Topic 1 - Biological Molecules Flashcards
1
Q
Define a monomer
A
Are the smaller units from which large molecules are made.
2
Q
Define a polymer
A
Are molecules made from a large number of repeating monomers joined together via polymerisation.
3
Q
What are monosaccharides?
A
Monomers.
4
Q
Name 3 monosaccharides
A
Amino acids, glucose and nucleotides.
5
Q
What are polysaccharides?
A
Polymers.
6
Q
Name 3 polysaccharides
A
Starch, glycogen and nucleic acids.
7
Q
Define a condensation reaction
A
Joins 2 molecules together with the formation of a chemical bond and involves the elimination of water.
8
Q
Define a hydrolysis reaction
A
Involves the breakdown of a chemical bond between 2 molecule and involves the use of a water molecule.
9
Q
What monosaccharides make up maltose?
A
2 glucose.
10
Q
What monosaccharides make up sucrose?
A
Glucose and fructose.
11
Q
What monosaccharides make up lactose?
A
Glucose and galactose.
12
Q
Where is the hydroxyl group on an alpha-glucose molecule?
A
On the bottom (same as left).
13
Q
Where is the hydroxyl group on a beta-glucose molecule?
A
On the top.
14
Q
What formula do hexose sugars have?
A
C6 H12 O6
15
Q
What bond joins 2 alpha-glucose molecules?
A
Glycosidic.
16
Q
What type of sugars are oxidised?
A
Reducing sugars.
17
Q
What is the only mono/disaccharide that gives a negative result in the Benedict’s test?
A
Sucrose.
18
Q
What is the qualitative Benedict’s test for a reducing sugar?
A
- Small sample into test tube with equal volume of Benedict’s solution.
- Heat in a water bath to over 80c.
- Positive=red precipitate Negative=blue
19
Q
What type of Benedict’s test doesn’t allow you to compare results from different samples?
A
Qualitative test (shorter).
20
Q
How do you compare results in the semi-quantitative Benedict’s test?
A
Compare the amount of precipitate visible in each sample.
21
Q
What is a negative about the semi-quantitative Benedict’s test?
A
Its subjective.
22
Q
What is the quantitative Benedict’s test?
A
- Perform the Benedict’s test on reducing sugar solutions of known concentrations.
- Use a colorimeter to measure the absorbance of each of the know solutions.
- Plot a calibration curve (x=concentration) and (y=absorbance value)
- Repeat the Benedict’s test with the unknown sample
- Use the absorbance value of the unknown to read off the calibration curve to find out its concentration.
23
Q
What is the test for a non-reducing sugar (sucrose)?
A
1.Carry out the Benedict’s test on a small sample to confirm a negative result.
2. Hydrolyse another sample of sucrose by boiling it with dilute acid.
3. When cooled, neutralise the acid with an alkali.
4. Add the same amount of Benedict’s solution and heat in a water bath.
5. A positive brick red precipitate will form indicating sucrose was originally present.
24
Q
Are polysaccharides reducing or non-reducing?
A
Non-reducing.
25
Name the polysaccharides found in human
Glycogen.
26
Name the 2 polysaccharides found in plants
Cellulose and starch.
27
What monomer composes starch and glycogen?
Alpha-glucose.
28
What monomer composes cellulose?
Beta-glucose.
29
What are the properties of starch?
-Large (can't cross the cell-surface membrane).
-Insoluble (osmotically inactive).
-Helical (compact store).
-Branched (glucose easily released for respiration).
30
Which of amylose and amylopectin are straight?
Amylose.
31
Describe the test for starch
1. Add 2-3 drops of potassium/iodide solution.
2. Positive=blue/black Negative=orange/yellow
32
What are the properties of glycogen?
-Insoluble (osmotically inactive).
-More branched than starch (rapid hydrolysis).
33
Where is cellulose found?
Cell wall of plants.
34
What is different about the arrangement of monomers in cellulose?
Every other molecule of glucose is inverted so that the hydrogen bonds line up.
35
What do the hydroxyl groups in cellulose produce?
3D structure known as microfibril which provides strength.
36
What elements compose proteins?
Carbon
Hydrogen
Oxygen
Nitrogen
Sometimes sulfur
37
What can proteins also be known as?
Polypeptides.
38
What do amino acids contain?
Amine group (NH2) and a carboxylic acid group (COOH) but have different R groups.
39
What is the structure of an amino acid?
Differing R groups
I
H2N - C - COOH
I
H
40
What bond joins amino acids together?
Peptide.
41
What does the condensation of 2 amino acids form?
Dipeptide.
42
What does the condensation of more than 2 amino acids form?
Polypeptide.
43
What does the primary structure of proteins refer to?
The sequence of amino acids in the polypeptide chain, which determines the specific shape of the protein.
44
What does the secondary structure of proteins refer to?
The folding or coiling of the polypeptide chain as a result of the hydrogen bonding between amino acids.
45
What does the tertiary structure of proteins refer to?
Further folding or coiling of the secondary structure due to hydrogen, ionic and disulfide bonds (between R groups). This determines an enzymes active site and its precise function.
46
What does the quaternary structure of proteins refer to?
Highly complex proteins consisting of more than 1 polypeptide chain.
47
Which bonds in a protein are typically broken during denaturing?
Hydrogen and ionic.
48
What is the test for proteins?
1. Add biuret reagent
2. Purple/lilac = positive
3. Blue = negative
49
What do enzymes lower?
Activation energy.
50
What do enzymes form which help lower activation energy?
Enzyme-substrate complexes.
51
What does the induced fit model represent?
Enzymes slightly changing shape by molding itself around the substrate so that it is complementary.
52
How does substrate concentration affect rate of reaction?
Higher substrate concentration increases rate of reaction until enzymes are limiting factor.
53
What shape is the graph of substrate concentration affecting rate of reaction?
Curved.
54
How does enzyme concentration affect rate of reaction?
Higher enzyme concentration increases rate of reaction until substrates are limiting factor.
55
What shape is the graph of enzyme concentration affecting rate of reaction?
Proportional then levels of suddenly.
56
How does temperature affect rate of reaction?
Higher temperature increases rate of reaction due to more kinetic energy of the molecules resulting in more successful collision per second.
Enzymes can denature due to higher temperature of usually 50c, altering active site.
57
What shape is the graph of temperature affecting rate of reaction?
Upwards sloping until optimum temperature then decreases.
58
How does pH affect rate of reaction?
Enzymes functioning at their optimum pH increases rate of reaction.
59
How do enzymes inhibitors affect rate of reaction?
Slow down the rate of which enzymes catalyse reactions.
60
How do competitive inhibitors affect rate of reaction?
Have a similar structure to the substrate competing for the active site.
Reduces the rate of reaction because inhibitors restrict the presence of enzyme-substrate complexes from forming.
61
How can competitive inhibition be mitigated in a reaction?
Adding more substrate.
62
What is the shape of the graph of competitive inhibitors affecting rate of reaction?
Curve is not as steep but plateaus at same y-value as a non-inhibited reaction.
63
How do non-competitive inhibitors affect rate of reaction?
Not similar in structure to substrate.
Binds to anything other than active site of enzyme, altering tertiary structure of protein thus active site changes.
Enzyme-substrate complexes no longer form.
64
What shape is the graph of non-competitive inhibitors affecting rate of reaction?
Graph is not as steep as a non-inhibited reaction and plateaus at lower y-value than the non-inhibited reaction.
65
What elements are present in lipids?
Carbon
Hydrogen
Oxygen
66
Name 2 types of lipids
Triglycerides and phospholipids.
67
What are triglyceride molecules composed of?
3 fatty acids and 1 glycerol in a condensation reaction.
68
What bond joins 3 FAs and 1 glycerol molecule?
Ester bonds.
69
What do saturated fatty acids contain?
No double bond between carbon atoms.
70
What do unsaturated fatty acids contain?
1 or more double bonds between carbon atoms.
71
Why are triglycerides not polymers?
Fatty acids and glycerol molecules are not the same, not repeating monomers.
72
What composes a phospholipid?
2 fatty acids
1 glycerol
1 phosphate group
73
What is the structure of a phospholipid?
Hydrophilic phosphate head
Hydrophobic fatty acid tails
74
Where can phospholipids be found?
Cell surface membrane.
75
What is the test for lipids?
1. Small amount of sample is placed in a test tube with ethanol
2. Shake the mixture allowing the fat to dissolve
3. Add this to water and mix the contents
4. White emulsion of fat droplets=positive
76
What are DNA and RNA?
Nucleic acids (polynucleotides).
77
What is the name of the sub-units making up DNA and RNA?
Nucleotides.
78
What is DNA composed of structurally?
Deoxyribose pentose sugar
Nitrogen-containing organic base
Phosphate group
79
What bond joins 2 polynucleotides strands together?
Hydrogen bonds.
80
What are the 4 nitrogen containing bases in DNA?
Cytosine
Adenine
Thymine
Guanine
81
What bases are complementary to each other in DNA?
Adenine and thymine
Cytosine and guanine
82
What orientation do the chains of DNA run?
Antiparallel to each other.
83
How does the sugar-phosphate backbone help the function of DNA?
Gives strength.
84
How does the helix shape help the function of DNA?
Compact shape
Protects the sequence of bases
85
How does the double stranded composition of DNA help with its function?
Each strand serves as a template in replication
Protects the sequence of bases
Makes the molecule more stable
86
How does the composition of DNA being a large molecule help with its function?
Large amount of information can be stored.
87
How does the high amount of hydrogen bonds within DNA with its function?
Gives stability
Individual hydrogen bonds are weak allowing helix to unzip easily for replication
88
How does the sequence of bases within DNA help with its function?
Codes for the specific sequence of amino acids in a polypeptide.
89
How do the complementary base pairings help DNA with its function?
Enables information to be replicated accurately.
90
What is the first stage of DNA replication involving DNA helicase?
DNA helicase unwinds the double helix and breaks the hydrogen bonds between the complementary bases of the 2 polynucleotide strands.
91
What is the second stage of DNA replication?
Each strand as a template for the formation of 2 new complementary strands, and free DNA nucleotides align and attach by hydrogen bonding to the exposed bases. Each base being complementary to the sequence.
92
What is the third stage of DNA replication involving DNA polymerase?
DNA nucleotides in each new strand are joined together via phosphodiester bonds by DNA polymerase to form complementary strands to the original DNA strands.
93
What bonds does DNA polymerase for between the nucleotides?
Phosphodiester bonds.
94
Why is DNA replication semi-conservative?
Because each new DNA molecule contains an original DNA strand a 1 new DNA strand.
95
What is RNA composed of structurally?
Pentose sugar ribose
Nitrogen-containing organic base
Phosphate group
96
What are the difference between DNA and RNA?
DNA is Deoxyribose pentose, RNA is ribose pentose
DNA contains thymine, RNA replaces this with base with uracil
DNA is double stranded, RNA is single stranded
97
What does ATP stand for?
Adenosine Triphosphate.
98
What is ATP composed of structurally?
Pentose sugar (ribose)
Adenine
3 phosphate groups
99
What is ATP constantly undergoing?
Hydrolysis of phosphate groups for energy and resynthesis.
100
What is enzyme is involved in hydrolysing ATP?
ATP hydrolase.
101
What does ATP hydrolase do?
Using water to split ATP into ADP and an inorganic phosphate (pi).
102
What is phosphorylation?
Adding phosphate to other compounds.
103
What enzyme is involved in resynthesizing ATP?
ATP synthase.
104
What does ATP synthase do?
Condensation reaction between ADP and an inorganic phosphate (pi) with the use of energy and the release of water.
105
Name 5 processes in which ATP can be used for
Photosynthesis
DNA replication
Cell division
Active transport
Muscle contraction
106
In what 3 situations does water help with?
Metabolic reactions
Solvent
Temperature regulation
107
How does water help in metabolic reactions?
Acts as metabolite for reactions such as condensation and hydrolysis to take place.
108
How does water help as a solvent?
Transports nutrients around organisms
Removes excretory products such as urea
Is a medium in which metabolic reactions occur
109
How does water help in temperature regulation?
Has a high specific heat capacity so it can absorb a lot of energy before rising in temperature
Has a high latent heat of vaporisation providing a cooling effect with little loss of water through evaporation.
110
What role does sodium help with?
Co-transport of glucose and amino acids across cell membranes.
111
What role does iron help with?
Component of haemoglobin which transports oxygen.
112
What role does hydrogen help with?
Important in determining pH and thus affecting protein structure and enzyme activity.
113
What role does phosphate help with?
Important as a structural component of DNA, RNA and ATP.
