BIOLOGY ASSIGNMENT SB015 :
MOLECULES OF LIFE & CELL
STRUCTURES AND
FUNCTIONS
NAME : SITI NUR FATIHAH BINTI MOHD ARIZAN
MATRIC NUMBER : MS2113173087
PRACTICUM : H3T01B
LECTURER'S NAME : SUBASHINI A/P SELVARAJU
THE MAIN TYPES OF MOLECULES OF LIFE :
PROTEINS CARBOHYDRATES LIPIDS
NUCLEIC WATER
ACIDS
TRIGLYCERIDES PHOSPHOLIPIDS
3 CLASSES OF
LIPIDS
STEROIDS
TRIGLYCERIDES
STRUCTURES & CHARACTERISTICS :
A triglyceride is a combination of a glycerol
molecule and three fatty acids
Glycerol is a type of alcohol which contains 3
carbon atoms & 3 hydroxyl (OH-) groups
A fatty acid consists of a long linear
hydrocarbon chain (R) and a carboxyl group
(-COOH)
Can be formed through condensation process
which forms ester bond and can be breakdown
through hydrolysis
Triglyceride can be in the form of fats (solid form
at room temperature) or oils (liquid form at room
temperature)
PHOSPHOLIPIDS
STRUCTURES & CHARACTERISTICS
Phospholipid consists of 1 glycerol, 2 fatty acids, 1
phosphate group & additional small molecule such as
choline
It has both hydrophobic (water-hating) hydrocarbon
tail and hydrophilic (water-loving) polar head
STRUCTURES & CHARACTERISTICS
Consists of 4 fused carbon rings
functional groups attached to the rings determine the
types of steroids
STEROIDS
structure of plasma Describe by the Fluid Mosaic
membrane : Model
The membrane is composed of 2
layers (bilayer) of phospholipids
with globular proteins embedded
The Fluid represent the
phospholipids and protein can
move laterally
COMPONENTS EXPLANATION
Phospholipids
hydrophilic heads facing outwards and attracted to the aqueous surrounding
Cholesterol hydrophobic tails facing inwards
Carbohydrate molecules that can pass through phospholipids are water,gases,urea and lipid soluble
substances
chains large molecules such as glucose, ions and polar molecules cannot pass through it
Proteins can be found between phospholipids
cholesterol prevents free movement of phospholipids molecules and reduces membrane
fluidity
can be found on the external surface of the plasma membrane
if the carbohydrate chain attaches to the protein,it is known as glycoprotein
if it attaches to phospholipids , it is known as glycolipid
act as identity markers/recognition
the second major component of plasma membrane
have 2 main categories which are integral protein & peripheral protein
integral protein are partially or fully embedded into the phospholipid bilayer
pheripheral proteins are attached to the outer and inner surfaces of the membrane
HOW CERTAIN TYPE OF LIPIDS ENSURES THE FLUIDITY OF THE
PLASMA MEMBRANE WHILE SOME OTHER TYPE OF LIPIDS MAY
REDUCEITS FLUIDITY :
Phospholipids and protein of plasma membrane
can move laterally
They are dynamic and this provides fluidity for
the plasma membrane
The cholesterol that is wedged between the phospholipid
prevents free movement of phospholipids molecules
at warm temperatures, cholesterol reduce membrane
fluidity
at cool temperatures, cholesterol prevent close packing of
phospholipids and slowdown solidication.