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Cells and Tissues
Cells and Tissues
 Carry
out all chemical activities needed to
sustain life
 Cells are the building blocks of all living
things
 Tissues are groups of cells that are similar
in structure and function
For Example: muscle tissue
Anatomy of the Cell
 Cells
are not all the same
 All cells share general structures
 All cells have three main regions
Nucleus
 Cytosol (cytoplasm)
 Plasma membrane

The Nucleus
 Control

center of the cell
Contains genetic material (DNA)
 Three
regions
Nuclear envelope (membrane)
 Nucleolus (plural nucleoli)
 Chromatin (DNA coiled around protein –
protein acts as support for fragile DNA)

The Nucleus
The Nucleus continued…

Nuclear envelope ( or
nuclear membrane)
 Barrier of the nucleus;
separates in from out
 Consists of a double
membrane
 Contains nuclear pores
that allow for exchange
of material with the rest
of the cell
The Nucleus continued….

Nucleoli



Nucleus contains one
or more nucleoli
Sites of ribosome
production
Ribosomes move into
the cytoplasm through
nuclear pores
Nucleolus
The Nucleus continued….
 Chromatin




Composed of DNA and protein
Present when the cell is not dividing
Scattered throughout the nucleus
Coils and shortens to form chromosomes when the cell
divides (protects fragile DNA during cell separation)
Plasma Membrane
Barrier for cell contents
 Controls what exits and enters the cell through
osmosis and diffusion
 Also contains proteins, cholesterol, and
glycoproteins (proteins with sugar attached)

Plasma Membrane
PLAY Membrane Structure
Plasma Membrane
Specializations

Microvilli


Finger-like projections
that increase surface
area for absorption
Microvilli are present
in our intestines; helps
absorp nutrients and
water we consume by
eating
Cytoplasm or Cytosol
 Cytoplasm
is the material outside the
nucleus and inside the plasma membrane
 It’s the fluid that all organelles are
suspended in
Cytoplasm
 Contains

Cytosol


Fluid that suspends other elements (jello)
Organelles



three major elements
machinery of the cell
“Little organs” that perform functions for the cell
Inclusions

Chemical substances such as stored nutrients or
cell products like waste
Cytoplasmic Organelles
Cytoplasmic Organelles

Mitochondria




“Powerhouses” of the cell
Change shape continuously
Carry out reactions where oxygen is used to break
down food
Provides energy for cell
Cytoplasmic Organelles
 Ribosomes
Made of protein and RNA
 Sites of protein production
 Found at two locations



Free in the cytoplasm
On Rough ER
Cytoplasmic Organelles
 Endoplasmic
reticulum (ER)
Fluid-filled tubes for carrying substances
 Two types of ER


Rough endoplasmic reticulum



Covered with ribosomes
Makes proteins
Smooth endoplasmic reticulum

Functions in lipid and steroid production and also
detoxifies drugs and pesticides that invade the cell
Rough Endoplasmic
Reticulum
Ribosome
mRNA
As the protein is synthesized
on the ribosome, it migrates
into the rough ER cistern.
Rough ER
In the cistern, the protein folds
into its functional shape. Short
sugar chains may be attached
to the protein (forming a
glycoprotein).
Protein
The protein is packaged in a
tiny membranous sac called a
transport vesicle.
Transport
vesicle buds off
The transport vesicle buds from
the rough ER and travels to the
Golgi apparatus for further
processing or goes directly to
the plasma membrane where its
contents are secreted.
Protein inside
transport vesicle
Cytoplasmic Organelles

Golgi apparatus


Modifies and packages
proteins
Produces different types of
packages



Secretory vesicles
Cell membrane components
Lysosomes
Proteins in cisterna
Rough ER
Cisterna
Membrane
Lysosome fuses with
ingested substances
Transport
vesicle
Golgi vesicle containing
digestive enzymes
becomes a lysosome
Pathway 3
Golgi
apparatus
Pathway 1
Pathway 2
Secretory vesicles
Proteins
Golgi vesicle containing
proteins to be secreted
becomes a secretory
vesicle
Secretion by
exocytosis
Golgi vesicle containing
membrane components
fuses with the plasma
membrane
Plasma membrane
Extracellular fluid
Lysosomes

Contain enzymes that digest worn-out or nonusable
materials within the cell
Cytoplasmic Organelles

Peroxisomes

Membranous sacs of
oxidase enzymes
 Detoxify harmful
substances such as
alcohol, hydrogen
peroxide and
formaldehyde
 Break down free
radicals (highly
reactive chemicals)
Cytoskeleton
Network of protein structures that extend
throughout the cytoplasm
 Provides the cell with an internal framework
which keeps the cell 3-Dimensional

Cellular Projections
Not found in all cells
 Used for movement

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Cilia move materials
across the cell surface


Located in the
respiratory system to
move mucus
Flagella propel the cell

The only flagellated
cell in the human
body is sperm