Test 1 (Cell Structure, Microscopy, Lipids And Carbohydrates) Flashcards
Why is a cold, buffered and isotonic solution used during cell fractionation?
Ice cold prevents enzyme activity that could break down organelles
Buffered maintains constant pH so enzymes won’t denature
Isotonic prevents osmosis causing damage/shrinking of organelles
What are the steps to cell fractionation?
(1) add substance to cold, buffered, isotonic solution
(2) mixed substance in blender
(3) filtered mixture
(4) used centrifuge at low speed
(5) poured off liquid into second tube and spin at higher speed
Why do you use a blender during cell fractionation?
It breaks the plasma membrane of the cells
And leaves the organelles in the homogenate
Why is the mixture in cell fractionation filtered?
To separate any large cell debris
Leaving behind the filtrate
Why are the test tubes spun at different speeds in cell fractionation?
So the organelles can separate
The densest (nucleus) goes first
Then chloroplasts + mitochondria
Then lysosomes
Then ER
Then ribosomes
Explain the advantages and limitations of using a TEM microscope to investigate cell structure
It has a higher Res and Mag so it can see smaller organelles
Higher Res due to electrons having shorter wavelength
Cannot view living cells as cells must be in a vacuum
Preparation may create artifact
What term is used to describe the different structures of alpha and beta glucose?
Isomers
What biochemical test can be used to determine if a solution contains reducing sugars?
Benedict’s test
Heat in water bath
Green/yellow low sugar content
Dark orange/brick-red high sugar content
(If non-reducing add acid)
What variables are controlled in Benedict’s test?
Volume of Benedict’s used
Volume of substance added
Describe how you would use the emulsion test to show something contains lipids
Grind up substance
Add ethanol and water
White means lipids are present
How is a phospholipid different from that of a triglyceride
Triglycerides are insoluble in water but phospholipids are soluble in water
A triglyceride has 3 fatty acids but a phospholipid has 2
What is meant by an unsaturated fatty acid?
Double bond present between the carbons
What monomer is present in cellulose?
Beta glucose
What reaction converts cellulose to its monomers?
Hydrolysis
How does cellulose give Cotten its strength?
Long, straight, unbranched chains
The chains lie side by side forming microfibrils
The H-bonds hold the chains together
