The document summarizes the key differences between prokaryotic and eukaryotic cells. Prokaryotes lack a nucleus and have simpler structures, while eukaryotes have membrane-bound nuclei and organelles. The main organelles of eukaryotic cells are then described in more detail, including their structures and functions. Organelles such as the nucleus, mitochondria, ER, Golgi apparatus, lysosomes and peroxisomes each have specialized roles in processes like DNA replication, protein synthesis, cellular respiration and metabolism.
3. The cells of biological systems
are divided into two
categories.
•Prokaryotes
•Eukaryotes
4. Prokaryotes
(Pro - before, karyon –
Nucleus).
• Lack a well defined nucleus and
possess relatively simple
structure.
• Lower organism - bacteria.
5. Eukaryotes
(Eu – true/good, karyon –
Nucleus)
• Have a membrane enclosed
nucleus encapsulating their DNA.
• Higher organisms - Plants and
animals.
6. Difference between
Eukaryotic and Prokaryotic
cell
Characteristics Prokaryotes Eukaryotes
1.Size
2.Cell membrane
3.Cytoplasm
1-10 μm
Rigid cell wall
Viscous, No
subcellular
organelle
10-100 μm
Plasma
membrane
Subcellular
organelle
present
7. Difference between
Eukaryotes and prokaryotes
Characteristics Prokaryotes Eukaryotes
4. Nucleus
5. Nucleolus
6. Mitochondria
7. Golgi
8. Cytoskeleton
9. Cell division
A nuclear zone
with DNA
Absent
Absent
Absent
Absent
Fission
Well defined
Nucleus
Present
Present
Present
Present
Mitosis
9. • Cells contain various organised
structures, collectively called as
cell orgenelles
• When cell membrane is
disrupted, the organised
particles inside the cell are
homogenised.
• Separated by differential
centrifugation
11. Plasma Membrane is the
limiting boundary of cell
Plasma membranes are viscous, yet plastic
Lipid bilayer Membranes are made of a diverse
mixture of various lipids ( phospholipids, steroids
like cholesterol) proteins & carbohydrates
12. Plasma Membrane- Nicolson
& Singer Fluid Mosaic model
The concept that
membranes are fluid
with proteins floating
in them like icebergs
was proposed by
Singer and Nicolson
in their "fluid mosaic
model".
13. • Structure:
• Membranes made up of lipids,
proteins & small amount of
carbohydrates
• Phospholipids (amphipathic) are
the most common lipids,
cholesterol also present.
14. •Phospholipids are
arranged in bilayers with
polar head groups oriented
towards ECF side &
cytoplasmic side with a
hydrophobic core.
15. • Total thickness 50-80 A˚
• Each leaflet 25 A˚
• Lipid bilayer shows free bilateral
movement of its components –
fluidity
• Exoctosis & endocytosis are due to
fluidity
18. Lipids are also unevenly distributed within each membrane leaflet
Saturated
chains
like to self
associate
due to
extensive
Van der
Waals
ie
hydrophobic
interactions
19. • Proteins – 2 types
- Peripheral & integral
- Peripheral – on the surface of the
bilayer, attached by ionic & polar
bonds to polar heads of lipids
- Integral – deeply embedded,
attached by hydrophobic bonds
20. • Some integral proteins span the
bilayer – transmembrane proteins
– serve as receptors (for hormones,
neurotransmitters), ion channels,
tissue specific antigens etc
• Carbohydrates are present as
glycoproteins or glycolipids
• Carbohydrate component always
towards the outer side
21.
22. Functions of Plasma
Membranes
• Protective sheath
• Selective transport of ions and
molecules.
• Recognition of various stimuli.
• Contains receptors for
biomolecules like hormones,
neurotransmitters etc.
26. • surrounded by 2 membranes, Nuclear
envelope, with the outer membrane
continuous with the membrane of ER.
• Inner - perinuclear membrane
• Nuclear envelope contains numerous
pores of about 90 nm in diameter.
• Nucleus contains a major sub
compartment – Nucleolus. Area for RNA
processing & ribosome synthesis
27. DNA is located
in the nucleus
as DNA-Protein
complex known as
chromatin that is
organized into
chromosomes.
29. Endoplasmic reticulum
• A network of interconnecting membranes
that thread from the nuclear envelope to
plasma membrane.
2 Types – based on microscopic appearance
Smooth ER
Rough ER
30. ER – functions
Protein synthesis
Glycoprotein &
lipoprotein synthesis
Cholesterol
synthesis
Metabolism of drugs
Smooth endoplasmic
reticulum
32. Golgi - Functions
• Modification, packaging and sorting
of proteins.
• Glycosylation of Proteins –
modification for the transport of
protein across the plasma membrane
• Major site of new membrane
synthesis - formation of lysosomes
and peroxisomes.
33. Mitochondria
• Spherical, oval or rod like bodies
• Size: 0.2- 0.8 μm
• Number of mitochondria
in a cell varies.
Erythrocytes no mitochondrion
Liver cell 800-2500
34. Mitochondria
• Bilayered
OMM – Smooth
IMM – convolutes into
folds - Cristae
2 Compartments
• Inter membranal space
• Matrix
41. • Metabolism of free oxygen radicals.
• Synthesis of ether lipids.
• Bile acid formation.
• Catabolism of long chain fatty acids.
Peroxisomes play an
important role in Lipid
metabolism
45. • cytoskeleton is made up of
a network of microtubules &
microfilaments
Microtubules – consist of tubulins
& several other proteins
Functions –
- formation of mitotic spindle
-movement of secretory granules
(exocytosis or endocytosis)
46. • Cytoskeleton is responsible for
- the shape of the cell
- its motility
- chromosomal movements during cell
division
