This document discusses the structure and function of cells. It begins with an overview of levels of biological organization from atoms to biomes. It then covers cell structure, including organelles and differences between prokaryotic and eukaryotic cells. The structure of the cell membrane is described as a fluid mosaic model with phospholipids and embedded proteins that regulate transport. Transport mechanisms across the membrane include passive diffusion and facilitated transport as well as active transport processes like endocytosis, exocytosis, and sodium-potassium pumps that require energy.

1. THEME: Introduction in to the course of
medical biology. Structural-functional
organization of cell.
1. Levels of biological organization. Cell
Theory.
2. Cell Structure.
3. Structure of the cell membrane.
4. Transport of substances across
membrane.

2. •Medical biologyMedical biology is a field of biology that has is a field of biology that has
practical applications in practical applications in medicinemedicine, health, health
care and laboratory diagnostics.care and laboratory diagnostics.
It includes many biomedical disciplines such as:It includes many biomedical disciplines such as:
cell biology, embryology, cell biology, embryology,
nanobiotechnology, biologicalnanobiotechnology, biological
engineering, cytogenetics, genetics, microbiologyengineering, cytogenetics, genetics, microbiology
, virology, parasitology., virology, parasitology.

3. Levels of biological organization in order fromLevels of biological organization in order from
smallest to largest.smallest to largest.
1. Atom1. Atom - The smallest identifiable form - The smallest identifiable form
of an element.of an element.
2. Molecule2. Molecule - Molecules are made from - Molecules are made from
two or more atoms covalently two or more atoms covalently
bonded together. Depending on the bonded together. Depending on the
number of atoms bonding, number of atoms bonding,
molecules can be very small (like molecules can be very small (like
carbon monoxide, made from one carbon monoxide, made from one
carbon and one oxygen atom), or carbon and one oxygen atom), or
they can be very large, like the they can be very large, like the
protein catalase shown to the right.protein catalase shown to the right.

4.  3. Organelle - Organelles are3. Organelle - Organelles are
membrane-boundmembrane-bound
compartments found withincompartments found within
eukaryotic cells. Eacheukaryotic cells. Each
organelle carries out aorganelle carries out a
specific function in the cell,specific function in the cell,
analogous to how each organanalogous to how each organ
in our body carries out ain our body carries out a
specific function.specific function.
 Not all cells containNot all cells contain
organelles - only eukaryoticorganelles - only eukaryotic
cells do (plants, fungi, animalscells do (plants, fungi, animals
and protists). Prokaryoticand protists). Prokaryotic
cells (bacteria and archaea)cells (bacteria and archaea)
lack organelles, including thelack organelles, including the
nucleus.nucleus.
 "Organelle is" the highest"Organelle is" the highest
level of biologicallevel of biological
organization that is notorganization that is not
considered to be "living" onconsidered to be "living" on

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6.  4. Cell - The cell is the smallest4. Cell - The cell is the smallest
level of biological organizationlevel of biological organization
that is able to livethat is able to live
independently. Some organismsindependently. Some organisms
are made of single cells, likeare made of single cells, like
eubacteria, archaebacteria andeubacteria, archaebacteria and
some protists.some protists.
 Other organisms are made ofOther organisms are made of
collections of cells.collections of cells.
 Cells are divided into two mainCells are divided into two main
types: prokaryotic cellstypes: prokaryotic cells
and eukaryoticcells. Prokaryoticand eukaryoticcells. Prokaryotic
cells do not contain organelles,cells do not contain organelles,
while eukaryotic cells do.while eukaryotic cells do.
 Cells arise from the division ofCells arise from the division of
pre-existing cells, an idea that ispre-existing cells, an idea that is
the basis of Cell Theorythe basis of Cell Theory

7. 5. TISSUE - group of similar5. TISSUE - group of similar
cells performing a job orcells performing a job or
functionfunction
 6. Organ - An organ is a6. Organ - An organ is a
collection of tissues thatcollection of tissues that
carry out a collectivecarry out a collective
function for a multi-celledfunction for a multi-celled
organism.organism.
 An example are lungs,An example are lungs,
which contain several layerswhich contain several layers
of tissue and together helpof tissue and together help
with absorption of oxygenwith absorption of oxygen
from the air you breathe.from the air you breathe.
 Organs are made fromOrgans are made from
tissues, and collections oftissues, and collections of
organs often make organorgans often make organ
systems.systems.

8. 7. Organ System - An organ7. Organ System - An organ
system is a group ofsystem is a group of
organs that together workorgans that together work
to fulfill a larger role for ato fulfill a larger role for a
multi-celled organism.multi-celled organism.
An example is theAn example is the
pulmonary system, shownpulmonary system, shown
to the left. In this organto the left. In this organ
system, organssystem, organs
connecting our nose andconnecting our nose and
mouth to our lungs workmouth to our lungs work
together to help ustogether to help us
breathe.breathe.
 Other examples of organOther examples of organ
systems include oursystems include our
skeletal system, ourskeletal system, our
nervous system, ournervous system, our
circulatory system andcirculatory system and
our gastro-intestinalour gastro-intestinal
system.system.

9.  8. Multicelled Organism -8. Multicelled Organism -
An organism made fromAn organism made from
two or more cells whentwo or more cells when
mature. All multicelledmature. All multicelled
organisms belong to theorganisms belong to the
Eukarya Domain, andEukarya Domain, and
include some protists,include some protists,
some fungi, all plants andsome fungi, all plants and
all animals. Multicelledall animals. Multicelled
organisms also canorganisms also can
contain some lower levelscontain some lower levels
of biological organizationof biological organization
not found in single-cellednot found in single-celled
organisms, includingorganisms, including
organ systems, organsorgan systems, organs
and tissues.and tissues.

10.  9. Population - A9. Population - A
group of membersgroup of members
of the sameof the same
species living in aspecies living in a
given area. Thegiven area. The
idea of aidea of a
population ispopulation is
important inimportant in
biology as this isbiology as this is
the organizationalthe organizational
level at whichlevel at which
reproduction andreproduction and
genetic change ingenetic change in
a species occurs.a species occurs.

11. 10. Community -10. Community -
Communities areCommunities are
formed throught theformed throught the
interactions of differentinteractions of different
populations of speciespopulations of species
living in the same area.living in the same area.
11. Ecosystem - All the11. Ecosystem - All the
living and non-livingliving and non-living
components of an areacomponents of an area
compose ancompose an
ecosystem. Non-livingecosystem. Non-living
components includecomponents include
temperature,temperature,
recipitation andrecipitation and
surroundingsurrounding
geography.geography.

12.  12. BIOME -Large12. BIOME -Large
areas of the worldareas of the world
with similar climateswith similar climates
and organismsand organisms
 13. Biosphere - All13. Biosphere - All
regions of the earth'sregions of the earth's
waters, surface, andwaters, surface, and
atmosphere whereatmosphere where
organisms live. Theorganisms live. The
biosphere includesbiosphere includes
all life on earth asall life on earth as
well as thewell as the
environments inenvironments in
which they live.which they live.

13.  History:History:
 -Discovery of the cell followed by the-Discovery of the cell followed by the
development of the microscopedevelopment of the microscope
 1665-Robert Hooke- observed cells from the1665-Robert Hooke- observed cells from the
fruiting bodies of fungifruiting bodies of fungi
 Anton van Leewenhoek- observed a variety ofAnton van Leewenhoek- observed a variety of
cells and called them "animalcules"cells and called them "animalcules"
 1830’s-Theodor Schwann and Matthias1830’s-Theodor Schwann and Matthias
Schleiden developed theSchleiden developed the cell theorycell theory

14.  Cell Theory states:Cell Theory states:
 1. All living organisms are1. All living organisms are
composed of cellscomposed of cells
 2. Cells are the functional units of2. Cells are the functional units of
living organismsliving organisms
 3. Cells arise from preexisting3. Cells arise from preexisting
cells via divisioncells via division

17. 2. Cell Structure.2. Cell Structure.

22. Superficially there are two types of organelles;Superficially there are two types of organelles;
organelles that are bound by a membrane andorganelles that are bound by a membrane and
those that are not.those that are not.
 Below are some examples of each:Below are some examples of each:
Membrane Bound OrganellesMembrane Bound Organelles
 VacuolesVacuoles
 LysosomesLysosomes
 Endoplasmic ReticulumEndoplasmic Reticulum
 Golgi ApparatusGolgi Apparatus
 MitochondriaMitochondria
 ChloroplastsChloroplasts
 Nonmembrane Bound OrganellesNonmembrane Bound Organelles
 RibosomesRibosomes
 CentriolesCentrioles
 MiscrotubulesMiscrotubules

41. 3. Structure of the cell membrane3. Structure of the cell membrane
(Plasma or Plasmolemma).(Plasma or Plasmolemma).

43.  The Plasma MembraneThe Plasma Membrane
 fluid mosaic model, semi-permeable (selectivelyfluid mosaic model, semi-permeable (selectively
permeable), double layer of phospholipids with embeddedpermeable), double layer of phospholipids with embedded
proteinsproteins
 Jobs of the cell membraneJobs of the cell membrane
 Isolate the cytoplasm from the external environmentIsolate the cytoplasm from the external environment
 Regulate the exchange of substancesRegulate the exchange of substances
 Communicate with other cellsCommunicate with other cells
 IdentificationIdentification
 Phospholipids (fats) contain a hydrophilic head and aPhospholipids (fats) contain a hydrophilic head and a
nonpolar hydrophobic tail, which creates a barrier.nonpolar hydrophobic tail, which creates a barrier.

45.  Cholesterol - stiffens the membrane by connectingCholesterol - stiffens the membrane by connecting
phospholipidsphospholipids
Glycolipids - signal moleculesGlycolipids - signal molecules
Glycoproteins - have an attached chain of sugarGlycoproteins - have an attached chain of sugar
(antibodies)(antibodies)
 Proteins embedded in membrane serve differentProteins embedded in membrane serve different
functionsfunctions
 1. Channel Proteins - form small openings for molecules1. Channel Proteins - form small openings for molecules
to difuse throughto difuse through
2. Carrier Proteins- binding site on protein surface2. Carrier Proteins- binding site on protein surface
"grabs" certain molecules and pulls them into the cell,"grabs" certain molecules and pulls them into the cell,
(gated channels)(gated channels)
3. Receptor Proteins - molecular triggers that set off cell3. Receptor Proteins - molecular triggers that set off cell
responses (such as release of hormones or opening ofresponses (such as release of hormones or opening of
channel proteins)channel proteins)
4. Cell Recognition Proteins - ID tags, to idenitfy cells to4. Cell Recognition Proteins - ID tags, to idenitfy cells to
the body's immune systemthe body's immune system
5. Enzymatic Proteins - carry out metabolic reactions5. Enzymatic Proteins - carry out metabolic reactions

46.  4. Transport Across4. Transport Across
MembraneMembrane
 -The membrane is-The membrane is
selectively permeableselectively permeable
(also called(also called
semipermeable )semipermeable )
- Small particles, or- Small particles, or
particles with noparticles with no
charge can passcharge can pass
through the bilayerthrough the bilayer
(carbon dioxide and(carbon dioxide and
oxygen)oxygen)
- Water has a charge,- Water has a charge,
does not easily crossdoes not easily cross
the membrane - athe membrane - a
channel protein,channel protein,
Aquaporin helpsAquaporin helps
water acrosswater across

47.  Passive TransportPassive Transport
 Simple Diffusion - water, oxygen and otherSimple Diffusion - water, oxygen and other
molecules move from areas of high concentrationmolecules move from areas of high concentration
to areas of low concentration, down ato areas of low concentration, down a
concentration gradientconcentration gradient
Facilitation Diffusion - diffusion that is assisted byFacilitation Diffusion - diffusion that is assisted by
proteins (channel or carrier proteins)proteins (channel or carrier proteins)
 Osmosis - diffusion of waterOsmosis - diffusion of water
Solutions: Hypertonic | Isotonic | HypotonicSolutions: Hypertonic | Isotonic | Hypotonic

51.  Active TransportActive Transport
 - involves moving molecules "uphill"- involves moving molecules "uphill"
against the concentration gradient, whichagainst the concentration gradient, which
requires energy (ATP)requires energy (ATP)
 Endocytosis - taking substances into theEndocytosis - taking substances into the
cell (pinocytosis for water, phagocytosis forcell (pinocytosis for water, phagocytosis for
solids)solids)
Exocytosis - pushing substances out of theExocytosis - pushing substances out of the
cell, such as the removal of wastecell, such as the removal of waste
Sodium-Potassium Pump - pumps out 3Sodium-Potassium Pump - pumps out 3
sodiums for ever 2 potassium's taken insodiums for ever 2 potassium's taken in
against gradient.against gradient.