Biological Molecules - Lipids, Carbohydrates, ATP, Water Flashcards
1
Q
Monomers
A
- the smaller units from which large molecules are made
- many are based on carbon
- examples: nucleotide, amino acid, monosaccharide
2
Q
Polymers
A
- polymers are molecules made from a large number of monomers joined together
- examples: polynucleotide, polypeptide, polysaccharide
3
Q
Condensation reaction
A
- joins two molecules together with the formation of a chemical bond
- result in the loss of a molecule of water/ releases a molecule of water
4
Q
Hydrolysis reaction
A
- breaks a chemical bond between two molecules
- uses a water molecule
- say “is hydrolysed” not “breaks”
5
Q
Alpha Glucose - isomer
A
- draw it
6
Q
Beta Glucose - isomer
A
- draw it
7
Q
Monosaccharides
A
- monomers from which larger carbohydrates are made
- common monosaccharides include: glucose, galactose and fructose
- a condensation reaction between two monosaccharides forms a glycosidic bond
8
Q
Disaccharides
A
- formed by a condensation reaction between two monosaccharides
- glucose + glucose = maltose
- glucose + fructose = sucrose
- glucose + galactose = lactose
9
Q
Glycogen
A
- made of many alpha glucose molecules joined together via glycosidic bonds
- glycogen is highly branched, making it useful for energy storage in animals
- branches are made when glucose molecules join together at different points of the molecule - e.g. alpha-1,4- glycosidic bonds from straight lines while alpha-1,6- glycosidic bonds from branches
- stored in liver and muscle cells, so it is ready to be hydrolysed into glucose when required for respiration
- branching provides large SA for enzymes to work
10
Q
Starch
A
- made of many alpha glucose molecules,rules joined by glycosidic bonds
- starch is less branched than glycogen
- the unbranched sections of starch are called amylose
- the branched sections are called amylopectin
- stored in leaf and root cells of the plant, so it is ready to be hydrolysed when glucose is required for respiration
- has no osmotic effect in the cell, as it is not very soluble in water
- the branching provides a large SA for enzymes to work
- amylose is wound tightly into tight coil that make the molecule very compact
- the hydroxyl groups facing inwards form hydrogen bonds, which result in the helix shape of amylose
11
Q
Cellulose
A
- made of many beta glucose molecules join by glycosidic bonds
- has no branches
- contains only beta-1,4- glycosidic bonds
- the chains of beta glucose are next to each other, so form hydrogen bonds between them
- many cellulose molecules joined together form a microfibril
- found in plant cells walls
- provides rigidity and strength
- provides a defence against pathogens
- due to its linear shape, it’s not good for energy storage - its surface area is too small for enzyme action and the many H bonds require a lot of energy to break
- not soluble in water
12
Q
What is a redox reaction?
A
When one substance is oxidised whilst another is reduced.
Oxidation = loss of electrons or hydrogen
Reduction = gain of electrons or hydrogen
13
Q
Redox reaction - Biochemical test for reducing sugars (explanation)
A
- reducing sugars lose electrons readily to another substance (such as an electron carrier).
- the reducing sugar (e.g. glucose, fructose) is oxidised as it had lost electrons whilst the other is reduced as it gains electrons.
14
Q
Redox reactions - Biochemical Test for Non-reducing sugars (explanation)
A
- non-reducing sugars aren’t readily oxidised
- therefore, they do not reduce (take electrons from) any other substances
15
Q
METHOD - non-reducing sugars test
A
- THIS FOLLOWS A NEGATIVE BENEDICT’S TEST
- add hydrochloric acid to the food sample and boil (put in water bath at 80 degrees)
- neutralise with sodium hydrogen carbonate
- add Benedict’s reagent and heat in the water bath again
- a negative result would be blue
- a positive result would be green, yellow, orange or brick red
16
Q
METHOD - reducing sugars test
A
- mix the food sample (in liquid form so grind and add water if necessary) with Benedict’s reagent and heat in water bath at 80 degrees celsius.
- a negative result would be blue
- a positive result would be green, yellow, orange or brick red
17
Q
METHOD - starch test
A
- add iodine to the food sample
- a negative result will be orange
- a positive result will be blue-black
18
Q
Triglyceride structure
A
- formed by the condensation of one molecule of glycerol and three molecules of fatty acid
- DRAW OUT
19
Q
Glycerol structure
A
- DRAW OUT
20
Q
Fatty acid structure
A
- DRAW OUT
21
Q
What bond does the condensation reaction between a glycerol and fatty acid cause?
A
Ester bond
22
Q
Saturated fatty acid structure
A
DRAW
23
Q
Unsaturated fatty acid structure
A
DRAW
24
Q
What is the difference between a saturated and unsaturated fatty acid?
A
- unsaturated fatty acids contain a carbon to carbon double bond, which causes a kink in the chain
- this allows the lipid molecules to sit further apart from one another, so therefore they are easier to break apart
25
Phospholipid structure
- would help to draw this out
- one of the fatty acids of the triglyceride is substituted by a phosphate-containing group
- **The phosphate group** - negatively charged, which allows it to from hydrogen bonds with water, making it hydrophilic
- **The fatty acids** - these are hydrophobic
- this is why the phospholipid bilayer of the cell membrane is made of two layers - the hydrophilic heads are exposed to the water outside of the cell, and the hydrophobic tails are hidden from the water inside the bilayer
26
Triglyceride properties
- the fatty acid tails contain a lot of chemicals energy , which is released when they are broken down
- they are not insoluble in water as they are non-polar. As they are hydrophobic, they form small droplets.
- because they are insoluble in water, triglycerides do not affect water potential
- in animals, triglycerides are found in adipose tissue and provide insulation, while in plants they are found in seeds and act as the energy source for germination.
27
Properties of phospholipids
- insoluble in water
- the heads do have a slightly negative charge which allows it to be hydrophilic
- can be found in single or double layers (which make up the bilayer of the cell membrane)
28
METHOD - test for lipids
- shake the food substance with ethanol so that it dissolves
- then add water
- if a milk white emulsion is formed, lipids are present
29
What is ATP?
- adenosine triphosphate
- it is a nucleotide derivative
- formed from a molecule of ribose, adenine and three phosphate groups.
30
Hydrolysis of ATP
- ATP is hydrolsyed in adenosine diphosphate (ADP) and an inorganic phosphate group (Pi)
- this is catalysed by ATP hydrolase, and enzyme.
- this hydrolysis is what produces energy for energy requiring reactions in the cells
- the inorganic phosphate released in the hydrolysis reaction can be used to phosphorylate (to cause an organic compound or take up or combine with phosphate group) other compounds, which often makes them more reactive
31
The condensation reaction of ATP
- ATP is re-synthesised by the condensation of ADP and Pi.
- this is catalysed by ATP synthase during respiration or photosynthesis.
32
Structure of water
- made up of 2 hydrogen atoms (slightly positive charge) and 1 oxygen atom (slightly negative charge)
- has no overall charge however
- considered to be polar molecules
33
WATER PROPERTIES - Water as a metabolite
- water is a metabolite in many metabolic reactions including condensation and hydrolysis
34
WATER PROPERTIES - water as a solvent
Water is an important solvent in which metabolic reactions occur
35
WATER PROPERTIES - heat capacity
Water has a relatively high heat capacity , buffering changes to temperature. This keeps a stable environment for fish.
36
WATER PROPERTIES - latent heat of vaporisation
Water had a relatively large latent heart of vaporisation, providing a strong cooling effect with little water loss through evaporation
37
WATER PROPERTIES- cohesive
- strong cohesion between water molecules
- this supports columns of water in the tube like transport cells of plants
- produces surface tension where water meets air - supports life such as water skaters
