1.2- Nucleic acids Flashcards
what are the two types of nucleic acids?
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
What is the function of DNA?
to store genetic information
What is the function of RNA?
to transfer genetic info from the DNA to the ribosomes
what is a nucleic acid?
long chains of nucleotides
what is the structure of a nucleotide?
one phosphate group
a pentose sugar
a nitrogenous base
what are the components of a DNA nucleotide?
deoxyribose sugar
a phosphate group
an organic base (adenine, guanine, cytosine or thymine)
what are the components of RNA nucleotide?
ribose sugar
a phosphate group
an organic base (adenine, guanine, cytosine or uracil)
what reaction occurs between two nucleotides to form a ____________ bond?
a condensation reaction forms a phosphodiester bond
what are 3 differences between a DNA molecule and a RNA molecule?
- DNA is a double helix, RNA is a single helix
- DNA is anti-parallel, RNA is not
- DNA contains thymine, RNA contains uracil
how many hydrogen bonds are there in each DNA pair?
A + T= 2
C + G= 3
what does semi-conservative replication of DNA mean?
ensuring genetic continuity between generations of cells as half of the strands in each new DNA molecules are from the original DNA molecule
what are the two enzymes involved in semi-conservative replication?
- DNA helicase -> breaks hydrogen bonds
- DNA polymerase -> breaks phosphodiester bonds
what is the first step for semi conservative replication?
- DNA helicase breaks the hydrogen bonds between bases on the two polynucleotide DNA strands. The helix unwinds to form two single strands.
second step for semi-conservative replication?
- Each original single strand acts as a template for a new strand. Complementary base pairing means the free- floating DNA nucleotides are attracted to the complementary exposed bases on each template strand (A with T and C with G)
third step of semi-conservative replication?
- Condensation reaction join the nucleotides of the new strands together, catalysed by the DNA polymerase. Hydrogen bonds form between the bases on the new and original strands
fourth step of semi conservative replication?
- Each new DNA molecule contains one strand from the original DNA molecule and one new strand
what is the structure of the nucleotide ATP?
- ribose
- adenine
- three phosphate groups
how is ATP broken down?
a hydrolysis reaction of ATP into ADP (adenosine diphosphate) and Pi (inorganic phosphate). A phosphate bond is broken and energy is released which is catalysed by the enzyme ATP hydrolase.
-> can be ‘coupled’ to energy requiring reactions
what is the purpose of the inorganic phosphate (Pi) ?
can phosphorylate other compounds, often making them more reactive
how is ATP re-synthesised?
a condensation reaction between ADP and Pi. The reaction is catalysed by the enzyme ATP synthase during photosynthesis, or during respiration
how is the structure of ADP different to ATP?
ADP (adenine diphosphate) has 2 phosphates
ATP (adenine triphosphate) has 3 phosphates
what are the 6 main properties of water?
- metabolite
- high latent heat of vaporisation
- a solvent
-high heat capacity - strong cohesion
what ions are a component for haemoglobin?
iron
(- the Fe2+ binds to the oxygen in haemoglobin.
- when oxygen is bound the Fe2+ ion temporarily becomes an Fe 3+ ion)
what ions determine the pH?
hydrogen ions
( the more H+ ions, the lower the pH= more acidic)
what is the role of sodium ions?
transport glucose and amino acids across membranes
( a molecule of glucose or an amino acid can be transported along side sodium ions = co-transport)
what ion makes up the components of DNA and ATP?
PHOSPHATE IONS
- in ATP, the bonds between phosphate groups store energy
- in DNA and RNA, phosphates groups allow nucleotides to join up and form polynucleotides
