1B (more bio mols)

Question 1

What are nucleotides made up of?

Answer 1

Pentose sugar
Nitrogen containing organic base
Phosphate group

Question 2

DNA bases and sugar
what makes each nucleotide different?

Answer 2

Pentose sugar- deoxyribose
Bases- adenine, thymine, cytosine, guanine
Each DNA nucleotide has same sugar and phosphate but diff bases

Question 3

Bases and sugar in rna

Answer 3

Penrose sugar- ribose
Bases- adenine, uracil, cytosine, guanine
Each nucleotide same apart from bases

Question 4

What is a polynucleotide?
How does it form?

Answer 4

Polymer of nucleotides eg DNA
Join via condensation reaction between phosphate of one and sugar of another forming phosphodiester bond- sugar phosphate backbone

Question 5

DNA structure

Answer 5

2 polynucleotide chains joined by H bonds between bases
Complimentary base pairing- A,T(2 H bonds) G,C(3 H bonds)
2 anti parallel stands form double helix

Question 6

Pyramidines and purines

Answer 6

Pyramidines- T and C, single ringed
Purines- A and G, double ringed
Pyramidines join to purines

Question 7

When was DNA discovered?

Answer 7

First in 1800s but doubted it carried whole genetic code
1953- proved it did
1953- Watson and Crick discovered double helix

Question 8

RNA structure

Answer 8

Single polynucleotide chain
Shorter than DNA polynucleotide

Question 9

Properties of DNA

Answer 9

Stable- backbone protects chemically reactive organic bases in double helix
3 H bonds c-g so more c-g means more stable
Diverse- infinite variety- 3.2 bill base pairings

Question 10

DNA adapted to function

Answer 10

Stable- doesn’t mutate when passes to generations
Stands joined by H bond so can separate
Large- carries lots of info
Bases protected by backbone
Base pairing means it can replicate and transfer info as mRNA

Question 11

Semi-conservative replication process

Answer 11

1) DNA helicase breaks H bonds between bases so unwinds forming 2 single strands
2) each og strand acts as template for new one. free floating nucleotides attach to complimentary exposed bases on template strands
3) condensation reaction joins nucleotides together catalysed by DNA polymerase. H bonds form between bases on new and old strands’
4) each new DNA molecule has 1 strand of og DNA molecule and one of new

Question 12

4 requirements for semiconservative DNA replication

Answer 12

1) 4 types of nucleotide w bases present
2) both strands act as template for attachment of nucleotides
3) dna polymerase present
4) source of chem energy required

Question 13

what does antiparallel mean?

Answer 13

dna strands run in opposite directions

Question 14

which way does dna polymerase work?

Answer 14

3’-5’ of the template strand so nucleotides added from 3’ of the template strand as active site of polymerase compliments 3’

Question 15

which direction is the new strand made in?

Answer 15

5’-3’

Question 16

which carbon does phosphate attach to?
which carbon does hydroxyl attach to?

Answer 16

5’
3’

Question 17

does dna polymerase run in the same direction or opposite on each strand?

Answer 17

opposite

Question 18

meselson and stahl’s experiment

Answer 18

1) 2 bacteria samples grown. 1 in broth w 14N other w 15N. bacteria reproduce taking up N from broth to help make nucleotides so becomes part of DNA
2) sample of dna taken from each batch and centrifuged. dna from heavy N settled lower
3) bacteria in heavy n put in light broth. replicated once and centrifuged
4)if conservative, og heavy would settle at bottom and light at top
5) if semi, would contain 1 old and 1 new strand so would settle in middle
6) it did settle in middle showing it contained 14N and 15N

Question 19

why is water vital to living organisms?

Answer 19

about 80% of cells contents
important metabolite in hydrolysis etc
solvent- most metabolic processes happen in solutions
very cohesive- helps water transport in plants etc

Question 20

does water have a high or low latent heat of vaporisation and specific heat capacity? advantages of this?

Answer 20

high
helps control body temperature

Question 21

is water polar or not? why?

Answer 21

polar
h positive as electrons pulled more to o
o negative as unshared electrons
allows hydrogen bonding

Question 22

6 useful properties of water

Answer 22

. metabolite- many metabolic reactions involve condensation
. high latent heat of vaporisation- lots of energy to break h bonds so lots needed to vaporise so can use water loss through evaporation to cool down wo losing too much water
. can resist changes in temp- h bonds absorb lots energy so high spec heat cap so no rapid temp changes
. good solvent- water polar so can surround ionic structures and dissolve them
. not easily compressed- supportive eg hydro-elastic skeleton in worms and turgor in plants
. transparent- aquatic plants can photosynthesise, light can penetrate fluid in eyes to reach retina

Question 23

what is cohesion?
why are water molecules so cohesive and benefits?

Answer 23

attraction between molecules of the same type/ tendency of molecules to stick together
because theyre polar
helps water flow- transporting substances up xylem

Question 24

surface tension

Answer 24

water has high surface tension when in contact w air as it is cohesive- water molecules pulled back into body of water

Question 25

what is capillary action?

Answer 25

water adheres to walls of column and moves upwards. narrower= moves further up as pull from meniscus overcomes mass of water in tube- smaller mass in smaller tube

Question 26

6 reasons why is energy important?

Answer 26

metabolic processes
movement/ muscle contractions
active transport- change shape of carrier proteins
secretion- form lysosomes needed
activating molecules
dna replication and cell division

Question 27

structure of ATP

Answer 27

energy released from glucose in respiration used to make ATP
made of adenine (the DNA base), ribose sugar and 3 phosphate groups
nucleotide derivative

Question 28

where is energy stored in ATP? how is it released?

Answer 28

high energy bonds (unstable so little activation energy to break) between phosphate groups
released in hydrolysis

Question 29

equation for break down of ATP
catalyst?

Answer 29

ATP-> ADP + Pi
ATP hydrolase

Question 30

what is phosphorylation?

Answer 30

Pi added to other compounds making them more reactive
phosphorylation- photosynthesis
oxidative phosphorylation- respiration
substrate level phosphorylation

Question 31

resynthesis of ATP equation and catalyst

Answer 31

ADP+ Pi -> ATP
ATP synthase
happens in respiration and photosynthesis

Question 32

ATP vs glucose

Answer 32

ATP is glucose in 38 parts- releases less energy so more manageable amount
quicker as glucose takes longer to breakdown
ATP is immediate
but cant be stored- constantly being made in mitochondria of cells that need it

Question 33

Iron ions

Answer 33

in haemoglobin which is 4 diff polypeptide chains with Fe2+ in centre
Fe2+ binds to O2 to temporarily become Fe3+

Question 33

What is an inorganic ion?

Answer 33

atom with a charge that doesnt contain carbon

Question 34

Hydrogen ions

Answer 34

determines pH which is a measure of conc of H+
more H+ is more acidic and lower pH
enzyme controlled reactions are affected by pH

Question 35

Sodium ions

Answer 35

glucose and amino acids need help crossing cell membranes
can be transported across in cotransport alongside Na+

Question 36

Phosphate ions

Answer 36

Phosphate ion attached to other molecules creates phosphate group
ATP, DNA, RNA all contain phosphate groups
bond between store energy in ATP
in DNA and RNA, join so allow nucleotides to form polynucleotides

Question 37

Advantage of hydrolysis of ATP being coupled to energy-requiring reactions within cells.

Answer 37

energy released can be directly used to make coupled reaction happen rather than being lost as heat

Question 38

Where can you find inorganic ions?

Answer 38

Cytoplasm of cells and bodily fluids of organisms

Question 39

Role of RNA

Answer 39

Transfers genetic info from DNA to ribosomes