nucleic acids, ATP, Water and inorganic ions Flashcards
what is a nucleotide and what is it made from
a monomer of a nucleic acid,
phosphate group,
nitrogen containing organic base,
deoxyribose sugar or ribose sugar
What is the sugar in DNA and name the 4 types of organic nitrogenous bases in DNA
deoxyribose sugar,
Adenine, cytosine, guanine, thymine
what is the sugar in RNA and name the 4 types of organic nitrogenous bases in RNA
ribose sugar.
adenine, cytosine. guanine, uracil
what bond is formed when nucleotides join together
phosphodiester bond
what is the difference between DNA and RNA
DNA has thymine whereas RNA has uracil,
DNA is double stranded whereas RNA is single stranded,
DNA has a deoxyribose sugar whereas RNA has a ribose sugar,
RNA has a relatively shorter polynucleotide chain than DNA
describe how the structure of DNA carries out its function.
- Sugar phosphate backbone provides strength and protects information in bases,
- Long molecule stores lots of information,
- Helical so compact,
- Double stranded so DNA replication can occur semi-conservatively strand can act as template.
- weak hydrogen bonds between bases allows easy strand separation for semi-conservative replication,
- many weak Hydrogen bonds so strong molecule
what does the enzyme DNA helicase do
unwinds the DNA and breaks hydrogen bonds
Describe Semi-conservative replication.
- Strands separate / H-bonds break;
- DNA helicase (involved);
- Both strands/each strand act(s) as (a) template(s);
- (Free) nucleotides attach;
- Complementary/specific base pairing due to H bonds forming between bases/ Adenine to Thymine and GC;
- DNA polymerase joins nucleotides (on new strand) forming phoshodiester bonds by condensation;
- Semi-conservative replication / new DNA molecules contain one old strand and one new strand;
Describe the role of DNA polymerase in the semi-conservative replication of DNA.
- Joins (adjacent DNA) nucleotides;
- (Catalyses) condensation (reactions);
- (Catalyses formation of) phosphodiester bonds (between adjacent nucleotides);
Name the two scientists who proposed models of the chemical structure of DNA and of DNA replication.
Crick and Watson;
Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA.
- Weak / easily broken hydrogen bonds between bases allow two strands to separate / unzip;
- Two strands, so both can act as templates;
- Complementary base pairing allows accurate replication;
Describe how an enzyme can be phosphorylated.
- Attachment/association of (inorganic) phosphate (to the enzyme);
- (Released from) hydrolysis of ATP OR (Released from) ATP to ADP + Pi;
Explain five properties that make water important for organisms.
- A metabolite in condensation/hydrolysis/ photosynthesis/respiration;
- A solvent so (metabolic) reactions can occur OR A solvent so allowing transport of substances;
- High heat capacity so buffers changes in temperature;
- Large latent heat of vaporisation so provides a cooling effect (through evaporation);
- Cohesion (between water molecules) so supports columns of water (in plants);
- Cohesion (between water molecules) so produces surface tension supporting (small) organisms;
ATP is an energy source used in many cell processes. Give 2 ways which ATP is a suitable energy source for cells to use.
- Releases small amount of energy,
- Can be rapidly re-synthesized
ATP is a nucleotide derivative.
Contrast a nucleotide found in DNA to a nucleotide found in ATP.
ATP- 3 phosphate groups, ribose sugar
DNA- deoxyribose sugar, 1 phosphate group
