CHAPTER 1: CELL

❖ CELL: Basic and fundamental unit of life

❖ TISSUE: Groups of similar cells that work
together to perform a specific function.
❖ ORGAN: Structures are made up of two
or more tissues that perform a specific
function.
❖ ORGAN SYSTEM: Groups of organs that
work together to perform major functions
or meet the physiological needs of the
body.
❖ ORGANISM: The organism is made up of
several organ systems.

Phospholipids Molecule in the

cell membrane
➢ HEAD - globular, polar, hydrophilic
➢ 2 TAILS - slender, non-polar,
hydrophobic
➢ Trilaminar (electron microscope)
- Two dark lines separated by a clear
unstained intermediate zone
- This appearance is due to the
arrangement of phospholipid
molecules in two different direction.
➢ FUNCTION:
- Highly impermeable structure
- Barrier that regulates the entry and
exit of substances to and from the cell

BASIC STRUCTURE OF EUKARYOTIC CELL

1. Cell Membrane
2. Cytoplasm with Organelles
3. Nucleus
 Polysaccharides Molecules in
the cell membrane
➢ Glycolipid
➢ Glycoprotein

In many cell, glycolipid and glycoprotein is only

present on the outer surface of the cell
membrane to form a coating called
Glycocalyx
➢ a gel-like layer of glycoproteins and
glycolipids that covers the cell membranes
of many cells, including bacteria, epithelial
cells, and endothelial cells.
➢ FUNCTION:
- Cell to cell recognition
- Cell to cell adhesion
Protein Molecules in the cell - Protection
membrane - Immunological response

➢ Accounts for about ½ of the mass of the

cell membrane
➢ 2 types of Protein
• Integral Proteins: span the
whole thickness
• Peripheral Proteins: simply
inserted into or are loosely bound
to the outer and inner surface of
the membrane
➢ FUNCTION:
- Transport of certain substance across
the cell membrane
- Participation in enzymatic activity
- Signal transduction
- Cell-to-cell recognition

Cholesterol Molecules in the

cell membrane
➢ Found in the irregular spaces between the
phospholipid molecules.
➢ FUNCTION:
- Serve to stiffen and strengthen the cell
membrane
- Make the cell membrane less
permeable to water soluble substances
 RIBOSOMES
CYTOPLASM
➢ Minute organelles, can be seen only via
➢ A thick solution that fills and contains all
high magnification electron
of the cell’s contents, excluding the
➢ Seen in the TEM as small electron dense
nucleus.
granules that occur singly in small clusters
➢ Made up of CYTOSOL, the liquid portion of
called POLYRIBOSOMES or
cytoplasm that surrounds organelles.
POLYSOMES.
CYTOSOL ➢ can occur in free in the cytoplasm (Free
Ribosomes) or attached (Attached
➢ is viscid, translucent, and colloidal in Ribosomes) to the surfaces of the
nature. membrane of ER.
➢ 3 FORMED ELEMENTS IN CYTOPLASM ➢ Site of protein synthesis
• Organelles – perform specific
function within the cells TWO SUBUNITS
• Inclusion – accumulation of
• SMALL (40S) – decodes the genetic
pigment, lipid, or other substances.
message or mRNA
• Fibrillar elements - form the
• LARGE (60S) – which form polypeptide
CYTOSKELETON, supporting
chains of amino acids
framework that maintains shape
and internal organization of the
cell

ORGANELLES
MITOCHONDRIA

➢ They are often hotdog-shaped, but they

can alter their shape.
➢ Powerhouse of the cell
➢ PARTS OF MITOCHONDRIA
• OUTER MEMBRANE – delimits ENDOPLASMIC RETICULUM
the mitochondria from cytoplasmic
➢ Most extensive membrane-bound
matrices
structure in the cytoplasm.
• INNER MEMBRANE – is in folded
➢ Connects to nuclear envelope and cell
to form shelf like tubular structure
membrane
(CRISTAE)
➢ Dynamic organelles
• INTERMEMBRANOUS SPACE -
➢ FUNCTION:
located between the inner and
- Serve as a supporting structure for the
outer membrane.
cytoplasm
• MATRIX – space located inside
- Involved in the production of
the mitochondria
numerous substance
• mtDNA – only DNA in the cell that
is found outside the nucleus. ROUGH ENDOPLASMIC RETICULUM

➢ There are ribosomes and polyribosomes

that attached to the surfaces of its
membrane.
➢ Receives the proteins that are synthesized
by attached ribosomes
➢ More extensive than sER except for liver
cell and striated muscles.
➢ Material are transported from Rough ER to
golgi complex by TRANSFER VESICLE.
SMOOTH ENDOPLASMIC RETICULUM LYSOSOME

➢ No attached ribosomes or polyribosomes ➢ Chemical-containing pouches that float in

➢ FUNCTION: the cytoplasmic matrix.
- Site of synthesis of lipids, ➢ Made up of hydrolytic enzymes like
phospholipid, cholesterol, and other proteases, lipases, carbohydrases,
steroid. esterases, and nucleases that formed in
- Regulates calcium (muscle cells) golgi complex.
- Destroy toxic substances (liver) ➢ Involved In HETEROPHAGY and
AUTOPHAGY.
➢ HETEROPHAGY
- Refers to the lysosomal digestion that
have been brought from the
extracellular environment into the cell
by the process of phagocystosis.
➢ AUTOPHAGY
- Refers to the digestion of unneeded or
senesescent cell organelles

GOLGI COMPLEX

➢ Contains several layers of membrane-

bound, smooth surfaced, and flattened
tubes that are stacked on top of each
other in a semicircular manner.
➢ Releases the proteins into the cytoplasmic
matric in the form of membraned-wrapped
structures called SECRETORY PEROXISOMES
VESICLES.
➢ Like lysosomes, a membrane-bound
➢ FUNCTION: modify, sort, and package
spherical bodies that contain chemicals.
molecules from ER. Production of
➢ Contain oxidases and catalase.
lysosomes
➢ Present in all cell but numerous in cells
➢ TWO PARTS
that are metabolically active (hepatocytes)
• CONVEX SURFACE – forming
➢ FUNCTION:
face; cis face
- Oxidative reaction
• CONCAVE SURFACE – maturing
- Fatty acid oxidation
face; trans face, the surface of the
- Synthesis of specialized phospholipids
organelle that is related to the
- Detoxification
nucleus.
- Signaling
- Energy homeostasis
 CENTROSOME GLYCOGEN GRANULES

➢ Where microtubules are assembled or ➢ The storage form of carbohydrate

produced. ➢ Abundant in liver and muscle cells
➢ PARTS OF CENTROSOME
• CENTRIOLES - Two barrel-
ZYMOGEN GRANULES
shaped organelles that are typically
perpendicular to each other. Each ➢ Characteristics of secretory epithelial cells.
centriole is made up of nine
bundles of three microtubules.
• CENTRIOLAR SATELLITES – A PIGMENT GRANULES
matrix of coiled-coil protein
1. MELANIN - pigment that accounts for the
➢ FUNCTION:
brown to black coloration of the skin.
- Microtubule organization
2. HEMOSIDERIN - brown pigment that is
- Cell division
the product of the lysosomal digestion of
- Cell polarity
hemoglobin.
- Cilia formation
3. LIPOFUSCHIN – yellowish-brown bodies
that are common in long lived cell like
cardiac muscle cells and Sertoli cells in the
testes

CRYSTALS

➢ Found in Interstitial cells of Leydig and

Sertoli cells of the testes
➢ Common in older individuals

DUST PARTICLE

➢ Brown to black membrane bound

structure that contains exogenous
materials like dust and particulate carbon
➢ Numerous in pulmonary alveolar
INCLUSIONS macrophages, especially in smokers and
city dwellers
➢ Generally temporary and inert structure
➢ Not all cells contain inclusion and no cell
contain all the known inclusion.
➢ EXAMPLE
CYTOSKELETON
- Lipid Droplets ➢ Helps cell maintain cell shape
- Glycogen Granules ➢ Made of proteins
- Zymogen Granules ➢ 3 CLASSIFICATION
- Pigment Granules • Microfilaments
- Crystals • Intermediate Filaments
- Dust Particles • Microtubules
➢ FUNCTION:
• Cell Structure
FAT OR LIPID DROPLES • Cell Movement
➢ Present in many cell, particular in adipose • Cell Connection
cell which is specialized to store lipid. • Cell Division
➢ Direct contact with the cytoplasmic matrix
MICROFILAMENTS MICROTUBULES
➢ Made up of ACTIN ➢ Made up of TUBULIN
➢ Average of 5 to 7 nm in diameter ➢ 25nm in diameter
➢ 2 TYPES OF ACTIN ➢ Can be assembled or disassembled rapidly
• F-ACTIN – filamentous form of as needed.
actin, formed when 2 strands of G- ➢ FUNCTION:
ACTIN coil around each other. - Internal support
• G- ACTIN – globular actin, soluble - Primary determinant of cell
form of the protein. morphology
- Form the structural correlate of the
mitotic spindle
INTERMEDIATE FILAMENTS - Functional core of cilia.
➢ 10 to 12 nm in diameter
➢ TYPES OF INTERMEDIATE FILAMENTS
• KERATIN FILAMENTS
✓ Present only in epithelial
cells. Example
KERATINOCYTES (skin)
✓ FUNCTION: protect epithelial
cell from mechanical and
non-mechanical stress
• DESMIN FILAMENTS
✓ Characteristics of muscle
cells, most likely in smooth
muscles
✓ FUNCTION: maintain
muscle cell architecture and
structure since they
connect and anchor
cytoplasmic components. NUCLEUS
• VIMENTIN FILAMENTS
➢ Central region of the cell.
✓ present in FIBROBLAST and
➢ Data bank of the cell.
MUSCLE CELLS
➢ Nucleoplasm
✓ FUNCTION: maintaining cell
- Viscous, homogenous substance
shape and integrity of
similar in composition to cytosol,
cytoplasm
- Where structures called
• NEUROFILAMENTS
chromosomes are embedded.
✓ Characteristics of nerve cell
✓ FUNCTION: provide internal
support
• GLIAL FILAMENTS
✓ Seen in supportive cell of
nervous system, GLIAL
CELLS.
• LAMINS (Nuclear Filaments)
✓ They form part of the
nuclear lamina of the
nucleus.
✓ FUNCTION: help to
maintain the shape of
nucleus and anchor the
nucleus to the ER.
NUCLEAR ENVELOPE • HETEROCHROMATIN
✓ Highly condensed and is
➢ Complex structure that surrounds the usually not transcribed.
nucleus of a cell, separating it from ✓ In routine histologic
cytoplasm preparations, they take up
➢ PARTS OF NUCLEUS stains and form clumps or
• Double Membrane – made up of granules
two concentric membranes, the ✓ Made up of parts of
inner and outer nuclear chromosomes that are not
membrane. actively producing RNA
• Perinuclear Space – space
between the two membrane
• Nuclear Pore Complexes –
protein structures that allow
molecules to pass in and out of the
nucleus.
• Nuclear Lamina - line the inner
surface of the nuclear envelope,
binds to chromatin and other
nuclear contents.
• Connection To Endoplasmic
Reticulum –the outer nuclear
membrane is continuous with
endoplasmic reticulum.
➢ FUNCTIONS:
- Selective Barrier HUMAN GENOMES
- Transporting Materials
➢ Refers to the total amount of DNA that
- Anchoring Telomeres
present in the chromosomes
- All somatic human cell contains 46
chromosomes – 22 pairs of somatic
and 1 pair of sex chromosomes.
- In males, one of the sex chromosomes
is referred to as X chromosomes while
other is referred to as Y chromosomes
- In females, both sex chromosomes are
X chromosomes
➢ DNA is a very long molecule whose
CHROMATIN structure resembles a twisted ladder.
- Made up of a deoxyribose (sugar), and
➢ Complex of DNA and proteins that forms a phosphate molecules form the side
chromosomes in the nucleus of eukaryotic of the ladder.
cells. - PURINES (Adenine, Guanine) - two
➢ TWO FORMS carbon nitrogen ring bases
• EUCHROMATIN - PYRIMIDINES (Cytosine,
✓ Less condensed and can be Thymine) - are one carbon nitrogen
transcribed. ring bases
✓ In routine histologic - In forming a rung of the DNA ladder,
preparations, they do not adenine pairs with thymine while
take up stains. cytosines pairs with guanine
✓ Made up of parts of
chromosomes that are
actively producing RNA
NUCLEOLUS
➢ Eccentrically located in the nucleus
➢ It disappears during prophase and
reappears only during late prophase
➢ THREE AREAS OF NUCLEOLUS
• NUCLEOLAR ORGANIZING
REGION – contains the rRNA
genes and sites where pre rRNA is
synthesized
• PARS FIBROSA – a dense fibrillar
component where transcription
occurs
• PRAS GRANULOSA– a granular
component where ribosomal
subunits are assembled.
➢ FUNCTIONS:
- PRODUCE AND ASSEMBLE
RIBOSOMES