This document discusses the cell theory and provides information about prokaryotic and eukaryotic cells. It states that all organisms are made of cells, the cell is the basic unit of life, and all cells come from existing cells. It then describes the key differences between prokaryotic and eukaryotic cells, noting that prokaryotes lack membrane-bound organelles while eukaryotes have organelles like the nucleus. The document also provides details on the structures and functions of organelles in plant and animal cells like the cell membrane, nucleus, mitochondria, chloroplasts and more.

1. Cells:
The Basic Units of Life
Dr. Santosh Gaherwal
Govt. Holkar Science College, Indore

2. The Cell Theory
1. All organisms are made of cells.
2. The cell is the basic unit of life in all
living things.
3. All cells come from existing cells.
THIS IS IMPORTANT BECAUSE IT SHOWS THAT
ALL LIVING THINGS SHARE A SIMILAR
STRUCTURE

3. • As you have already learned, everything
is made up of living cells.
• And the cells themselves are made up
of many different parts .
• There are many different cells that do
many different things, but all of these
cells fall into one of the two main
categories:
– Prokaryotic cells
&
– Eukaryotic cells

4. • Two categories:
1. Cell that have
membrane-bound organelles
– Called Eukaryotic Cells
2. Cells that do not have
membrane-bound organelles
– called prokaryotic cells
• Unicellular organisms such as
bacteria are examples of
prokaryotes.

5. What the words mean
Prokaryotes
• Pro = before
• Karyose = kernel,
which represents
the nucleus
• So prokaryotes
occurred before
cells with a
nucleus
• Ex. Bacteria
Eukaryotes
• Eu = true
• Karyose = kernel,
the nucleus
• So eukaryotes
are the cells with
a true nucleus
• Ex. Found in
animals, plants,
and fungi (yeast)

6. Type # 1. Prokaryotic Cell:
(Gr., pro-primitive; karyon-nucleus). As the name indicates
these cells are simple in structural organization and most
primitive types.
They include:
1. Bacteria,
2. Pleuropneumonia-Like Organisms (PPLO),
Type # 2. Eukaryotic Cell:
In addition to the nucleus, the cytoplasm of the cell
usually contains a number of distinct bodies or
structures that presumably carry out one or more
rather specific functions.

7. The Two Types of Cells
1. Prokaryotes have no membrane-
enclosed compartments.
2. Eukaryotes have membrane-enclosed
compartments called organelles, such
as the nucleus.

8. Two Types of Cells
All cells, whether they are prokaryotic or eukaryotic, have
some common features

9. Prokaryotic Cells:
• Have no membrane
covered nucleus
• Have no membrane
- covered organelles
• Have circular DNA
• Are bacteria

10. Eukaryotic Cells:
• Have a nucleus
• Have a membrane -
covered organelles
• Have linear DNA
• Are all other cells

11. Organelles
Organelles are structures that enable
the cell to live, grow and reproduce.

12. Cell Membrane
• Outer layer of cell
• Allows nutrients
into the cell and
wastes outside of
the cell
Cell Membrane
“Gate into the
city”

13. Cytoplasm
• Cytoplasm a
jelly-like fluid
contained in
the cell that
holds the
organelles.

14. The Nucleus
• The control
center of the
cell
• Contains the
Cell’s DNA
DNA
Nuclear Membrane
Nucleolus
“Mayor’s office”

15. Mitochondria
• Power center of
cell
• Provides the
energy the cell
needs to move,
divide, etc.
Outer Membrane
Inner Membrane
“Electric company of
the cell”

16. Ribosomes
• Site where
proteins are
made
• Cell parts are
made of
proteins “Factories of the
cell”

17. Endoplasmic Reticulum
• Transportation
system of cell
• Rough ER-
ribosome's
attached
• Smooth ER- no
ribosome's
Ribosomes
Endoplasmic Reticulum
“Roadways of the cell”

18. Golgi Complex
• Packaging house of
cell
• Packages,
processes, and
ships out the
stuff the cell
makes
“UPS of the cell”

19. Lysosomes
• Digests food
particles and cell
parts
– “Garbage men”
• Protects cell by
digesting foreign
invaders
– “Police men

20. Vacuole
• Stores water,
food & wastes
Vacuole
Vacuole is largest
organelle in plant
cell

21. Cell Wall
• Found only in
plant cells
• Protects and
supports the cell

22. Chloroplasts
• Found only in plant
cells
• Contains
chlorophyll (makes
plants green)
• Where
photosynthesis
takes place

23. Plant or Animal Cell?
Found in Plant and Animal cells: Found only in Plant Cells:
• Nucleus
• Golgi Complex
• Mitochondrion
• Lyosomes
• Endoplasmic
Reticulum
• Cell Membrane
• Ribosomes
• Vacuoles
• Chloroplasts
• Cell Wall

24. Prokaryotic cell structure
• Prokaryotes are single-celled organisms that are the earliest
and most primitive forms of life on earth.
• prokaryotes include bacteria and archaeans. Some prokaryotes,
such as cyanobacteria, are photosynthetic organisms and are
capable of photosynthesis.

25. Many prokaryotes are extremophiles and can live and thrive
in various types of extreme environments including
hydrothermal vents, hot springs, swamps, wetlands, and the
guts of humans and animals (Helicobacter pylori).
Prokaryotic bacteria can be found almost anywhere and are
part of the human microbiota.
They live on your skin, in your body, and on everyday
objects in your environment.

26. • Prokaryotic cells are not as complex as eukaryotic cells. They
have no true nucleus as the DNA is not contained within a
membrane or separated from the rest of the cell, but is coiled up
in a region of the cytoplasm called the nucleoid.
• Prokaryotic organisms have varying cell shapes. The
most common bacteria shapes are spherical, rod-shaped, and
spiral.
• Using bacteria as our sample prokaryote, the following
structures and organelles can be found in bacterial cells:

27. •Capsule: Found in some bacterial cells, this additional outer
covering protects the cell when it is engulfed by other
organisms, assists in retaining moisture, and helps the cell
adhere to surfaces and nutrients.
•Cell Wall: The cell wall is an outer covering that protects
the bacterial cell and gives it shape.
•Cytoplasm: Cytoplasm is a gel-like substance composed
mainly of water that also contains enzymes, salts, cell
components, and various organic molecules.
•Cell Membrane or Plasma Membrane: The cell
membrane surrounds the cell's cytoplasm and regulates the
flow of substances in and out of the cell.

28. •Pili (Pilus singular): Hair-like structures on the
surface of the cell that attach to other bacterial cells.
Shorter pili called fimbriae help bacteria attach to
surfaces.
•Flagella: Flagella are long, whip-like protrusions that
aid in cellular locomotion.
•Ribosomes: Ribosomes are cell structures responsible
for protein production.
•Plasmids: Plasmids are gene-carrying, circular DNA
structures that are not involved in reproduction.
•Nucleoid Region: Area of the cytoplasm that contains
the single bacterial DNA molecule.

29. Cell Types
• Eukaryotic cells-
– Cells that contain organelles which are held together
by membranes
– Examples include plant and animal cells.

30. Eukaryotic Cell Structure
• The plasma
membrane/cell
membrane
– the flexible boundary of a
cell
– separates a cell from its
surroundings

31. Plasma Membrane/Cell
Membrane continued:
• allows nutrients to enter the cell and waste
to be removed
– This is referred to as selective permeability.
*(Selective=Chooses, Permeability=filter through)*
• keeping a healthy balance of nutrients and
water within the cell is called homeostasis

32. Overview of Organelles
• Nucleus-
– Largest organelle in the cell and it is the most inner
compartment of the cell
– contains chromatin (DNA); genetic information on
strands called chromosomes
– “control center” for cell metabolism and reproduction
• Chromatin- Directions on how to make proteins
• Nucleolus- Found inside nucleus; ribosomes are
made here

33. Overview Cont’d
• Ribosomes- make proteins (made up of RNA and protein);
thought of as “factories”
• Cytoplasm- clear gel like fluid inside the cell, which suspends
all organelles
• Endoplasmic Reticulum- extensive network of
membranes
– Rough ER: with ribosomes
– Smooth ER: with no visible ribosomes
• Golgi Apparatus- sorts proteins made by the ribosomes
and sends them to needed places in the cell

34. • Ribosomes- make proteins (made up of RNA and protein);
thought of as “factories”
• Cytoplasm- clear gel like fluid inside the cell, which suspends
all organelles
• Endoplasmic Reticulum- extensive network of
membranes
– Rough ER: with ribosomes
– Smooth ER: with no visible ribosomes

35. • Lysosomes- organelles that are filled with digestive
enzymes to remove waste and invading bacteria
• Mitochondria- often referred to as the “powerhouse”
of the cell
– release energy for the cell
– It converts the energy stored in glucose into ATP for the cell
• Vacuoles- fluid filled organelles enclosed by a
membrane
– Store materials such as food, sugar, water, and waste
products

36. Eukaryotic plant cell
• Plant cells are also Eukaryotic cells, but plant
cells contain some organelles that are not found
in animal cells.

37. Plant Cell Organelles
• Cell wall- rigid wall outside the plasma membrane. It
provides the cell with extra support.
• Chloroplasts- captures light and energy; and
converts it into chemical energy.
• Chlorophyll- green pigment found inside the
chloroplast.
• Plastids- organelles that store things such as food in
the plant cell.

38. How are prokaryotic and
eukaryotic genomes different
• The majority of genetic material is
organized into chromosomes that
contain the DNA that controls cellular
activities. Prokaryotes are typically
haploid, usually having a single circular
chromosome found in the
nucleoid. Eukaryotes are diploid; DNA
is organized into multiple linear
chromosomes found in the nucleus.

39. Difference # Prokaryotic Cell:
• 1. Nuclear membrane is absent in prokaryotic cell.
• 2. Chromosomes are single in prokaryotic cell.
• 3. DNA is naked.
• 4. Nucleolus is absent in prokaryotic cell.
• 5. Mitochondria is absent. Respiratory and
photosynthetic enzymes present in plasma-
membrane.
• 6. Endoplasmic reticulum is absent in prokaryotic cell.
• 7. Ribosomes – 70S type/size, made up of 5OS and
30S sub-units. All ribosomes are free in cytoplasm.

40. Difference # Prokaryotic Cell:
• 8. In prokaryotic cell, chloroplast is absent.
However, present in blue-green algae is
associated with lamellae. These lamellae are
not enclosed by membrane.
• 9. Golgi bodies are absent in prokaryotic cell.
• 10. Lysosome is absent in prokaryotic cell.
• 11. Cell-Wall is thin. Non cellulosic, contains
amino sugars and muramic acid.
• 12. Cytoplasmic streaming or Amoeboid
movement does not occur in prokaryotic cell.
• 13. Division of cell is amitosis or direct

41. Difference # Eukaryotic Cell:
• 1. Nuclear membrane is present in eukaryotic cell.
• 2. In eukaryotic cell, chromosomes are many in
number.
• 3. DNA is combined with proteins.
• 4. Nucleolus is present in eukaryotic cell.
• 5. Mitochondria is present in cytoplasm of eukaryotic
cell.
• . Endoplasmic reticulum is present in eukaryotic cell.

42. Difference # Eukaryotic Cell:
• 7. Ribosomes – 80S type/size. In plants these
dissociate into 60S and 40S sub-units. Most of the
ribosomes attached to endoplasmic reticulum. Some
ribosomes are free in the cytoplasm.
• 8. All green plants have typical chloroplasts which
have grana.
• 9. Golgi bodies are present in eukaryotic cell.
• 10. Lysosome are present in eukaryotic cell.
• 11. Cell-Wall is thick, cellulosic, does not contain
amino and muramic acid.
• 12. Cytoplasmic streaming or Amoeboid movement
may occur in eukaryotic cell.
• 13. Division of cell is indirect. Mitosis and Meiosis.

43. • “The DNA in prokaryotes are smaller
in size, circular and present in
cytoplasm while the eukaryotic DNA
is larger in size, arranged on
chromosomes and located in the
nucleus of the cell.”