2.3 CARBOHYDRATES AND LIPIDS Flashcards
Macromolecules and subunits (monomers)
Protein/ polypeptides=
Amino acid
Carbohydrates/ polysaccharide=
Monosaccharide
Lipids/ triglyceride=
3 fatty acids + glycerol
Nucleic acid=
Nucleotides
Functions of lipids
Energy storage
Heat insulator due to poor conduction (non-polar)
–> blubber for artic animals
Buoyancy: float as fat is less dense than water
Energy storage overview
Lipids are more suitable for long term energy storage in humans than carbohydrates
Reasons for using lipid as energy storage
Quantity of E released in cell respiration per gram is more than double than carbs (16 kJ <39kJ)
–> half as much body mass is needed for same Q of E
Lipids are six times more efficient
Lipids have secondary roles that carbs don’t: heat insulators
Reasons for using carbohydrates/ glycogen as energy
Glycogen for short term E storage as it is rapidly broken down and easily transported by the blood
whilst fats in adipose tissue (lipids) cannot be mobilised as quickly
Glucose can do both anaerobic and aerobic respiration but lipids can only respire aerobically
Monosaccharide
Glucose
Blood sugar; made by plants
Galactose
Dairy products; less sweet
Fructose
Very sweet; honey
Disaccharides
Maltose
2 glucose M; malt sugar
Lactose
Galactose + glucose; milk
Sucrose
Sugarcane; glucose+ fructose
Polysaccharides
Starch (made of glucose)
Storage E in plants
Glycogen ( when there is too much glucose)
Storage E in animals
Cellulose
Plant cell walls
Function of glucose in animals
A source
Of energy
Function of lactose in animals
sugar in milk of mammals
Energy source
To young
Function of glycogen in animals
Use sore short term E storage in the liver
Function of fructose in plants
Source of E (honey)
Function of sucrose in plants
Transport and store E (sugar cane)
Function of cellulose in plants
Fibres arranged in layers
Provide strength in cell wall
Fatty acids
Saturated: single bonds between all C atoms
Unsaturated: at least one double bond
Polyunsaturated: more than one double bond
Unsaturated fatty acids
CIS
H atoms are always on the same side of the 2 C aroma that are double bonded
Bend in hydrocarbon chain at double bond
Bad for packing regularly
Lower melting point
Usually liquid ART
Unsaturated fatty acids
TRANS
H on opp sides No bend Higher melting point Solid ART Produced artificially: margarine/ processed foods
Carbohydrates
Monosaccharides monomers are linked together by condensation reaction
Disaccharide and polysaccharide polymers
Glucose M
Hexagon
Ribose M
Pentagon
Cellulose
Straight
Unbranched polymer of beta and D glucose
Forms cross links with hydrogen bonds
Very strong
Starch
Helical shape
Polymer of alpha and D glucose M
Amylose: 1,4 links unbranched
Amylopectin: some 1,6 links branched
Plants use it to store glucose
Glucogen
Branches polymer of alpha and D glucose
More 1,6 links more branched than amylopectin
Mammals use it to store glucose in liver / muscle cells
INSOLUBLE
if glucose is stored, water would enter cells, making them burst because glucose is soluble
Links between glucose sub units
1,4 bonds
Some 1,6
Lipids
Triglycerides
Phospholipids
Steroids
Triglycerides
3 fatty acids and I glycerol hay condensation
3 hydrocarbon tails
Fats/
Oil
Phospholipids
2 fatty acids linked to glycerol and phosphate group
Partly hydrophobic
Form membranes
Steroids
Four fuses rings Cholesterol Estrogen Progesterone Testosterone
