Tuesday, February 17, 2009

Happy Birthday Pei Ying

Posted by Voon Kaen at Tuesday, February 17, 2009 1 comments Links to this post

Wednesday, February 11, 2009

Biology - The structure of cell

Posted by LeoZz at Wednesday, February 11, 2009 0 comments Links to this post
The cell is the structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life.[1] Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular.
In form 1, we learned that the living component of a cell is called protoplasm, which is the combination of the cytoplasm and nucleus. The protoplasm is being surrounded by the plasm membrane. And now, in form 4, we have learned that the cytoplasm contains structures called organelles. Every organelles perform specific functions with enable the cell to function as a unit of life.
Cell membrane
The cell membrane is a general term that refers to all membranes that found in the cell. The membrane at the surface that enclose the contents of the cell is called plasma membrane. The plasma membrane is the combination of the protein and phospholipids. It form a boundary that separates the content of the cell from the outer environmen. The plasma membrane is semi- permeable which act as a selective barrier that can regulates the movement of these substances into and out the cytoplasm.
Cell wall
The cell wall is the rigid outer layer that surrounds the plasma membrane of plant cells. It is composed of the cellulose, a tough and fibrous carbonhydrates. The cell wall is permeable to allow substances move freely into and out of the cell. It gives a shape to the cell and provide mechanical support to the cell. It also protects the plant cell from rupturing due to excessice intake water.
Cytoplasm
The cytoplasm is a region between the nucleus and the plasma membrane. It consists of a jelly-like matrix in which the organelles of the cell is suspended. Cytoplasm contains organic and inorganic substances and act as a medium for biochemical reactions in the cell. It also provides the external environment to the organelles.
Nucleus
The nucleus appears a large, dense, spherical organelle enclosed by a nuclear membrane. It contain the nucleoplasmand a dark spehrical structure called the nucleolus. Chromatin, the form of choromosomes take when the cell is not dividing, is contained withing the nucleoplasm. Chromosomes carry DNA which determines the characteristic and functions of the cell. The nucleus control all the activities which takes place in cell.
Vacuole
A vacuole is fluid-filled sac which is surrounded by tonoplast, a semi-permeable membrane. The fluid contain a vacuole is called cell sap. A typical plany cell has a large central vacuole while a young plant cell has a numerous smaller vacuoles. Freshwater microorganism such as Paramecium sp. has contractile vacuole and food vacuole. The vacuole act as a storage place in a cell. The cell sap contains water, organic acids, sugars, amino acids, mineral salts, waste substances, pigments and metabolic by- products.The cell sap supports herbaceuos plants to prevent them wilt.
Mitochondria
Mitochondria is a small spherical or cylindrical-shaped organelles. Mitochondria are involved in cellular respiration. It has double layer. The process of releasing energy through the oxidation of food substance such as glucose. Energy is generated in the form of ATP which can be used readily be cell.
Ribosomes
It is compact, spherical organelles. Each ribosomes is composed of two-sub units, each consisting of RNA and protein. It is found either suspended freely in the cytoplasm or attached to the surface of the rough endoplasmic reticulum Ribosomes are the sites of protein synthesis. The instruction required for the synthesis of these proteins is stored in the chromatin.
Endoplasmic reticulum (ER)
Consist of an extensive network of folded membranes which form interconnected tubes and sacs in the cytoplasm. The membranes of the ER are continuous with the nuclear envelope.There are two types of ER: smooth ER which does not has ribosomes and also rough ER that has ribosomes. The rough ER transport protein made by the ribosomes while the smooth ER synthesis lipids and carries out detoxification of drugs and metabolic products.
Golgi apparatus
It consists of stack of flattened membrane-bound sacs. New membrane is continuously added to one end of the Golgi apparatus and buds off as vesicles at the other end. Functions as a processing packaging and transport centre of carbohydrates, proteins and gylcoproteins.
Lysosomes
It is a small, spherical sacs surrounded by a single membrane. It also contains hydrolytic enzymes which is a digestive enzymes. It function as digestive compartments in a cell. The hydrolytic enzymes digest or break down complex organic molecule. In certain unicellular organism, lysosomes fuse with food vacuoles and release their enzymes into these vacuoles to digest the contents of the vacuole. The breakdown products are absorbed into the cytoplasm of the cell.
Centrioles
Centrioles is a small cylindrical structures that occurs in pairs, next to the nucleus in animal cells. It is composed of a complex arrangement of microtubules. Centrioles does not present in plant cells. Centrioles form spindle fibres during cell division in animal cells.
Chloroplast
Choroplast are lens-shaped organelles. They also have double membrane. The internal chloroplast membranes contain the green pigment, chlorophyll. Chlorophyll captures the sunlight energy and converts light energy into chemical energy during photosynthesis. The green pigment of chlorophyll gives plants their green colour.

Sorry for the super duper late for this note, it waste me a lot of time to compare the success and the saksbadi note. So, it is a perfect note. Do enjoy to read it.

Saturday, February 7, 2009

MONDAY

Posted by bottle at Saturday, February 07, 2009 1 comments Links to this post
Monday is a holiday. Works of cleaning, painting will be continue on Monday. Today, only some of the members came to help so we left many works to do, and we have not enough time. Therefore, we need people to help us out. It's real!!!!
time: 9~~ unconfirmed. Bring along some paint brush, cloth and newspaper if can. Your cooperation and help are greatly appreciated.

Friday, February 6, 2009

inter-class competition

Posted by bottle at Friday, February 06, 2009 3 comments Links to this post
A 'pertandingan keceriaan' was held by Pn.Teh who is a kaunselor in SMK SRI SENTOSA. Started before chinese new year, and will be ended at next tuesday. so, we. 4a12, trying our best to decorate our class. Therefore, our leader, lowzhenning, need all 4a12 members' help and co-operation. there will be a decorating and cleaning session this saturday ( 6/2/2009)- 8 a.m.~4p.m. You can be late or be back earlier. We need your attendance and help even just a while. On that day, we will paint, clean, and decorate our class. So, those who is free, please come and help us out.

Besides that, i had taken some photo of all 4a12 class members today. Some of you were not very satisfied with them. Attention then, if you were not satisfied with those photos, please send me your photo by today or tomorrow. MUST!! send me photo, wearing school uniform and plain background. Thanks.

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happy birthday to CYNDI

Posted by bottle at Friday, February 06, 2009 3 comments Links to this post
6/2 is a special date for CYNDI (huixin). it's her birthday. so let's wish her have a sweet day and all the best in 2009. And of course, the last wish is dreamt by all girls no matter where they are...... ~~~ be more and more pretty!!!! good luck!!!!


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Wednesday, February 4, 2009

Happy birthday to Sim Tee

Posted by LeViN [ShEnG] at Wednesday, February 04, 2009 2 comments Links to this post
Today was a special day for one of our classmate, Sim Tee, I guess in this 4 year in Smk Sri Sentosa, she was in A12. I guess, pressure and homework to her is nothing. Rite?


Happy birthday to you and have a happy 15 and welcome 16 with a happy mood, HAPPY BIRTHDAY.

Monday, February 2, 2009

happy birthday to PENG

Posted by bottle at Monday, February 02, 2009 3 comments Links to this post
Today is a special day for one of our classmates. Let's wish her happy birthday.

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To: CHAN KAI PENG. A new student from 3a2 and 4a11. Haing this opportunity I will like to tell her, not to be so stress and welcome to 4a12.

4a12, prove,we are a fun class!!!

School Reopening Soon

Posted by LeViN [ShEnG] at Monday, February 02, 2009 2 comments Links to this post
HEY HEY HEY, to all of the student of 4A12 Smk Sri Sentosa, School are reopening soon, how is you guys or girls holiday???
I had saw many complain of stack of homework during the holiday. Sure will be busying on homework now, Well good luck and wish you all have a happy holiday and happy new year.
HAPPY HOLIDAY and LETS WELCOME THE SCHOOL REOPEN.

GOOD LUCK FRIENDS.

It was a fact that we are the best class in form 4 smk sri sentosa, although not all the best student, but we are the best class when we combine, therefore teacher put a high hope on us, will push us hard and well, keep on give us homework is because wan us continue be the best of the best in SMK SRI SENTOSA.

Levin [Sheng]
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