Chapter 2 Nucleic Acids Flashcards
name 5 useful properties of water
it is an important metabolite high latent heat of vaporisation buffers changes in temperature good solvent strong cohesion between water molecules
what makes water a good metabolite
many metabolic reactions involve a condensation or hydrolysis reaction
where water is produced as a new bond is formed or used to break an existing bond
why is it important that water is a good metabolite
amino acids are joined together to make polypeptides in condensation reactions
why does water have such high latent heat of vaporisation
it takes a lot of energy to break the hydrogen bonds between water molecules
when water molecules evaporate from a body of water they take a lot of energy with them so the body of water cools down
why is it important that water has such a high latent heat of vaporisation
animals can keep cool by sweating and plants cool down when water evaporates from leaves
why does water have such a high specific heat capacity
the hydrogen bonds between water molecules can absorb a lot of energy so it absorbs a lot of heat energy before a significant change in temperature occurs
why is it important that water has such a high specific heat capacity
it makes aquatic environments great habitats because the temperature is stable
water buffers temperature changes inside our bodies so our internal body temperature is constant
why is water such a good solvent
many compounds are ionic they consist of one positively charged ion and one negatively charged one
because water is polar the positive end of it will attach to the negative end of the compound and vice versa
this means the compound will get surrounded by water molecules and will eventually dissolve
why is it important that water is such a good solvent 2
many reactions inside the body can only happen when the reactants are dissolved in water
dissolved substances like glucose can be transported around the body
why was water molecules so cohesive
they are polar molecules so hydrogen bonds form between the differently charged ends of the molecule
important of waters strong cohesion 2
water flows so it is great for transporting substances
surface tensions means small insects can live on surface
describe the structure of water
the shared hydrogen electrons are pulled to one side of the hydrogen atoms leaving the other side with a slight positive charge
the unshared electrons on the oxygen give it a slight negative charge
the slightly negative oxygen atoms join to the slightly positive hydrogen ones
these are called hydrogen bonds
what is one nucleotide made out of
a pentose sugar
a phosphate group
a nitrogen containing organic base
function of DNA
it stores all the genetic information we need to grow and develop
function of RNA
it transfers genetic information from the nucleus to the ribosomes
what are the four bases in DNA
adenine thymine guanine cytosine
what pentose sugar is found in DNA
deoxyribose
what are the four bases of RNA
adenine uracil guanine cytosine
what pentose sugar is found in RNA
ribose
what is a polynucleotide
a polymer made of numerous nucleotides
how do the sugar base and phosphate group going together
a condensation reaction occurs between the sugar and phosphate group
how is a polynucleotide formed
a condensation reaction occurs between the sugar of one dna group and the phosphate group of another forming a phosphodiester bond
what bond is formed the two nucleotides join
phosphodiester
how are the two strands of DNA held together
hydrogen bonds
what are the complimentary base pairs
adenine and thymine
cytosine and guanine
how many hydrogen bonds form between a and t
two
how many hydrogen bond form between c and g
three
what does antiparallel mean
the two dna strands run in opposite directions
why is dna very stables
the phosphodiester backbone protects the more reactive organic bases and the hydrogen bonds between complimentary bases are strong
why is dna said to be antiparallel
the enzyme DNA polymerase can only attach nucleotides to the 3’ carbon on the dna molecule
what name is given to the current theory on dna replication
the semi conservative model
what does the enzyme dna helicase do
breaks hydrogen bonds between the base pairs
what does the enzyme DNA polymerase do
joins activated nucleotides together
what is the semi conservative model of dna replication
dna helicase breaks the hydrogen bonds so the strands of dna split apart
each exposed strand then acts as a template for the new strand
complimentary base pairing means that free floating bases are attracted to their exposed complimentary bases on the template strand
DNA polymerase joins two strands together in a condensation reaction forming hydrogen bonds
each new strand of dna contains one strand from the original dna molecule and one new strand
what is the structure of a molecule of ATP
contains adenine ribose ad a chain of three phosphate groups
how does atp store energy
between the three phosphate groups there are weak bonds with a low activation energy
when they are broken a lot of energy is released in a hydrolysis reaction
what is produced when atp is hydrolysed
adp + p + energy
which enzyme catalyses the reaction of atp to adp
atp hydrolase
what is special about the use of atp
it is reversible energy can be used to add a phosphate to adp to make atp
what enzyme is used to make atp from adp
atp synthase
what can the phosphate group released when atp releases energy be used for
it can join to another compound to make it more reactive
why is atp only a short term energy source
the bonds between phosphates are very unstable
why is atp a Better energy source than glucose 2
energy is released in much smaller more manageable amounts
the hydrolysis of atp to adp is a single reaction that releases immediate energy
5 uses of atp
metabolic processes movement active transport secretion activation of molecules
how is atp used in metabolism
it provides the energy to make larger molecules from their units
how is atp used in movement
it provides the energy for muscle contraction
how is atp used in active transport
it provides the energy for proteins to change shape
how is atp used in secretion
it creates the lysosomes necessary for secretion
how is atp used to activate molecules
the phosphate produced can make other molecules more reactive
what did meselson and stahl do
provide evidence for semi conservative dna replication
what was meselson and stahl’s experiment
they grew two samples of bacteria one in heavy and one in light nitrogen
when placed in a centrifuge heavy nitrogen would settle at the bottom and light nitrogen would float
at the end of the experiment the bacteria floated in the middle showing they had taken dna from both types of nitrogen
what is an ion with a positive charge called
a cation
what is an ion with a negative charge called
an anion
what is special about an inorganic ion
it doesn’t contain any carbon
where are iron ions found
haemoglobin
what are hydrogen ions used for
determining ph
what are sodium ions used for
co transport
what are phosphate ions used for
bonds between phosphates in ATP store up energy
