2 - Lipids and Proteins Flashcards Preview

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Flashcards in 2 - Lipids and Proteins Deck (19):
1

Structure of triglycerides?

Storage molecules
Glycerol 3 fatty acids tails - have long tails made of hydrocarbons which are hydrophobic
Ester bonds between
Formed by condensation reaction producing triglyceride and 3 water
insoluble in water
O =C - R
-OH (O attached to C)

2

Saturated lipids

No C=C bonds present
Fatty acid chains are straight
Solid at room temperature
Animal fats

3

Unsaturated lipids

C=C bonds present
Polyunsaturated lipids when more than one
Fatty acid chains have a kink
Liquid at room temp
Plant oils

4

Structure of phospholipids

2 fatty acids
1 glycerol
1 phosphate group
Main component of cell membranes
Hydrophobic tails
Hydrophilic head

5

Emulsion test for lipids

If substance solid, crush up
Add few drops of ethanol
Shake the mixture
Pour Water
If emulsion forms (milky white precipitate) then lipid present

6

What are proteins?

Polymer molecules made up of one of more polypeptide chains

7

Structure of amino acids?

H
NH3 CO(OH)
(Amino group) (Carboxylic acid group)

R Group

8

Formation of peptides?

Two amino acids bonded by peptide bond in condensation reaction.
C-N bond
H20 Produced

9

Polypeptides

Amino acids bonded together in a straight chain
Folded into a specific 3D shape
4 levels: Primary, secondary, tertiary and quaternary

10

Primary proteins

The sequence of amino acids in a polypeptide chain (the primary structure determines the tertiary structure)

11

Secondary proteins

The coiling (alpha helix) or folding (Beta-pleated sheet) of a polypeptide chain with the addition of hydrogen bonds

12

Tertiary proteins

The further coiling or folding of a polypeptide chain with the addition of hydrogen, ionic and disulfide bonds and hydrophobic interactions to create a specific 3D shape

13

Quaternary proteins

More than 1 polypeptide chain linked together

14

Bonding in proteins

Hydrogen between O and H in all levels of structure
Hydrophobic interactions between non-polar sections
Disulfide bonds, strongest bond, between cystine amino acids

15

Fibrous proteins

Parallel polypeptide chains held together by cross links
Long, rope like fibres with high tensile strength
Collagen - tendons and cartilage
Keratin - Hair and nails
Silk - spider webs

16

Globular proteins

Spherical shapes caused by tightly folded polypeptide chains, hydrophillic parts on the outside, hydrophobic on the inside, soluble in water
Transport proteins
Enzymes
Hormones

17

Biuret test for proteins

Add few drops of sodium hydroxide solution
Add bruit reagent to solution
Mix gently
If protein present, purple or lilac
Blue if nothing present

18

What denatures proteins

Temperature and pH

19

Use of Triglycerides

Long hydrocarbon tails - lots of chemical energy - released when broken down - twice as much energy per gram as carbohydrates
Insoluble - dont affect water potential - form insoluble droplets due to hydrophobic tails