Bio Flipbook

BIOLOGY 1 SB015 ASSIGNMENT 2026/2027

BIO FLIPBOOK: MOLECULES OF LIFE & CELL STRUCTURE AND FUNCTIONS Set C:

Name: Koay Yu Xuan Matric number: MS2613108309 Praticum: H3T1B Lecturer: Madam Zakiah binti Rashid

Set C Questions:

Main Types of Molecules of Life(5m)

Carbohydrates

Protein

Nucleic acid

Water

Lipid

Classify lipids into three main types based on their structure (15m)

Triglycerides

Consist of 1 glycerol molecule + 3 fatty acid molecules.

Fatty acids are joined to glycerol by three ester bonds through condensation process.

Fatty acid consist of a long linear hydrocarbon chain(R) and carboxyl group(-COOH).

Phospholipid

Consist of 1 glycerol molecule + 2 fatty acid molecules + 1 phosphate group and additional small molecule.

Have a hydrophilic (polar) phosphate head Have two hydrophobic (non-polar) fatty acid tails Amphipathic molecule (contains both hydrophilic and hydrophobic regions).

Arranges naturally into a phospholipid bilayer.

Steroid Consist of four fused carbon rings.

Three six-membered rings and one fivemembered ring.

Do not contain glycerol and fatty acids.

Hydrophobic molecule.

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 [10 marks].

Peripheral protein

chain

Plasma membrane follows the Fluid Mosaic Model.

Membrane components are dynamic and can move sideways (laterally).

Proteins are embedded within the phospholipid bilayer, forming a mosaic pattern.

The membrane consists of a phospholipid bilayer.

Each phospholipid has: —Hydrophilic (polar) phosphate head – faces the aqueous environment.

—Hydrophobic (non-polar) fatty acid tails – face inward Integral proteins are partially or fully embedded in the bilayer while peripheral proteins are attached to the surface of membrane

While observing animal cells under the microscope, a biology student noticed that the plasma membrane is neither too rigid nor too fluid. Explain how the different types of lipid in the plasma membrane causes and regulate membrane fluidity [5 marks].

Lipids That Increase Membrane Fluidity 1.Unsaturated Phospholipids Contain one or more double bonds.

Double bonds create kinks (bends) in the fatty acid tails.

Kinks prevent phospholipids from packing closely together.

Increase membrane fluidity.

Can move laterally,making the membrane dynamic

2. Cholesterol (at low temperature) Prevents phospholipids from packing tightly.

Prevents the membrane from becoming too rigid.

Maintains/increases membrane fluidity at low temperature.

Lipids That Reduce Membrane Fluidity 1. Saturated Phospholipids Do not contain double bonds.

Fatty acid tails are straight.

Pack closely together.

Reduce membrane fluidity and make the membrane more rigid.

2. Cholesterol (at high temperature) Restricts the movement of phospholipids.

Prevents excessive movement of the phospholipids .

Reduces membrane fluidity at high temerature.

Kinks