2.1.3: Nucleotides & ATP

Question 1

DNA is a polymer of

Answer 1

nucleotides

Question 2

The main components of a nucleotide are:

Answer 2

• Phosphate group
• Pentose monosaccharide –> deoxyribose for DNA, ribose for RNA
• Nitrogenous base

Question 3

Nucleotides join together by ____________ reactions

Answer 3

condensation

Question 4

Adenine base pairs with

Answer 4

thymine

Question 5

Thymine base pairs with

Answer 5

adenine

Question 6

Cytosine base pairs with

Answer 6

guanine

Question 7

Guanine base pairs with

Answer 7

cytosine

Question 8

Molecules in the DNA double helix are:

Answer 8

• Complementary
• Antiparallel
• Run in 3’ to 5’, and 5’ to 3’

Question 9

Structure of DNA

Answer 9

• Double helix of polynucleotide strands

* Hydrogen bonds between complementary bases

Question 10

What are the two types of nitrogenous bases?

Answer 10

• Purines

* Pyrimidines

Question 11

Purine

Answer 11

• Larger nitrogenous base
• Double ring
e.g. adenine, guanine

Question 12

Pyrimidine

Answer 12

• Smaller nitrogenous base
• Single ring
e.g. cytosine, thymine

Question 13

When cytosine pairs with guanine, they are held together by how many hydrogen bonds?

Answer 13

3

Question 14

When adenine pairs with thymine they are held together by how many hydrogen bonds?

Answer 14

2

Question 15

How DNA differs from RNA

Answer 15

• DNA double-stranded; RNA single-stranded
• RNA contains uracil; DNA contains thymine
• Pentose sugar: in DNA = deoxyribose, in RNA = ribose

Question 16

RNA

Answer 16

Ribonucleic acid
• Molecules involved in transfer and copying of genetic information from DNA.
• Polynucleotides consist of ribose sugar + U, C, A or G.

Question 17

ATP

Answer 17

Adenosine triphosphate

⟶ Modified nucleotide

Question 18

ATP contains:

Answer 18

• Triphosphate group
• Adenine
• Ribose

Question 19

Processes in cells that require ATP

Answer 19

• Secretion: endo/exocytosis, vesicle formation, fusion with plasma membrane
• Active transport
• Muscle contraction
• Synthesis of macromolecules

Question 20

Properties of ATP

Answer 20

• Small
• Water soluble
• Contains bonds between phosphate groups with intermediate energy
• Releases energy in small quantities
• Easily regulated

Question 21

How small size makes ATP suitable for function?

Answer 21

Moves easily into, out of and within cells.

Question 22

How water solubility makes ATP suitable for function?

Answer 22

Energy requiring processes happen in aqueous environments.

Question 23

How intermediate energy phosphate group bonds makes ATP suitable for function?

Answer 23

Large enough to be useful for cellular reactions, not so long energy wasted as heat.

Question 24

How energy release in small quantities makes ATP suitable for function?

Answer 24

Quantities suited to cellular needs so energy not wasted as heat.

Question 25

How easily regeneration makes ATP suitable for function?

Answer 25

Can be recharged with energy.

Question 26

The monomers making up DNA are

Answer 26

nucleotides

Question 27

Difference between DNA and RNA nucleotides

Answer 27

DNA nucleotides: • Contain deoxyribose • Contain Thymine RNA nucleotides: • Contain ribose • Contain Uracil

Question 28

Genetic code (characteristics)

Answer 28

* Triplet * Non-overlapping * Universal * Degenerate

Question 29

Transcription

Answer 29

1) DNA helicase unwinds and unzips section of DNA containing gene, exposing unpaired bases 2) Free RNA nucleotides complementary base pair with the exposed bases on the antisense strand 3) RNA polymerase catalyses the formation of phosphodiester bonds between RNA nucleotides 4) mRNA copy of gene exits nucleus via nuclear pore

Question 30

Semi conservative replication

Answer 30

1) DNA helicase unwinds and separates the two strands, breaking the hydrogen bonds between them 2) Free nucleotides in excess at replication site hydrogen bond to complementary bases 3) Deoxyribose sugars of adjacent nucleotides are joined by phosphodiester bonds formed in condensation reaction, catalysed by DNA polymerase 4) One polynucleotide strand from the original molecule is conserved in each new molecule that is produced; two new molecules are identical

Question 31

Translation

Answer 31

1) mRNA attached to ribosome; tRNA molecules carry amino acids to ribosome. 2) tRNA anticodon complementary to mRNA's codon. 3) 2 amino acids joined by peptide bone catalysed by peptidyl transferase. 4) tRNA leaves amino acid behind. Ribosome moves along mRNA. 5) Process continues, producing polypeptide chain until 'STOP' codon. 6) Polypeptide moves away from ribosome; translation is complete.

Question 32

What is the role of rRNA in translation?

Answer 32

Ribsomal RNA (rRNA) = "reads" the order of amino acids

Question 33

Why do purines always pair with pyrimidines?

Answer 33

To ensure that the polynucleotide strands are always the same distance apart.

Question 34

How are nucleotides in DNA linked?

Answer 34

* 3' to 5' linkages | * Phosphate group forms bridge between carbon 5 of one deoxyribose molecule and carbon 3 of the next

Question 35

Antiparallel

Answer 35

run in opposite directions

Question 36

At the 5' end of DNA there is what?

Answer 36

A terminal phosphate group linked to carbon 5 of a deoxyribose molecule

Question 37

At the 3' end of DNA there is what?

Answer 37

A hydroxyl group attached to carbon 3 of a deoxyribose molecule

Question 38

Cytosine and guanine number of hydrogen bonds

Answer 38

3

Question 39

Adenine and thymine number of hydrogen bonds

Answer 39

2

Question 40

DNA extraction from plant material

Answer 40

1) Grind sample using mortar and pestle (breaks cell walls) 2) Mix sample with detergent (breaks cell membrane, releasing contents of cell into solution) 3) Add salt (breaks H-bonds between DNA and water) 4) Add protease enzyme (breaks down proteins associated with DNA in the nuclei) 5) Add layer of ethanol on top of sample (causes the DNA to precipitate out of solution) 6) DNA (white strands) form between layer of sample and layer of alcohol

Question 41

How does a stop codon work?

Answer 41

* Does not code for an amino acid | * Has no matching tRNA anticodon