2. An Introduction to Cells
Cell Theory
Developed from Robert
Hooke’s research
Cells are the Building
Blocks of all plants and
animals
Cells are the smallest
Microscopic units that
perform all vital
physiological functions
7. An Introduction to Cells
Somatic cells (soma = body)
Also known as Non-Reproductive cells.
Performs all the body functions apart from reproduction
Sex cells (germ cells)
Reproductive cells
Male sperm
Female oocyte (a cell that develops into an egg)
8. Cell Functions
Metabolism
– Use molecules for cellular functions, to make ATP and heat
Molecule synthesis
– Different cells synthesize different molecules.
Communication
– Cells produce and respond to chemical and electrical signals
Reproduction and inheritance
– Most cells have a complete copy of all of our genetic information.
This is passed down from cell to cell and from parent to child
9. An Introduction to Cells
A cell is surrounded by a watery medium known as the
extracellular fluid
Extracellular fluid = interstitial fluid + plasma +
cerebrospinal fluid + synovial fluid
The plasma membrane separates Intracellular fluid
(cytoplasm) from the Extracellular fluid (ECF)
Intracellular fluid (Cytoplasm) = cytosol + organelles
Cytosol = liquid
Organelles are intracellular structures
12. Organelles
Nonmembranous organelles
No membrane
Direct contact with cytosol
Includes the cytoskeleton, microvilli, centrioles, cilia,
ribosomes.
Membranous organelles
Covered with plasma membrane
Isolated from cytosol
Includes the nucleus, endoplasmic reticulum (ER), the
Golgi apparatus, lysosomes, peroxisomes, and
mitochondria
13. Nonmembranous Organelles
The Cytoskeleton — structural proteins for
shape and strength
Microfilaments
Intermediate filaments
Microtubules
16. Nonmembranous Organelles
Microfilaments—thin filaments
composed of the protein actin
Provide additional mechanical strength
Pair with thick filaments of myosin for
muscle movement
17. Nonmembranous Organelles
Intermediate filaments—mid-sized
between microfilaments and thick filaments
Durable (collagen)
Strengthen cell and maintain shape
Stabilize organelles
Stabilize cell position
18. Nonmembranous Organelles
Microtubules—large, hollow tubes of
tubulin protein
Strengthen cell and anchor organelles
Change cell shape
During cellular division they form the spindle
apparatus that attaches to chromosomes to
pull them to opposite ends of the dividing cell
20. Microvilli
Microvilli
Extension of the cell to
increase surface area of
the cell
Found in brush border of
small intestine,
stereocilia of ear, WBC,
and oocyte.
21. Cilia
Cilia
Small, whip-like, motile
extensions of the cell
surface
Ciliary movement move
fluids across the cell
surface
Found in bronchioles
and fallopian tubes
24. Nonmembranous Organelles
Ribosomes
Composed of two subunits containing = protein + RNA
Made in nucleus and shipped to cytoplasm
Build polypeptides in protein synthesis
Two types
Free ribosomes in cytoplasm:
– manufacture proteins for cell
Fixed ribosomes attached to ER:
– manufacture proteins for cell membrane, lysosomes, or secretion
28. Nucleus
Houses the DNA
Serves as the “Control Center of the Cell”
Surrounded by two membranes, together called
the nuclear envelope
The nuclear envelope is studded with nuclear pores.
Nuclear pores regulate traffic into and out of the
nucleus.
Membranous Organelles
29. Inside the nucleus:
Chromatin – composed of DNA + proteins
Nucleolus – site of ribosome manufacture
Nucleoplasm – fluid inside the nucleus
Membranous Organelles
30. Membranous Organelles
Endoplasmic reticulum (ER)
Continuous with outer nuclear envelope
Has cisternae are storage chambers within
membranes
Functions
Synthesis of proteins, carbohydrates, cholesterol and lipids
Storage of synthesized molecules and materials
Transport of materials within the ER, to Golgi Apparatus, and
extracellularly
Detoxification of drugs or toxins
32. Membranous Organelles
Smooth endoplasmic reticulum (SER)
No ribosomes attached
Synthesizes lipids and carbohydrates:
Metabolizes lipids and breaks down glycogen glucose
Absorbs, synthesizes and transports lipids
Detoxifies drugs, pesticides and carcinogens (liver/ kidney)
Modified SER in skeletal muscle and cardiac muscle for
storage of Ca+2
33. Membranous Organelles
Rough endoplasmic reticulum (RER)
Surface covered with ribosomes:
active in protein and glycoprotein synthesis
folds polypeptides protein structures
encloses products in vesicles that go to Golgi apparatus
35. Golgi Apparatus
A stack of membranous sacs
Vesicles pinch off from the ER to fuse with the
Golgi apparatus and empty their digestive
enzyme, protein or lipid contents.
The lipids and proteins are then modified, sorted,
and sent to their appropriate destination in new
vesicles that bud off from the Golgi apparatus.
Called as Packaging and Shipping Station of the
cell
Membranous Organelles
36. Golgi Apparatus
Cisterns
New vesicles
forming
Transport
vesicle
from
trans face
Cis face—
“receiving” side of
Golgi apparatus
Transport vesicle
from rough ER
Trans face—
“shipping” side of
Golgi apparatus
Newly secreted
proteins
Secretory vesicle
New vesicles forming
Golgi
apparatus
Transport vesicle at
the trans face
Electron micrograph of the Golgi
apparatus (90,000)
Many vesicles in the process of pinching off
from the Golgi apparatus
41. Mitochondria
Uses carbs, lipids, and proteins to
synthesize ATP
Has outer and inner membranes separated
by the intermembrane space
Inner membrane carries proteins involved in
ATP production
Matrix is site of reactions that release energy
from nutrients
Membranous Organelles
42.
43.
44. Plasma Membrane
Functions of the Plasma Membrane
Physical isolation
Barrier
Regulates exchange with environment
Ions and nutrients enter
Wastes eliminated and cellular products released
Monitors the environment
Extracellular fluid composition
Chemical signals
Structural support
Anchors cells and tissues
45. Plasma Membrane
Comprised of a phospholipid bilayer
Hydrophilic heads — toward watery environment, both
sides
Hydrophobic fatty-acid tails — inside membrane
48. Plasma Membrane
Membrane Proteins
Integral proteins
Span the membrane
Peripheral proteins
Bound to inner or outer surface of the membrane
50. Plasma Membrane
Several Types of Membrane Proteins
Anchoring proteins (stabilizers)
Attach to inside or outside structures
Recognition proteins (identifiers)
Label cells as normal or abnormal
Enzymes
Catalyze reactions
Receptor proteins
Bind and respond to ligands (ions, hormones)
Carrier proteins
Transport specific solutes through membrane
Channels
Regulate water flow and solutes through membrane
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63. Function of Connective
Tissue
• Function
• Supporting fabric
of all parts of the
body
• Bind other organs
together, hold
organs in place,
cushion them, and
fill space.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74. • Function
• Secretes a thin watery fluid called serous fluid that decreases
friction on organs during movement
• 3 Types
• Pleura — line thoracic cavity & lungs
• Serous pericardium — line the heart
• Peritoneum abdomen & abdominal organs ,largest serous
membrane
Serous Membranes aka Mesothelium