6th June, 2008 Friday

Today...
Morning, woke up very early (6am) and went to the driving school at kampung jawa.
That fellow actually asked me to go from wednesday to friday to learn car de..but he keep postpone till friday, the last day only let me go learn.
I thought this holiday can learn it all and take the test then after holiday can fully concentrate on study already but seems like all got screw up cause of him. Wth..
8.30 am only i got my turn to drive. Learned parking, go up the hill and cornering. Keep turning around and doing the same thing for at least 3 hours. Damn bored..
Around 11 something asked me go to the office to wait to go back. Waited till 1.30 something only leave that stupid place. Luckily got sin chew jit poh there, read up on the news about fuel price rising (this really affect my family and surely it affects everyone too.) and played the soduku in the paper, didn't manage to solve it~ haha.. Also read up on my biology as i brought the book along for tuition at 3pm.
That fellow fetched and drop me at center point and I walked to Delta, that's around 2 pm. Must eat my lunch 1st before go tuition if not later hungry during tuition can't concentrate. Haha.. So I called up Boon Oong to come to delta earlier to accompany me eat but he didn't answer. Then I called wei lun he also didn't answer too. Sweat~
But when i reached the restaurant opposite Delta and I saw Boon Oong was entering the restaurant too. Lol..rupanya he just finished his math tuition and wanted to have his lunch there too. So we ate together. After that, went to pay tuition fee, the counter was full of students paying fees as today is 6th of the month.(some of you who know delta's policy will know why they need to pay up their fees before 7th of each month)
Then, Bio class started. Today the class had a sudden increase in the number of students as this is the 1st week of June.
Next is what I've learned today.

Today lesson is a continuous of last week lesson on Transport of Substances across the Plasma Membrane. I was not so concentrate in the class cause felt quite sleepy. (Haha, can't blame, yesterday slept around 1.30am and today woke up so early.)

First of All, we learn about Active transport.
Active Transport requires energy in the form of ATP to move a substance through the plasma membrane against its concentration gradient with the aid of carrier protein.

3 kinds of carrier(transport) protein involve in Active Transport:
a)Uniport carrier-transport 1 type of ions/polar molecules in a single direction.
b)Symport Carrier-transport 2 types of ions/polar molecules in an opposite direction.
C)Cotransport Carrier-transport 2 types of ions/polar molecules in the same direction.

2 types of Active Transport:
a) Direct Active Transport (eg: Na+/K+ pump)
The ATP molecule breaks down to form ADP and a Phosphate. The phosphate will bind to the transport protein (the transport protein is said to be phosphorylated) and causes the conformation of the transport protein to change. The protein will transport the Na+ ions which has a low concentration in the cell to the outside of the cell. And K+ ions will be transported from in the cell when the protein is dephosphorylated, i.e the Phosphate ion break from the transport protein. This process is called the DIRECT Active Transport because the ATP molecule is used directly in the transportation process.

b) Indirect Active Transport (eg: proximal convulated tubule of nephron in kidney)
In the proximal convulated tubule, the Na+ concentration in the cell is low because it is transported out of the cell by active transport. But when its concentration is low, it will be transported back to the cell by facilitated diffusion down its concentration gradient. There is a protein called the cotransport protein. The cotransport protein has 2 binding site, 1 is to transport the Na+ ions into the cell down its concentration gradient and another 1 is for the binding of glucose molecule. The glucose molecules will diffuse in to the cell with the Na+ ion through the cotransport protein. The energy used in his process is the electrical potential energy of Na+ ion gradient. This is called the INDIRECT Active Transport cause no binding of ATP molecules to the cotransport protein to transport the glucose molecules in the cell, but they is the binding of ATP molecules to the transport protein which pump the Na+ ions out and thus making the concentration of Na+ ions inside the cell is lower than the outside. So, the glucose molecule is transported indirectly into the cell against its concentration.
*Active transport is ceased/inhibited by respiratory poison such as cyanide and when there is a low level of oxygen. This is because Active Transport need energy in the form of ATP which is make from the cellular respiration in the mitochondria.

Next, is Bulk Transport.
Bulk Transport can be classified as Endocytosis and Exocytosis.
Endocytosis is further divided into Phagocytosis, Pinocytosis and Receptor-mediated.
Endocytosis is a process where cells absorb material from the outside by engulfing it with their cell membrane. It is used by all cells of the body because most substances important to them are large polar molecules, and thus cannot be transported through the phospholipid bilayer by diffusion or active transport.
Phagocytosis(cell-eating) is the process of which cell ingest large objects (Solid)
Pinocytosis(cell-drinking) is the process of which cell ingest fluid.
Receptor-mediated is a specific transport where there is receptor lining on the cell membrane and the cell will ingest objects which has the same binding site as the receptor.
Exocytosis is the process where cells secrete, excrete or egest objects from it.
Secretion occurs when the cell release useful products (made by the cell itself) to the outside of the celll..
Excretion occurs when the cell release waste products made by the cell to the outside.
Egestion occurs when the cell release waste products that is taken up by the cell from the outside.

Also learned about the relationship between Nucleus, RER, Golgi Apparatus and Vesicles. Will write on it next time. ^^