Transcript Cellular, Element, and Molecular Building Blocks of Living Systems

Cellular Principles
Mohamed Bingabr, Ph.D.
Associate Professor
Department of Engineering and Physics
University of Central Oklahoma
Cells
• There are 50 – 200 trillion cells in an average person
• Cells have the same DNA
• There are 200 different types of cells in human
• Different cells have different functions
Liver cells have abundant enzymes for
detoxifications of chemical
Red blood cells have hemoglobin for oxygen
transport
Eukaryotic Cells 1
Cytoskeleton: Protein filament that gives the cell its
shape, movement, division, and provide tracks for
substance transport among organelles.
Eukaryotic Cells 2
Rough Endoplasmic Reticulum (rER): contain
chaperone proteins that help properly fold the newly
proteins.
Golgi Apparatus: package, sort, and processes protein.
Smooth ER: Lipid synthesis
Eukaryotic Cells 3
Lysosomes: contain digestive enzymes (Proteases) to
breakdown proteins and other cellular components.
Peroxisomes: Contain 50 different types of enzymes
for detoxification.
http://www.youtube.com/watch?v=NiiLS_ov
LwM&feature=related
Tissue
Tissue is a collection of cells of similar types.
Muscle cells: specialized for movement
Nervous cells: initiating signals and transmitting them
from cell to cell
Epithelial cells: sheets that cover human body (skin,
intestine)
Connective cells: rich in extracellular material that
provide mechanical strength and anchors adjacent
tissues and circulating blood.
Organ: Function unit that consist of collection of two or
more primary tissues. (Ex: stomach has 4 tissues)
Extracellular Matrix (ECM)
Hold cells together to form tissues.
ECM Consist of:
- 3-dimensional array of protein fibers and filaments
- Hydrated gel of high molecular weight
(carbohydrate-rich molecule)
ECM
Protein categories in ECM
1) Structural
-
Collagen for strength
-
Elastin for elasticity (vessel wall of aorta)
2) Adhesive
-
Fibronectin bind the other matrix component
together
-
Laminin attachment of cells to ECM.
BME Application
Synthesis of scaffolds from fibronectin for cell
Proteins in Cell Membrane
Plasma membrane consist of phospholipids bilayer that
supports a wealth of coupled membrane protein.
Function of Protein in Cell membrane
1) Cell recognition
2) Cell signaling
3) Transport of molecule
4) Adhesion to the ECM
Membrane Proteins Regulate
Transport in Cell
Many molecules such as polar molecules (Sodium,
potassium, sugar, amino acids) do not diffuse through
lipid bilayers.
Methods of transportation
1) Facilitated Transport via transporter (no energy
needed)
2) Primary active transport (energy required)
3) Secondary Active Transport (energy required)
Facilitated Transport via Transporter
Channel conformation occurs because of natural
thermal fluctuations in the membrane. Transporter
does not need energy.
Primary Active Transport
Energy (ATP) is required for transporter conformation.
Secondary Active Transport
Driven by energy stored in the concentration gradient
of one solute.
Na/glucose
Na/Ca
Specialized Ion Channels
Ion channels regulated by
a) Voltage
b) Binding of chemical ligand,
c) mechanical stretching of the membrane.
http://www.youtube.com/watch?v=1ZFqOv
xXg9M&feature=related
Receptor-Mediated Endocytosis
Binding of some molecules (ligands) to membrane
receptor proteins can lead to rapid intenralization of the
molecule and receptors.
http://www.youtube.com/
watch?v=PifagmJRLZ0&f
eature=related
Membrane Protein in Cell Adhesion
Cell membrane proteins form strong noncovalent
bonding with either components of the ECM or
molecules extending from the surface of other cells.
Integrins:
-Adhesion molecule
-Signaling (Ligand binding to
integrin triggers downstream
activation of genes that can
influence the behavior of a cell
shape, movement, and
differentiation.
Cell Adhesion - Selectins
Selectins on the surface of leukocytes (WBC)
recognize carbohydrate groups of glycoproteins on the
surface of endothelial cells lining the blood vessel.
Cell Proliferation and Cell Cycle
Read section 5.5
How do cells know when to initiate DNA synthesis?
-Cyclins protein enhance cell division.
-Cells donated by aged organism has less doubling than
cells donated by younger organism.
Telomere: Repetitive DNA sequence appear at the end of
chromosomes.
- Ensure accurate replication of the DNA sequence near
the end.
-Shorten by 50 base pairs in length with each division.
-Telomerase enzyme preserves telomere length and is
found in stem cells.
Cell Differentiation and Stem Cells
Characteristic of Embryonic and Adult stem cells
- Capacity for self-renewal
- Multilineage differentiation
- Repopulation of tissue in recipients
Classification of Stem Cells
1) Unipotent: a stem cell that differentiates into one
type of progenitor
2) Pluripotent: a stem cell that can differentiates into
multiple types of lineages.
Differentiation of Stem Cells
What controls the differentiation of a stem cell down a
lineage path?
- Interaction with molecule in the environment
- Fate-specific proteins enhance the survival of
certain cells.
Cell Death
50 to 70 billion cells die an average human each day.
1) Selective Death: Reproductive tract in embryo development
2) Aging: cell of the skin
3) Cell murder: T cells kill infected host cells
Two types of cell death
- Necrosis: Tissue damage
- Apoptosis: Programmed cell death
Cell Culture Technology
1) Hematopoietic Stem Cells (HSC) can be isolated from donor
tissue and transplanted into patients.
2) Cell proliferation in medium that contains vitamins, essential
amino acids, glucose, and salts.
Model of Cell Proliferation
dx
 X
dt
t
X  X 0e
tD 
ln 2

Homework
Solve the following problems in Chapter 5 page 200
in the textbook: 3, 5, 8, 9
Explain the mechanism that control the
Hematopoietic Stem Cells differentiation to white
blood cell.