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 1Cytoskeleton: Protein filament that gives the cell its shape, movement, division, and provide tracks for substance transport among organelles.

Eukaryotic Cells 2Rough 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 3Lysosomes: 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_ovLwM&feature=related

TissueTissue 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 MembranePlasma 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 TransportEnergy (ATP) is required for transporter conformation.

Secondary Active TransportDriven by energy stored in the concentration gradient of one solute.

Na/glucose Na/Ca

Specialized Ion ChannelsIon channels regulated by

a) Voltage

b) Binding of chemical ligand,

c) mechanical stretching of the membrane.

http://www.youtube.com/watch?v=1ZFqOvxXg9M&feature=related

Receptor-Mediated EndocytosisBinding 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&feature=related

Membrane Protein in Cell AdhesionCell 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 - SelectinsSelectins 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 CycleRead 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 CellsCharacteristic of Embryonic and Adult stem cells

- Capacity for self-renewal

- Multilineage differentiation

- Repopulation of tissue in recipients

Classification of Stem Cells1) 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 CellsWhat 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 Death50 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 Technology1) 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

2ln0

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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.