Molecules (lipids)- topic 1 Flashcards

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1
Q

what are the elements that lipids contain?

A

-carbon
-hydrogen
-oxygen

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2
Q

what makes lipids and carbohydrates different if they consist of the same elements?

A

-the proportion of hydrogen relative to oxygen is much greater than carbohydrates where the ratio is 2:1

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3
Q

are lipids polymers?

A

-they do form large molecules known as macromolecules however they are not polymers

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4
Q

what substances are lipids soluble in?

A

-they are not soluble in water (hydrophobic) but are soluble in organic solvents such as ethanol

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5
Q

what are the 4 types of lipids?

A

-triglycerides
-phospholipids
-waxes
-steroids

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6
Q

how are triglycerides formed?

A

-through a combination of glycerol and fatty acids
-each triglyceride contains one glycerol molecule which is joined with three fatty acid molecules

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7
Q

what are fatty acids and how are they formed ?

A

-organic acids that form long hydrocarbon tails linked to a carboxyl group at one end of the chain
-different fatty acids have different lengths of hydrocarbons

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8
Q

what is a carboxyl group?

A

-a group linked to the end of a fatty acid molecule
-COOH

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9
Q

how can different triglycerides be formed and why is this?

A

-there are over 70 types of fatty acids which can be the same or a range of different types in one triglyceride

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10
Q

in triglycerides where does the condensation reaction occur ?

A

-it occurs between the OH hydroxyl group of the glycerol and the COOH carboxyl group of each fatty acid

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11
Q

following a condensation reaction what is the bond called between the fatty acids and the glycerol?

A

-an ester bond holds the two in place

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12
Q

how does the hydrolysis of a triglyceride occur? when does this occur ?

A

-it uses three molecules of water and produces three fatty acids and one molecule of glycerol
-happens during lipid digestion

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13
Q

what are saturated fatty acids and why are they called this?

A

-they contain the maximum amount of hydrogen molecules along the length of hydrocarbon chain i.e. each carbon atom is linked with two hydrogen atoms
-all the carbons are saturated

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14
Q

how are the carbon atoms linked in saturated fatty acids?

A

-by single carbon to carbon bonds

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15
Q

how are the carbon atoms linked in unsaturated fatty acids?

A

-they have at least one carbon to carbon double bond (monounsaturated fatty acids) or contain more that one double bond (polyunsaturated fatty acids)

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16
Q

are fats and oils triglycerides?

A

-yes and they are both chemically very similar

17
Q

how does the condition of fats and oils differ at room temperature ? how else do fats and oils differ?

A

-fats are usually solid at room temp whereas oils are liquid
-fats are animal sources and oils are made from plant sources
-fats are formed form saturated fatty acids whereas oils are formed from unsaturated hydrocarbon chains

18
Q

what are triglycerides used for?

A

-they are an excellent energy store as they release more energy per unit mass than carbohydrate
-fats are used for insulation and are stored in a layer just below the skin
-fat also protects organs of the body

19
Q

how do phospholipids differ from triglycerides?

A

-they are similar however one of the fatty acid molecules is replaced by a phosphate group

20
Q

what is the effect of fatty acids in a phospholipid molecule?

A

-they repel water by forming hydrophobic tails

21
Q

what is the effect of a phosphate group attached to the glycerol in a phospholipid molecule?

A

-it attracts water by forming hydrophilic heads
-it makes the phospholipid soluble in water

22
Q

what type of molecule are phospholipids and why is this important?

A

-they are polar which helps determine their orientation and function in cell membranes