Lipids and Proteins spec Flashcards

(20 cards)

1
Q

What are the 2 groups of lipids

A

Triglycerides anf phospholipids

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2
Q

What are lipids

A

varried group of substances that share the following characteristics:
contain carbon, hydrogen, and oxygen
insoluble in water
soluble in organic solvents

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3
Q

How are triglycerides formed

A

by condensation reactions of one molecule of glycerol and three molecules of fatty acid

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4
Q

what does a condensation reaction between glycerol and a fatty acid form

A

An ester bond (RCOOH)

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5
Q

the R-group of a fatty acid can be what?

A

saturated or unsaturated

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6
Q

Phospholipids what is substituted

A

one of the fatty acids of a triglyceride is substituted by a phosphate- containing group

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7
Q

what is the emulsion test

A

-take a completly dry and greese free test tube
-to the sample add ethanol
-shake throughly to disolve any lipid in the sample
-add water and shake gently
-a milky-white emulsion indicates the presence of a lipid
-as a control, repeat the procedure using water instead of the sample, the final solution should remain clear

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8
Q

Roles of lipids

A

-cell membranes
-source of energy
-waterproofing
-insulation
-protection

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9
Q

Triglycerides structure

A

they have three fatty acids combined with glycerol
each fatty acid forms an ester bond with glycerol in a condensation reaction
hydrolyis therfore produces glycerol and three fatty acids

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10
Q

Saturated triglyceride

A

there are no double bonds between carbon atoms
they tend to be solid as the chains can lie close together

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11
Q

Unsaturated triglyceride- mono-unsaturated

A

single double bond between carbon atoms
tend to be oils- liquid due to the ‘kinks’ in the chain

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12
Q

unsaturated triglyceride- polyunsaturated

A

if more than one double bond is present between carbon atoms
oils - liquid as the chains cant lie close together due to the ‘kinks’

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13
Q

The structure of triglycerides relates to their properties which are:

A

-high ratio of energy-storing carbon-hydrogen bonds to carbon atoms so good source of energy
-low mass to energy ratio- good storage molecules- small
-large non- polar molecules, insoluble so storage doesn’t effect osmosis or water potential
-high ratio og hydrogen-oxygen atoms, sso they release water when oxidised so provide an important source of water especially for organisms livining in dry desert conditions

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14
Q

Phospholipids

A

simillar to lipids except one fatty acid molecule is replaced bay a phosphate molecule
two parts to them a head and tail

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15
Q

phospholipid head

A

hydrophillic (attracted to water but not fats)
polar part of the phospholipid

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16
Q

Phospholipid tail

A

hydrophobic (oreintates itself away from water but mixes readily with fat)
non-polar part of the phospholipid

17
Q

The structure of phospholipids related to their properties

A
  • polar molecules , hydrophillic phosphate head and a hydrophpbic tail- this creates a bi-layer acting as a hydrophobic barrier between the inside and outside of a cell
  • hydrophillic head help to hold at the surface of the cell-surface membrane
18
Q

Proteins

A

very large molecules made up of amino acids

19
Q

Structure of an amino acid

A

basic monomer unit which combine to make a polymer called a polypeptide
polypeptides are then combined to form proteins
has a central carbon atom to which an amino group, carboxyl group (-COOH), hydrogen atom and a R group is all attached

20
Q

The formation of a peptide bond

A

condensation reaction between monomers of amino acids.
The water removal is made by combining an -OH from the carboxyl group of one amino acid and a -H from the amino group of another amino acid