Sunday, November 2, 2014

F4- Biology- Chapter 2.1- Cell Structure and Function

Summary of descriptions and functions of cellular structures

Cellular ComponentDescriptions & Functions
Plasma Membrane- made of protein and phospholipids
- semi permeable = selective barrier

Function: regulate movement of substance in and out of cytoplasm
Cell Wall- permeable to all fluids ( has tiny pores)

1. gives shape
2. provide mechanical support
3. protect the plant cell from rupturing due to excessive intake of water
Cytoplasm- contain organic and inorganic substances

1. Acts as medium for biochemical reactions in the cell
2. Provide substances obtained from the external environment to the organelles.
NucleusFunction of Nucleus: Controls all the activities which take place in the cell

Consists of
1. Nuclear membrane
2. Nucleolus

3. Chromatin (the form that chromosomes take when the cell is not dividing, is contain within nucleoplasm

4. Chromosomes

Function of Chromosomes:

a. Carry genetic information which determines the characteristics and functions of a cell.

b. contain coded information which regulate synthesis of protein
  • fluid filled sac
  • surrounded by tonoplast (semi-permeable membrane)

Cell sap
  • fluid contained in a vacuole
  • contains water, organic acid, sugar, amino acids, mineral salts, waste substances, pigments and metabolic by-products
  • supports herbaceous plants so they do not wilt easily.

Types of vacuole
1. Contractile vacuole :

a. help to regulate water balance in these organisms.
b. acts as a storage place in a cell

2. Food vacuole : storage pocket for food
MitochondriaFunction: release energy by going through process of cellular respiration
(when food substances such as glucose are broken down with the help of enzymes present in mitochondria)

- energy released stored in the form of ATP (adenosine triophosphates) that can be readily used by cells.
  • attach to the surface of rough endoplasmic reticulum or suspended freely in cytoplasm 
  • each ribosome consists 2 sub-units, 1 small 1 large, each of which comprises a type of ribonucleic acid (RNA) and protein. 
  • place where synthesis of protein takes place 
  • use information carried by the chromosomes to make these protein.
Endoplasmic ReticulumTwo types of endoplasmic reticulum:

1. Rough Endoplasmic Reticulum ( rough ER)

  • has ribosomes attached to its surface
  • transport proteins made by ribosomes
  • protein departs from rough ER are enclosed in vesicles. 
  • these protein can be transported from one cell to another

2. Smooth Endoplasmic Reticulum ( smooth ER)

  • does not have ribosomes attached to its surface
  • site of important metabolic reactions
  • example: synthesis of lipids and detoxification of drugs and poison.

Golgi ApparatusFunction:
  • processing, packaging and transporting centre of carbohydrates, proteins, phospholipids and glycoproteins.

  • contain hydrolytic enzymes 
  • which digest or break down complex organic molecules such as protein, lipids, polysaccharides and nucleic acid
  • eliminate worn out mitochondria and other damaged organelles to enable to renew itself
  • fuse with food vacuole and dispense enzymes into these vacuoles to digest the contents of vacuole ( in cells of certain organisms)
  • digest bacteria by breaking down the bacterial cell wall

Centrioles- composed of a complex arrangement of microtublules
- does not present in plant cell.


  • located just outside the cuclues
  • from spindle fibres during cell division in animal cells

Chloroplasts- contain green pigment chlorophyll 

Function of chlorophyll in chloroplasts:

  • traps sunlight and converts light energy into chemical energy during photosynthesis

Comparison of animal and plant cells

have plasma membrane, cytoplasm, nuclues, endoplasmic reticulum, Golgi apparatus, ribosomes and mitochondria.
Animal cells AspectPlant cell
AbsentCell wallPresent
If present, are scattered throughhout the cellVacuoleHas one or few large vacuole(s)
PresentLysosomenormally absent

Relation between number of certain organelles with the functions of specific cells 

Types of cells FunctionOrganelles found abudantly in the specific cells
Sperm cellsRequire large amounts of energy to propel towards the uterus and Fallopian tube during fertilisationMitochondria
Flight muscle cells in insects and birdsContract and relax to enable movements and flightMitochondria
Cells in the meristemsDivides actively Mitochondria
Mesophyll palisade cellsCatch the energy from the sunlight for photosynthesisChloroplasts

Wednesday, April 3, 2013

F5- Chemistry Chapter2 -Reactions of propene

The molecular formula or structural formula of the product for every reaction of propene.

The following is the short notes I've made. Sorry for not updating for so long >.< my laptop was spoilt uhh. If you have any questions, please comment!! We could discuss together :)

Thank you for viewing and I hope you enjoy.