Rev Flashcards
What is the polysaccharide energy store in plants?
Starch
Where is starch most commonly found?
In photosynthesising cells, leaves and seeds
How is starch stored?
It is compacted into dense insoluble grains
What is starch stored in?
Amyloplast
What two polysaccharides does starch consist of?
Amylase + amylopectin
Describe the structure of amylase:
A long chain of alpha glucose molecules
Coiled into a helix shape (storage purposes)
Two accessible ends where enzymes can bind
Describe the structure of amylopectin:
A long chain of alpha glucose molecules join bye 1-4 glyosidic bonds
Occasionally has 1-6 glycosidic bond
What does the addition of 1-6 glycosidic bonds mean amylopectin has?
The additional 1-6 glycosidic means amylopectin has side branches with more accessible ends
This allows amylopectin to be released quicker than amylose
What is the polysaccharide store animals?
Glycogen
What type of cells is glycogen found in?
Cells with a high metabolic rate e.g liver and muscle cells
Describe the structure of glycogen:
A long chain of alpha glucose molecules join bye 1-4 glyosidic bonds
Occasionally has 1-6 glycosidic bond
Why does glycogen have a high number of accessible ends? And why is this important?
This allows it to be rapidly hydrolysed to an alpha glucose. This important because animals require a faster metabolic rate than plants.
What type of polysaccharide is cellulose
A structural polysaccharide
Describe the structure of cellulose:
A long chain of beta glucose molecules joined by 1-4 glyosidic bonds
What do beta glucose molecules in cellulose have to do to form 1-4 glycosidic bonds
Invert 180 degrees
What does beta glucose molecules inverting do?
Keeps cellulose form coiling + results in a long straight chain
What molecules do triglycerides contain?
one glycerol molecule + 3 molecules of fatty acids
How do triglycerides form?
the condensation of one glycerol molecule + 3 molecules of fatty acids
Where is chemical energy stored in triglycerides?
The fatty acid tails
Why are triglycerides insoluble in water?
The fatty acid tails are hydrophobic
Why is it important that triglyceride are insoluble in water?
So water potential isn’t affected
What are phospholipids the main component of?
cell membranes
What is the difference between phospholipids and triglycerids?
Phospholipids are compose of one phosphate head, one glycerol and 2 fatty acids
How do you know when a fatty acid is saturated?
If there are only single bonds between carbon atoms
What does the emulsion test, test?
The presence of lipids
What is the 1st step of the emulsion test?
Place a sample in a boiling tube with ethanol
what is the 2nd step of the emulsion test?
Shake well and leave upright for 2-3 mins
What is the 3rd step of the emulsion test?
Pour the solution into a boiling tube containing distilled water
What is the 4th step of the emulsion test?
If a lipid is present the solution will turn a milky white
When two monosaccharides join what is formed?
Disaccharides
What disaccharide does: glucose + glucose form
Maltose
What disaccharide does: glucose + fructose form
sucrose
What disaccharide does: glucose + galactose form
lactose
