Biological Molecules Unit 1 Flashcards
(153 cards)
1
Q
What’s a monomer
A
Monomers are the smaller units from which larger molecules are made
2
Q
What’s a polymer
A
Molecules made from a large number of monomers joined together
3
Q
What are the types of monomers?
A
Monosaccharides, amino acids and nucleotides
4
Q
What’s an isomer
A
Same molecular formula different structure
5
Q
What are monosaccharides
A
Monomers of carbohydrates
6
Q
Examples of monosaccharides
A
Glucose, fructose and galactose
7
Q
Glucose exists as 2 isomers
A
α-Glucose has a H above Carbon 1 and an OH below.
β-glucose has a H below Carbon 1 and an OH above
8
Q
What are disaccharides?
A
Made of 2 monosaccharides. Joined by a glycoisidic bond. Formed via a condensation reaction.
9
Q
Examples of disaccharides
A
Maltose, lactose, sucrose
10
Q
What’s a condensation reaction?
A
Joining 2 molecules together and forms a chemical bond and releases water.
11
Q
What’s a hydrolysis reaction?
A
Breaks chemical bond between monomers and uses water
12
Q
Types of polysaccharides
A
Starch, cellulose, glycogen
13
Q
What’s starch created from
A
2 polymers of alpha glucose.
14
Q
Where’s starch found
A
Starch grains inside plant cells
15
Q
What’s the function of starch and glycogen?
A
Insoluble store of glucose
16
Q
Wheres glycogen found
A
In muscle and liver cells on animals
17
Q
Structure of glycogen
A
Highly branched molecule glucose is (easily) released for respiratio Has 1-4 glycosidic bonds and even more 1-6 glycosidic bonds than amylopectin. Can be compacted easily. [ fit large amount of glucose in small space) is a polysaccharide of alpha gluc9se
18
Q
What’s cellulose formed from?
A
Beta glucose
19
Q
Where’s cellulose found
A
Cell wall of plant cells
20
Q
What’s function of cellulose
A
Provid3s structural strength to cell wall
21
Q
Structure of cellulose
A
1-4 glycosidic bonds. Long straight chains line up parallel to eachother. Held in place by many hydrogen bonds. This is a fibril. Provides structural strength due to the number of hydrogen bonds. - individual hydrogen bond is weak
22
Q
How does the structure of starch lead to its function?
A
Helical so compact
Branched structure Branched so glucose is (easily) released for respiration
Large (molecule) so cannot leave cell/cross
cell-surface membrane
Insoluble - won’t affect water potential
23
Q
How does the structure of cellulose lead to its function?
A
Many hydrogen bonds provide collective strength.
Insoluble - won’t affect water potential
24
Q
How does the structure of glycogen lead to the function?
A
- Insoluble (in water), so doesn’t affect water
potential; - Branched helix, so makes molecule compact;
- Polymer of (α-)glucose so provides glucose for respiration;
- Branched so more ends for fast breakdown
- Large so can’t cross the cell membrane
25
What are the 2 groups of lipids?
Triglycerides and phospholipids
26
How are triglycerides made?
Involves 3 seperate condensation reactions with 1 glycerol. Forms 3 ester bonds and 3 molecules of water (since its removed to be bonded)
27
What are R groups
Fatty acids which can be saturated or unsaturated
28
What's the difference between saturated and unsaturated fatty acids?
Saturated fatty acids only have single bonds between carbons. Whilst unsaturated fatty acids have atleast one double bond between carbons
29
Properties of triglycerides (how structure results in properties)
1) Energy storage- due to large ratio of energy- storing carbon- hydrogen bonds compared to the number of carbon atoms, a lot of energy is stored in the molecule
2) due to the high ratio of hydrogen to oxygen atoms they act as a metabolic water source. Triglycerides can release water if they are oxididised. This is essential of animals in the desert ,such as camels.
3) triglycerides do not affect water potential and osmosis. This is because they are large and hydrophobic, making them insoluble in water.
4) lipids have a relatively low mass. Therefore a lot can be stored without increasing the mass and preventing movement
30
What's the structure of phospholipids?
Made of a glycerol molecule two fatty acid chains and a phosphate group. (Attached to the glycerol)
The 2 fatty acids also bond to the glycerol via 2 condensation reactions resulting in 2 ester bonds
31
What happens when phospholipids are put into water?
Arrange themselves in 2 layer structure- phospholipid bilayer. Have 2 charged regions so they're polar, The heads are hydrophilic so they're attracted to water whilst tails are hydrophobic so they are repelled from water.
This forms a phospholipid bilayer membrane structure which makes up the plasma membrane around the cells
32
What are proteins made up of?
Amino acids. Amino group, carboxylic group, R( variable group) hydrogen.
33
Describe how amino acids are joined together to form a dipeptide
Condensation reaction, water is removed. Peptide bond forms between OH of carboxyl and H of amine group
34
What is a protein?
Polymer, made up of the monomer amino acids
35
What is the primary structure of a protein?
Order of amino acids in a polypeptide chain. This is a polymer.
(All joined by several condensation reactions the polypeptide chain holds the amino acids together this is extra info)
36
What is the secondary structure of amino acids?
The sequence of amino acids causes parts of a protein molecule to bend in a helic shapes or fold in b pleated sheets. Secondary structure held in place by hydrogen bonds.
37
Whats the location of the hydrogen bonds in the secondary stage?
Hydrogen bonds form between the C=O groups of the carboxyl group of one amino acid and the H in the amine group of another amino acid
38
What's the tertiary structure of amino acids?
The further folding of the secondary structure to form a unique 3D shape. Held in place by ionic hydrogen and disulphide bonds
39
Wats the location of the ionic and disulfide bonds in the tertiary structure of amino acids?
The ionic and disulfide bonds form between the R groups of different amino acids. Disulphide bonds only sometimes occur, as there must be a sulfur in the R groups for this bond to occur (S----S) (disulphide bond that occurs between 2 different sulfurs)
40
What's the quaternary structure of amino acids?
A protein made up of more than one polypeptide chain.
41
What does it mean if a protein denatured?
If a protein is denatured, this means that bonds which hold the tertiary and secondary structure in shape break, and therefore the unique 3D shape is lost.(eg enzymes lose their unique active site shape)
42
Whys the sequence of amino acids the key importance in the definition ?
(The exact sequence of amino acids is what determines the ionic, hydrogen and disulfide bonds form in a tertiary structure and where those bonds form determines the unique 3d shape. )So, even if one amino acid in the sequence is different then it will cause the ionic/hydrogen/ disulfide bonds to form in a different location. This results in a different 3D shape
Enzymes will have diff shaped active site(will be non functionaling)
Carrier proteins will have a different shaped binding site (molecules no longer complementary and cannot be transported across membranes
43
What might cause a change to amino acid sequence?
Mutations. Change in dna sequence might code for a different amino acid sequence and therefore,primary structure changes
44
What's the role of hydrogen bonds, ionic bonds, and disulfide Bridges in the structure of proteins?
The position of the bond, which is determined by the amino acid sequence, determines how the protein folds. Therefore, the position of the bond determines the final 3D shape and the function of the protein,
45
What are enzymes?
Tertiary structure proteins which catalyse reactions.
Whilst enzymes are Relatively large molecules, it's only a small part of the enzymes that attaches to a substrate to catalyse a reaction. This site is known as active site
46
What do enzymes do. And models
When enzymes attach to the substrate they can lower the activation energy needed for the reaction to occur, and therefore speed up the reaction
Lock and key model and induced fit model
47
What's the lock andkey model
This model suggests that the enzyme is like a lock and that the substrate is like a key that fits into it due to their complementarity in shape.
It suggests that the enzyme acitive site is a fixed shape and that due to random collisions the substrate can collide and attach to the enzyme. This forms an enzyme substrate complex
Once the enzyme substrate complex has formed the charged groups within the active site are though to distort the substrate and therefore lower the activation energy. The products are then released, and the enzyme active site is empty and ready to be reused
48
How do non competitive inhibitors affect enzymes
Non competitive inhibitors attacu to the allosteric site.this causes the active site to change shape. No longer complementary in shape less enzyme substrate complexes form and can't be overcome by increasing substrate
49
What does dna do
Deoxyribonucleic acid (DNA) codes for the sequence of amino acids in the primary structure of a protein, which in turn determines the final 3d shape structure and function of protein.
It's essential therefore that cells contain a copy of genetic code and that it can be passed onto new cells without being damaged
The dna polymer is a double helix
50
What is RNA and function
Is a polymer of a nucleotide formed of a ribose, a nitrogenous base and a phosphate group.
The nutrogenous bases in RNA are adenine, guanine, cytosine, uracil
The function of the RNA is to copy and transfer the genetic code from DNA in the nucleus to the ribosomes. Some RNA is combined with proteins to create ribosomes
51
What's MRNA
Messenger RNA is a single stranded straight chained molecule, made of bases which are read in triplets called codons
It's role is to carry the genetic code out of the nucleus to the ribosome for the formation of 1 polypeptide. 1 codon codes for 1 amino acid
mRNA short because its only the length of one gene
52
What's TRNA
Transfer RNA found in the cytoplasm. It's single stranded but folded to create a shape that looks like a cloverleaf. This shwp3 ishelf by hydrogen bonds.
The function of tRNA is to attacg one of the 20 amino acids and transfers this amino acid to the ribosome to create the polypeptide chain. Specific amino acids attach to specific tRNA molecules and thusis determined by 3 bases found on the tRNA which are complementary to the 3 bases on mRNA
These are called the anticodon because they're complementary to the codon on mRNA
53
What's RRNA
Ribosomal RNA is the type of RNA that makes up the bulk of ribosomes.
54
What's the biomedical test for a reducing sugar
Benedicts reagent.
1) Add excess Benedicts to the test solution
2) Boil the mixture
3) If a reducing sugar is present the solution will change from blue to green, yellow, orange brick red
55
What do reducing sugars mean
It means they can donate electrons to other molecules to reduce them
56
Whas the biochemical test for a non reducing sugar
Sucrose is a non reducing sugar. Negative result with benedicts reagent.
1) add benedicts regeant and heat if it remains blue the following steps
2) add hydrochloric acid and heat it
3) neutralise the acid with sodium hydroxide
4) add benedicts reagent and boil.
5) if the solution now turns red then a non reducing sugar was initially present
57
Biochemical test for starch
Iodine dissolved in potassium iodide reacts with starch, resulting in a colour change from orange - brown to blue black
Qualitative test accurate conc can't be determined.
58
Biochemical test for lipids
1) mix sample with ethanol
2) add water
3) milk white emulsion will appear if the result is positive
59
Suggest how glycogen acts as a source of energy
Hydrolysed to glucose which is then used in respiration
60
Biochemical test for protein
1) add biuret reagent
2) if there's a positive result it turns purple/ lilac
61
How does low pH affect the rate of enzyme controlled reactions
too low a pH will interfere with the charges in the amino acids in the active site due to an excess of H+ ions.
This can break the ionic and hydrogen bonds holding the tertiary structure in place and therefore the active site changes shape. Therefore the enzyme denatures and fewer enzyme - substrate complexes form
62
How does high pH affect rate of enzyme controlled reactions
Too high a pH will interfere with the charges in the amino acids in the active site due to an excess of OH- ions
This can break the ionic and hydrogen bonds holding the tertiary structure in place and therefore the active changes shape. Therefore the enzyme denatures and fewer enzyme substrate complexes form.
63
How does enzyme concentration affect enzyme controlled reactions?
At a low concentration, enzyme concentration is the limiting factor so as more enzyme is added, the rate increases as there will be more available active sites.
The rate plateaus at high enzyme concentrations because the substrate concentrations the limiting rate.
64
Describe how substrate concentration effects enzyme controlled reactions
At low concentrations, the substrate concentrations thelimit8ng factor. As more substrate is added the rate increases as there will be more successful collisions between the enzyme and substrate
65
What's dna replication
Dna replication occurs during interphase. It ensures accurate replication of DNA before a cell divides
The process of dna replication is semi Conservative replication. (New molecule of dna contains one original strand and one strand which is newly synthesised)
66
Process of DNA replication
1) DNA helicase seperates the DNA strands by breaking the hydrogen bonds between base pairs
2) each strand acts as a template.
3) Free DNA nucleotides attach to the exposed bases by complementary base pairing
4) DNA polymerase joins nucleotides on new strands forming a phosphodiester bond.this creates the sugar phosphate backbone. H bonds reform
5) each new molecule of DNA contains one original strand and one new strand, made up of new nucleotides.
67
Semi Conservative replication hypothesis
Each replicated dna molecule contains one of the original DNA strands strand and one newly synthesised dna strand
68
Function of ATP
Immediate source of energy for biological processes. Metabolic reactions in cells must have a constant, steady supply of ATP
69
ATP STRUCT7RE
Adenine , a nitrogenous base ribose and 3 inorganic phosphate groups (bc the don't contain any carbon atoms)
70
How's ATP produced
ATP is made during respiration from ADP, adenine diphosphate, by the addition of an organic phosphate via condensation reaction and using the enzyme ATP synthase.
This takes energy to create
71
How atp an immediate source of energy
ATP can be hydrolysed into ADP + Pi using enzyme ATP hydrolase.
The bonds between the phosphate groups are weak and are easily hydrolysed, when the terminal bonds hydrolysed energy's released
Small amount of energy released
72
How can ATP transfer energy
ATP can also transfer every to different compounds. The inorganic phosphate released during the hydrolysis of ATP can be bonded onto different compounds to make them more reactive . This is known as phosphorylation and this happens to glucose at the start of respiration to make it more reactive
73
Properties of ATP. Atp vs glucose
Immediate energy souce
1) releases energy in small manageable amount so no energy is wasted (so cells don't overheat)
2) it's small and soluble to easily transported around the cell
3)only 1 bond has to be hydrolysed in one step to release energy (glucose would need several bonds to be broken
4)it can transfer energy to another molecule by transferring one of its phosphate groups
5)atp can't leave cells through membranes(cell can run out of glucose but will always have constant supply of ATP
74
Biochemical test to confirm presence of amylase
Add biuret solution, becomes purple
Add start(leave for a bit) test for reducing sugar
75
ATPs uses and properties as an energy source 5 mark
1) releases relatively small amount of energy/little energy lost as heat
2) releases energy instantaneously
3) phosphorylates other compounds, making them more reactive
4) can be rapidly re synthesises
5) doesn't leave cells
76
ATP structure compared with DNA nucleotide
1) atp has ribose and DNA has ozy ribose
2) ATP has 3 phosphates and DNA nucleotide has 1 phosphate
3) base is always adenine in atp whilst in dna they vary, (agc or t)
77
Structure of water
Bipolar molecule. Has an uneven distributed charge as oxygen is slightly negative and hydrogen are slightly positive
78
Five properties of water
Hydrogen bonds form Between water molecules between the oxygen and a hydrogen atom.
1) it's a metabolite In condensation/eg more
2) solvent so metabolic reactions can occur
3) high specific heat capacity, so buffers changes in temperature
4) has high latent heat of vaporisation, providing a cooling effect with loss of water through evaporation
5) has strong cohesion between water molecules, this supports water coloumns and provides surface tension
79
What does water being a metabolite mean
Waters involved in many reactions eg photosynthesis hydrolysis ans condensation
One reas
80
What does water being a good solvent mean
Many substances dissolve in it due to the fact that its dipolar. Acts as transport medium as some chemicals dissolve n it eg blood
81
What does water having high specific heat capacity mean
A lot of energy is required to raise the temperature of water. This is because some of the heat energy is used to break the hydrogen bonds between water molecules . Prevents large fluctuations in water temp
82
What does water having a large latent Heat of vaporisation mean
Lot of energy is required to convert water in its liquid state to a gaseous state. Cooling effect
83
What does water having a strong cohesion mean
Water molecules stick together by hydrogen bonds
Provides high surface tension- allows some organism to walk on surface
Tall coloumns of water can be drawn up xylem vessels in tall trees
84
What's an ion
Charged particle that has either chained or lost electrons
85
Sodiums function
Used in the co port of glucose because sodium moved by active transport. Creates sodium concentration and affects water potential
86
Hydrogen function
Changes the pH of the solutions by making it more acidic
Can also be used to create electrochemical gradients in the production of ATP
87
Iron function.
Component of heamaglobin in red blood cells
Haemoglobin binds with oxygen
88
Phosphate funtion
Joins nucleotides in dna, used to produce atp
Affects water potential and phosphorylates and is hydrophilic
89
What's a polymer
Long chains made up of many monomers chemically bonded together in a repeating pattern
90
Student investigated difference in reducing sugar of 2 juices. He used colorimeter with each test result.
Describe how results from colorimeter can identify fruit juice containing higher sugar content
Higher absorbance (has more sugar)
Lower transmittion (has more sugar)
91
Other method other than using colorimeter to measure the quantity of reducing sugar in a solution
Filter and dry the precipitate
Find mass
92
Why would using a colorimeter in investigation improve the repeatability of results
Quantitative
93
What is the function of phospholipids
To form a phospholipid bilayer in cell membranes and cell organelles
94
Give the differences in the structure and properties of triglycerides and phospholipids
1. Both contain ester bonds
2. Both contain glycerol;
3. Fatty acids on both may be saturated or unsaturated;
4. Both are insoluble in water;
5. Both contain C, H and O but phospholipids also
contain P;
6. Triglyceride has three fatty acids and phospholipid has two fatty acids plus phosphate group;
7. Triglycerides are hydrophobic and phospholipids have hydrophilic and hydrophobic region;
8. Phospholipids form bilayer (in water) but triglycerides don’t;
95
Describe the biochemical test for lipids
Emulsion test
Add ethanol then water and mix
A milky emulsion forms
96
Explain why a phospholipid has both hydrophobic and hydrophilic regions
Phospholipid has hydrophilic head
Since the phosphate group has a negative charge and so attracts water
And a hydrophobic tail
Since the fatty acids have no charge and so repel water
97
Describe how a triglyceride molecule is formed
One glycerol and three fatty acids
Condensation and removal of 3 molecules ofbwater
Ester bonds formed
98
Why would scientists use a data logger to measure the length of the root rather than a ruler
To increase accuracy because reduces risk of human error
99
Explain why phospholipids can form a bilayer but triglycerides cannot
Phospholipid polar/ both hydrophobic and hydrophilic
Triglycerides only hydrophobic
Hydrophilic attracts water
100
If % of unsaturated fatty acids increased how would this increase fluidity
Increase in fluidity caused by increased unsaturated fatty acids
Unsaturated fatty acids cause bend in fatty acid tail
101
Give the difference between globular and fibrous proteins
Globular are soluble proteins and biochemical function is enzymes and hormones
Fibrous are insoluble proteins and have structural functions
Eg keratin In naiks and hair
102
Describe how a peptide bond is formed between 2 amino acids to form a dipeptide
Condensation reaction
Between amine and carboxyl
103
Describe how the secondary structure of a polypeptide is produced by bonds between amino acids
Hydrogen bonds
Between NH group of one amino acid and C=O group
104
Explain why 2 proteins have same number of amino acids but different tertiary structure
3 marks
Different sequence of amino acids
Form ionic/hydrogen/disulfide bonds in different places
Resulting in different folding and 3d shape
105
Describe how a quaternary protein is formed from its monomers
Amino acids joined by peptide bonds
By condensation reaction
Secondary structure is formed by hydrogen bonding
Tertiary structure formed by interactions between R groups
Quaternary structure contains more turn one polypeptide
106
A solution contained mixture of 3 amino acids, scientists passed electric current
Why would 2 move to the negative electrode and one is further away
Because positively charged
Spots move different distances bc they have different charge
One spot has 2 amino acids becuase they have the same charge
107
Describe the effect of temp on the rate of activity of amylase
Using gtapj
Rate increases from (temp to temp)
Increase in kinetic energy
More successful collisions
Optimum is (highest rate reached on graph)
Above optimum rate or reaction decreases
Bc hydrogen bonds break
Active site changes shape so less enzyme substrate complexes formed
108
Why would reaction come to end / become slower
Enzyme denatured breaking of hydrogen bonds
Less enzyme substrate complexes formed
109
Explain how the active site of an enzyme causes a high rate of reaction
Lowers activation energy
Induced fit causes active site to change shape
So enzyme substrate complex cause bonds to break
110
Student investigated effect of substrate concentration without inhibitor and it had the largest rate why? 2 marks
(Graph)
Increases bc more enzyme substrate complexes are formed
Levels off because all enzyme molecules involved in enzyme substrate complexes
111
Describe the structure of DNA
Polymer of nucleotides
Each nucleotide formed from deoxyribose, phosphate nitrogenous base
Phosphodiester bonds
Double helix
Hydrogen bonds between adenine thymine and cytosine guanine
112
Compare and contrast the structure of RNA and DNA 5 marks
Both polynucleotides
Both joined by phosphodiester bonds
Dna is a long molecule while RNA is short
Dna has deoxyribose sugar whilst rna has oxyribose
Dna has thymine in base whilst rna has uracil
113
Describe how the structure of DNA is related to its functions 6 marks
dna is long so It allows information to be stored
dna is double stranded so each strand can be used as a template for dna replication
Dna has sugar phosphate backbone which provides strength and stability
Dna has weak hydrogen bonds so it can be easily unzipped for dna replication
Dna is a helix so it's compact
Dnas base sequence allows information to be stored
114
Describe how the structure of DNA results in accurate replication
1) 2 strands therefore semi Conservative replication possible
2) hydrogen bonds hold strands together
3) hydrogen bonds weak allows strands to seperate
4)bases act as a template
5) complementary copy
6) DNA has one original strand and only newly synthesised strand
115
Whys DNA helicase important in DNA REPLICATION
Because it seperates the DNA strands by breaking the hydrogen bonds so nucleotides can attach
116
Describe the role of DNA polymerase
Joins nucleotides
Catalyses condensation reactions
Catalyses formation of phosphodiester bonds
117
Describe how an enzyme can be phosphorilated
Attachment of inorganic phosphate
Released from hydrolysis of ATP
118
Whys ATP important in biological processes 4 marks
1) releases energy in small amounts
2) broken down in one step
3) phosphorylates
4) reformed
119
What does water being polar mean
Acts as solvent
120
Explain how the organic bases in DNA help to stabilise the structure of It
Hydrogen bonds between base pairs
Holds 2 strands together
Many hydrogen bonds provide strength
121
Describe how a phosphodiester bonds formed between 2 nucleotides within a DNA molecuke 3 marks
Condensation reaction forming phosohodiester bond between phosphate group and deoxyribose and the removal of water
Catalysed by DNA polymerase
122
Name the protein associated with the DNA in a Chromosome
Histose
123
Explain why new nucleotides can only be added in a 5' to 3' direction 3 marks
Dna polymerase synthesises new DNA strands which is specific
Only complementary with 3' end of strand
Shapes of 5' end and 3' are different
124
Give 2 ways in which the hydrolysis of ATP is used in cells
To provide energy for other reactions
To add phosphate to other substances & make them more reactive
125
Describe competitive and non competitive inhibition of an enzyme. 5 marks
Inhibitors reduce binding of enzyme to substrate
Competitive- similar shape to substrate. Binds to active site. Can be overcome by substrate
Non competitive- binds to allosteric site. Changes shape of active site . Cannt be overcome by adding more substrate
126
What's a t test
Looking for differences between 2 means
Differences are significant
127
How would students know pH of solution didn't change
Use buffer
128
What happens in graph with high temperature when reaction stops earlier and it goes straight across
High temp causes denaturation of all of enzyme
Reaction stops sooner because shape of active site changed
Substrate still available but no converted to product
129
How do formation of enzyme substrate complexes increase the rate of reaction? 2 marks
Reduces activation energy due to bending bonds
130
Student investigated affect of lipase concentration on the hydrolysis of lipids
He placed pH probe. Why did he not use buffer
Student was measuring change in pH
( buffer would maintain pH)
131
How to test piece of food for presence of lipid
Dissolve In alcohol then adds water
White emulsion test shows presence of lipids
132
What's the role of bases on one strand of DNA
Determines sequence of amino acids
133
What's the role of single stranded dna fragments 1)
2) dna nucleotides
1)acts as template and determines order of nucleotides
2) joins complementary pairs
134
Arrows in figure 2 show Directions in which new dna strands being produced
Explain why arrows point in different directions 4 marks
DNA has antiparallel strands
Shape of nucleotide is different
Enzymes have an active site with specific shape
Only 3' end can bind with active site of enzyme
135
Compare and contrast the processes by which water and inorganic ions enter cells
Both move down concentration gradient
Both move through channels in membrane
Ions can move against a concentration gradient by active transport
136
2 properties of water that would be important in cytoplasm
Polar molecule so as solvent
Solvent so reactions occur faster in solution
137
Why is DNA replication described as semi Conservative
Each strand acts as template
Dna molecule contains one original strand and one newly synthesised strand
138
Give 2 ways prokaryotic dna is different from eukaryotic dna
Non linear
Not associated with protein
139
What's standard deviation and advantages of it instead of the range
Measure of how spread out your repeats are from your mean
Range only diff between higher and lowest value whilst sd shows spread of data around mean
Sd reduces affect of anomalies
140
Name the type of petidase which will hydr9l6se tye bond formed in a polypeptide chain
Endopetidase
141
Describe the induced fit model
Substrate binds to the active site
Active site changes shape so it's complementary to substrate
Reduces activation energy
142
Draw diagram to show structure of Triglyceride
H2-C-OOCR
H -C- OOCR
H2-C.- OOCR
glycerol has 3 OH groups and its prop. fatty acid is just carboxyl with R at end
143
describe induced fit model
before reaction active site not complementary.
shape of active sit changes as substrate binds
bending bonds reduced activation energy
144
In which direction is DNA replicated in
New DNA strands are replicated in a 5' to 3' direction. Polymerase enzymes have an active site which is complementary and specific to the 3' end of the DNA chain. this means that new nucleotides are added in the 5' to 3' direction.
dna replication 5' to 3'
dna polymerase 3' to 5'
145
Meselson and Stahl experiment
proved that DNA replicated in a semi-conservative fashion, rather than dispersive and conservative.
grew E Coli bacteria in a broth containing Nitrogen. This originally contained a heavy isotope of Nitrogen(15N). The E Coli incorporated the 15N into any newly
made nucleotides. After a while they transferred a sample of E Coli from the 15N broth into a broth containing a lighter isotope (14N) of Nitrogen – now any time the E Coli made new nucleotides they would incorporate the 14N making this DNA less dense the DNA containing
15N
The first generation of DNA
molecules contained both heavy and light DNA so ruled out conservative replication. The second generative of DNA contained intermediate molecules and molecules which only contained light DNA, this ruled out dispersive, proving that semi-conservative was the correct mode of DNA replication
parental dna most dense so at bottom, first gen in middle as its mkix and second gen is at most top.
146
how can cancer form
uncontrolled mitosis
147
dna vs RNA
1. Polymers of nucleotides;
2. (Nucleotide has) pentose, base and a phosphate (group);
3. Cytosine, guanine and adenine (as bases);
4. Have phosphodiester bonds;
5. Deoxyribose v ribose;
6. Thymine v uracil;
7. Long v short;
8. Double helix/stranded v single stranded
148
how are monomers join together to form primary structure of protein
Condensation reaction between amino acids;
2. (Forming) peptide bonds;
3. Creating (specific) sequence/order of amino acids
149
Describe one similarity and one difference between the induced-fit model of enzyme action
and the lock and key model of enzyme action.
Substrate binds to active site
active site not complementary to substrate with induced-fit, but is
complementary in lock and key;
150
Give one feature of the chloroplast that allows protein to be synthesised inside the
chloroplast and describe one difference between this feature in the chloroplast and similar
features in the rest of the cell.
DNA
Is circular but nuclear DNA is linear
151
Explain the arrangement of phospholipids in a cell-surface membrane
Bilayer
2. Hydrophobic (fatty acid) tails point away from water
Hydrophilic (phosphate) heads point to water/are attracted to water
152
a virus has 31% adenine and 23% thymine
why is the structure if this virus different from other organisms 2 marksb
A doesnt equal T
No base pairing
153
In humans, the enzyme maltase breaks down maltose to glucose. This takes place at normal body temperature explain why maltose only breaks down maltose 5 marks
1. Tertiary structure of enzyme (means)
2. Active site complementary to maltose
3. Description of induced fit( maltose binds to enzyme forming enzyme substrate complex]
4. Enzymes a catalyst so lowers activation energy
5. By forming enzyme substrate complex
