OCR ALevel Biology - Module 2 - Definitions - Topic 2.3 : Nucleotides And Nucleic Acids

Question 1

What is adenosine triphosphate (ATP)?

Answer 1

A nucleotide consisting of a molecule of ribose joined to the nitrogenous base adenine and three phosphate groups.

Question 2

What does ‘degenerate’ mean in the context of the genetic code?

Answer 2

A term used to describe the fact that some amino acids can be coded for by multiple different codons.

Question 3

What is deoxyribonucleic acid (DNA)?

Answer 3

A double stranded polynucleotide that contains the genetic material of an organism and is made up of deoxyribonucleotide monomers joined together by phosphodiester bonds.

Question 4

What is a DNA nucleotide?

Answer 4

The monomer that makes up DNA and consists of deoxyribose, a nitrogenous base and a phosphate group.

Question 5

What is the function of DNA polymerase?

Answer 5

An enzyme that catalyses the formation of phosphodiester bonds between nucleotides during the synthesis of a new DNA strand.

Question 6

What is the role of RNA polymerase?

Answer 6

An enzyme that catalyses the formation of phosphodiester bonds between nucleotides during the synthesis of a new RNA strand.

Question 7

What does helicase do?

Answer 7

An enzyme that catalyses the unwinding and unzipping of DNA in many processes like replication and transcription.

Question 8

What is messenger RNA (mRNA)?

Answer 8

A type of RNA that carries genetic information from the DNA in the nucleus to the ribosomes for translation.

Question 9

What does ‘non-overlapping’ mean in the genetic code?

Answer 9

A term used to describe the fact that each base is only part of one codon and that each codon is read one at a time in order.

Question 10

What is a nucleotide?

Answer 10

The monomer from which nucleic acids are made that consists of a pentose sugar, nitrogenous base and phosphate group.

Question 11

What is a phosphodiester bond?

Answer 11

A type of bond that joins nucleotides together to create polynucleotides.

Question 12

What are purines?

Answer 12

A class of nitrogenous bases which are made up of two rings that adenine and guanine are members of.

Question 13

What are pyrimidines?

Answer 13

A class of nitrogenous bases which are made up of a single ring that cytosine, thymine and uracil are members of.

Question 14

What is ribosomal RNA (rRNA)?

Answer 14

A type of RNA that makes up ribosomes.

Question 15

What is an RNA nucleotide?

Answer 15

The monomer that makes up RNA and consists of ribose, a nitrogenous base and a phosphate group.

Question 16

What is semi-conservative replication?

Answer 16

The replication of DNA to produce two new DNA molecules which both contain one new strand and one old strand from the original DNA molecule.

Question 17

What is transcription?

Answer 17

The process of synthesising a new mRNA strand from a molecule of DNA.

Question 18

What is transfer RNA (tRNA)?

Answer 18

A type of RNA that has three hairpin loops, an anticodon for attachment to the mRNA codon and an amino acid binding site and is used to carry amino acids to the ribosome.

Question 19

What is translation?

Answer 19

The process of protein synthesis where complementary tRNAs carrying amino acids are brought to each codon in an mRNA molecule as it moves through a ribosome.

Question 20

What does ‘triplet’ mean in the genetic code?

Answer 20

A term used to describe the fact that DNA is grouped into three base long codons that are read together and code for an amino acid.

Question 21

What does ‘universal’ mean in the context of the genetic code?

Answer 21

A term used to describe the fact that the same codons code for the same amino acids in all organisms.