2. nucleic acids

structurally what is DNA

a polymer made up of 4 bases

name of the 4 bases found in DNA

adenine, guanine, cytosine, thymine

what is the primary function of RNA

transferring information from DNA to ribosomes for protein synthesis

DNA stands for

deoxyribonucleic acid

RNA stands for

ribonucleic acid

4 bases found in rna

adenine, cytosine, guanine, uracil

what are dna and rna polymers of

nucleotides

what do nucleotides consist of

pentose sugar, phosphate group and a nitrogen containing organic base

components of a DNA nucleotide

deoxyribose sugar, phosphate group and one nitrogen containing organic base

components of rna

ribose sugar, phosphate group and one nitrogen containing organic base

nucleotides join together by

phosphodiester bonds formed in condensation reactions

purines

double ring structure - A and G

pyrimidines

single ring structure - C, T and U

what do the condensation reactions occur between

the phosphate group of one nucleotide and the pentose sugar of the other nucleotide

called a phosphodiester bond as...

consists of a phosphate group and two ester bonds (phosphate with double bond oxygen attached)

sugar-phosphate backbone

alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds

3 differences between rna and dna

RNA has ribose, RNA has uracil not thymine, RNA not a double helix

3 similarities between rna and dna

Triplet

every 3 bases codes for an amino acid

who discovered the structure of DNA

Crick and Watson

what joins the two strands of bases together in the double helix

hydrogen bonds

adenine pairs with

Thymine

guanine pairs with

Cytosine

how many hydrogen bonds are between A and T

2

how many hydrogen bonds are between C and G

3

4 ways DNA has adapted

stable structure rarely mutates, hydrogen bonds between 2 strands can be broken for replication and protein synthesis, large so can carry lots of information, protection from the sugar-phosphate backbone

first 2 stages of semiconservative replication

1\.DNA helicase breaks the H bonds linking the base pairs

2\.double helix separates into 2 strands and unwinds

3rd stage of semiconservative replication

each polynucleotide strand acts as a template and complementary free nucleotides bind by specific base pairing to each strand

4th and 5th stages of semiconservative replication

4\.DNA polymerase joins together the nucleotides in a condensation reaction to form the new strand

5\.each new DNA molecule contains 1 new and 1 old strand

DNA helicase function

separates the 2 strands of dna by breaking the hydrogen bonds

DNA polymerase function

joins nucleotides together by forming phosphodiester bonds

the 2 strands in DNA are said to be

antiparallel

polynucleotide

A polymer consisting of many nucleotide monomers in a chain

3 types of rna

transfer, messenger, ribosomal

other hypothesis over dna replication

conservative replication

conservative replication argues

one dna strand is completely new and the other is entirely original material

who discovered the correct form of dna replication

Meselsohn and Stahl

what 3 facts did Meselsohn and Stahl base their work on

all bases in dna contain nitrogen, nitrogen has two isotopes, one is lighter and one is heavier and bacteria will incorporate nitrogen from their growing medium into any new dna made

a single nucleotide

monomer

ATP stands for

adenine triphosphate

once energy is used atp becomes

adp

structure of atp

adenine, ribose, 3 phosphate groups

why are the bonds between the phosphates easily broken

they're unstable and so have low activation energy

what type of reaction is atp to adp

hydrolysis

when the 3rd bond between the phosphate is broken what happens

energy is released

adp to atp is what type of reaction and what does it require

condensation reaction, requires energy

energy is released when atp

is hydrolysed to form adp and a phosphate molecule

why is water important

it's a metabolite used in many reactions - hydrolysis and condensation reactions

what solution do a cell's metabolic reactions occur in

aqueous

what are most of its properties a result of

the ability for the molecules to attach to one another

what type of molecules are water molecules

polar

what type of nucleotide is atp

phosphorylated

ATP is described as a

universal energy currency - used in all organisms and used and reused for different purposes

ATP as an 'energy-currency' is beneficial because :

hydrolysis of atp can be carried out quickly, useful quantity of energy is released when one molecule is hydrolysed and atp is relatively stable at cellular pH levels

maximum amount of atp in a human's body at any given time

200g

how much atp do humans use on average per day

50kg

waste product of atp synthesis

water

two ways atp can be synthesised

substrate-linked phosphorylation and chemiosmosis

What makes water polar?

the covalent bonds of water

why is there an uneven distribution between the oxygen and hydrogen atoms

oxygen atom attracts the electrons more strongly than hydrogen atoms - resulting in a weak negatively charged region on the oxygen atom and a weak positively charged region on hydrogen atoms

dipole

separation of charge due to the electrons in the covalent bonds being unevenly shared

where do hydrogen bonds form on water molecules

oxygen of one water molecule to the hydrogen atom of another

6 important properties of water

solvent, high specific heat capacity, high latent heat of vaporisation, less dense when solid, high surface tension and acts as a reagent

water's specific heat capacity

4200J/KgC

hydrogen bonds between water molecules allow for

cohesion between water molecules

examples of cohesion

in the xylem of plants and through blood vessels in animals

why does water have a high specific heat capacity

water molecules stick together with hydrogen bonds - lost of energy required to break these

what causes the surface tension at the water-air boundary to be high

strong cohesion

where do inorganic ions occur

in solution in the cytoplasm and body fluid of organisms

4 of the essential ions

hydrogen ions which determine the pH of substances, iron, sodium and phosphate

why are iron ions essential

component of haemoglobin - an oxygen carrying component in red blood cells

the higher the concentration of hydrogen ions

the lower the pH (more acidic)

what are sodium ions involved in

co-transport of glucose and amino acids

what are phosphate ions a component of

DNA and ATP