Nucleic Acids Flashcards
what are the 2 types of nucleic acid
Deoxyribonucleic acid
Ribonucleic acid
are nucleic acids monomers
no theyre polymers
what monomers make up nucleic acids
nucleuotides
what do nucleic acids do
they store, transmit and help express genetic or heredity information in the cell
what does DNA do
holds genetic information
what does RNA do
transports genetic information from DNA to ribosomes
what are ribosomes formed from
rRNA (ribosomer RNA) and proteins
what is the structure of a nucleotide
phosphate group, pentose (sugar) and a nitrogenous base
what is the name of the pentose in DNA and RNA
Deoxyribose in DNA
Ribose in DNA
which carbons on the pentos are the phosphate group and nitrogenous base bonded
nitrogenous base - 1’C
phosphate group - 5’C
what is the only difference between RNA and DNA
DNA lacks an oxygen atom on carbon 2 on the pentose, whilst ribose has a hydroxyl group on carbon 2
what are the 2 types of nitrogenous bases (not the names)
purines
pyrimidines
describe pyrimidines, and which bases are they
- 6 membered single ring
- 3 hydrogen bonds form
C, T, U
describe purines and which bases are they
- larger than pyrimidines
- have a six membered ring joined to a 5 membered ring (double ring)
A, G - form 2 hydrogen bonds
what are the full names of the five bases
Adenine
Guanine
Cytosine
Thymine
Uracil
what bond forms in nucleic acids
phosphodiester bonds
what is the name for 2 nucleotides bonded together? many?
2 - Dinucleotide
many - Polynucleotide
where do phosphodiester bonds form to produce nucleic acids
OH group on carbon 3 of one nucelotide and the phosphate groups OH on carbon 5 of another nucleotide
what catalyses the condensation reaction that forms phosphodiester bonds
DNA polymerase
what are the two ends of the 2 polyneucltods that form DNA called
5 prime end where the phosphate group is
3 prime end where the OH is
what is the word to describe the orientation of the two strands of the double helix
antiparallel
what bonds form between the complementary bases in DNA
hydrogen
how many hydrogen bonds does the A-T base pairing form
2
how many hydrogen bonds does the C-G base pairing form
3
how many nucleotide chains does RNA have
one
what are the 3 types of RNA
mRNA - Messanger RNA
rRNA - Ribosomal RNA
tRNA - Transfer RNA
what does mRNA do
carries genetic information for making a protein from DNA to ribosomes
what does rRNA do
its an important part of the structure of ribosomes and has catalytic functions needed for protein synthesis
what does tRNA do
it bonds with its specific amino acid type and carries it to the ribosome during protein synthesis
which is longer, DNA or RNA
DNA
what is the name for the process in which DNA replicates
Semi conservative replication
what are the 2 enzymes needed for semi conservative replication
DNA helicase
DNA polymerase
what are the 4 conditions needed for semi conservative replication
- a pool of all 4 nucleotides must be present
- both strands of the DNA need to be copied to act as a template
- the enymes DNA helicase and DNA polymerase must be present
- a source of ATP must be present
what does DNA helicase do
breaks the hydrogen bonds between the complementary nitrogenous bases (it unwinds the DNA)
what happens after DNA helicase unwinds the double helix
free nucleotides start to be attracted to their complementary bases on the templates
in what orientation is the new strand created in relation to the template
in the antiparallel direction (if the template is 5’ -> 3’, the new strand will be 3’ -> 5’).
where does DNA polymerase work from, what does this mean for the direction of new strands
it binds to 3’ because its specific, so the new strand will always start from there (creating a 5’ end) and work towards the templates 5’.
what bonds does DNA polymerase form
phosphidester bonds between the nucleotides phosphates and deoxyribose sugars
are the new DNA strands identical to the template strands in semi conservative replication
yes
what equiptment is used to prove semi conservative replication, why is it used
ultracentrifuge
its so sensetive that it can seperate molecules that contain different nitrogen isotopes (N15 and N14)
what collects at the bottom of the ultracentrifuge during semi conservative replication
N15, the heavier molecules
what are the 3 theorised methods of DNA replication
Semi conservative
Conservative
Dispersive
describe the conservative DNA replication method
suggests parental DNA would remain intact and a seperate new DNA molecule would be made from scratch
describe the semi conservative DNA replication method
suggests the parental molecule would seperate into 2 seperate strands that would act as a template for the formation of a new strand to be filled with free nucleotides
describe the dispersive DNA replication method
the newly synthesis DNA strand would consist of a mix of parental and daughter strands
what experiment was carried out to determine if DNA replicated via conservative / semi conservative
they grew bacteria on a medium made of N15, which would causse it to have heavier DNA due to semi conservative replication
describe the distibution of DNA bands for bacteria grown on N15, that is then moved to N14 for three replications
originally 100% N15
rep 1 - 100% N15/N14
rep 2 - 50% N15, 50% N14
rep 3 - 25% N15, 75% N14
what does ATP stand for
Adenosine Triphosphate
what type of molecule is ATP
a nucelotide derivative
describe the structure of ATP
Ribose, adenine, 3 phosphate groups
Adenine bonds to C5
Phosphates bond to C1
what hydrolises ATP
ATP hydrolase
what is produced from ATP + H2O with ATP hydrolase present
ADP - adenosine diphosphate
Pi - inorganic phosphate group
what does the inorganic phosphate produced during ATP hydrolysis do
phosphorylates other compounds, making them more reactive
what condenses ADP and Pi to ATP and H2O
ATP synthase
what type of reaction is the hydrolysis of ATP
exergonic - releases energy
describe the ATP cycle
- the hydrolysis of ATP releases energy, so it supplies energy requiring reactions like active transport
- the condensation of ADP + Pi requires energy, which it gets from energy releasing reactions like photosynthesis
why is ATP important (2)
Movement for functions such as the movement of chromosomes during cell division
- It supplies energy for active transport which is important for transporting some molecules and ions across the cell membrane
what type of molecule is water
polar due to unequal charge distribution
what causes water to have its properties
the attractions between oppositely charged atoms of different water molecules, which form hydrogen bonds
what are the 6 properties of water and why are they important
- a metabolite for reactions such as condensation and hydrolysis reactions
- a solvent where metabolic reactions occur
- has a high heat capacity which buffers temperature changes and allows organisms to maintain a stable body temp
- has a large latent heat of vaporisation, which provides a cooling effect with little loss of water through evaporation
- strong cohesions between water molecules so it can support columns of water in plants
- strong cohesions between water molecules so produces surface tension, so it can support small organisms
where are inorganic ions found
as solutions in the cytoplasm and body fluids of organisms
what are the 4 inorganic ions
iron
phosphate
hydrogen
sodium
what is the role of iron ions in living organisms (2)
- found in the haemoglobin molecule in red blood cells
- this haemoglobin binds with oxygen
what is the role of phosphate ions in living organisms (5)
- affects osmosis
- found in nucleuotides
- used to produce ATP
- phosphorylates other compounds to make them more reactive
- hydrophylic
what is the role of hydrogen ions in living organisms
determines the pH of cells and tissues so they’re suitable for cell functions
what is the role of sodium ions in living organisms (3)
- co transports glucose as sodium is moved out by active transport
- creates a sodium concentration
- affects osmosis
what is the equation for pH
-log10[H+]
