BIOLOGY ASSIGNMENT SEM 1 2022 (KHALEEDA ZAINOL)

BIOLOGY FLIPBOOK
MOLECULES OF LIFE

&
CELL STRUCTURES

AND FUNCTION

NAME : NUR KHALEEDA BINTI ZAINOL

MATRIC : MS2113173409
NUMBER

PRACTICUM : K4T01A

LECTURE'S : ANIZA BINTI ABU BAKAR
NAME

Main types of
molecules of life

Water

Carbohydrates

Lipid

Protein

DNA and RNA
molecules

Three main
classes of lipid

TRIGLYCERIDES

Also known as triacylglycerol
consists of 1 glycerol and 3 fatty acids
Glycerol : 3 carbon atoms (C) & 3
hydroxyl (OH) groups.
A fatty acid consists of a long linear
hydrocarbon chain (R) and a carboxyl
group(-COOH).
Fat
Solid at room temperature
Oil
Liquid at room temperature

PHOSPHOLIPIDS

The structure of a phospholipid molecule contains
phosphoric acids, nitrogen bases, alcohol and fatty
acids. These compound lipids are major
components of the cell membrane and also
provide a fluid character to the membranes. In cell
membranes, these phospholipids have a hydrophilic
head and a hydrophobic tail, which forms the
inside of the bilayer.

Lecithin

Consists of 1 phosphate acid, choline, 1
glycerol and 2 fatty acids
Component of cell membrane

STEROIDS

Cholesterol

Consists of 4 fuse carbon rings.
Can be found between phospholipids.
Increase flexibility and stabilizes the
membrane structure by regulating the fluidity
of the membrane.
Precursor for sex hormone example
testosterone.

Plasma
membrane

This structure is known as the Fluid
Mosaic Model proposed by S.J Singer
and G.L Nicolson The Fluid Mosaic
Model membrane is composed of 2
layers(bilayer) of phospholipids with
globular protein embedded in the
bilayer. Fluid is phospholipids and
protein can move laterally(move side to
side).

Mosaic proteins are embedded in the
phospholipid bilayer like the mosaic
tiles embedded in mortar. In addition to
the phospholipids, the plasma
membranes of animal cells contain
glycolipids and cholesterol.

The glycolipids are found exclusively in
the outer leaflet of the plasma
membrane, with their carbohydrate
portions exposed on the cell surface.
Accounted for the amphipathic
characteristic of phospholipids and
protein. amphipathic molecules have
both hydrophobic regions and
hydrophilic regions. Hydrophobic is
known as non-polar or "water-hating"
and hydrophilic known as polar or
"water-loving".

The hydrophilic heads of
phospholipids face outwards and are
attracted to the aqueous
surroundings. Meanwhile, the
hydrophobic tails of phospholipid
face inwards. Molecules that can
pass through phospholipids are
water, urea, and gases like O2, CO2
and lipid-soluble substances. Other
than that, molecules that cannot
pass through phospholipids are ion,
polar, and large molecules example
glucose.

Type of lipids ensures the fluidity
of the plasma membrane while

some other type lipids may reduce
its fluidity

The type of lipid that ensures the
fluidity of the plasma membrane is
cholesterol, which is another type of
lipid embedded between the membrane's
phospholipids and helps reduce the
effects of temperature on fluidity. The
membrane's fluidity is provided by
phospholipid and the membrane becomes
dynamic. At the same time, cholesterol
Increases flexibility and stabilizes the
membrane structure by regulating the
fluidity of the membrane. Precursor for
sex hormone example testosterone.

Cholesterol reduces membrane fluidity
by preventing the free movement of
phospholipid molecules.

Warm temperatures: cholesterol reduce
membrane fluidity by preventing the free
movement of phospholipids molecules.

Cool temperatures: cholesterol
prevents close packing & slows down
solidification.

THANK YOU_)