Introduction to the Medical
biology. Biology of cell
Questions to answer






General and medical Biology as the sciences.
Characteristics of living things.
Levels of living organization.
The cell theory in its modern form.
Cellular level of life organization:
-prokaryotic and eukaryotic cells
-the differences between plant and animal
cells.
The main components of eukaryotic cell.
Characteristics of living
things.









use energy – have a metabolism- the building up and breaking down of
chemicals
grow and develop become larger and more complex
respond to their surrounding
reproduce- produce offspring that are similar to the parents
have the chemicals of life, carbohydrates, proteins, lipids and nucleic
acids (genetic material)
have cells
The fundamental characteristics of living things:
reproduction (self-reproduction), which is the process that gives rise to
offspring;
genes (self-renewal) are the units of inheritance, passed prom parent to
offspring, that control many daily functions.
Finally, populations of living organisms adjust to environment variations
through evolution, a change in the traits of a species over time (selfregulation).
CELLS- are the basic units of structure and
function in living things.
 ROBERT HOOKE- first to
look at cells
looked at a thin section of
cork
 ANTON VAN
LEEUWENHOEK – made his
own lenses made first
compound microscope drew
pictures that we can still
identify today
 Schleiden –concluded all
plants are made of cells
 Schwann – concluded all
living things are made up of
cells
Three main levels of living
organization:
 Microsystem - molecular, subcellalar,
cellular levels;
 Mesosystem – tissular, organellic,
organismic;
 Macrosystem of population and species,
biocenotical, biosheric.
Cell theory



All organisms are composed of one or more
cells, within which the life processes of
metabolism and hereditary occur.
Cells are the smallest living things, the basic
unit of organization of all organisms.
Cells arise only by division of a previously
existing cell.
What are the cells?
 Basic unit of life
 Properties
- biomembrane enclosed
- four biomolecules: proteins, polysacharides,
nucleic acids, lipids
- metabolism and energy transformation
Two major types:
- Prokaryotic: lack defined nucleus
- Eukaryotic: contain membrane bound nucleus
What are the differences between
prokaryotic and eukaryotic cells?
 Kindoms
1. Monera (Fubacteria)
2. Archaea (Archaebacteria)
Characteristics
1. Lack a nuclear membrane
Kindoms
1. Protista
2. Fungi
3. Plantae
4. Animalia
Characteristics
1. Have a nuclear membrane
2. Have no membrane bound organels 2. Have membrane bound organels
Current evidence indicates that eukaryotic evolved from prokaryotic between
1 and 1,5 billion years ago
What are the differences between
plant and animal cells?
 1. Chloroplast
 2. Vacuole
 3. Cell wall
1. Centriole
2. Lysosome
Survey of organelle
structure and function











Cytoplasm and cytosol
Plasma membrane
Mitochondria and plastids
Endoplasmic reticulum
Golgy apparatus( complex)
Lysosomes
Nucleus
Ribosomes
Nonmembane
Vacuoles
organelles
Centrioles
Cytosceleton.
Membranbound
organelles
Cytoplasm
 Viscous contents of cell between the
nuclear membrane and the plasma
membrane. This include cell organelles
 Cytosol- aqueous part. The semi-fluid
medium found in the cytoplasm. This
does not include the organelles
 Cytoskeleton nightly organized network
fibrous proteins that support the cell.
Mitochondria
 A double membrane cellular organelle with its
own circular DNA (prokaryote like genomes)
and ribosomes found in both plants and
animals.
 Likely evolved from bacteria that were
endocytosed (ingested).
 It is the site of cellular respiration, a catabolic,
exergonic, oxygen requiring process that uses
energy extracted from organic macromolecules
(like glucose) to produce ATP.
Endoplasmic reticulum
 Extensive membranous networks of tubules and sacs
called cisternae
 Three distinct regions and maybe more
 A .Rough Endoplasmic reticulum (RER)
Studded with ribosome's. Site of protein synthesis.
Carbohydrate Addition and modification
B. Smooth Endoplasmic reticulum (SER)
Synthesizes lipids, phospholipids and steroids. Detoxifies
drugs, alcohol and poisons
Carbohydrate Addition and modification
C. Endoplasmic reticulum exit sites
Accumulation of proteins (cargos ready for export)
 Liver Cell,
TEM
Ribosomes
 Nuclear and cytoplasmic organells. Composed
of 60 % protein and 40% ribosomal RNA rRNA
 Site of protein synthesis
 Can be found or as Polyribosomes
Golgy apparatus
(complex)
 Stacked, flattened
membranous organelle
with sacs called cisternae
 Modifies, stores, and
routes products from the
ER to the Plasma
membrane
 Size 1 to 3 nm diameter
by 4 to 7 membranous
atacks high number up to
100 per cell.
Golgi Body & Lysosomes

Transport vesicles
 A membrane organelle
that transits materials
from one part of the cell
to another
 ER-to Golgy apparatus
 Golgy apparatus-to ER
 Golgy apparatus-to PM
 PM-to Golgy apparatus
Lysosomes endosomes
 Membrane-enclosed bag
of hydrolytic enzymes
(digestive enzymes)
 Degradation of old cell
components or ingested
materials
 Low pH (membrane
proteins pumps in H+ )
 Degradative enzymes
(nucleases, proteases)
 They vary in shape, size
and number per cell
 Mean size: 50-710 nm in
diameter
 Golgi body & Peroxisome
which is a specialized
form of lysosome.
Vacuoles
 Large membraneclosed sac for
cellular storage
 Three types
 Food vacuole
(lysosomes attach)
 Contractile vacuole
(Protozoons)
 Central vacuole
(mature plant cell)
Plasma membrane
 The boundary of every cell approximately 8nm
thick
 Separates the living cell from its nonliving
surroundings.
 Functions
 Acts as selective barrier
 Regulate movement of material into and out of
the cell
 Cellular recognition
Plasma membrane
 envelops the cell and aids in
maintaining its structural
and functional integrity.
 Composed of lipid bilayer
and associated proteins.
 -composed of an inner
leaflet (facing the
cytoplasm) and an outer
leaflet (facing the
extracellular environment).
 Membrane proteins may be
integral (are dissolved in the
lipid bilayer) and peripheral
proteins (don‘t extend into
the lipid bilayer).
Plasma membrane
 Lipid bilayer is composed
by phospholipids
(hydrophilic and
hydrоphobic), glycolipids
and cholesterol.
 Glycolipids are present in
outer leaflet only. They have
polar carbohydrate residues
that extend from the outer
leaflet into the extracellular
space, forming part of
glycocalix.
Plasma membrane
 Cholesterol is located in
both leaflets of the plasma
membrane. It is constitutes
approximately 2 % of the
plasmalemma lipids and
assists in maintaining the
structural integrity of the
plasma membrane.
 Fluidity of the lipid bilayer
is crucial to such activities
as exocytosis, endocytosis,
membrane trafficking and
membrane biogenesis.
Glycocalyx
 is a sugar coat
commonly associated
with the
extracytoplasmic
aspects of the outer
leaflet of plasma
membrane (in animal
cells).
 Functions
 aiding in cellular
attachment to
extracellular matrix
components
 binding of cellular and
enzymes to the cell
Plasma Membrane
Transport Processes.
 These processes include transport of a
single molecule (uniport) or cotransport
of two different molecules in the same
(symport) or opposite (antiport) direction.
Passive transport includes
simple and facilitated diffusion.
 Neither of these processes requires
energy because molecules move
across the plasma membrane down
a concentration or electrochemical
gradient.
 1. Simple diffusion transports
small nonpolar molecules (02 and
N2) and small, uncharged, polar
molecules (H20, C02, and glycerol).
 2. Facilitated diffusion occurs via
ion channel and/or carrier proteins,
structures that exhibit specificity for
the transported molecules. It is
faster than simple diffusion.
 3. Osmosis is the diffusion of water
across a selectively permeable
membrane in response to its
concentration gradient.
Active transport




is an energy-requiring process which transports a
molecule against an electrochemical gradient via
carrier proteins.
Na+-K+pump. Mechanism. The Na+-K+ pump
involves the antiport transport of Na+ and K+ ions
mediated by the carrier protein, Na+-K+ ATPase.
Na+ ions are pumped out of the cell and two K+
ions are pumped into the cell.
The hydrolysis of a single ATP molecule by the
Na+-K+ ATPase is required to transport five ions.
Comparison active and
passive transport
Exocytosis
 is way that substances can
exit cells.
 Part of the plasma membrane
pinches off and forms a small
membrane-bound sac, or
vesicle, around some
substance.
 Vesicles even form around
tiny cells (such as a
bacterium) and fluids.
 In exocytosis, vesicles form
inside the cytoplasm and then
move to the plasma
membrane and fuse with it, so
that their contents are moved
to the outside.
Endocytosis
 is way that
substances can exit
cells.
 a patch of plasma
membrane encloses
material at the cell
surface.
 it sinks in and
pinches off, forming a
vesicle that either
transports the
material into the
cytoplasm or stores it
there.
Phagocytosis and
Pinocytosis
 Phagocytosis (cell
eating) is transport
process by which
amoeboid-type cells
engulf large material,
forming an
intracellular vacuole.
Pinocytosis
 When macromolecules
are taken in by
endocytosis, the process
is called Pinocytosis
(cell drinking), and the
result is formation of
vesicle.
 Both phagocytic
vacuoles and pinocytic
vesicles can fuse with
lysosomes, whose
enzymes digest their
contents.
CYTOSKELETON
 Network of fibers through out the cytoplasm.
 Aids in cellular support and movement.
 Composed of three components:
1. Microfilaments - globular protein (actin)
- support and cellular contraction
2.
Intermediate filaments - fibrous protein
- support
3.
Microtubles - globular protein (tubulin)
- support and cell motility

In these cells, actin filaments appear light purple, microtubules yellow,
and nuclei greenish blue. This image, which has been digitally colored,
won first place in the 2003 Nikon Small World Competition.
TORSTEN WITTMANN
Cytoskeleton
CENTRIOLES
 found in animal cells only
 Paired cylindrical organelles
near nucleus
 - Composed of nine tubes,
each with three tubules
 - Involved in cellular division
 - Lie at right angles to each
other
Nucleus
 The cell nucleus is a
conspicuous membranebound cellular organelle.
 It functions to:
 Store genes into
chromosomes to allow cell
division
 Transport regulatory factors
and gene products vie nuclear
pores
 Produce messages
(messenger ribonucleic acid
or mRNA) that code for
proteins
 Organise the incoiling of
DNA to replicate key genes
Nucleolus
 Spherical region in
nucleus
 Found in nondividing cells
 It is nuclear
organizers and
synthesize rRNA
 Sometimes more
than one nucleolus
present
Nuclear envelope
 Encloses the nucleus
 A double membrane
perforated wit pores
through which
materials enter and
leave the nucleus.
 The pores are
octagonal orifices
about 60nm in
diameter forming the
pore complex with
the annulus
Heterochromatin -- tightly packed regions
Euchromatin --- Regions where DNA is more openly
packed, location of most functional genes
Chromosome banding (requires special stains)
 Types
of
chromo
somes
Karyotype is a diploid number of chromosomes
and it is a characteristics of the number and
morphology of chromosomes, that is peculiarities
of each species.
 Male karyotype
 46=22A+XY
 Female karyotype
 46=22A+XX
Thank you for attention!