CELL STRUCTURE

Lesson 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.

MICROSCOPES 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 MICROSCOPE EYEPIECE LENS COARSE ADJUSTMENT FINE ADJUSTMENT CLIP STAGE HEIGHT ADJUSTMENT NOSEPIECE OBJECTIVE LENS STAGE DIAPHRAGM LEVER CONDENSER MIRROR OR LIGHT SOURCE

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? 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 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 MICROSCOPE CELL (PLASMA) MEMBRANE PROTOPLASM NUCLEUS CYTOPLASM

PLANT CELL AS SEEN UNDER A LIGHT MICROSCOPE NUCLEUS VACUOLE CHLOROPLASTS CELL MEMBRANE CELL WALL CYTOPLASM

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

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 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 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 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 MEMBRANE

FUNCTIONS OF 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

NUCLEUS NUCLEOLUS CHROMATIN NETWORK NUCLEAR PORES NUCLEAR ENVELOPE

FUNCTIONS 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 nucleus NUCLEAR ENVELOPE CHROMATIN NETWORK NUCLEAR PORE NUCLEOLUS

THE NUCLEOLUS This is an area in the nucleus which stains very darkly This is where ribosomes are made

CYTOPLASM The cytoplasm is the liquid inside cells Contains a number of small bodies called organelles Many chemical reactions take place here

MITOCHONDRIA 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 MITOCHONDRIA

INNER MEMBRANE OUTER MEMBRANE CRISTAE MATRIX Photomicrograph of liver cell mitochondria

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

CHLOROPLASTS CHLOROPLAST DNA STARCH GRAIN INNER MEMBRANE OUTER MEMBRANE THYLAKOID GRANASTROMA

Photomicrograph of guard cell mitochondria STROMA INNER MEMBRANE OUTER MEMBRANE STARCH GRAIN THYLAKOID GRANA

Ribosomes Very small organelles Protein synthesis

CELL ULTRASTRUCTURE WITH REFERENCE TO A GENERALISED PLANT CELL NUCLEAR PORE CHROMATIN (DNA) NUCLEAR MEMBRANE MITOCHONDRION CELL WALL CELL MEMBRANE CYTOPLASM VACUOLE RIBOSOMES CHLOROPLAST

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 Level By the end of this lesson you should know: The difference between prokaryotic and eukaryotic cells

PROKARYOTIC AND EUKARYOTIC CELLS

What have you learned? Do you know…. The difference between prokaryotic and eukaryotic cells?