Generalized Eukaryotic Cell (3)

* The functions of the major organelles/ Structure & functions of the plasma membrane
Cytosol - fluid component of the cytoplasm and consists of an aqueous solution ( proteins,nutrients, other solutes)

^Plasma membrane - regulates the passage of materials into and out of the cell.
- phospholipid bilayer with transport proteins embedded throughout - allow certain ions and polar molecules to pass through
- Cell adhesion molecules(CAMs) - cell recognition and adhesion.
- Receptors are complex proteins or glycoproteins embedded with sites that bind to specific molecules in the cell's external environment.

^Nucleus - contains the DNA, with structural proteins(histones) to form chromosomes.
- Nucleolus - dense structure in the nucelus where ribosomal RNA(rRNA) synthesis occurs.

^Ribosomes - sites of protein production & synthesized by the nucleolus. 2 subunits(Prokaryotes - 30S & 50S; Eukaryotes: 40S & 60S).

^Endoplasmic Reticulum - RER : with ribosomes - involved in protein synthesis
- SER : w/o ribosome - lipid synthesis; detoxification of drugs & poison

^Golgi Apparatus - Modify contents from SER, repack, redistribute. - secretory vesicles. Vesiciles/ Vacuoles.

^Lysosomes - pH5, contains hydrolytic enzymes.

^Microbodies - peroxisomes - oxidative enzymes. H2O2. Glyoxysomes to convert fats into sugars until seedling is mature to produce own sugars.

^Mitochondria - Site of aerobic respiration; supply of energy. Semiautonomous; contain their own DNA & ribosomes, self- replicate through binary fission.

^ Chloroplasts - contain chlorophyll, site of photosynthesis. Semiautonomous.

^Centrioles - specialized type of microtubue involved in spindle organization during cell division.

^Cytoskeleton -
- Microtubules - polymerized tubulins to provide support. Centrioles direct the separation of chromosomes during cell division. Cilia & Flagella - involved in cell motility.

- Microfilaments - actin in muscle contraction. amoeboid movement.

- Intermediate filament - maintenance of cytoskeletal integrity.

*How the size of a typical eukaryotic cell compares to the size of a bacterium or virus

Virus = 20 -300nm
Bacteria=1 - 10um
Eukaryotic cell = 10 -100um

*Osmosis, Passive transport, Active transport, Endocytosis, Exocytosis

Osmosis - simple diffusion from region of lower solute concentration to a region of higher solute concentrations through a selectively permeable membrane.

^Passive transport - down gradient, No carrier, No energy required
^Facilitated transport - down gradient, carrier, No Energy required
^Active Transport - against gradient, Carrier, Energy required
^Endocytosis - process in which teh cell membrane invaginates, forming a vesicle.

*Structure & functions of the cytoskeleton

General function - cell mechanical support, maintain it's shape, function in cell motility.

^Microtubules - hollow polymerized tubulins that radiate throughout the cell & provide support. (Etc: centrioles- direct the separation of chromosomes during cell division) ( Cilia & flagella - involved in cell motility).

^Microfilament - actin- involved in cell movement as well as support. Myosin- actin interaction.

^Intermediate filaments - involved in maintenance of cytoskeletal integrity.

*Mitosis : where it falls in the cell cycle

Protein Kinase M(PKM) in cerebral Cortex

Continuity activity is necessary to maintain longe-term memory
Insluar cortex associates with taste memory.

27th February

2.00 -3.30pm : verbal Reasoning:
Resentment:(n): A feeling of deep and bitter anger.
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3.30-4.30pm : Biology Respiration Review:
The structures of the respiratory system:
Air enters the nose(external nares--> nasal cavity)--> Pharynx -->pass epiglottis-> larynx (voice box)->trachea--> bronchi->bronchioles-->alveoli

*Inspiration occurs when the medulla oblongata of the midbrain signals the diaphragm to contract.
*Rate of breathing is affected by central chemoreceptors in the medulla & peripheral chemoreceptors located in the carotid arteries and aorta.

The mechanics underlying ventilation:
*Dependent on the pressure changes in the thoracic cavity(heart+ lung).
*Space between the parietal pleura & visceral pleura = intrapleural space.
*The pressure difference prevents the lungs & the space prevents the lungs from collapsing.
1) Inhalation
a) Diaphragm, external intercostal muscles contract [internal intercostal muscles relax]
b) Ribcage chest wall up
c) thoracic cavity increase
d) intrapleural pressure reduce
[opposite for exhalation]

Where gas exchange takes place in the lung:
Gas exchange occurs by diffusion across the pulmonary capillaries surrounding the alveoli.
*gases move from regions of higher partial pressure -> lower partial pressure
*o2 diffuses into the deoxygenated blood that has a lower partial pressure(where it binds to the hemoglobin) and travels back to the heart via pulmonary veins.
*Co2 diffuses from the capillaries into the alveoli for expulsion during exhalation.

The role of surfactant in gas exchange:
*Surfactant lowers the surface tension of the alveoli and facilitates gas exchange across the membranes.

The role of the respiratory system in thermoregulation,protection against disease, and protection against particulate matter.
Nasal Cavity- filters, moistens and warms incoming air
hair- traps large dust particles
Mucus- secreted by goblet cells trap smaller dust particles and moistens the air
Cilia- moves the mucus and dust back toward the pharynx for removal by spitting or swallowing

Oxygen dissociation curve is shfited right by increase in
1)CO2
2) H ion concentration
3) temperature

17th of January & University of Queensland

17th of January:

29th January - Start of Revision: List to be updated again
http://www.valuemd.com/queensland.php

http://www.uq.edu.au/study/program.html?acad_prog=2046

http://www.uq.edu.au/study/index.html?page=17631&pid=17502 --> Australian Visa

PSU Transcripts: http://www.pdx.edu/registration/transcripts.html
Obtain from Neuberhall - days 5 days to process.

University of Adelaidehttp://www.international.adelaide.edu.au/apply/#apply

#University of Adelaide

The link to apply tentatively before 30 June 2007 http://www.health.adelaide.edu.au/international/pdf/Intent%20to%20Apply%20form%202007.pdf
http://www.health.adelaide.edu.au/international/

#Footnote

Target that was set was not meet. :(.. Nevertheless
I bought 3 New MCAT books for preparation. the NEW MCAT45, NEW MCAT Premier Program 2007 edition and the MCAT physics book. Totaling to an amount of US $130. (=.

#3 Virus

To Be continued...

#2 BIOLOGY 18th DEC 06 -THE CELL

Cell Theory

• Basic functional unit of life
• Arise only from pre-existing cells
• Carry genetic information in the form of DNA( passed from parent cell to daughter cell)
• [All living things are composed of cells]

All cells come from pre-existing cells

SIZE Conversion

1 cm = 10 mm
1mm = 1000 um(micrometers)
1um = 10,000 A (angstrom units)
1 Angstrom = 1.0 x 10^-10m = 0.1nm = 100pm

Eukaryotic cells ~ 10um
Mitochondria ~ 1 um
Bacteria ~ 1um
virsues ~ 0.1 um
macromolecules ~ 0.01 um
molecules ~ 0.001 um
Hydrogen ion ~ 0.0001 um

Resolution
Ability to discriminate two points and visualize them as 2.
Resolving power: Human eye ~ 0.1mm
Light microscope ~ 0.2 um
Electron microscope ~ 2-5 A
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General structure of Membranes in Cells
- Plasma membrane ( serves as the permeability barrier between the cell and its environment)
- Eukaryotic cell contains membranes that separate different compartments within the cell(consist of phospholipid bilayers with associated proteins)

PASSIVE TRANSPORT
Mechanisms Moving Molecules Across Cell Membranes:
a. Simple Diffusion
- Net movement of particles from a region of higher concentration to a region of lower concentration
- No Energy required
Osmosis- simple diffusion of water from a region of lower solute concentration(hypotonic --> Swell & Burst) to a region of higher solute concentration(hypertonic --> Shrink). Isotonic - Same total solute concentration
Etc: Water, Oxygen, carbon Dioxide

b. Facilitated Diffusion
- Net movement of particles down their concentration gradient with the help of carrier molecules.
- No Energy Required
Etc: Channel/ uniporter carrier (usually proteins)
-demonstrates saturation kinetics( increasing the graident beyond a pt causes no further increase in transport)

ENERGY- REQUIRING TRANSPORT
a.Active transport
Net movement of particles against their concentration gradient with the help of transport proteins
-carrier consumes Energy
- ETC : Required to maintain membrane potentials in specialized cells such as neurons
b.Endocytosis
- Process whereby the cell membrane engulfs extracellular material, moves it into the cell, and forms membrane- bound vesicles [low density lipoprotein (LDL)]
-Phagocytosis - Engulfing of large particles (bacterium/organic matter)
-Pinocytosis - Ingestion of fluids or small particles
c. Exocytosis
-reverse of endocytosis
- vesicle within the cell fuses with the cell membrane and relseases its contents to the outside.

***[[Animation of Endocytosis ]]***
*Note that in both endocytosis & exocytosis, the material never actually crosses through the cell membrane
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Prokaryote Vs Eukaryote in a nut shell:
1) Cell wall present in all prokaryote vs Cell wall present in fungi and plants only
2) unicellular (Bacteria) vs unicellular(protistans) or Multicellular ( fungi,plants)
3) no Nucleus vs Nucleus
4)Ribosomes(Subunit = 30S &50S) vs Ribosomes (Subunit 40S& 60S)
5) No membrane-bound organelles vs Membrane- bound organelles
* Plant cells have no centrioles
Prokaryote
- plasma membrane lacks glycolipids and cholesterol
-Flagella are used for locomotion.

[- Pili - hollow protein tubes that attach bacteria to surfaces and transfer DNA btw cells during conjugation
- capsule or slime layer consisting of polysaccharide gel to protect against host defense mechanisms
- Gram- Positive bacteria have a cell wall with thick layer of petidoglycans(sugars + amino acids)
-Gram -Negative bacteria are surrounded by a more complex wall structure consisting of a thin layer of petidoglycans surrounded by lipoplysaccharide and protein.] - Add INFO from Microbiology

Eukaryote organelles:

-* Fluid Mosaic Model + Diagram of a Eukaryotic Cell
- Transport Proteins - membrane spanning molecules that allow certain ions & polar molecules to pass through the lipid bilayer
-Cell adhesion molecules (CAMs) - proteins that contribute to cell recognition and adhesion (important during development)

a.Nucleus - Controls the activities of the cell
- Surrounded by a nuclear membrane

b.Ribosomes - Sites of protein production and are sythesized by the nucleolus
- Consist of 2 subunits

c.Endoplasmic Reticulum - RER(rough ER with ribosomes lining its outer surface)
- SER (Smooth ER without ribosomes)
- General:transport of materials throughout the cell
-Smooth : involved in lipid synthesis and detoxification of drugs and posions
- Rough: involved in protein syntehsis

d. Golgi apparatus - stack of membrane- enclosed sacs
- receives vesicles and their contents from smooth ER, modifies them.
- Secretory vesicles produced by Golgi release their contents to the cell's exterior via exocytosis.

e.Vesicles/ Vacuoles - membrane-bound sac involved in the transport and storage of materials

f. Lysosomes - membrane- bound vesicles that contain hydrolytic enzymes involved in intracellular digestion
Autolysis - "self-destruction" through the release of the hydrolytic enzyems(PH 5)
g. Microbodies -
1)Peroxisomes : contain oxidative enzymes that catalyze a class of reactions in which hydrogen peroxide is produced.Peroxisomes break fats down, used in the liver to detoxify compounds harmful to the body.

2)Glyoxysomes: found in fat tissue of germinating seedlings. Used to convert fats into sugar.

h. Mitochondria - sites of aerobic respiration & suppliers of energy
- inner membrane has many convolutions : cristae
- semiautonomous : contain their own DNA(circular) and ribosomes which enables them to produce some proteins and self- replicate by binary fission.

i.Cytoskeleton - gives the cell mechanical support, maintains its shape, functions in cell motility.
- Tubulins (Microtubules), Cilia, actin(Microfilaments)
*Note: Not all cells have the same rleative distribution of organelles.
Etc: Sperm cells: Mitochondria
Pancreatic cells: Golgi bodies (secretion)
RBC : no organelles (transport)

First Post - 18th DEC 06 Inauguration

#1a Introduction :
Neurology is a branch of medicine dealing with disorders of the nervous system. Physicians specializing in the field of neurology are called neurologists and are trained to diagnose, treat, and manage patients with neurological disorders. Most neurologists are trained to treat and diagnose adults. Pediatric neurologists, nearly always a subspecialty of pediatrics, treat neurological disease in children. Neurologists are also involved in clinical research, clinical trials, as well as basic research and translational research.

#1b THE PLAN
This is the following devised plan that I'm going to follow through to achieve my dream. :).
From 18th DEC - 27th DEC: Inauguration study Plan.
Daily Routine:
1) 3-4 Sessions (77 mins each)
2) 0.5 session review on verbal reasoning
3) 2 sets of 8(Chin up) daily
4) 4 x 30 crunches daily
5) 0.5 session review on previous day material

Weekly Routine:
1) Write 2 Essays based on MCAT Writing Samples each week: http://www.aamc.org/students/mcat/about/wsitems.htm
2) 2 - 3 5km run per week
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During Odd weeks - I'll study Biology/Organic- chem
During Even weeks - I'll study Physics/ General Chem
Daily Verbal Reasoning (0.5 session)


1C THE TARGET
1) April 12 MCAT
2) Registration by March 29th