LOH SING WEN H6T02A

BIO FLIPBOOK

MOLECULES OF LIFE & CELL STRUCTURES AND FUNCTIONS

NAME : LOH SING WEN



MATRIC NUMBER : MS2213103995



PRACTICUM : H6T02A

SET C QUESTIONS

i. State the main types of molecules of life.

WATER CARBOHYDRATES LIPIDS

PROTEINS DNA AND RNA MOLECULES

ii. Classify lipids into three main types based on their structure and characteristics.

Triglycerides Saturated Fatty Acids Fatty Acids

- No double bond between carbon atom

- High melting point Unsaturated Fatty Acids

- Low rancidity - 1 more double bonds between carbon atom
- Low melting point
- Solid at room temperature - High rancidity
- Liquid at room temperature
also known as triacylglycerol - Generally from animal source

consist of 1 glycerol and 3 fatty acids

glycerol is a type of alcohol that contain 3 - Generally from fish or plant source

carbon atoms & 3 hydroxyl groups Formation and Breakdown of Triglycerides

A fatty acid consist of a long linear

hydrocarbon chain & a carboxyl group

- Solid at room
temperature

FAT

- Liquid at room
temperature

OIL

Phospholipids - Consists of 1 glycerol, 2 fatty acids,
1 phosphate group & additional small
meolecule (such as choline)

- Lecithin is a mixture of fats that are
essential to cells in the human body.
- Contain nutrient choline found in

EGG YOLK MILK

A complex mixture of phospholipids form lecithin PEANUT SOYA BEAN

Steroids

- Characterized by a 4 ring structure
- Component of cell membrane
- Influence the membrane's fluidity
- They can also act as hormone in body
- Precursor for sex hormone
- For example :

Testosterone

iii. Plasma membrane of cells consists of lipids and some other organic molecules. With the aid of a labeled diagram,

briefly describe the structure of plasma membrane.

- The components of plasma membrane are:

Glycoprotein Carbohydrate

- Comprise protein and - Sugar molecules

carbohydrate chains - Monosaccharides, disaccharides,

- Function in structure, oligosaccharides, polysaccharides

reproduction, immune system, and nucleotides
hormones, and protection of - Body's primary source of energy

cells and organisms Globular protein

Cholesterol Glycolipid - spherical ("globe-like")
proteins
- Waxy substance - lipids with a carbohydrate - Example :
found in your blood attached by a glycosidic Haemoglobin
- maintain fluidity of - maintain the stability of
- Plasma membrane is composed of a lipid the cell membrane
layer which is semipermeable cell membranes

- Responsible to regulate the transportation of Integral protein Peripheral protein
Channel protein
materials and the movement of substances in - Has specific site - Attached to the intracellular or
and out of the cell - Allow specific - Special arrangement of extracellular surface of the lipid
- consists of both lipids and proteins molecules, such as amino acids which bilayer
- fundamental structure of the membrane is the ions, nutrients to pass embeds in the cell - Function in support,
phospholipid bilayer through plasma membrane communication, enzymes, and
membrane - Provide a hydrophilic molecule transfer in the cell.
passageway for water and

small, polar ions

iv. Explain how certain type of lipids ensures the fluidity of the plasma membrane while some other type of lipids may
reduce its fluidity.

- Component that helps the lipids to ensure the fluidity of the plasma membrane is cholesterol.

- Cholesterol acts as a bidirectional regulator of membrane fluidity.

- At high temperatures, phospholipid in the bilayer have much kinetic energy and they do not cluster
together closely, cause decreasing of intermolecular interactions and increasing membrane fluidity.
Thus, the cholesterol stabilizes the membrane and raises its melting point.

- Whereas at low temperatures, phospholipids in the bilayer do not have as much kinetic energy and they cluster
together more closely, cause increasing intermolecular interactions and decreasing membrane fluidity. Thus, the
cholesterol will intercalates between the phospholipids and prevents them from clustering together and stiffening.

- Phospholipid tails can be saturated, which consist of one bond between carbon atom in the fatty acid
tails or unsaturated, which contain one or more than one bonds between carbon atom in the fatty acid
tails.
- Saturated fatty acid tails have no double bonds and as a result have straight, unkinked tails, while
unsaturated fatty acid tails have double bonds and, as a result, have crooked, kinked tails.
- Hence, saturated fatty acids tails are arranged in a way that maximizes interactions between the tails.
These interactions decrease bilayer fluidity.
- Whereas, the unsaturated fatty acids have more distance between the tails and thus fewer
intermolecular interactions and more membrane fluidity.

Thyoaun!k