1) Biological Molecules Flashcards
1
Q
What is the basic unit of starch?
A
Alpha glucose
2
Q
What is the basic unit of glycogen?
A
Alpha glucose
3
Q
What is the basic unit of cellulose?
A
Beta glucose
4
Q
What is the structure of starch? (3 points)
A
- 30% amylose (a spiral with 1,4 bonds)
- 70% amylopectin (has branches with 1,4 and some 1,6 bonds)
- combined to give appearance of tightly wound molecule
5
Q
What is the structure of glycogen? (3 points)
A
- has 1,4 and 1,6 bonds
- similar structure to amylopectin, however is further branched
- branched structure
6
Q
What is the structure of cellulose? (2 points)
A
- has 1,4 bonds
- straight chains of beta glucose units
7
Q
What is the function of starch?
A
Main storage molecule in plants
8
Q
What is the function of glycogen?
A
Main storage carbohydrate in mammals
9
Q
What is the function of cellulose?
A
Gives plant cell walls their structural strength
10
Q
How does the structure of starch aid the function? (3 points)
A
- must be quite big so it isn’t soluble; this prevents an osmotic effect
- must be compact to hold its content
- can be easily hydrolysed to soluble sugars
11
Q
How does the structure of glycogen aid the function?
A
It needs to meet the superior energy demand of animals, so the long branched structure enables a quicker build up and break down of glycogen
12
Q
How does the structure of cellulose aid the function?
A
Given their strength as they are made of microfibrils
13
Q
How are microfibrils made? (cellulose)
A
When hydrogen bonds form as the straight beta glucose chains are laid next to each other, strengthening them into larger sub units
14
Q
What is a condensation reaction?
A
Joins 2 or more monosaccharides
15
Q
What is released in a condensation reaction?
A
Water
16
Q
What bond is formed in a condensation reaction?
A
Glycocidic
17
Q
What is a hydrolysis reaction?
A
Separating of polysaccharides into disaccharides or monosaccharides
18
Q
What does hydrolysis USE?
A
Water
19
Q
What are energy sources for cells?
A
Monosaccharides and disaccharides
20
Q
What are monosaccharides and disaccharides energy sources for?
A
Cells
21
Q
What is the simplest carbohydrate?
A
Monosaccharide
22
Q
How many sugar molecules in a monosaccharide?
A
1
23
Q
What monosaccharides are reducing sugars?
A
- glucose
- fructose
- galactose
24
Q
What does the condensation of 2 monosaccharides form?
A
Disaccharide
25
What does the combination of 2 glucose monosaccharides form?
Maltose
26
What makes up maltose?
Glucose + Glucose
27
What does the combination of glucose and fructose monosaccharides form?
Sucrose
28
What does the combination of glucose and galactose monosaccharides form?
Lactose
29
What makes up sucrose?
Glucose + Fructose
30
What makes up Lactose?
Glucose + Galactose
31
What disaccharides are reducing sugars?
- maltose
| - lactose
32
What disaccharide is a non-reducing sugar?
Sucrose
33
What is polysaccharide?
Long polymers; many monosaccharides and disaccharides combined
34
What are examples of polysaccharides?
- starch
- glycogen
- cellulose
35
What test can be used for reducing sugars?
Benedicts solution test
36
What test can be used for starch?
Iodine in potassium iodide
37
How do you carry out the benedicts test for reducing sugars?
Heat the benedicts solution with the sugar at least at 73degreesC
38
What shows a positive result for reducing sugars in the benedicts test?
The solution will turn from blue to dark red
39
How do you carry out the iodine in potassium iodide test for starch?
Mix it with the reducing sugars
40
What shows a positive result for starch in the iodine test?
It will turn from orange to blue/black
41
What carbohydrates contain glucocidic bonds?
Disaccharides and Polysaccharides
42
What is the only part of the animo acid that distinguishes them from each other?
The carbon containing variable group
43
What test can be used for proteins?
Biuret test
44
How do you carry out the biuret test for proteins?
1) Add some sodium hydroxide solution to make the test solution alkaline
2) Add some copper sulphate solution
45
Why do you add sodium hydroxide to the test solution when testing for proteins?
To make the solution alkaline
46
What colour does the positive biuret test for protein show?
Purple
47
What colour does the negative biuret test for protein show?
Pale blue
48
How are amino acids linked?
In a simple condensation reaction that releases a water molecule
49
What are the bonds between amino acids called?
Peptide bonds
50
How many amino acids in a dipeptide?
2
51
How many animo acids in a polypeptide?
More than 2
52
What are the 4 main functions of proteins?
- enzymes
- antibodies
- transport proteins
- structural proteins
53
Explain enzymes as a function of proteins
They are soluble and have roles in metabolism and synthesis
54
Explain transport proteins as a function of proteins
Transport molecules and ions across membranes
55
Explain antibodies as a function of proteins
They are involved in immune responses
56
Explain structural proteins as a function of proteins
They are physically strong with cross linked polypeptide chains
57
Describe Collagen (6 points)
- secondary structure
- lots of glycine to help close packing
- insoluble in water
- has structural functions
- fibrous (skin/tendon/cartilage/bone)
- formed when superhelix's form (3 polypeptide chains form then join to form collagen)
58
Describe Haemoglobin (4 points)
- tertiary structure
- globular protein
- contains iron
- metabolic functions such as hormones and antibodies
59
Describe the primary structure of proteins (3 points)
- order and length of an amino acid chain
- straight chain of animo acids
- amino acids held together by peptide bonds
60
Describe the secondary structure of proteins (3 points)
- hydrogen bonds form and cause the chain to change
- coils into alpha helix
- folds into beta helix sheets
61
Describe the tertiary structure of proteins (4 points)
- further bending and coiling of chains to form a specific 3D shaped protein with more bonds forming
- hydrogen bonds
- ionic bonds
- disulphide bridges
62
Describe hydrogen bonds
Easily broken
63
Describe ionic bonds
- easily broken
- stronger than disulphide bridges
- formed between any carboxyl and amino acid
64
Describe disulphide bridges
- strong and not easily broken
- formed when 2 molecules of cytosine come together
- cytosine is an amino acid
65
Describe the quarternary structure of proteins
Linking of several polypeptide chains to make a more complex protein
66
Give 3 examples of proteins with a quarternary structure
- haemoglobin
- insulin
- collagen
67
What 3 types of atom do lipids contain?
- carbon
- hydrogen
- oxygen
68
In what 3 states do lipids exist?
- fats
- oils
- waxes
69
How is a triglyceride formed?
The condensation of 1 glycerol and 3 fatty acid chains
70
What process joins the glycerol and fatty acid chains together to form a triglyceride?
Esterification
71
What bonds are formed in a triglyceride?
Ester bonds
72
What is a fatty acid?
A hydrocarbon chain with an acid group (COOH) at the end
73
What is a saturated hydrocarbon?
- no double bonds
| - e.g. animal fats
74
What is an unsaturated hydrocarbon?
- 1 double bond
| - e.g. plant fats
75
What is a polyhydrocarbon chain?
- 2 or more double bonds
| - e.g. plants
76
Describe stearic acid
- saturated
- no double bonds
- no kinks in chain
- more H2
77
Describe oleic acid
- unsaturated
- double bonds
- kinks in chain
- less H2 due to double bonds
78
Are fatty acids soluble?
No
79
Is the polar group soluble?
Yes
80
What is the role of a phospholipid? (2 points)
- make up the liquid bilayer in cell membranes
- membranes that form the endoplasmic reticulum surround the organelles and separate the reactions that occur within the cells
81
What are the 3 roles of lipids?
- fats and oils
- animals
- waxes
82
Describe fats and oils as a role of lipids
- good energy stores as compact and insoluble, so can be stored in high concentration
- release twice as much energy per gram as carbohydrates
83
Describe animals as a role of lipids
- fat stored in adipose tissues around body organs
- protects vital organs
- provides insulation
- aids buoyancy in aquatic animals
84
Describe waxes as a role of lipids
- waterproofing function
- forms additional layer on cuticle of aerial plants to stop them drying out
- in animals wax may be found on fur and feathers
- in insects wax is found on cuticles
85
What molecule is the polar group associated with?
Phosphate molecule
86
What are enzymes?
Globular proteins that act as catalysts
87
Why is an enzyme-substrate complex formed?
Lower the activation energy so the enzyme can catalyse the reaction
88
What is the lock and key theory?
Where the shape of the enzyme and substrate are complimentary and fit together nicely
89
What is the induced fit model?
The enzyme changes shape slightly to hug the substrate and form the enzyme-substrate complex and be able to catalyse the reaction
90
How does temperature affect enzyme activity? (5 points)
- above the optimum point the enzyme vibrates
- vibrations break the weak bonds holding it together
- structure of the enzyme changes
- enzyme substrate complex can't form
- denaturation
91
How does substrate concentration affect enzyme activity? (3 points)
- higher concentration = faster rate of reaction
- only until all enzymes are working as fast as possible
- to increase the rate of reaction further, you need to add more enzyme
92
How does pH affect enzyme activity? (6 points)
- measure of its hydrogen-ion concentration
- each enzyme has an optimum pH
- major change = denaturation
- minor change = decreased rate of reaction
- pH change alters charge of animo acids that make the active site, so substrate can no longer become attached
- tertiary structure may also break with extreme changes as the active site will change shape
93
What molecule is the polar group associated with?
Phosphate molecule
94
Is stearic acid saturated or unsaturated?
Saturated
95
Is oleic acid saturated or unsaturated?
Unsaturated
96
Which fatty acid contains kinks?
Oleic acid
97
Which fatty acid contains no kinks?
Stearic acid
98
Which fatty acid contains double bonds?
Oleic acid
99
Which fatty acid contains no double bonds?
Stearic Acid
100
Why does oleic acid have less H2?
It has double bonds
