CELL STRUCTURECELL STRUCTURE

Lesson objectivesLesson objectives

By the end of this lesson you should know:

• The parts of a compound light microscope and their functions

PA: Be familiar with and use the light microscope.

MICROSCOPESMICROSCOPES

• Robert Hooke first used microscope to look at cells

• Simple microscope has 1 lens

• Compound microscope has 2 lenses

• Both use light to show the image

THE COMPOUND LIGHT MICROSCOPETHE COMPOUND LIGHT MICROSCOPEEYEPIECE LENS

COARSE ADJUSTMENT

FINE ADJUSTMENT

CLIP

STAGE HEIGHT ADJUSTMENT

NOSEPIECE

OBJECTIVE LENS

STAGE

DIAPHRAGM LEVER

CONDENSER

MIRROR OR LIGHT SOURCE

MAGNIFICATION?MAGNIFICATION?

• To magnify an object means to make it look bigger

• The compound microscope uses 2 lenses

-eyepiece lens

-objective lens

• To calculate total magnification you multiply the power of the 2 lenses

What have you learned?What have you learned?

Do you know……

• The parts of a compound light microscope and their functions?

Are you familiar with and can you use the light microscope?

Lesson objectivesLesson objectives

By the end of this lesson you should know:

• The parts of a plant and animal cell as seen with a light microscope

• PA: To prepare and examine plant (onion) cells stained and unstained using a light microscope

ANIMAL CELL AS SEEN UNDER A LIGHT ANIMAL CELL AS SEEN UNDER A LIGHT MICROSCOPEMICROSCOPE

CELL (PLASMA) MEMBRANE

PROTOPLASM

NUCLEUS

CYTOPLASM

PLANT CELL AS SEEN UNDER A LIGHT PLANT CELL AS SEEN UNDER A LIGHT MICROSCOPEMICROSCOPE

NUCLEUS

VACUOLE

CHLOROPLASTS

CELL MEMBRANE

CELL WALL

CYTOPLASM

SO CAN YOU SPOT THE DIFFERENCES SO CAN YOU SPOT THE DIFFERENCES BETWEEN ANIMAL AND PLANT CELLS?BETWEEN ANIMAL AND PLANT CELLS?

What have you learned?What have you learned?

Do you know….

• The parts of a plant and animal cell as seen with a light microscope?

• Have you prepared and examined plant (onion) cells stained and unstained using a light microscope?

Lesson objectivesLesson objectives

By the end of this lesson you should know:

• The uses of electron microscopes

• Know the ultrastructure of cells with reference to: nucleus, nuclear pores, nucleolus, cytoplasm, mitochondria, choroplasts, cell wall and ribosomes

CELL ULTRASTRUCTURECELL ULTRASTRUCTURE• LIGHT MICROSCOPES HAVE

MAX MAGNIFICATION OF ABOUT x1000

• ELECTRON MICROSCOPES USE A BEAM OF ELECTRONS INSTEAD OF LIGHT AND ALLOW IMAGES TO BE SEEN AT MAGNIFICATIONS OF 250 000 AND HIGHER

• THE FINE DETAIL SEEN IN CELLS USING THE ELECTRON MICROSCOPE IS CALLED CELL ULTRASTRUCTURE

• 2 MAIN TYPES OF ELECTRON MICROSCOPE-TRANSMISSION ELECTRON MICROSCOPE-SCANNING ELECTRON MICROSCOPE

CELL OR PLASMA MEMBRANECELL OR PLASMA MEMBRANE

FUNCTIONSFUNCTIONS OF THE CELL MEMBRANEOF THE CELL MEMBRANE

• Membranes retain cell contents

• They control what enters and leaves the cell – selectively (or semi) permeable

• Membranes give some support to the cell

• Membranes recognise molecules that touch them

NUCLEUSNUCLEUSNUCLEOLUS

CHROMATIN NETWORK

NUCLEAR PORES

NUCLEAR ENVELOPE

FUNCTIONS OF THE NUCLEUSFUNCTIONS OF THE NUCLEUS• Control centre• Nuclear pores control the entry

and exit of materials from the nucleus

• Nucleus contains strands of DNA in the form of a “thread like mess” called the chromatin network

• During cell division the chromatin network becomes visible as X shaped structures called chromosomes Genes are located at sections of chromosomes

Photomicrograph of liver cell Photomicrograph of liver cell nucleusnucleus

1

2

3

4

NUCLEAR ENVELOPE

CHROMATIN NETWORK

NUCLEAR PORE

NUCLEOLUS

THE NUCLEOLUSTHE NUCLEOLUS• This is an area in

the nucleus which stains very darkly

• This is where ribosomes are made

CYTOPLASMCYTOPLASM

• The cytoplasm is the liquid inside cells

• Contains a number of small bodies called organelles

• Many chemical reactions take place here

MITOCHONDRIAMITOCHONDRIA

• These supply energy to the cell – site of respiration

• Cells which need a lot of energy have many mitochondria

• It is on the inner membrane especially the infoldings that energy is released

INACTIVE AND ACTIVE MITOCHONDRIAINACTIVE AND ACTIVE MITOCHONDRIA

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2

3

4

INNER MEMBRANE

OUTER MEMBRANE

CRISTAE

MATRIX

Photomicrograph of liver cell Photomicrograph of liver cell mitochondriamitochondria

CHLOROPLASTSCHLOROPLASTS

• These are green structures in plants which contain the green pigment chlorophyll and within which photosynthesis takes place

CHLOROPLASTSCHLOROPLASTS

CHLOROPLAST DNASTARCH GRAIN

INNER MEMBRANE

OUTER MEMBRANE

THYLAKOID

GRANA STROMA

Photomicrograph of guard cell Photomicrograph of guard cell mitochondriamitochondria

STROMAINNER MEMBRANEOUTER MEMBRANE

STARCH GRAINTHYLAKOIDGRANA

RibosomesRibosomes

• Very small organelles• Protein synthesis

CELL ULTRASTRUCTURE WITH REFERENCE TO A CELL ULTRASTRUCTURE WITH REFERENCE TO A GENERALISED PLANT CELLGENERALISED PLANT CELL

NUCLEAR PORE

CHROMATIN (DNA)

NUCLEAR MEMBRANE

MITOCHONDRION

CELL WALL

CELL MEMBRANE

CYTOPLASM

VACUOLE

RIBOSOMES

CHLOROPLAST

What have you learned?What have you learned?

Do you know….

• The uses of electron microscopes?

• Know the ultrastructure of cells with reference to: nucleus, nuclear pores, nucleolus, cytoplasm, mitochondria, choroplasts, cell wall and ribosomes?

Lesson objectives – Higher Lesson objectives – Higher LevelLevel

By the end of this lesson you should know:

• The difference between prokaryotic and eukaryotic cells

PROKARYOTIC AND EUKARYOTIC PROKARYOTIC AND EUKARYOTIC CELLSCELLS

What have you learned?What have you learned?

Do you know….

• The difference between prokaryotic and eukaryotic cells?