DNA

Question 1

what is DNA nucleotide made up of?

Answer 1

a pentose sugar (has five carbon atoms)
a phosphate group
a nitrogen containing organic base.

Question 2

what are the names of all the organic bases?

Answer 2

cytosine, guanine, adenine, thymine and uracil.

Question 3

what is a phosphodiester bond?

Answer 3

a phosphodiesta bond is the bond that forms between two mononuclodides. it forms between the deoxyribose sugar of one and the phosphate group of the other. this forms a new structure called a dinucleotide.

Question 4

what is RNA made out of?

Answer 4

RNA is a relatively short polynucleide chain containing a pentose sugar that is always ribose. it consists of the organic bases; adenine, thymine, cytosine and uracil.

Question 5

what is the job of RNA?

Answer 5

one type of RNA transfers genetic information from DNA to ribosomes. these ribosomes are made up of proteins and another type of RNA. a third type of RNA is involved in protein synthesis.

Question 6

who discovered the structure of DNA?

Answer 6

watson and crick in 1953

Question 7

how are the bases in DNA bonded to each other?

Answer 7

the bases are bonded to their corresponding base via hydrogen bonds.

Question 8

why is DNA a stable structure?

Answer 8

the phosphodiester backbone products the more reactive organic bases inside the double helix.
hydrogen bonds link the organic base pairs forming bridges between the phosphodiesta uprights. as there are three hydrogen bonds between c-g the higher concentration of these parings wioll mean that the DNA is more stable.

Question 9

hiw is the DNA molecule adapted to carry out its function?

Answer 9

its very stable structure is passed from generation to generation, very rarly does it mature.
its two separate strands are joined with only with hydrogen bonds, which allow them to separate during cell replication.
it is an extremely large molecule and therefor carries a large amount of genetic information.
by having the base pairs within the helical cylender of the deoxyribose-phosphate backbone, the genetic information to some extent is protected from being corrupted by outside chemical and physical forces.
base pairing leads to DNA being able to replicate and to transfer information as mRNA.

Question 10

what is nuclear division?

Answer 10

nuclear is the process by which the nucleus is divided. there are two types of nuclear division, miotic and mitotic.

Question 11

what is cytokinesis?

Answer 11

cytokenisis follows nuclear division and is the process in which the whole cell divides.

Question 12

what are the four requirements for semi-conservative replication to occur?

Answer 12

all four nucleotide containing the 4 main bases must be present
both strands of the DNA molecule act as a template for these nucleotides
the enzyme DNA polymerase must be present
a source of chemical energy is required to drive the process.

Question 13

explain the process of semi conservative replication

Answer 13

1) the DNA helices breaks the hydrogen bonds linking the base pairs of DNA
2) as a result the DNA splits into two strands and unwinds
3) each of the polynucleotide strands acts as a template in which complimentary free nucleotides join to their corresponding base
4) the nucleotides then join with one another via the addition of the enzyme DNA polymerase through condensation reactions creating a polynucleotide backbone
5) the new DNA then re coils

Question 14

what is the theory of conservative replication?

Answer 14

this was the theory that when DNA replicated itself it produced an exact copy of itself instead of splitting in two.

Question 15

why is used as the main energy source t carry out processes within cells?

Answer 15

ATP

Question 16

what does ATP stand for?

Answer 16

adenosine triphosphate

Question 17

what are the three parts of ATP

Answer 17

ribose, 3 phosphate groups, adenine.

Question 18

how does ATP store energy?

Answer 18

the main components in ATPs ability to store energy is in its phosphate groups. the phosphate groups form unstable bond between each other meaning that they have a low activation energy and so are therefore easy to break. when they do break a large amount of energy is released. generally in mammals it the terminal phosphate that is released, forming ADP

Question 19

where does the synthesis of ATP occur?

Answer 19

in chlorophyll containing plant cells during photosynthesis (photophosphorylation)
in plant and animal cells during reparation (oxidative phosphorylation)
in plant and animal cells when phosphate groups are transferred from donor molecules to ADP (substrate level phosphorylation)

Question 20

why is ATP a better immediate energy source than glucose?

Answer 20

each ATP molecule produces less energy than each glucose molecule however this energy is in more manageable quantities than the energy from the glucose.
the hydrolysis of ATP to ADP is an immediate reaction where as the break down of glucose is a long series of reactions and therefore the energy release takes longer.

Question 21

what energy requiring processes within the cell is ATP needed?

Answer 21

metabolic processes - it provides the energy needed to build up macromolecules from their basic units.
movement - provides the energy for muscle contraction, provides the energy for muscle filaments to slide passed one another and therefore shorten the overall length of the muscle.
active transport - it provides the energy for carrier protons to change shape in plasma membranes, allowing molecules to move against the concentration gradient.
activation of molecules - the inorganic phosphate released during hydrolysis can be used to to phosphorylate other compounds ignorer to make them more reactive, thus lowering the activation energy of in the enzyme-catalysed reaction.

Question 22

why is the specific heat capacity of water important?

Answer 22

it takes more energy to heat a given mass of water, therefore water acts as a buffer against sudden temperature variations, making an aquatic environment a temperature stable one. as organisms are mostly water it also acts as a buffer to sudden changes to body temperature.

Question 23

why is the latent heat of vaporisation for water good?

Answer 23

it means that a lot of energy i required to evaporate 1 g so therefor sweating is a good way of cooling the body down

Question 24

what are the important features of water?

Answer 24

water is used in metabolism
water is a solvent
evaporation cools organisms allowing them to control their temperature
not easily compressed
i is transparent so therefor aquatic plants can photosynthesise.