This document discusses cell structure and function. It describes how cells can be fractionated using centrifugation to separate out organelles. The plasma membrane is discussed as the outer boundary of cells, with its fluid mosaic model composed of lipids and embedded proteins. The plasma membrane functions to transport materials, protect internal components, and facilitate both active and passive transport through semi-permeability. Endocytosis is mentioned as a process where the plasma membrane folds inward to engulf molecules through phagocytosis of solids or pinocytosis of liquids.

1. Inhibitors, General
Structure of Cell,
Cytoplasm
26 NOV 2020

2. •INHIBITORS:
• “Enzyme inhibitors are substances which alter the catalytic action of
the enzyme and consequently slow down, or in some cases, stop
catalysis”.
• Examples:
1. Poison like Cynaide
2. Anti-biotics
3. Anti-metabolites
Types of inhibitors:
1) Irreversible
2) Reversible

3. •Irreversible Inhibitor:
• A chemical that attaches to active site of enzyme
covalently and blocks it permanently.
•REVERSIBLE INHIBITOR: An inhibitor that is loosely attached to an
enzyme.
•Types
• 1) Competitive 2) Non-Competitive
That attaches to the
active site of enzyme and
if the concentration of
substrate increases it
detaches from active site
That does not attaches to active
sit of enzyme but with the
structure of enzyme. It does not
compete with substrate to get
attached with active site.

5. •CHAPTER 4
•THE CELL

6. •Cell is the:
A.Basic
B.Functional and
C.Structural unit of life.
Initially discovered by Robert Hooke in 1665, the cell has a rich and interesting
history that has ultimately given way to many of today's scientific advancements.
GENERAL STRUCTURE OF CELL:
Cell can be studied under electron microscope. We first extract sample
of cell and do it’s fraction divide it into it’s components(organelles).

7. •CELL FRACTION PROCESS:
• It is as follow:
• Take a cell from any source
• Place it in a test tube and add solution of CsCl which lyse the cell
membrane of cell.
• Now place this test tube in a centrifuge and spin it at normal speed.
• The CsCl will puncture cell membrane and cellular organelles will
come out of cell.
• Centrifugation technique will arrange these organelles according to
their weight with lightest organelle on top and heaviest in the bottom
of test tube.
• If any organelle is still left un-separated ultracentrifuge the cell.

8. Cell Fraction

11. •PLASMA Membrane
• It’s the outer most boundary of cell in animals and inner membrane
than cell wall.
• Chemical composition: 60-80% PROTEINS and 20-40% LIPIDS and
small quantity of CARBOHYDRATES.
• LIPID BILAYER SANDWICH MODEL:
• In past it was thought that:
Protein is present in two layers and in between these layers
are Lipid is just like a slice of cheese between two bread
slices. This structure is present all cell types and is called
UNIT MEMBRANE.
But later on using advance technology scientist found this
model false.

13. •FLUID MOSAIC MODEL:
• According to this model the
• Protein is not in a layer but is present embedded in between
the chain of Phospholipids.
• This is called FLUID MOSAIC MODEL. It is an accepted
model of cell membrane.
• It has charged pores and allows both active and passive
movements across it.

15. Functions of Cell Membrane:
1. Transport of material.
2. Semi-permeable and allows only specific elements to pass through it.
3. Protects all cellular organelles from extremes and changes of environment.
4. Small gas molecules, water, glucose can easily cross it.
5. Supports two types of Transport:
Active Transport which use energy to move the elements against gradient.
Passive Transport which need no energy and elements from high to low
concentration.
EDOCYTOSIS:
In many animal cells, cell membrane allows cell to take in molecules from
environment by folding and forming a vacuole around the element called as
endocytosis (endo-inside, cyte -cell).
Types:
Phagocytosis: If the particle to be taken in is a solid substance.
Pinocytosis: If the particle to be taken in is liquid molecule.