Chapter 1 - Cell as a Basic Unit of Life - Part 1

OBJECTIVES

• By the end of the lesson, students should be able to :1.Explain 4 basic principles in Cell Theory– Describe the cell as the smallest

independent unit of life & form the basis of living organism.

2. Prokaryotic and eukaryotic cells– Describe & compare the structure of

prokaryotic cell & eukaryotic cell

•All organisms are composed of one or more cells.

Semua benda hidup berasal daripada sel.

1.1) Cell Theory

1

Sel ialah unit asas kehidupan.

•Cells are the “basic unit of life”.

Lesson Objective:

1.Explain 4 basic principles in Cell Theory1.0 CELL AS A UNIT OF LIFE

•New cells are produced from the earlier cells (mother cells)/pre existing cell through cell division.

Sesuatu sel baru berasal daripada sel yang terdahulu melalui pembahagian sel.

2

Lesson Objective:


•Cell is a unit in which all metabolic processes take place.

Sel berfungsi sbg satu unit di mana semua proses metabolisme berlaku di dalamnya.

3

Lesson Objective:


•Each cell carries heritable/genetic information that can be passed on to the daughter cells during the cell division. Setiap sel mempunyai maklumat

genetik/pewarisan yang boleh diturunkan kepada sel anak semasa pembahagian sel.

4

Lesson Objective:


1.2) Prokaryotic and eukaryotic cells

Prokaryotic Cell

e.g. bacteria, cyanobacteria (blue-green algae)

pro- = early(before), primitive, first karyo- = nucleus

prokaryotic cell =

cell that bears primitive nucleus, or nuclear material that is not enclosed by

nuclear membrane

prokaryotic organisms prokaryotes

?

Lesson Objective:

2. Prokaryotic and eukaryotic cells1.0 CELL AS A UNIT OF LIFE

• A major difference between prokaryotic and eukaryotic cells is the location of chromosomes.

• In an eukaryotic cell, chromosomes are contained in a membrane-enclosed organelle, the nucleus.

• In a prokaryotic cell, the DNA is concentrated in the nucleoid without a membrane separating it from the rest of the cell.

BACK

Lesson Objective:


(1.2) Prokaryotic Cell Typical Structure (i)

capsulepili

cell wall

plasma membrane

stored foodDNA without nucleo envelope

flagellum

cytoplasm

polysomes

ribosomes

MesosomeCarry out respiration

Lesson Objective:


(1.2) Prokaryotic Cell Typical Structure (ii)

Lesson Objective:


Prokaryotic Cells

Lesson Objective:


(1.2) Prokaryotic Cell

Typical Features

•small (diameter: 0.5 - 10m)•cytoplasm surrounded by a plasma membrane and•encased within a rigid cell wall •no distinct interior compartment•nuclear material: DNA•no membrane bound organelles•contain simple structures like ribosome•membrane folds contain pigments for photosynthesis

Lesson Objective:



Typical Features (Cell walls)

•composed of peptidoglycan* •protect the cell •maintain its shape•prevent excessive water uptake

peptidoglycan* •consists of a carbohydrate matrix that is cross-

linked by short polypeptide units •characterizes different types of bacteria:

Gram positive and Gram negative

Lesson Objective:



Typical Features (Flagella)•some bacteria use a flagellum for locomotion and feeding•long, threadlike structures•protruding from the surface of the cell•move in rotation (why?)

Lesson Objective:


(1.3) Eukaryotic Cell

e.g. Protoctists;protozoa cells, plant cells, fungus cells, animal cells, algae,

eu- = true/after karyo- = (something to do with)

nucleus eukaryotic cell =

cell that bears true nucleus, or nuclear material that is enclosed by a nuclear

membrane

eukaryotic organisms eukaryotes?

1.0 CELL AS A UNIT OF LIFELesson Objective:

2. Prokaryotic and eukaryotic cells

Eukaryotic Cell Typical Structure (i)

cytoplasm

plasma membrane

nucleus

nuclear membrane

nucleoplasmachromatinnucleolus

mitochondrion

Golgi apparatuscentrosome

temporary small vacuole

secretive granules

protoplasm

Cytoplasm



Typical Features•diameter: 10 - 100m)•within the cytoplasm is a variety of membrane bounded organelles of specialized forms and functions (compartmentalization)•nuclear material: DNA + proteins•contain vesicles, small sacs that store and transport a variety of materials•supported by internal protein scaffold, cytoskeleton

A network of fibers permeating the matrix of eukaryotic cell that provides a supporting frame work for organells, organells movements etc



• In eukaryote cells, the chromosomes are contained within a membranous nuclear envelope.

• The region between the nucleus and the plasma membrane is the cytoplasm.– All the material (organelles) within the plasma

membrane is known as cytoplasm.

• Within the cytoplasm of a eukaryotic cell is a variety of membrane-bounded organelles of specialized form and function.

• These membrane-bounded organelles are absent in prokaryotes.



The Differences between Prokaryotic and Eukaryotic Cell. Prokaryotic

Cell size


Eukaryotic Cell small (0.5-10.0)

larger (10 -100)

true nucleus absent present*

chromosome circular helix DNA

linear helix DNA with histone prot.

cell wall peptidoglycan cellulose ribosomes small large

cytoskeleton absent presentflagella helix flagellin &

lack of microtubule. microtubules (9+2) structure



Cell / organism size compare to Organism Sizes• Most cells are much smaller than one millimeter.

– Some as small as one micrometer.

• Small cells are likely to have an adequate surface area for exchanging wastes for nutrients.

– Cells that specialize in absorption have modifications that greatly increase the surface area per volume of the cell.



1.3) Microscopic Structure of Plant & Animal Cells

OBJECTIVES

• By the end of the lesson, students should be able to :

- Illustrate the detailed structures of typical plant & animal cells.

- Compare between plant & animal cells

1.3) Structure of animal & plant cells


Illustrate the detailed structures of typical plant & animal cells.

ANIMAL CELLS• As seen under light microscope, animal cells

contain protoplasm (nucleus + Cytoplasm )• Cytoplasm=cytosol+organelles)• Large central nucleus surrounded by cytoplasm.• Nucleus contains coiled DNA called Chromatin +

protein called histone. • Cytoplasm contains;organelles & glycogen

granules (food storage polysaccharide)• Have either small vacuole or none at all.



Typical Structure (ii): Plant Cells

middle lamella



Plant cells• Protective, rigid, cellulose cell wall

surrounding the cell.

• Chloroplasts in the cytoplasm contain chlorophyll pigments which carry out photosynthesis.

• Large vacuole. Central vacuole, filled with sap (photosynthesis product)

• Contain starch granules



The Differences between Plant and Animal Cells (i)

Plant Cells shape

Animal Cells

rigid not rigid lysosomes usually absent present

chloroplasts in photosynthetic cells

absent

cell wall plasmodesmata middle lamella

absent


Compare between plant & animal cells.

The Differences between Plant and Animal Cells (ii) Plant Cells Animal Cells

vacuoles large contain cellular fluid tonoplast

too small @ absent

centrioles absent, except in more primitive plants

present

stored carbohydrat

e

starch glycogen

cilia absent, except in more primitive plants

present


Compare between plant & animal cells.

Documents

Chapter 1 - Cell as a Basic Unit of Life - Part 1