2. Objectives:
The different Microscopes used
The Cell Theory
The two major categories of cells
The overview of Eukaryotic cells
The membrane structure
The organelles
10. 2 important factors in microscopy:
1. Magnification – is an increase in the object’s
image size compared with its
actual size.
2. Resolving power – the clarity of that
magnified image
- The ability of an optical
instrument to show two objects
as separate.
11. Sizes of Biological Structures
• Thickness of leaf
• Paramecium
• Sharp end of pin
• Plant cell
• Animal cell
• Mitochondrion
• Bacterium
• Ribosome
• DNA molecule
• Hydrogen atom
• O.5mm
• 200μm
• 100 μm
• 40μm
• 20μm
• 1μm
• 0.5-1μm
• 20nm
• 2nm
• 0.04nm
23. Schleiden and Schwann are credited as the founders of
The Cell Theory [1839]
• All living things are made of cells.
• Cells exhibit the fundamental characteristics of life:
▫ Obtain energy—photosynthesis, chemosynthesis, or digestion
▫ Use energy—respire
▫ Excrete Waste
▫ Show Order
▫ Homeostasis
▫ Evolve
▫ Reproduce
▫ Move
▫ Respond to changes in environment
▫ Grow and repair damage to self
24. The development of the Cell Theory involved the input of numerous
individuals from various nationalities over many years
25. stated “omnis cellula a cellula ” [all cells arise from pre-existing cells
based on observations of dividing cells [1855]
Rudolph Virchow
26.
27. The Cell Theory was modified to
incorporate Virchow’s work
• All organisms are made of cells
• Cells are the smallest structural and functional
unit of an organism [that carries out the life
processes]
• All cells come from pre-existing cells
28. And, what about
viruses?
• Are not composed of cells but
consist of a nucleic acid (DNA or
RNA) in a protein coat
• Yet conduct all of the cell
processes (although with help,
not independently)
29. SO:
• Could there be an organism that does not contain a single cell?
• Might there be some other fundamental unit of life? At least, in
some cases?
• Are the life processes sufficient criteria to distinguish between the
living and the non-living?
32. Cell Types
Prokaryotes - simple cells that do
not have internal membranes
example = bacteria
Eukaryotes - more complex cells
that do have internal, membrane-
bound structures
examples = plants and animals
35. Key Differences:
Prokaryotes
• Lack a nucleus and
other membrane
bounded structures.
• Have small ribosomes
• DNA is not organized
into chromosomes
• Flagella are not made of
microtubules and does
not have a 9+2
structure????
• Cell walls are made of
peptidoglycan, not
cellulose
Eukaryotes
• Have a nucleus and other
membrane bounded
structures.
• Have large ribosomes
• DNA is organized into
chromosomes
• Flagella are made of
microtubules and have a
9+2 structure
• Cell walls are made of
cellulose
36. All cells have……
•Plasma (cell) Membrane
•Nucleus (eukaryotes only)
•Cytoplasm (an area)
•Organelles (structures with
specialized functions)
39. Why Are Cells So Small?
•Transport- Cell volume to surface
area ratios favor small size.
•Control- Nucleus to cytoplasm
consideration.
•Metabolic requirements-
……..we’ll come back to this later.
42. The Cell
• All living things are made of cells.
• Cells are the smallest living unit of life.
• Each cell performs the necessary functions to
sustain life.
• Cells can replicate themselves. Cancer occurs
when cells replicate haphazardly.
• Cellular function is carried out by organelles.
43. • Cellular reactions are mediated (controlled) by
ENZYMES.
• Enzymes speed up chemical reactions.
• All the chemical reactions in the body make up
its METABOLISM.
• There are 10 organelles that you are responsible
for.
44. Plasma Membrane • Outer covering of
the cell.
• Also called the
PLASMALEMMA.
• Separates the
intracellular
(inside) fluid and
the extracellular
(outside) fluid.
• Double layer of
lipids (fat) with
protein molecules
between the layers.
45. • Polar Head (like
water)
• Non-polar tails (do
not like water)
• Proteins within the
membrane. They
give support to the
membrane and
prevent it from
collapsing.
• Carbohydrates are
attached to the
integral proteins.
These form the
GLYCOCALYX.
Plasma Membrane
46. • The glycocalyx is a
sticky coat that
allows the cell to
bind to other cells.
• The glycocalyx also
serves as a marker.
i.e.: certain
antibiotics
recognize the
glycocalyx
and attach to the
cell.
Plasma Membrane
47. Functions of the Plasma Membrane
• Allows entry into the cell (Endocytosis)
Phagocytosis – cell eating
Pinocytosis – cell drinking
Receptor-Mediated - hormones
• Allows movement out of cells (Exocytosis)
48. Cytoplasm • Cytosol is a gel
like substance
which holds all
the internal
cellular
organelles.
• Contains ions,
water, and
enzymes.
50. Nucleus • Parts of the nucleus:
Chromatin : material consisting
of DNA and proteins
: visible as individual
chromosomes in a
dividing cell
Nucleolus : nonmembranous
organelle involved in production
of ribosomes
: a nucleus has one or
more nucleoli
Nuclear envelope
: double membrane
enclosing the nucleus
: perforated by pores
51. THE ORGANELLES • Perform all the cellular
functions.
• “Little Organs”
54. ENDOPLASMIC RETICULUM • Subway system of
the cell.
• Network of
membrane-walled
tubes that twist
through the
cytoplasm.
• Active in membrane
synthesis and other
synthetic and
metabolic processes
• ROUGH E.R. – have
ribosomes attached.
• SMOOTH E.R. – do
not have ribosomes
attached.
55. GOLGI
APPARATUS
• Stacks of disk
shaped
membranes
• Active in synthesis,
sorting and
secretion of cell
products
56. LYSOSOMES • Sacs containing
digestive enzymes
that can break
down almost all
types of biological
materials
(macromolecules)
57. PEROXISOMES • Contain oxidases
(use oxygen to
neutralize
aggressive
compounds known
as free radicals).
• Free radicals can
damage cellular
proteins,
membranes, and
DNA if left to
accumulate.
• Produces H2O2
58. CYTOSKELETON • System of complex
rods that run
throughout the
cytoplasm.
• Reinforces cell’s shape,
functions in cell
movement
• Microtubules
• Microfilaments
• Intermediate filaments
59. CENTROSOME • Contains a matrix
and an inner pair of
centrioles which
are important in
cellular division.
61. CENTRAL VACUOLE and
TONOPLAST
• Prominent organelle
in older plant cells
• Functions include
storage, breakdown
of waste products
• Enlargement of
vacuole is a major
mechanism of plant
growth
• Tonoplast –
membrane enclosing
the vacuole
62. CELL
WALL
• Outer layer that
maintains cell’s
shape and protects
cell from mechanical
damage
• Made of cellulose ,
other
polysaccharides and
protein
64. Related Clinical Terms
• NECROSIS – cellular death due to disease or
injury.
• HYPERTROPHY – increase in size.
i.e. Muscle cells become hypertrophic in
response to exercise.
69. OBJECTIVES for Tissues
• Be able to list the four basic tissue types and give
examples of each.
• Describe the functions of each tissue type.
• Describe the cellular components of each tissue
type.
• Describe and identify the morphology of
epithelial tissue types.
70. Tissues
• Cells do not operate independently.
• Related cells work and operate together in
organized groups.
The bottom line:
Tissues are clubs of cellular organization.
73. Epithelial Tissue
• Occurs at the interface of two different
environments.
i.e. The epidermis is between the inside and
the outside of the body.
• Protects the body by detecting harmful stimuli.
i.e. Receptors for pain are found within the
skin.
74. • Secretion
release of molecules from the cell
• Absorption
bringing small molecules into the cell.
75. • Ion transport – moves ions (charged molecules)
across a membrane.
• The epithelium filters fluids that cross the
barrier.
76. Characteristics of Epithelial Tissue
1. Cellularity – composed almost entirely of
cells.
2. Specialized Contacts – connects adjacent
cells.
• gap junctions, tight junctions, desmosomes
3. Polarity – under surface called the “basement
membrane”.
4. Avascular – lacks blood vessels. Receives
nutrients through the underlying connective
tissue
78. Shapes of Epithelial Tissue
• Simple Epithelium – one layer
• Stratified Epithelium – more than one layer
• Squamous – cells are wider than tall
• Cuboidal – cells are just about as tall as wide
• Columnar – cells are taller than wide.
79.
80. CONNECTIVE TISSUE
• Types of connective tissue
Fat
Cartilage
Ligaments and Tendons
Bone
Blood
Collagen
81. Functions of Connective Tissue
• 1. Support and bind other tissues. (tendons,
ligaments)
• 2. Hold body fluids (ground substance).
• 3. Defend against infection
- mast cells
- macrophages
- plasma cells
- neutrophils
• 4. Store nutrients as fat.
82. Muscle Tissue
• Brings about body movement.
• Moves by shortening.
• Three Types:
1. skeletal – pulls on long bones. Striated.
2. cardiac – only in the heart.
3. smooth – no visible striations. Found in walls
of hollow visceral organs such as digestive
system, urinary organs, blood vessels, and
uterus. Mostly involuntary.
83. Nerve Tissue
• Uses electrical impulses to transport
information.
• Can Regenerate
