Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

biology year 1 > enzymes and nucleic acids > Flashcards

enzymes and nucleic acids Flashcards

1
Q

describe the structure of enzymes

A

-tertiary proteins with globular shape
-has a pocket or cleft area which has a specific 3D shape called an active site where reactions take place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

function of enzymes

A

-act as biological catalysts
-provide an alternate pathway during a reaction
-hydrolyse polymers into monomers in digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

define biological catalyst

A

proteins that speed up metabolic reactions without being used up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how do enzymes lower activation energy?

A

by providing an alternate pathway during a reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the importance of the enzyme catalase?

A

-hydrolyses hydrogen peroxide into water + oxygen
-H202 is a toxic by-product of metabolism so must be removed
-catabolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

whats the importance of the enzyme RUBISCO?

A

-RuBP +CO2 into glycerate + phosphate
- fixes CO2 from atmosphere in photosynthesis
-anabolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

whats the importance of the enzyme ATPsynthase?

A

ADP +Pi into ATP
-energy requiring process
-active transport
-anabolic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

whats the of the enzyme glycogen synthetase?

A

-converts glucose to a storage compound -glycogen (polysaccharide)
-anabolic
condensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

define activation energy

A

the extra energy that is required to enable a reaction to occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where is the activation energy usually supplied through?

A

heat in a loboratory reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

whats the importance of a model?

A

it provides simplified visual representations to explain how a process may work

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe the lock and key model of enzyme action

A

-specific active site is complementary to the substrate molecule so able to bind
-bonds broken
-2 products are formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe the induced fit hypothesis of enzyme action

A

-active site not fully complementary
-strain on bonds lowers activation energy
-the active site becomes complementary to the substrate
-an enzyme-substrate complex forms
-substrate no longer fits active site so products are released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what biochemical food test would determine if an enzyme was present?

A

-biuret solution (NaOH + CuSO4)
-blue to lilac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what factors may affect the rate of reaction of enzyme?

A

-pH
-temperature=Ke
-substrate concentration
-enzyme concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

why will an enzyme only bind to one substrate molecule?

A

active site is only complementary to one type of substrate molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is a limiting factor?

A

factors that effect maximum rate of reaction being achieved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

explain how a very high temp can stop an enzyme from working?

A

-bonds will break
-active site denatures
-can no longer bind, no longer complementary to the substrate
-no enzyme-substrate complexes can form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

explain how extreme pH can affect the overall shape of the enzyme

A

-hydrogen ions can interfere with R group interactions between amino acids as H+ will cluster around negatively charged R groups and disrupt the hydrogen and ionic bonds which maintain the tertiary structure of a protein and shape of active site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is meant by the saturation point in an enzyme controlled reaction?

A

when all enzymes active sites are occupied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the limiting factor when increasing the substrate concentration?

A

enzyme concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

explain the effect of temperature on enzyme activity

A

-as temp increases, the molecules have more kE
-more successful collisions between substrates and the enzymes active sites
-so more enzyme-substrate complexes
-so rate of reaction happens faster

-when the temp goes beyond optimum, H bonds break
-enzyme denatures + tertiary 3D structure of active site changes
-active site changes shape so more difficult to become complementary to the substrate
-so fewer to no enzyme-substrate complexes can form
-so rate of reaction slows down and stops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

why are rate of reactions very slow at low temps?

A

enzymes and substrate molecules have little kinetic energy
and few enzyme-substrate successful collisions taking place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

explain the effect of pH on enzyme activity?

A

-as the pH moves away from optimum, rate decreases
-because changes in pH changes charges on the R groups of the amino acids
-therefore this changes the ionic and hydrogen bonding
-therefore 3D tertiary structure of enzymes changes
-so active site denatures, no longer easy for active site to become complementary
-so fewer enzyme-substrate complexes can form
-so rate decreases then stops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what are the 2 main ways of measuring the rate of a reaction?
-start the reaction, then measure either the concentrations of product formed or substrate used up after a fixed time intervals
26
define initial rate
the rate of reaction is at its highest at the first few seconds beginning of the reaction when the conc of substrate molecule is highest and therefore more enzyme-substrate collisions so more ESCs formed
27
define v-max
point at which the reaction is fastest as all the enzyme active sites are occupied no more enzyme substrate complexes can be formed
28
formula for rate
1/time
29
explain the effect of increasing concentration of substrate on the rate of an enzyme catalysed reaction?
-if conc of enzymes remains constant and conc of substrate increases the number of collisions will increase -more ESCs -rate increases -saturation point will be reached -conc of enzymes active site limiting factor
30
explain the effect of increasing enzyme concentration on the rate of an enzyme catalysed reaction?
-as the enzyme conc increases there are more active sites available -greater chance that substrates will collide with the active sites -more ESCs can form -initial rate increases -conc of substrate limits any further increase
31
what are the 2 types of inhibitors?
non-competetive competitive
32
describe how competitors work
-similar shape to the substrate molecule -complementary shape to the active site of the enzyme -they enter active site and bind forming an enzyme-inhibitor complex -prevent normal substrate from entering by blocking active site -number of ESCs that can form are reduced and rate of reaction falls
33
describe how non-competitors inhibitors work?
-dont compete with substrate for active site -attatch away at allosteric site and distort the 3D tertiary shape of the enzyme- change in active site shape -substrate no longer fits active site -ESC cannot form, rate of reaction decrease -inhibitor may be completely diff shape to substrate
34
what are reversible inhibitors?
do not permanently bind with the active site or away from the active site so not permament
35
what are permament inhibitors?
permanently bind to the active site or away from the active site
36
what are the 2 types of nucelic acids?
DNA- deoxyribonucleic acid RNA ribonucleic acid
37
what do nucleic acids form?
monomers called nucleotides
38
what are the components of nucleic acids?
1. phosphate group 2. pentose 5c carbon sugar dna- deoxyribose rna- ribose 3. nitrogen containing bases DNA- adenine, Thymine, cytosine and guanine RNA- adenine, uracil, cytosine and guanine
39
define the complementary base pairing rule
-adenine is able to pair through hydrogen bonds with thymine (or uracil in RNA) -guanine is able to pair through hydrogen bonds with cytosine -pyrimidines on one strand of DNA form H bonds with purines to hold strands together
40
how are nucleic acids formed?
-nucleotides link together to form polynucleotides -condensation reactions -covalent phosphodiester bond forms between C3 of one nucleotide and the phosphate of adjecent nucleotides -forms sugar-phosphate backbone
41
what are purines complementary to?
pyrimidines
42
what are purines?
2 carbon nitrogen ring bases -adenine -guanine (Pure As Gold)
43
what are pyrimidines?
1 carbon nitrogen ring bases -cytosine -uracil -thyine (pyramids CUT)
44
describe and explain the structures and functions of DNA
S=hydrogen bonds which join the 2 strands are weak bonds F= allows easy separation of strands during DNA replication and protein synthesis S= two strands F= both can act as a template in DNA replication S=many hydrogen bonds between base pairs F= strength, stabalises structure S=complementary base pairing F= accurate DNA replication and transcription and allows a specfic sequence of bases to code for a specific primary structures of protein
45
structure of RNA
-short single stranded polynucleotide chain -pentose sugar is ribose -organic bases are adenine, uracil, guanine and cytosine
46
what are the 3 types of RNA?
-mRNA=messenger RNA - transfers the genetic information from DNA to the ribosome -rRNA=ribosomal RNA - together with proteins makes up the ribosome -tRNA= Transfer RNA- transfers specific amino acids to the ribosome for protein synthesis
47
describe the process of semi conservative replication
1) double helix is untwisted 2)enzyme DNA helicase breaks the hydrogen bonds exposing nucleotide bases 3)both strands act as a template 4) free complementary DNA nucleotide bases hydrogen bond to exposed bases 5)complementary base pairing rule 6)phosphodiester bonds are formed to join sugar phosphate backbone by DNA polymerase 7) one conserved old strand and one new strand
48
what is the active site of DNA polymerase compemenyary to? whats the importance?
the 3' end of deoxyribose. means the enzyme can only add new nucleotides to the new strand at the 3' end because the strands are antiparallel DNA polymerase working on one of the template strands works in the opposite direction to the DNA polymease working on the oher strand
49
who provided evidence for semi conservative replication?
messelson and stahl
50
what did messelson and stahk do?
they grew E coli bacteria for many generations in a medium of 15N-heavy nitrohen
51
why was the DNA in the bacteria grown on 15N denser?
because the bases contained N15
52
describe the steps of the experiment of semi conservtive replication
-E coli grown in 15N DNA us centrifuged in CsCk = heavy DNA band -bacteria transfered to 14N and griw for one generation -DNA is centrifuged in CsCl = hybrid DNA -grown for second generation in 14N -DNA centrifuged in CsCl = 2 bands onr hybrid one light
53
what modes were disproved by messelson and stahl experiment?
-conservative model -dispersive model
54
describe the conservative model
each replication results in one DNA molecule that consists of both original strands of DNA, and one DNA molecule that consists of 2 completely ne strands of DNA
55
describe the dispersive model
each replication results in 2 DNA molecules that are combinations of original and new DNA
56
what does ATP stand for?
adenosine triphosphate
57
describe the structure of ATP
-phosphorylated nucleotides -formed from a nitrogen containing orgaic base = adenine -a 5 carbon ribose sugar -and a chain of 3 phosphate groups
58
whats the advantage of the phosphate bonds in ATP being unstable?
makes ATP a good energy source immediate source as cell cant get energy directly from glucose
59
whats the role of ATP synthase?
catalyses the energy needed by phosphates to form a condensation reaction
60
whats the role of ATP hydrolase?
breaks phosphate bonds releasing small packets of energy in a hydrolysis reaction
61
what is ATP used for?
-phosphorylation of compounds= makes more reactive -active transport = change shape of carrier proteins in plasma membranes- moving molecules agaisnt a conc gradient -metabolic processes -exocytosis -movement = muscle contraction
62
give 2 examples of phosphorylation of compounds
-glucose to glucose phosphate in glycolysis -photophosphorylation in plant cells during photosynthesis
63
give 2 examples of ATPs use in metabolic processes
-synthesising glycogen from glucose -polypeptides from amino acids
64
whats the formula for ATP synthesis?
ADP + Pi = (condensation) ATP + H2O
65
How might a change in the primary structure result in a non-functional enzyme?
A change in amino acid sequence results in different R groups Results in a change in hydrogen / ionic / disulfide bonds Which results in a change in the tertiary structure Which changes the shape of the active site; Substrate is not complementary to the active site so no enzyme-substrate complexes form.
66
Describe the INDUCED FIT model
Enzymes have an active site with a specific shape. Before the reaction the active site is not complementary to the substrate. The active site changes shape and becomes complementary as substrate binds An enzyme- substrate complex is formed This stresses and bends the bonds in the substrate which allows the reaction to occur
67
How do enzymes affect the activation energy?
Enzymes lower the activation energy allowing chemical reactions to take place at lower temperatures than they would otherwise occur (e.g. body temperature).
68
What is the active site of an enzyme and what is it’s function?
It is the functional part of the enzyme that binds to the substrate by becoming complementary to the shape of the substrate. This allows the formation of an Enzyme-Substrate Complex (E-S complex).
69
How will a high substrate concentration affect the number of collisions? with non-comp and comp inhibitor?
non-comp= At high substrate concentrations there are less enzyme-substrate collisions comp= At high substrate concentrations there are more enzyme-substrate collisions
70
explain function of following structures on DNA Sugar-phosphate backbone Helix/Coiling Large Molecule Sequence of bases Double helix with many hydrogen bonds Double stranded/Two strands Double helix Hydrogen bonds between the bases are weak and easily broken Complementary base pairings
Gives strength Gives it a compact shape Stores lots of information Allows information to be stored/codes for amino acids Makes the DNA molecule stable BOTH strands can act as templates during semi-conservative replication Prevents the code being corrupted Allows the strands to be separated for replication and also for protein synthesis Allows accurate replication
71
What is meant by specific base pairing?
Each base is complementary to one other base – this is the one that it binds to. Guanine and cytosine are complementary to each other and therefore ONLY bind to each other Adenine and thymine are complementary to each other and therefore ONLY bind to each other
72
Describe the differences between DNA and RNA (5 marks)
DNA has A,T,C,G bases whereas RNA has A,U,C,G DNA has a deoxyribose sugar whereas RNA has a ribose sugar DNA is double stranded wheras RNA is single stranded DNA is a large polymer RNA is a short polymer DNA holds genetic information in the nucleus whereas RNA transports genetic information to the ribosome
73
Describe the differences between DNA in prokaryotes and Eukaryotes
DNA in eukaryotes is coiled up around proteins called HISTONES whereas the DNA in prokaryotes is not DNA in eukaryotes is linear whereas DNA in prokaryotes is circular DNA in eukaryotes is found in a nucleus, whereas DNA in prokaryotes is in the cytoplasm
74
What is the link between DNA bases, amino acids and a protein?
A sequence of bases codes for a sequence amino acids to form a polypeptide chain which can fold into a protein.

biology year 1 (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions