ANIMAL CELL

OBJECTIVE
• Introduction
•The cell
•Cell theory
•Parts and function of cell
INTRODUCTION
• An animal cell is a eukaryotic cell containing membrane bound
organelles. Cell organelles present in animal cells are endoplasmic
reticulum, Golgi body, ribosomes, cytoplasm, mitochondria and the
nucleus.
• The body contains approximately 200 types of cells, differing greatly
in size, appearance, and function.
• Specific functions are identified with specific structural components
and domains within the cell.
THE CELL
CELL
• Cells are the basic structural and functional units
of all multicellular organisms.
• All living organisms contain a multitude of cell
types, whose main functions are to maintain a
proper homeostasis in the body, which is
maintaining the internal environment of the
body in a relatively constant state.
CELL
• Cells are the basic structural and functional units
of all multicellular organisms.
• All living organisms contain a multitude of cell
types, whose main functions are to maintain a
proper homeostasis in the body, which is
maintaining the internal environment of the
body in a relatively constant state.
THE CELL THEORY

• There are two components to the cell theory.

1. All organisms are composed of cells.
2. Cells come only from preexisting cells.
TYPES OF CELLS
Cells are divided into two types according
to the way their DNA is stored.
1. Prokaryotic cells: which lack a membrane
covered nucleus, have their DNA located in
a part of the cell called the nucleoid.
2. Eukaryotic cells: have a membrane-
covered nucleus which stores the cell's DNA.
 PROKARYOTIC CELL
BACTERIAL STRUCTURE
• Bacterial cytoplasm:
üsurrounded by a cell membrane
and a cell wall
ühas thousands of tiny particles called
ribosomes that make all of the proteins needed
by the cell.
The DNA of a bacterium is a single circular
chromosome that resides in the nucleoid.
Bacteria can have appendages(flagella, pili, curli,
and spinae) with specific functions.
EUKARYOTIC CELL
• Have a membrane bound
nucleus that contains their
DNA.
• Are larger than prokaryotic
cells with a lower surface area
to volume ratio.
• Have a number of
membrane-bound inner
compartments
Parts and function of
cell
COMMON FEATURES OF CELLS
• Cell / Plasma membrane - forms an important
barrier or boundary between the internal
environment and the external environment.
• Cytoplasm - the cell matrix containing organelles and
other cell contents
• Organelles - small structures that carry out various
functions within the cell. Cells of humans (with the
exception of the mature red blood cell) and other
eukaryotic organisms contain a nucleus.
 THE PLASMA MEMBRANE
• A phospholipid bilayer that forms the cell
boundary as well as the boundaries of
many organelles within the cell
• This property of the cell membrane is
called selective permeability
• Embedded in the phospholipid bilayer of
the cell membrane are the integral
membrane proteins and peripheral
membrane proteins, which make up
almost half of the total mass of the
membrane.
Molecular Organization of the Cell
Membrane
• The lipid bilayer of the cell membrane has a fluid
consistency, and, as a result, the compositional
structure of the cell membrane is characterized as a
fluid mosaic model.
• Two layers :
a. polar heads: arranged on both the inner and
outer surfaces of the cell membrane.
b. non-polar tails: lipid layers face each other in
the center of the membrane
FUNCTIONS OF MEMBRANE PROTEINS
1. Channel proteins are simple protein
pores that allow substances to move
across the membrane from one side to
the other. They can be used to make
chemicals for human use (e.g.,
industrial chemicals, medicines).
2. Cell recognition proteins are
glycoproteins that have several
functions, such as recognition of
pathogens. These proteins serve as a
cell's "identity badge".
FUNCTIONS OF MEMBRANE PROTEINS
3. Enzymatic proteins are
membrane proteins that carry
out chemical reactions. They
speed up the change of substances
into other substances.
Transport mechanisms of Plasma membrane:
1. Endocytosis : performs the uptake and transfer
of molecules and solids across the cell
membrane into the cell interior
2. Exocytosis : process of releasing material from the cell
cytoplasm across the cell membrane to the exterior
3. Pinocytosis : process by which cells ingest small
molecules of extracellular fluids or liquids.
4. Phagocytosis : ingestion or intake of large solid particles,
such as bacteria, worn-out cells, or cellular debris, by
specialized cells.
Cytoskeleton
• maintains cell shape and helps in the
movement of organelles.

1. Filament:
a. microfilaments (actin filaments): flexible chains of
actin molecules,
b. intermediate filaments: ropelike fibers formed from
a variety of proteins
***Both groups providing tensile strength to withstand
tension and confer resistance to shearing forces.

2. Microtubules:
Continuously elongate (by adding tubulin dimers) and shorten
(by removing tubulin dimers), a property referred to as
dynamic instability;
ORGANELLES
The two types of energy-related organelles have
their own genetic material and ribosomes

• Mitochondria are found in all eukaryotic cells.

These bean-shaped organelles have a double
membrane with inner folds enclosing
important metabolic enzymes.
• Chloroplasts are found in the cells of
photosynthetic eukaryotes
• Chemicals which interfere with
mitochondrial function include:
ü Cyanide
üHydrogen sulfide
üCocaine
üOrganochlorine pesticides such as DDT
üCarbon tetrachloride
üDrugs such as acetominophen, doxorubicin
(adriamycin), cocaine
ü Toxic metals such as mercury
• Nucleus
ØThis membrane-encapsulated structure contains various materials
but most importantly the genetic material of the cell.
- Chromosomes : consist of deoxyribonucleic acids (DNA) and proteins
including histones.
The nucleus controls overall cellular activity, such as protein synthesis
and storage and processing of genetic information in cooperation with
ribonucleic acid (RNA).

• Ribosomes
ØThese are very small structures in the cell cytoplasm involved with
protein manufacturing. They are made up of RNA and proteins.
Ribosomes
ØThese are very small structures in the cell cytoplasm
involved with protein synthesis. They are made up of RNA
and proteins.
• Protein synthesis:
1. Transcription: In the nucleus, the gene sequence is
copied into messenger RNA (mRNA),
2. Translation: this occurs in the ribosome.
The mRNA is used as a template and transfer RNA
(tRNA) brings amino acids to assemble along the template
to build proteins.
Endoplasmic Reticulum
• The ER is a complicated system of membranous channels
and flattened vesicles (saccules). It is responsible for
making lipids and proteins and it sometimes stores small
ions
• Two types:
1. ROUGH ENDOPLASMIC RETICULUM: site of protein
synthesis and modification of newly synthesized
proteins;
2. SMOOTH ENDOPLASMIC RETICULUM: region of
endoplasmic reticulum involved in lipid and steroid
synthesis but not associated with ribosomes;
Golgi apparatus
Ø Membranous organelle composed of multiple flattened cisternae
responsible for modifying, sorting, and packaging proteins and lipids for
intracellular or extracellular transport.
Endosomes
ØMembrane-bounded compartments interposed within endocytotic pathways
that have the major function of sorting proteins delivered to them via
endocytotic vesicles and redirecting them to different cellular compartments
for their final destination.
ØRegulate trafficking of proteins and lipids among other subcellular
compartments of the secretory and endocytic pathway,
Lysosomes
Øsmall organelles containing digestive enzymes that are formed from endosomes
by targeted delivery of unique lysosomal membrane proteins and lysosomal
enzymes
Golgi Apparatus
üThe Golgi apparatus consists of numerous flattened
saccules.
üThe Golgi apparatus receives protein transport
vesicles from the ER, then modifies the molecules
and repackages them in new vesicles
Vacuoles
üAre membranous storage sacs that are larger than vesicles.
Peroxisomes
üThese are smaller vesicles than lysosomes. They contain a large
variety of metabolic enzymes, including some that oxidize lipids
such as fatty acids.
JUNCTIONS BETWEEN ANIMAL
CELLS
1. Adhesion junctions: form sturdy flexible
sheets of cells

2. Membrane proteins: of adjoining cells can

attach together to form tight junctions.
3. Cells communicate across Gap Junctions :
Gap junctions form when plasma membrane channels form
two different cells join together.
CELLULAR COMPOUNDS
1. Exogenous substance : foreign chemical
2. Endogenous chemicals: physical agent may interfere
with or damage biochemicals normally present in
the bodys

Some interference in HEMEOSTASIS in the body:

1. Interference with absorption or disposition of an
essential nutrient.
2. Interference with nerve transmission
3. Damage to components of a cell organelle which
prevents it from functioning
Types of organic chemical
compounds found in the cell.