Chapter 3- Biological Molecules Flashcards
1
Q
Name the covalent bond between two adjacent amino acids
A
Peptide bond
2
Q
Name the type of reaction involved in breaking peptide bonds and what happens
A
Hydrolysis
Water added
3
Q
How can you control pH?
A
Add buffer solution
4
Q
Why is it good to repeat investigations?
A
- improve reliability
- allows you to calculate mean
- identify anomalous results
5
Q
What are the three main lipids?
A
- triglycerides
- phospholipids
- cholesterols
6
Q
Which elements do triglycerides and cholesterols contain?
A
Carbon
Hydrogen
Oxygen
7
Q
Are lipids soluble or insoluble?
A
Insoluble
8
Q
Which lipids are important in membrane structure?
A
- phospholipids
- cholesterol
9
Q
How to do emulsion test for lipids and how positive result identified?
A
- mix with ethanol and water
- if positive = goes cloudy
10
Q
How might the lipid content of food that comes from microorganisms differ from food that comes from animals?
A
- less lipids
- less saturated fat
- more saturated fat
- less cholesterol
11
Q
Describe the primary level of protein structure
A
-sequence of amino acids joined by peptide bonds
12
Q
Describe the secondary level of protein structure
A
- initial folding of polypeptide chain
- hydrogen bonds
13
Q
Describe the tertiary level of protein structure
A
- ionic bonds
- Hydrogen bonds
- disulfide bonds
- hydrophobic and hydrophilic interactions
- secondary structure undergoes further folding
14
Q
Describe the quaternary level of protein structure
A
When 2 or more polypeptides are joined together to form a protein
15
Q
Describe formation of hydrogen bond between 2 water molecules and why water can form these bonds
A
- between electropositive H and electronegative O of adjacent water molecules
- water molecule is polar
16
Q
Water is a solvent. Why is this good for the survival of organisms?
A
- able to dilute toxic substances
- medium for metabolic reactions
- organisms can take in minerals like tissue fluid, xylem, phloem
- internal transport medium
17
Q
General structure of amino acid
A
COOH
H C R group
NH2
18
Q
Property of collagen that makes useful component of blood vessel walls
A
- strong
- insoluble
19
Q
Structure of collagen?
A
- peptide bonds between amino acids in polypeptide
- every 3rd amino acid is glycine
- glycine is a small R group thus allows closeness of polypeptide chains
- 3 polypeptide chains twisted around each other
- H bonds between polypeptide chains
- no hydrophilic R groups on outside of molecule
20
Q
Ways in which structure of haemoglobin differs from that of collagen?
A
- contains prosthetic haem group
- globular
- hydrophilic R groups on outside of molecule
- 4 sub units which are 2 alpha and 2 beta sub units
21
Q
Describe the formation of a peptide bond between 2 amino acids
A
- between amine group of one amino acid and carboxyl group of another
- H from amine combines with OH from carboxyl to produce water molecule in condensation reaction
22
Q
Describe high latent heat of vaporisation as a property of water that allows organisms to survive over a range of temperatures
A
- large amount of energy needed to change from liquid to gas
- evaporation is efficient cooling mechanism
- e.g. sweating
23
Q
Describe high specific heat capacity as a property of water that allows organisms to survive over a range of temperatures
A
- large amount of energy needed to raise temp
- stable environment for aquatic organisms
- thus organisms use less energy on temp control
- temp of organism changes slowly
- metabolic reactions carried out normally
- due to many hydrogen bonds between water molecules. Lot of energy needed to break these bonds.
24
Q
Describe ice is less dense than water as a property of water that allows organisms to survive over a range of temperatures
A
- floats
- surface of ice provides habitat for organisms
- ice forms an insulating layer
- keeping water below ice still liquid
- thus organisms do not freeze
- and can still move
25
Describe surface tension as a property of water that allows organisms to survive over a range of temperatures
Habitat for insects
26
Describe transparency as a property of water that allows organisms to survive over a range of temperatures
-allows underwater photosynthesis
27
Where hydrogen bonds found in biological molecules
- between water molecules
- protein secondary structure
- protein tertiary structure
- between chains of cellulose
28
Roles of cholesterol?
- make vitamin D
- make bile
- stabilises membranes
- waterproofs skin
29
How molecular structure of cholesterol similar to molecular structure of a carbohydrate
-6 membered ring
30
Disease which high blood cholesterol is a risk factor
- stroke
- type 2 diabetes
- coronary heart disease
31
Why glycogen is a good storage molecule?
- insoluble = doesn’t affect water potential of cell
- compact= stores lot of energy
- lots of branching for enzymes to attach
- can be broken down and built up easily
32
Function of glucose?
- provides energy
| - used for respiration
33
Structure of glycogen?
- made from alpha glucose
- 1,4 and 1,6- glycosidic bonds present
- branched
- all glucose units in same orientation
34
Primary structure of haemoglobin?
- sequence or amino acids
| - amino acids joined by peptide bonds
35
Secondary structure of haemoglobin?
- hydrogen bonds present
| - forms alpha helix and beta pleated sheets
36
Tertiary structure of haemoglobin?
- secondary structure undergoes further folding
- hydrogen, disulfide, ionic bonds present
- hydrophobic or hydrophilic interactions
- soluble so hydrophilic R groups on outside of molecule
37
Quaternary structure of haemoglobin?
- 4 sub units which are 2 alpha and 2 beta chains
- each polypeptide has 1 prosthetic haem group
- prosthetic haem group contains Fe2+ ions
38
Ways that the structure of haemoglobin is similar to collagen?
- more than 1 polypeptide
- have quaternary structure
- both have amino acid sequences
- both have peptide bonds
- both have hydrogen, disulfide, ionic bonds
- both have hydrophobic or hydrophilic interactions
39
Why is ice less dense than water?
Water molecules spread out to form lattice structure
40
Structure of triglyceride?
-one glycerol attached to 3 fatty acids by 3 ester bonds
41
Roles of lipids?
- insulation
- energy store
- used in membranes
- waterproofing
- buoyancy
42
What causes anaemia and what does this do?
- Lack of iron
| - body unable to produce sufficient amounts of haemoglobin
43
What is wrong with the graph used to determine whether someone is underweight or overweight?
- does not distinguish between male and female
- doesn’t take into account bone density
- may be pregnant
44
Diseases associated with obesity?
- coronary heart disease
- type 2 diabetes
- cancers
- gall stones
45
Describe how R groups interact to determine tertiary structure of proteins
- can form disulfide bonds
- can form hydrogen bonds
- can form ionic bonds
- hydrophilic R groups on outside of molecule
- hydrophobic R groups on inside of molecule
46
Differences between structure of glycogen and collagen
```
+carbohydrate
-protein
+made of alpha glucose units
-made of amino acid units
+glycosidic bonds
-peptide bonds
+branched
-linear
```
47
Properties of collagen
- strong
- insoluble
- flexible
- does not stretch
48
How the conc of a reducing sugar can be measured using colorimeter?
- using known concentrations of reducing sugar, heat with Benedicts
- ensure same vol of solution each time
- solution changes to brick red
- remove precipitate
- calibrate colorimeter using water and red filter
- record reading of transmission
- more transmission = more sugar present
- draw calibration curve plotting transmission against sugar conc
- use transmission reading of unknown and read off graph to find conc
49
Why is water a solvent?
-high solubility due to charged ions being attracted to and binding with water molecules
50
Colour of iodine solution in presence of starch?
Blue-black
51
Meaning of primary structure?
Sequence of amino acids
52
When proteins heated to high temperature, tertiary structure disrupted. Why?
- increases K. E
- h, disulfide, ionic bonds break
- hydrophobic and hydrophilic interactions break
- change in 3D shape
- protein denatures
53
Why enzyme is described as extracellular?
-works outside cell
53
Structure of amylose?
- coiled
- contains alpha glucose
- all monomers in same orientation
- no h bonds between molecules
- alpha 1,4 glycosidic bonds
53
Structure of cellulose?
- straight chained
- contains beta glucose
- beta 1,4 glycosidic bonds
- adjacent monomers in opposite orientation
- h bonds between molecules
53
Which properties of cellulose make it suitable for cell wall?
- strong
| - insoluble
53
Bonds in triglyceride?
3 Ester bonds
53
Uses of carbohydrates in organisms
- provide energy
- store energy
- build macromolecules
53
What is a condensation reaction?
When 2 monomers become bonded together through the removal of a molecule of water
54
Glucose + glucose =
Maltose
55
Galactose + glucose =
Lactose
56
Glucose + fructose =
Sucrose
57
How is the structure of cellulose related to its function?
- beta glucose monomers arranged in straight chains
- chains joined by h bonds
- provides strength and structure
58
Where and how is glucose stored in humans?
Stored as glycogen in liver / muscles
59
Similarities between starch and glycogen?
- both msdemof alpha glucose molecules
- both contain branched chains
- compact
- insoluble
60
Name the polysaccharide chains in starch and how is their structure adapted to function of starch?
- amylose
- straight chain polymer
- forms helix for max compact storage
- amylopectin
- branched
- max surface area for enzyme action
61
How benedict’s test is carried out and what to expect if reducing sugar present?
- sample must be in solution
- Benedict’s reagent added
- test tube heated in water bath
- turned brick red if present
62
Carbohydrates that are reducing sugars?
- galactose
- glucose
- fructose
- maltose
- lactose
63
Example of non reducing sugar?
Sucrose
64
Uses of lipids in animals?
- storage as fat
- cell membranes
- waterproofing
- thermal insulation
65
Main use of triglyceride?
Energy storage molecule
66
Describe the structure of a triglyceride using hydrophobic and hydrophilic
- one glycerol molecule attached to 3 fatty acid chains
- glycerol head is hydrophilic- interacts with water
- fatty acid tails are hydrophobic- repel water
67
Example of where unsaturated fats are found?
Vegetable oil
Olive oil
68
Difference between saturated and unsaturated lipids?
- In the hydrocarbon tail of saturated lipids all the carbon atoms are joined by a single bond.
- in unsaturated lipids two or more of the carbon atoms are joined by a double bond
69
How does the presence of a double bond in a lipid affect its boiling point?
-lowers the boiling point
70
What is a hydrolysis reaction?
Spilling up a bond with water
71
Significance of R group?
- variable group
| - gives each amino acid its specific characteristics
72
What 2 forms can secondary protein structure take?
- alpha helix
| - beta pleated sheets
73
How test for protein works?
- sample mixed with equal volume of sodium/ potassium hydroxide
- few drops of copper sulphate added
- purple colour change in presence of protein
74
How glucose molecule is well suited to its function?
- soluble so easily transported around organism
- easily broken down to produce ATP and release energy
- molecules can join to produce maltose
75
Structural similarities between lactose and maltose?
- made up of 2 hexoses
| - glycosidic bonds
