Nucleotides and nucleic acids

Draw + label the basic structure of a nucleotide

Draw a nucleotide showing the structure of the pentose sugar and where the phosphate group and nitrogenous base attach using the standard system for numbering the carbons in the sugar

Organic base = carbon 1

Phosphate group = carbon 5

What are the two main types of nucleic acid

RNA and DNA

Similarities and differences between DNA and RNA

DNA uses deoxyribose sugars

RNA uses ribose sugars

DNA has thymine

RNA has uracil

Basic nucleotide structure is the same

Draw the structures of ribose and deoxyribose and identify the difference between the two pentose sugars.

Deoxyribose has less oxygen

List all nitrogenous bases in nucleic acids

Adenine

Guanine

Thymine

Cytosine

Uracil

Name the two types of nitrogenous base and state which bases belong to which type

Purines: double ring structure - Adenine and Guanine

Pyrimidines: single ring structure - Cytosine, Thymine and Uracil

Define monomer

Individual molecules that make up a polymer

Define polymer

Long-chain molecules composed of bonded individual molecules (monomers) in a repeating pattern

Define nucleic acid

Large polymers formed from nucleotides. Contain the elements: carbon, hydrogen, nitrogen, phosphorous and oxygen

Define nucleotide

The monomers used to form nucleic acids.

Made up of a pentose monosaccharide, a phosphate group and a nitrogenous base

Define polynucleotide

A linear polymer composed of many nucleotide units, constituting a section of a nucleic acid molecule

Define phosphodiester bond

Covalent bonds formed between the phosphate group of one nucleotide and the hydroxyl group of another

Draw and label a diagram to show how nucleotides can link together to form polynucleotides (including the production of water).

State the name of the reaction that joins nucleotides to other nucleotides and the name of the reaction that breaks phosphodiester bonds.

Condensation

State 3 main types of activity for which cells require energy with examples

Synthesis - e.g. making proteins

Transport - e.g. pumping molecules across membranes using active transport

Movement - e.g. protein fibres that cause muscle contraction

Draw + label diagram of ATP and ADP

ATP - ribose, adenine and 3 phosphates

ADP - ribose, adenine and 2 phosphates

Give similarities and differences between the structure of ATP and DNA and RNA nucleotides

ATP uses ribose like RNA

Structure very similar but base is always adenine and has 3 phosphates instead of 1

Draw a reaction to show how energy is released from ATP to provide energy for cellular activities.

A small amount of energy is needed to break bond holding last phosphate on but lots of energy given out when that ion then takes part in further reactions making bonds.

State 5 properties of ATP and explain why each makes it ideally suited to function as an energy transfer molecule

Small - moves easily into, out of and within cells

Water soluble - energy requiring processes happen in an aqueous environment

Contains bonds between phosphates of intermediate energy - enough to be useful but not so much that lots is wasted as heat

Releases energy in small quantities - suitable for cellular needs but not too much lost as heat

Easily regenerated - can be recharged with energy

Define the term "phosphorylation"

The addition of phosphate group to a molecule

Draw and label a diagram of the structure of DNA

Define complimentary base pairing

Specific hydrogen bonding between nucleic acid bases. Adenine bonds to thymine or uracil and guanine bonds to cytosine

Define sugar-phosphate backbone

Forms the structural framework of nucleic acids composed of alternating sugar and phosphate groups

Define antiparallel

The two strands are parallel but run in opposite directions (one 3 to 5 the other 5 to 3)

Define double-helix

A pair of parallel helixes intertwined about a common axis

Define strand

One of the two polynucleotide chains that make up a DNA molecule

State the complementary base pairing rules, name the bond that holds them together, and state the number of bonds that hold each pair together

Adenine and Thymine are held by 2 hydrogen bonds

Guanine and Cytosine are held by 3 hydrogen bonds

Explain why a DNA molecule has equal amounts of adenine and thymine and equal amounts of cytosine and guanine

A and T are always paired together so will always appear in equal amounts. The same is true for C and G

Describe how purines and pyrimidines are arranged in the complementary base pairing rules

Always paired a pyrimidine with a purine as purines slightly bigger (two rings) and each rung must be the same length.

Describe the significance of the double stranded, complementary base paired nature of DNA for its function

The two strands allow it to be replicated accurately by semi-conservative replication and the complementary bases means once the strands have split, their is only one option to pair with each base to form the next strand

Describe the significance of the sequence of bases in a DNA strand for its function

The sequence of bases codes for amino acids and the full gene for a protein.

Describe, and explain the importance of the steps in the isolation and purification of DNA by precipitation

Grind up plant material with a pestle and mortar - breaks down the cell walls

Mix sample with detergent - breaks down cell membranes

Add salt to the solution - breaks hydrogen bonds between DNA and water

Add protease - breaks down proteins associated with DNA

Add layer of ethanol - causes DNA to precipitate between the two layers (ethanol on top, water on bottom)

The white strands of DNA can be picked up by spooling onto a glass rod