Unit 1 KA1

Question 1

Nucleic acids

Answer 1

Class of chemicals including DNA and RNA

Question 2

DNA

Answer 2

Complex molecule made of 2 polynucleotide strands. Contains genetic information in its sequence of bases (the genetic code).

Question 3

Nucleotide

Answer 3

Building block of nucleic acids (DNA and RNA). Made of a 5C sugar, a phosphate and one of 4 bases - adenine, cytosine, guanine and thymine (DNA) or uracil (RNA).

Question 4

Complementary base pairing

Answer 4

Matching bases join by hydrogen bonds to hold 2 strands of nucleotides together.

adenine - thymine/uracil

cytosine - guanine

Question 5

Double helix

Answer 5

The double stranded DNA molecule twists to form this shape.

Question 6

Antiparallel

Answer 6

One DNA strand is upside down compared to the other strand.

Question 7

Sugar-phosphate backbone

Answer 7

The deoxyribose of one nucleotide joins to the phosphate of the next with a strong covalent bond creating the sides of the DNA ladder.

Question 8

Deoxyribose

Answer 8

5 carbon sugar which forms part of the structure of a DNA nucleotide.

Question 9

Genetic code

Answer 9

The sequence of bases in a gene, which determines the amino acid sequence of a protein.

Question 10

Transforming principle

Answer 10

A chemical (now known to be DNA) can transfer from a dead to a live bacterium and transform it into a different strain.

Question 11

Bacteriophage

Answer 11

A virus that attacks bacterial cells. Used to discover that DNA is the genetic material.

Question 12

X-ray crystallography

Answer 12

A technique that allows molecules to be photographed.

When X-rays are fired at a molecule, a scatter pattern is created.

Used to work out the structure of DNA.

Question 13

Prokaryote

Answer 13

Lack a true nucleus, eg. bacteria and archaea.

Have circular DNA free in the cytoplasm

Question 14

Plasmid

Answer 14

A tiny DNA ring found in bacterial cells (and some fungal cells).

Question 15

Eukaryote

Answer 15

DNA is contained in a true membrane-bound nucleus eg. animal, plant and fungal cells.

Question 16

Histones

Answer 16

Linear DNA is wrapped around these proteins, to allow it to be organised and packaged into the nucleus.

Found in eukaryotes.

Question 17

Covalent bond

Answer 17

A strong chemical bond.
Joins nucleotides together.

Question 18

Hydrogen bond

Answer 18

A weak bond resulting from an attraction between hydrogen and other atoms.
Used to hold strands of nucleotides together (complementary base pairing).

Question 19

3’ end

Answer 19

The end of the DNA strand that has deoxyribose.

Question 20

5’ end

Answer 20

The end of the DNA strand that has phosphate.