Biomolecules Flashcards
(81 cards)
1
Q
Why is water referred to as a ‘polar molecule’?
A
- Has a positively charged hydrogen end
- Has a negatively charged oxygen end (unpaired electrons)
2
Q
What type of bonds form between water molecules?
A
Hydrogen
3
Q
What are the properties of water?
A
- Universal solvent (transport)
- Transport medium (cohesion)
- High surface tension (cohesion)
- Coolant (solid less dense than liquid)
- High specific heat capacity (habitat)
4
Q
What is the importance of water being a universal solvent?
A
- Most things dissolve in water
- Has a positive and negative end so will become attracted to many different types of molecules, e.g. NaCl
- Acts as a transport medium
5
Q
What is the importance of water having a high specific capacity?
A
Requires a high amount of energy to raise the temperature of 1g of water by 1 degrees celsius - stable habitats
6
Q
What is the importance of water having a high surface tension?
A
- Due to hydrogen bonds having strong molecular interactions (cohesion)
- Allows insects to stand on water
7
Q
What is the importance of water density decreasing under 4°C?
A
Ice floats on water providing insulating layer and stable habitat
Water organisms can float as the water density is high
8
Q
What is the importance of water having cohesion and adhesion?
A
- Form water columns that flow uphill (xylem)
- Good transport medium
- High surface tension
9
Q
What is cohesion?
A
Joining of water molecules to other water molecules
10
Q
What is adhesion?
A
The joining of water to different polar molecules
11
Q
What are polymers?
A
A long molecule made up of any smaller molecules (monomers)
12
Q
What are monomers?
A
Small molecules that are the building block of polymers
13
Q
Give 4 examples of biomolecules
A
1- Carbohydrates
2- Proteins
3- Lipids
4- Nucleic acids
14
Q
What are the monomers in carbohydrates called?
A
Monosaccharides (glucose)
15
Q
What are the polymers in carbohydrates called?
A
Polysaccharides
16
Q
What are the monomers in proteins called?
A
Amino acids
17
Q
What are the monomers in lipids called?
A
Triglyceride
18
Q
What are the monomers in nucleic acids called?
A
Nucleotides
19
Q
What are the polymers in nucleic acids called?
A
DNA/RNA
20
Q
What is condensation?
A
When 2 molecules join together to form one larger molecule and one molecule of water
21
Q
What is hydrolysis?
A
When 2 molecules are split apart using a molecule of water
22
Q
Draw an alpha glucose molecule
A
A
23
Q
Draw a beta glucose molecule
A
B
24
Q
What is amylose and amylopectin used for?
A
Glucose/energy storage in plants
25
What is a glycosidic bond?
A bond that forms between carbohydrates
26
What is a disaccharide?
2 monosaccharides
27
Glucose + Glucose = ?
Maltose
28
Glucose + Fructose = ?
Sucrose
29
Glucose + Galactose = ?
Lactose
30
How is maltose formed?
Glucose + Glucose
31
How is sucrose formed?
Glucose + Fructose
32
What is ribose?
- A pentose monosaccharide
(5 carbon atoms)
- Sugar that forms RNA nucleotides
33
How is lactose formed?
Glucose + Galactose
34
What is the structure of amylose?
Alpha 1, 4 glycosidic bonds
| Helix shape
36
What is the structure of amylopectin?
Alpha 1, 4 and alpha 1, 6 glycosidic bonds
| Branched shape
37
What are the properties of amylose?
Good storage molecule for glucose
| Insoluble (no effect on WP or osmosis)
38
What is the structure of cellulose?
Beta 1, 4 glycosidic bonds
| Straight chain shape
39
What are the properties of amylopectin?
Increased SA so can be hydrolysed quicker
Good storage molecule for glucose
Insoluble (no effect on WP or osmosis)
40
What are the properties of cellulose?
Good mechanical support
| Insoluble
40
What is glycogen used for?
Glucose/energy storage in animals
41
What is the structure of glycogen?
Alpha 1, 4 and 1, 6 glycosidic bonds
| Highly branched shape
42
What are the properties of glycogen?
Good storage molecule for glucose
| Insoluble
44
What are peptides?
Polymers made up of amino acid molecules
44
What is a peptide bond?
The bond between amino acids in all proteins
45
What is the structure of an amino acid?
Contain:
- Amine group (NH2)
- Carboxylic acid group (COOH)
- R group
46
Draw an amino acid structure
A
47
What is a dipeptide?
When a peptide bond forms between 2 amino acids and water is produced
48
What is the primary structure of a protein?
The sequence of amino acids
49
What are the 2 main types of secondary protein?
Alpha helix and beta pleated sheet
49
What is the secondary structure of a protein?
- Long chains of amino acids fold into regions with repeating patterns due to hydrogen bonds
- There are two types: alpha helix and beta pleated sheets
51
Give 4 bonds involved in protein tertiary structure
Hydrogen
Ionic
Disulfide
Hydrophobic/hydrophilic interactions
51
What is the tertiary structure of a protein?
The folding of the protein into it’s final 3D shape
52
What interactions occur between R-groups?
- Hydrophilic/Hydrophobic interactions: weak interactions between polar and non-polar R-groups
- Hydrogen bonds: these are the weakest bonds formed
- Ionic bonds: these are stronger than hydrogen bonds and form between oppositely charged R-groups
- Disulfide bonds: these are covalent and are the strongest of the bonds but only form between R-groups that contain sulfur atoms
53
What is the quaternary structure of a protein?
The result of 2 or more individual proteins (subunits) interacting
54
How do you test for a carbohydrate?
Benedict’s test for reducing sugars:
- Place sample to be tested in boiling tube. If it’s not in liquid form then grind it or blend in water
- Add an equal volume of Benedict’s reagent
- Heat mixture gently in boiling water bath for 5 mins
Reducing sugars will react with copper in reagent - brick red precipitate
Non-reducing sugars:
Remain blue after warming
56
How do you test for starch?
Iodine test:
- A few drops of iodine solution dissolved in potassium iodide solution is mixed with a sample
If the solution changes from yellow/brown to purple/black then starch is present
58
How do you test for lipids?
Emulsion test:
- Sample is mixed with ethanol
- The resulting solution is mixed with water and shaken
If a white emulsion forms as a top layer on top of the solution, lipid is present
Clear = negative
61
How do you test for proteins?
Biuret test
| If proteins are present = pink/purple
62
How do you calculate Rf value?
Distance travelled by component/ distance travelled by solvent
64
Describe the structure of a haemoglobin molecule
- Chain of a.a
- Joined by peptide bonds
- Hydrophilic R groups on outside
- Hydrophobic R groups on inside
- 4 polypeptides
- 2 alpha chains and 2 beta chains
- 4 haem groups
65
What are globular proteins?
- Compact, water soluble, and usually roughly spherical in shape.
- Hyrophilic R groups on inside of molecule
- Hydrophobic R groups on outside of molecule
67
Give an example of a globular protein
Insulin
It is a hormone involved in the regulation of blood glucose concentration.
Hormones are transported in the bloodstream so need to be soluble. They also have to fit into specific receptors so need to have precise shapes
68
What are conjugated proteins?
Globular proteins that contain a prosthetic group
69
Draw the structure of a triglyceride
T
70
What is an ester bond?
Formed when a molecule having the carboxylic group reacts with another molecule having a hydroxyl group. The carboxylic group loses its hydrogen and oxygen while the alcohol loses hydrogen of its hydroxyl group.
71
What are lipids made of?
Glycerol and 3 fatty acids
72
How are lipids joined?
By ester bonds to form a triglyceride by condensation
73
Describe unsaturated fatty acids
- Have double bonds between carbon atoms
| - Have less hydrogen
74
Describe the structure of a phospholipid
- Has a phosphate head (hydrophilic)
- Glycerol
- Joined to 2 fatty acids by ester bonds (hydrophobic)
75
Describe saturated fatty acids
- Don’t have double bonds between carbon atoms
| - Cause an increase in cholesterol
76
Give an example of a prosthetic group
Haem groups
| Haemoglobin is a red, oxygen-carrying pigment found in red blood cells
76
What is catalase?
An enzyme
| A quaternary protein containing 4 haem prosthetic groups
76
What are fibrous proteins?
Formed from long, insoluble molecules
76
Examples of fibrous proteins
- Keratin (group of fibrous proteins in hair, skin and nails)
- Elastin (found in elastic fibres - walls of blood vessels and alveoli of lungs)
- Collagen (connective tissue found in skin, tendons, ligaments and the nervous system)
76
What are cations?
Positively charged ions
76
What are anions?
Negatively charged ions
77
Name 6 cations
- Calcium (Ca2+)
- Magnesium (Mg2+)
- Sodium (Na+)
- Potassium (K+)
- Hydrogen (H+)
- Ammonium (NH4+)
78
Name 5 anions
- Nitrate (NO3-)
- Hydrogen carbonate (HCO3-)
- Chloride (Cl-)
- Phosphate (PO43-)
- Hydroxide (OH-)
79
What are biosensors?
Use biological molecules to test for the presence of another molecule
- E.g. enzyme tests for specific substrate
80
Describe how a biosensor would be used to test for specific substrates of an enzyme
- Immobilise enzyme/single stranded DNA to a surface
- Add sample
- If it hybridises or forms a complex
- It’s detected and a transducer converts it into an electrical signal
- Interpreted by a display
- Gives quantitative concentration
81
How does a colorimeter work?
The more of a substance that’s present in a sample, the greater the colour change
