Structure of Ribonucleic Acid

Question 1

What determines the sequence of amino acids in proteins?

Answer 1

• The sequence of nucleotide bases in DNA determines the sequence of amino acids in the proteins of an organism.
• In Eukaryotic cells DNA is confined to the nucleus

Question 2

What does mRNA do?

Answer 2

• Transfers the DNA code from the nucleus to the cytoplasm, acts as a messenger

Question 3

Why is the mRNA suited to its role?

Answer 3

• Small enough to leave the nucleus through the nuclear pores to enter the cytoplasm
• Where the coded information that it contains is used to determine the sequence of sequence of amino acids in the proteins which are synthesised there

Question 4

What is a codon?

Answer 4

Codon refers to the sequence of three bases on the mRNA that codes for a single amino acids

Question 5

What is the genome?

Answer 5

The complete set of genes in a cell, including those in mitochondria/chloroplasts

Question 6

What is the proteome?

Answer 6

• Full range of proteins produced by the genome
• Referred to as the complete proteome ( refers to the proteins produced by a given type of cell under a certain set of conditions

Question 7

What is the complete proteome?

Answer 7

Proteins produced by a given type of cell under a certain set of conditions

Question 8

What is DNA composed of?

Answer 8

Two nucleotide chains wound around each other ( double helix ).

Question 9

How many nucleotide chains is RNA made up of?

Answer 9

1

Question 10

What is RNA?

Answer 10

• Polymer made up of repeating mononucleotide sub units.
• Forms a single strand in which each nucleotide is made up of:
- Pentose sugar ribose
- One of the organic bases, A, G,C and U
• Phosphate Group

Question 11

What is RNA made up of?

Answer 11

• Repeating mononulcoetide sub units:
Single strand, where each nucleotide is made up of:
- Pentose sugar ribose
- One of the organic bases, A, G,C and U
- Phosphate Group

Question 12

What are the two types of RNA that are important in protein synthesis?

Answer 12

• mRNA

* tRNA

Question 13

What is the base sequence of mRNA determined by?

Answer 13

Base sequence of mRNA is determined by the sequence of bases on a length of DNA in a process called transcription.

Question 14

What happens when mRNA is formed?

Answer 14

• Many types of mRNA
• Once formed, mRNA leaves the nucleus via p;pores in the nuclear envelope, and enters the cytoplasm, where it associates with the ribosomes.
• It then acts as a template for protein synthesis

Question 15

How is mRNA’s structure suited to its function?

Answer 15

Suited to its function as a template for protein synthesis because:
• Possess information in the form of codons ( Three bases that are complementary to a triplet in the DNA )

Question 16

What does the sequence of codons determine?

Answer 16

The amino acid sequence of a specific polypeptide that will be made

Question 17

what is tRNA?

Answer 17

• Relatively small molecule made up of 80 nucleotides.

* Single stranded chain folded into a clover leaf shape.

Question 18

What is the structure of tRNA?

Answer 18

• One end of the chain extends beyond the other

* This is the part of the tRNA molecule to which an amino acid can easily attach

Question 19

Why are there many types of tRNA?

Answer 19

• Each binds to a specific amino acid.

* Each tRNA is specific to one amino acid, and has an anti codon that is specific to that amino acid.

Question 20

What is the anticodon?

Answer 20

Opposite end of the tRNA molecule, is a sequence of three other organic bases, called the anti codon.

Question 21

How does code being degenerate affect the tRNA molecule?

Answer 21

• Code is degenerate

* This means that there must be as many tRNA molecules as there are coding triplets

Question 22

Where is the anti codon loop present?

Answer 22

• Opposite to the point of attachment of amino acid

* Opposite end of the tRNA molecule.