CH:6 - Nucleic Acids and Protein Synthesis

Question 1

Nucleotide

Answer 1

A molecule consisting of a nitrogen-containing
base, a pentose sugar and a phosphate group.

Question 2

Polynucleotide

Answer 2

A chain of nucleotides joined together by phosphodiester bonds.

Question 3

Dinucleotide

Answer 3

Two nucleotides joined together by a phosphodiester bond.

Question 4

Phosphodiester bond

Answer 4

A bond joining two nucleotides together; there are two ester bonds, one from the shared phosphate group to each of the sugars either side of it.

Question 5

Complementary Base Pairing

Answer 5

The hydrogen bonding of A with T or U and of C with G in nucleic acids.

Question 6

DNA Polymerase

Answer 6

An enzyme that copies DNA; it runs along the separated DNA strands lining up one complementary nucleotide at a time ready for joining by DNA ligase.

Question 7

Leading Strand

Answer 7

During DNA replication, the parent strand that runs in the 3′ to 5′ direction is copied to produce the leading strand.

Question 8

Lagging Strand

Answer 8

During DNA replication, the parent strand that runs in the 5′ to 3′ direction is copied to produce the lagging strand.

Question 9

DNA Ligase

Answer 9

An enzyme that catalyses the joining together of two nucleotides with covalent phosphodiester bonds during DNA replication.

Question 10

Semi-Conservative Replication

Answer 10

The method by which a DNA molecule is copied to form two identical molecules, each containing one strand from the original molecule and one newly synthesised strand.

Question 11

Gene

Answer 11

A length of DNA that codes for a particular polypeptide or protein.

Question 12

Transcription

Answer 12

Copying the genetic information in a molecule of DNA into a complementary strand of mRNA; a single strand of the DNA is used as a template (this is called the template or transcribed strand) – the enzyme responsible is RNA polymerase.

Question 13

Translation

Answer 13

A stage in protein synthesis during which a sequence of nucleotides in a molecule of messenger RNA (mRNA) is converted (translated) into a corresponding sequence of amino acids in a polypeptide chain; it takes place at ribosomes.

Question 14

Codon

Answer 14

Sequence of three bases on an mRNA molecule that codes for a specific amino acid or for a stop signal.

Question 15

Anticodon

Answer 15

Sequence of three unpaired bases on a tRNA molecule that binds with a codon on mRNA.

Question 16

Gene Mutation

Answer 16

A change in the base sequence in part of a DNA molecule.

Question 17

Chromosome Mutation

Answer 17

A random and unpredictable change in the structure or number of chromosomes in a cell.

Question 18

Frame-shift Mutation

Answer 18

A type of gene mutation caused by insertion or deletion of one or more nucleotides, resulting in incorrect reading of the sequence of triplets in the genetic code due to a shift in the reading frame.