the nucleus via a pore in the nuclear envelope.

Question 19

Protein synthesis transcription tRNA

Answer 19

In the cytoplasm there are amino acids and tRNA molecules. At one end of the tRNA molecule is a binding site for the amino acid, at the other end is three unpaired nitrogen bases. Each tRNA molecule binds with a particular amino acid with the help of an enzyme and energy from ATP.

Question 20

anticodon

Answer 20

triplet of bases on the tRNA molecule

Question 21

codon

Answer 21

triplet of bases on the mRNA molecule.

Question 22

Protein synthesis translation

Answer 22

The mRNA binds to a ribosome in the cytoplasm. The anticodon of each tRNA molecule lines up with the complimentary codon of the mRNA molecule. Two tRNA molecules can fit into the ribosome at any one time, a peptide bond forms between the two amino acids which is catalysed by peptidyl transferase. The ribosome moves along the mRNA molecule reading the next three bases. The third tRNA molecule brings another amino acid which joins to the second one and the first tRNA leaves the ribosome. The peptidyl chain grows until a stop codon is exposed to the ribosome.