2. LEARNING OBJECTIVES
State the cell theory
Compare the structures of prokaryotic and
eukaryotic cells;
Compare typical animal and plant cells as seen
under electron microscopes
State the cell theory
Compare the structures of prokaryotic and
eukaryotic cells;
Compare typical animal and plant cells as seen
under electron microscopes
State the cell theory
Compare the structures of prokaryotic and
eukaryotic cells;
Compare typical animal and plant cells as seen
under electron microscopes
State the cell theory
Compare the structures of prokaryotic and
eukaryotic cells;
Compare typical animal and plant cells as seen
under electron microscopes
State the cell theory
Compare the structures of prokaryotic and
eukaryotic cells
Compare typical animal and plant cells as seen
under electron microscopes
3. The English scientist Robert Hooke first used the term “cells” in 1665 to
describe the small chambers within cork that he observed under a
microscope of his own design.
Robert Hooke
4. The Origins of Cell Theory
Leeuwenhoek is commonly known as the "Father of Microbiology", as he
was the first person to ever see microorganisms.
He later improved the microscope, and contributed towards the
establishment of microbiAntonie Philips van Leeuwenhoekology.
Antonie Philips van Leeuwenhoek
5. The Origins of Cell Theory
in 1838, Matthias Schleiden (1804–1881), a German botanist who made
extensive microscopic observations of plant tissues, described them as
being composed of cells.
Matthias Schleiden
6. The Origins of Cell Theory
Theodor Schwann (1810–1882), a noted German physiologist, made similar
microscopic observations of animal tissue.
In 1839, after a conversation with Schleiden, Schwann realized that
similarities existed between plant and animal tissues. T
his laid the foundation for the idea that cells are the fundamental
components of plants and animals.
Theodor Schwann
7. The Origins of Cell Theory
In 1852, Robert Remak (1815–1865), a prominent neurologist and
embryologist, published convincing evidence that cells are derived from
other cells as a result of cell division.
However, this idea was questioned by many in the scientific community.
Robert Remak
8. The Origins of Cell Theory
Three years later, Rudolf Virchow (1821–1902), a well-respected
pathologist, published an editorial essay entitled “Cellular Pathology,”
which popularized the concept of cell theory using the Latin phrase omnis
cellula a cellula (“all cells arise from cells”), which is essentially the second
tenet of modern cell theory.
Rudolf Virchow
9. PRINCIPLES OF CELL THEORY
ALL ORGANISMS ARE MADE OF CELLS
ALL EXISTING CELLS ARE PRODUCED BY
OTHER LIVNG CELLS
THE CELLS IS THE MOST BASIC UNIT OF LIVE
10. PROKARYOTIC CELLS
The word “prokaryotes” is coined from two Greek words
pro, before, and karyon, nut or kernel.
Prokaryotic cells are unicellular (single-celled) organisms
that lack true nucleus and membrane-bound cell
organelles.
The majority of prokaryotic DNA is found in a central region
of the cell called the nucleoid, and it typically consists of a
single large loop called a circular chromosome.
12. EUKARYOTIC CELLS
Eukaryotes (eu, true) which include the protoctists, fungi, animal
and plants
Eukaryotes cells are true cells with DNA inside the nucleus
A eukaryotic cell has a true membrane-bound nucleus and has
other membranous organelles that allow for compartmentalization
of functions.
Like a prokaryotic cell, a eukaryotic cell has a plasma membrane,
cytoplasm, and ribosomes.
15. Comparison between the structures of prokaryotic and
eukaryotic cells
Prokaryotes Eukaryotes
1. Average diameter of cell 0.5 —5 µm Average diameter of cell 10-100 urn
2. Genetic material is a circular double strand
of DNA, not surrounded by double-membrane
nuclear envelope found in the nucleoid region.
Most DNA are associated with histone proteins to form
chromosomes. Chromosomes are surrounded by a
double-membrane nuclear envelope. Circular DNA are
present in mitochondria and chloroplasts.
3. Some bacteria have small circular DNA
plasmids.
Plasmids are absent.
4. Few organelles. No double
membrane-bound organelles such as mitochondria
and chloroplasts.
Many organelles. Presence of double membrane-
bound organelles such as nucleus, mitochondria and
chloroplasts in plants and algae.
16. Comparison between the structures of prokaryotic and
eukaryotic cells
Prokaryotes Eukaryotes
5. Mesosomes in bacteria and plasma
menfbrane of cyanobacteria contain
respiratory enzymes. No mitochondria.
There are no mesosomes. Mitochondria function
as sites for cellular respiration to produce ATP.
6. Some prokaryotes are
photoautotrophs. Photosynthetic
membranes not stacked into grana. No
chloroplasts.
Chloroplasts containing grana.
7. Flagella, if present, contain flagellin and
lack microtubules.
Flagella, if present, have a '9+ 2'
arrangement of microtubules.
8. Some prokaryotic cells have enzymes that
can fix atmospheric nitrogen for use in amino
acid synthesis.
Eukaryotic cells do not contain enzymes that
can fix atmospheric nitrogen.
17. Comparison between the structures of prokaryotic and
eukaryotic cells
Prokaryotes Eukaryotes
9.No mitosis or meiosis.
No spindle formation.
Mitosis, meiosis or both can occur.
There is spindle formation.
10.Ribosomes are smaller, 70S ribosomes
occur as free particles in the cytoplasm.
Ribosomes are larger, 80S ribosomes
occur as free particles in the cytoplasm or
are bound to the endoplasmic reticulum.
11. Rigid cell walls containing murein
(peptidoglycan).
Cell walls of plants and algae contain
cellulose, fungi contain chitin'and animal
cells have no cell walls.
12. Mesosomes ire bacteria and plasma
membrane of cyanobacteria contain
respiratory enzymes. No mitochondria.
There are no mesosomes. Mitochondria
function as sites for cellular respiration
to produce ATP.
20. THE STRUCTURE OF ANIMAL CELLS
An animal cell as seen with a light microscope contains a
protoplasm (nucleus and cytoplasm) surrounded by a thin plasma
membrane (cell surface membrane)
Each cell has a relatively large central nucleus surrounded by
cytoplasm.
The nucleus contains coiled threads called chromatin.
21. THE STRUCTURE OF ANIMAL CELLS
Chromatin contains DNA and proteins called histones which
together condense to form chromosomes during cell division.
DNA carries genetic material which controls cell activities and
determines the organism's characteristic.
Cytoplasm contains organelles such as mitochondria suspended
in the cytosol. They are specialised to carry out specific
functions.
Cytoplasm contains glycogen granules, a food storage
polysaccharide.
25. THE STRUCTURE OF PLANT CELLS
Many of the structures found in an animal cell also occur in the plant cell.
There is a protective, rigid, cellulose cell wall surrounding the cell
Chloroplasts in the cytoplasm contain chlorophyll pigments which carry
out photosynthesis.
A large central vacuole filled with cell sap is present in mature plant cells.
The vacuole is surrounded by tonoplast.
The nucleus and cytoplasm are usually peripheral.
Plant cells contain starch granules as polysaccharide food storage.
26. COMPARISION BETWEEN TYPICAL ANIMAL CELLS AND PLANTS CELL
Animal cell Plant cell
1. No cellulose cell wall, only plasma
membrane (cell surface membrane)
Have rigid cellulose cell wall and plasma
membrane (cell surface membrane)
2. No plasmodesmata and pits
Plasmodesmata and pits present in
cell wall
3. No chloroplasts
Chloroplasts present in photosynthetic
cells
4. Small, temporary vacuoles
Large, permanent central vacuole filled
with cell sap
5. No tonoplast
Tonoplast around vacuole
6. Nucleus often central. Cytoplasm
throughout the cell
Nucleus and cytoplasm usually
peripheral
27. COMPARISION BETWEEN TYPICAL ANIMAL CELLS AND PLANTS CELL
Animal cell Plant cell
7. Centrioles present No centrioles
8. Contains glycogen granules for
carbohydrate storage
Contains starch granules for
carbohydrate storage
9. Some cells have cilia or flagella, for
example, ciliated epithelium of trachea,
oviductus, flagellum of spermatozoon
No cilia and flagella
10. Lysosomes present
Lysosomes usually absent except
insectivorous plants, for example,
Nepenthes and Utricularia
11. Smaller than plant cells
Often larger than animal cells,
although cell size varies greatly
