Post on 27-May-2015
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CHAPTER 2 : CELL STRUCTURE &
CELL ORGANISATION
2.1 Cell Structure & Function2.2 Cell Organisation
2.1 CELL STRUCTURE & FUNCTION
Learning Outcomes :1. Draw & label an animal cell and a plant
cell2. Identify the cellular components of an
animal cell & a plant cell3. State the functions of the cellular
components in an animal and a plant cell4. Compare & contrast an animal cell with a
plant cell5. Relate the density of certain organelles
with the functions of specific cells.
HISTORY Robert Hooke (1665) was first
discovered the cell structure of plant
He examined fine slices of cork with a primitive microscope
He saw many ‘box-like’ structures , then he called ‘cells’, from Latin for ‘little rooms’.
THE CELL THEORY(Schleiden M & Schwann T)
All living organisms are made up of one or more cells
New cells are formed by the division of pre-existing cells
Cells contain genetic material of an organism which is passed from the parent cells to daughter cells
Cells are the basic unit of structure & function in living things
ORGANELLES specialised structures which are each surrounded by its own membrane & perform specific function
PLASMA MEMBRANE
Thin, semi-permeable Made of protein, lipid Controls the
movement of substances in and out of the cell
Non-organelle
CYTOPLASM Jelly-like substance
that contains water & mineral salts
Contains organelles and food such as carbohydrates (glucose)
Medium for metabolic reactions
Supplies the substances required by organelles
Non-organelle
CELL WALL Thick layer outside
the plasma membrane Made up of cellulose,
fully permeable Maintains the shape
of the plant cells Provides mechanical
support Non-organelle
NUCLEUS Spherical shape with
double membrane Contains nucleolus,
chromosomes, nucleoplasm & nuclear membrane
Controls & regulates all the activities of cell
Contain the heredity factors responsible for the traits
RIBOSOME Small particles
consisting of RNA Exists freely in the
cytoplasm or on the surface of the endoplasmic reticulum
Synthesis of protein
ENDOPLASMIC RETICULUM A system of membrane-
enclosed tubules closely packed together and continuous with the nuclear membrane
RER has ribosome, SER does not have
Transport system for protein & lipids within the cell
RER transport protein to other part of cell
SER stimulates the synthesis of lipids & cholesterol & transport within the cell
GOLGI APPARATUS Vacuolar region
surrounded by a complex meshwork of vesicles budding off at its end
Received protein & lipids from ER & modify them to form specific secretion such as enzymes & hormones
Pack the secretions formed into secreting vesicles & transport them to plasma membrane to be secreted
Controls the secretory activity of cells
Formation of lysosomes
VACUOLE Filled with cell sap,
surrounded by semi-permeable membrane called the tonoplast
Contain water, sugar & dissolved minerals
Maintain turgidity of cells in plants
MITOCHONDRIA Rod-shape with a
double membrane Outer membrane is
smooth, inner membrane is folded to form cristae
Known as ‘power-house’ of the cell
Releases energy as it is the site for aerobic respiration
CHLOROPLAST Disc-shape organelle
with a double membrane
Consist of an orderly arrangement of grana within the stroma. Granum contains chlorophyll
Site of photosynthesis Trapped light energy
and change it into chemical energy
LYSOSOMES Membrane-bound
vesicles found in animal cells
Contain enzymes which control breakdown of protein & lipids
Contain enzymes that digest aged or defective cell components or materials taken in by the cell from its environments such as food particles or bacteria.
CENTRIOLES A pair of small
cylindrical structures (microtubules)
Form spindle fibre for cell division
COMPARE & CONTRAST
ANIMAL CELL SIMILARITIES PLANT CELL
A plasma membrane surrounding the cytoplasm
Both contain nucleus & cytoplasm
Both contain organelles such as mitochondria, ER, Golgi apparatus &
ribosomes
ANIMAL CELL DIFFERENCES PLANT CELLSmaller than plant
cellSIZE Larger than animal
cellIrregular shape SHAPE Often regular in
shapeAbsent CELL WALL PresentAbsent CHLOROPLAST Present
No large vacuoles. If present, small &
numerous.
VACUOLES Large central vacuole filled with
cell sapIn a form of glycogen
in liver & muscle tissues
FOOD STORAGE In a form of starch
Present CENTRIOLES AbsentSome animal cell
have cilia or flagellaCILIA & FLAGELLA Absent
RELATIONSHIP BETWEEN THE STRUCTURE OF AN ANIMAL CELL
& A PLANT CELL
The number of specific organelles in a cell varies on the type of cell and its function.
Active cell many mitochondria to provide enough energy for its activities. Eg. : sperm cells, flight muscle cell (insects & birds)
Cell in meristems of plant shoot & root
Green plants more chloroplasts to carry out photosynthesis such as palisade mesophyll cells and spongy mesophyll cells, also guard cells.
EXERCISE 2.11. What are the organelle structures of a
cell?
2. What are the functions of each structure describe above?