F212 1.2 - Nucleic Acids

Question 1

3’ and 5’ ends

Answer 1

The two ends of a polynucleotide chain.

Question 2

Adenine

Answer 2

A purine found in DNA and RNA.

Question 3

Anticodon

Answer 3

A set of 3 successive nucleotides in a tRNA molecule complementary to an mRNA codon and responsible for aligning the correct amino acid at the correct point in the developing sequence in the ribosome.

Question 4

Chromatin

Answer 4

The material formed by the association of DNA and histones in the eukaryotic nucleus.

Question 5

Codon

Answer 5

A set of 3 successive nucleotides in DNA or mRNA responsible for the insertion of a specific amino acid at a specific point in a growing polypeptide chain or for terminating chain synthesis.

Question 6

Complementary base pairs

Answer 6

The specific pairs of purines and pyrimidines held together by hydrogen bonds forming the rungs of the double helix or twisted ladder in DNA (or RNA or a hybrid of the 2). C pairs with G, A pairs with T or U.

Question 7

Cytosine

Answer 7

A pyrimidine found in DNA and RNA.

Question 8

DNA

Answer 8

Deoxyribonucleic acid. A type of nucleic acid essential for the storage of genetic information and its replication and transmission to subsequent generations of daughter cells/organisms.

Question 9

Double helix

Answer 9

Describes the structure of DNA, two helical polynucleotide molecules joined by complementary base pairing.

Question 10

Euchromatin

Answer 10

The less condensed form of chromatin containing the currently active sections of the genome i.e. those genes being transcribed.

Question 11

Guanine

Answer 11

A purine found in DNA and RNA.

Question 12

Heterochromatin

Answer 12

The more condensed form of chromatin containing the currently inactive sections of the genome i.e. those genes not being transcribed together with other non-coding sections of DNA.

Question 13

Histone

Answer 13

A very basic type of protein associated with DNA (which is acidic) so that the overall structure is electrostatically neutral and can therefore be packed or condensed into the relatively small volume of the eukaryotic nucleus.

Question 14

Messenger RNA

Answer 14

The type of RNA that brings the coding sequence from the DNA to the ribosome so that the amino acids can be joined together in the correct order via peptide bond formation.

Question 15

Nitrogenous base

Answer 15

A type of compound containing C,H,N and O occurring as one of the 3 components of nucleotides.

Question 16

Nucleoside

Answer 16

A molecule consisting of an organic, nitrogenous base and a pentose sugar.

Question 17

Nucleotide

Answer 17

A molecule consisting of an organic, nitrogenous base, a pentose sugar and one or more phosphate groups.

Question 18

Phosphodiester bond

Answer 18

The type of bond formed by the loss of 2 water molecules i.e. by 2 condensation reactions between a central phosphoric acid group and two alcohol/hydroxyl groups, each provided by a monosaccharide on either side. Found in nucleic acids.

Question 19

Purine

Answer 19

A nitrogenous base with two fused rings in its structure. Adenine and guanine are purine bases.

Question 20

Pyrimidine

Answer 20

A nitrogenous base with a single ring in its structure. Cytosine, thymine and uracil are pyrimidine bases.

Question 21

Ribosomal RNA

Answer 21

The type of RNA that is used to build the 2 ribosomal subunits by combining with the ribosomal proteins.

Question 22

Ribosome

Answer 22

The name given to the organelle associated with the rough endoplasmic reticulum or lying free in the cytoplasm where protein synthesis occurs. Small 70S ribosomes occur in prokaryotes and organelles like mitochondria and chloroplasts, large 80S ribosomes are found in eukaryotes.

Question 23

RNA

Answer 23

Ribonucleic acid. A type of nucleic acid essential for the conversion of stored genetic information into proteins. 3 main types, transfer or tRNA, ribosomal or rRNA and messenger or mRNA. The genome of some viruses e.g. HIV is RNA

Question 24

Semiconservative replication

Answer 24

The mechanism whereby an original double helix of DNA is split into two single strands each of which acts as a template to direct the synthesis of its complement thereby giving rise to two daughter duplexes each containing one old and one new strand identical to the original or parental DNA.

Question 25

Sugar-phosphate backbone

Answer 25

The linear structure of alternating pentose sugar and phosphate residues that makes up the outward facing part of a DNA (or RNA in some viruses) double helix. Sometimes likened to the sides of a twisted ladder.

Question 26

Thymine

Answer 26

A pyrimidine found in DNA only.

Question 27

Transcription

Answer 27

The process whereby the sequence of bases in the DNA is converted into the equivalent sequence of bases in RNA when making tRNA, rRNA or mRNA. It occurs in the nucleus in eukaryotes (and mitochondria and chloroplasts) or in the cytoplasm in prokaryotes.

Question 28

Translation

Answer 28

The process whereby the sequence of bases in mRNA is converted into the corresponding sequence of amino acids in a protein on a ribosome using codon (on mRNA)/ anticodon ( on tRNA) recognition.

Question 29

Transfer RNA

Answer 29

The type of RNA that functions as an adaptor during protein synthesis by bringing the correct amino acid to the ribosome at the correct place in the developing protein sequence for insertion.

Question 30

Uracil

Answer 30

A pyrimidine found in RNA only.