CELLS- The basic unit of life

• Name: Gugu Msana

• Student number: 201181428

• Module : Professional studies 3a

• Course: B. Education

• List of sources provided in the last slide

TOPIC

CELLS: THE BASIC UNIT OF LIFE

what is a cell ?

Cell is the basic unit of life.All organisms are composed of cellSome organisms are unicellular .eg: bacteriaAnd while some are multicellular . eg: humanCell is the fundamental structural and functional unit of all living organisms.

PLANT CELL

ANIMAL CELL

History of cell studyRobert hooke-1665Coined the word “cell”.Looked at cork cells.

Robert brown-1831

Discovered the “nucleus”.

Theodor Schwann- 1838

Cells are unit of biological structures.

Mattias Schleiden-1850

Cell are the fundamental basis of life.

Virchow-1858All cells come from cells.

Theodor Schwann Mattias Schleiden

Rudolf Virchow Robert Brown

1. Every organisms is made up of at least one cell.2. Cells are the basic structural and functional

unit of multicellular organisms.3. All cells arise from preexisting cells.

CELL WALL1. a non living rigid structure .

2. Forms an outer covering for

plasama membrane.

function:

1) Determining Cell Shape.

2) Strength.

3) Controlling Turgor Pressure.

4) Passage of Substances.

5) Protection.

Primary wall:

• The wall which help to grow in

youger plant

• diminishes as cell get mature.

Endomembrane system contains only those organelles whose functions are coordinated.It consists of: Endoplasmic reticulum(ER) Golgi complex lysosomes Vacuoles

Discovered by porter and thompson.

ER are a network of tiny tubular structures

scattered in the cytoplasm.

consists of 30-40% of endomembrane system

ER divides into 2 compartments.

1. luminal(inside ER)

2. extra luminal(cytoplasm)

FUNCTIONS:

1. Mechanical support

2. Conduction of information

3. Intercellular transport

4. Localization of enzyme

5. Large surface area.

Endoplasmic reticulum cont…. • Dicovered by porter and

thompson.

• It is a complex membrane

lined network of flattened

sac, tubles etc..

• runs through out

cytoplasm of eukaryotic

cells.

• Cosist of 30-40% of total

endomembrane system.

• Divides the intercellular

space into components.

Luminal and

extraluminal

• Has two main types:

Smooth endoplasmic reticulum and

rough endoplasmic reticulum.

Functions:

1. Mechanical support

2. Conduction of information

3. Intercellular transport

4. Localisation of enzymes.

5. Large surface area.

Function of RER:

1. Protein for transport

2. Protein processing

Function of SER:

1. Storage.

2. Glycogenolysis.

Golgi apparatus• Is a cytoplasmic organelle osf

smooth membrane sac.

• Dicovered by camillo golgi,

• Found in eukaryotic cells (except

mammalian erythrocytes)

• Occur between nucleus and

exposed cell surface.

• Surrounded by zone of cytoplasm

which is devioded of ribosomes,

mitochondria, etc...

Functions:

Package materials. And important

for formation of glycoprotein.

Lysosomes and vacuolelysosomes

• Membrane bound vesicular structure

• Formed by packaging of golgi appartus.

• Very rich in hydrolytic enzymes.

• Enzymes are capable for digesting

carbohydrate, protein, lipid, mucleic acid.

• Polpularly called as “suicide bags”,

Vacuoles:

• Membrane bound space found In

cytoplasm.

• Bounded by single membrane called

tonoplast,

• In amoeba, called contractile vacuole

and in proista food vacuole

mitochondria• These are double –membrane bound, sausage –

shaped semi-autonomous organelles.

• The electron micrograph shows that the

boundarymembranes are separated by a fluid

filled spacecalled outer compartment.

• The outer membrane is smooth but the inner

smooth projects in the form of many folds

calledcristae into the matrix.

• The matrix is rich in enzymes, a circular DNA

• molecule and many small ribosomes.

• The inner membrane and the cristae bear a number

of particles, which have a spherical head– piece

(F1 subunit) and a stalk (F0 subunit) that is

embedded in the lipid of the membrane.

• The F0 – F1 combination functions as ATP

synthetase.

• The main function of mitochondria is aerobic

respiration and ATP synthesis

…Plastids…Found in plants and euglenoids.

They are large

They contain pigments, imparting colors and storage products.

Plastids can be classified into:

*CHLOROPLAST *CHROMOPLAST *LEUCOPLAST

•Contains chlorophyll and

carotenoid pigments.

•Found mainly in mesophyll of

leaves .

•These are lens shaped, oval

shaped, spherical, discoid or

even ribbon-like organelles.

•Contains fat soluble

carotenoid pigments like

carotene, xanthrophylls

and others are present.

•Found in yellow, orange,

red.

•Colorless plastids

•Various shapes and sizes

with stored nutrients

•LEUCOPLAST can be divided

into 3:-

1.Amyloplasts – store

carbohydrates

2.Elaioplasts – store oils

and fats

3. Aleuroplasts – store

proteins.

plastids• Plastids are double – membrane bound organelles of

different shapes, that are found only

• in plant cells and contain pigments and storage

products.

• These are three types of plastids, depending on their

colour and functions.

• Chromoplasts

• These are the coloured plastids containing mainly the

yellow, red and orange pigments (carotene and

xanthophylls).

• (iii) Chloroplasts

• These are the green plastids containing mainly

chlorophylls and very little of carotene and

xanthophylls.

• Chloroplasts may be lens – shaped, oval,spherical,

discoid, ribbon-like or cup –shaped

• Each chloroplast has a double membrane

• covering, enclosing the colourless matrix

• called stroma.

Reference list • Robayda, A. (2013). cell the unit of life. Available:

http://www.slideshare.net/AishaRobayda/cell-the-unit-of-life-1?qid=12bc18e8-e13c-

4232-9b02-cf1652411b05&v=qf1&b=&from_search=3 (Accessed 07 march 2014)

• ittah,E. (2013). Cell- The basic Structure of life.

Available: http://www.slideshare.net/ericittah/eric-ittah-canada-eric-

ittah?qid=12bc18e8-e13c-4232-9b02-cf1652411b05&v=qf1&b=&from_search=5

(accessed 07 march 2014)

• Baiju, V. (2011). Cell The unit of life. Available:

http://www.slideshare.net/VigneshBaiju/cell-the-unit-of-life-

10230437?qid=12bc18e8-e13c-4232-9b02-

cf1652411b05&v=qf1&b=&from_search=8 (accessed 07 march 2014)