Cell Structure and Microscope
The Microscope
Learning Objectives
By the end of this topic, you will be able to:
1. Identify the parts of a light microscope
2. Give the function of each part of the light microscope
3. Describe how to use a light microscope
4. Distinguish between the light and the Electron Microscope
5. Calculate magnification
There are 2 types of microscope
1. Light microscope 2. Electron microscope
Light Microscopes
a. The Eyepiece Lens is the lens that you look through.b. The objective lens is the lens that is immediately above the specimen.
1. Simple microscope: 1 lense2. Compound microscope: 2 lenses. These
are the microscopes used in our lab
Parts of the Microscope
Parts of the MicroscopePart Function
Lenses (eyepiece & objective)
Magnification
Stage To place the slide on
Clips Hold the slide in place
Diaphragm To control the amount of light reaching the object
Coarse Focus Knob To focus the image
Fine Focus Knob To precisely focus the image
Light source To supply light to the object
Nose piece Revolves to move desired lens into place
Stage height adjustment Allows longest lens to fit over slide
RememberMicroscope magnifications
Eyepiece lens Objective lens Total
X 5 X 10
X 10 X 40
True or False, if the eyepiece lens of a microscope is marked X10 and the objective lens is marked X4, the total magnification is X14
Exam Qs 2007 OL
Recording what you can see:
Onion Cells
Cheek Cells
Recording what you can see:
Nucleus
Animal CellCell
membrane
CytoplasmNucleus
Plant CellCell membrane
Cytoplasm
Nucleus
Cell wallNucleus
Vacuole
Chloroplast
How are we going to look at an animal cell?
Preparing Onion Slides
Now Fill out your workbooks
Recording what you can see:
Cheek Cells
Things outlined in black are probably air bubbles!Get us to help you if you can’t see!
Recording what you can see:
Animal CellCell
membrane
CytoplasmNucleus
What do all the bits do?What do the organelles do?•Nucleus
•Cell membrane•Cytoplasm•Chloroplast•Cell wall•Vacuole
Controls what happens in the cell (contains
DNA)
Jelly-like substance
where reactions happen
Keeps substances in the cell and
controls what goes in and
out
Contain chlorophyll –
where photosynthesis
happens
Contains cell sap – keeps the cell firm
Made of cellulose and supports the
cell
ELECTRON MICROSCOPE
Electron Microscope• Uses Electrons instead of light
• Resolution is much better
• Magnification is much greater
• Allows us to see the cell ultrastructure (organelles of the cell)
Images from Electron Microscope
Bacteria
Cytoplasm
Platelet
Learning CheckWhat is the function of each of these parts of the Microscope?
Eyepiece Lens Eyepiece Lens Objective LensObjective Lens
StageStage ClipsClips
DiaphragmDiaphragm Coarse Focus KnobCoarse Focus Knob
Fine focus KnobFine focus Knob Light Light
What have you learned?
Can you?
1. Name the parts of the microscope and their functions.
2. Outline the differences between the light microscope and the electron microscope
2004 OL(a)Name the parts of the light microscope
labelled A and B.
(b) Answer the following in relation to preparing a slide of stained plant cells and viewing them under the microscope.From what plant did you obtain the cells? Describe how you obtained a thin piece of a sample of the cellsWhat stain did you use for the cells on the slide?Describe how you applied this stain What did you do before placing the slide with the stained cells on the microscope platform?
7. (a)
A = eye piece B = objective or lens or high power(allow lens for A or B but not for both)X 400
22 2
(b) (i) name of plant 3
(ii)description – peel off thin film of plant tissue with forceps / cut thin section of plant tissue with blade (or microtome) or any other correct method i.e. How = 3 plus instrument = 3
2(3)
name of stain 3
application of stain – use dropper to place stain on tissue on slide or place tissue in stain or any other correct method.
3
put on cover slip or remove excess stain any one
3
cell wall/ chloroplasts or chlorophyll/ (large) vacuoles/ (starch) granules/ leucoplasts/ chromoplasts / shape any two
2(3)
Can you…..
1. Identify the parts of a light microscope
2.Give the function of each part of the light microscope
3.Describe how to use a light microscope
4.Distinguish between the light and the Electron Microscope
5.Calculate magnification
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Aidhm1. Identify the parts of a plant cell as seen under light
microscope
2. Identify the parts of an animal cell as seen under light microscope
3.Give the function of each of parts of a cell under light microscope
4. Identify the ultra structure and give the function of part of cell
6.Draw the ultra structure of the mitochondrion and the chloroplast
7.Definition of prokaryotic and eukaryotic cells (HL)
Anton von Leeuwenhoek
Anton von Leeuwenhoek with his hand-held microscope, was the first person to observe
and describe Living Cells in the early 17th century
Robert HookeRobert Hooke looked a thin slices of cork under a microscope.
He thought the spaces he saw reminded him of Monks Cells
Hence the name cells
Plant Cell as seen under a light microscope
Cells
• All living things are composed of one or more cells.
• Cells are the basic units of structure and function in an organism.
• Cells come only from reproduction of existing cells.
Organelles
• Cells contain ORGANELLES.
• An organelle has a SPECIFIC FUNCTION FOR THE CELL.
Organelles we need to know
• Cell membrane• Nucleus• Mitochondria• Chloroplast• Ribosomes• DNA• Cell Wall• Vacuole
Learning Check
What are Cells?
What are organelles?
Can you name 8 organelles?
Video Intro to animal cells
• https://www.youtube.com/watch?v=Fzj6TRnXmps&feature=player_embedded
Animal Cells
Animal Cells contain the following structures
Cell Membranes
Nucleus
Cytoplasm
Mitochondrian
Parts of nucleus
Ribosomes
can be seen under the light microscope
can be seen under electron microscope
• Protoplasm: All the living parts of the cell• Cytoplasm: The living parts outside the nucleus
Cell Membrane
Cell Membrane
Cell Membranes are made up of
phospholipids and proteins
The phospholipids and proteins are in constant motion.
Membranes are fluid.
Functions of Cell Membranes
• Separate the cell organelles and cytoplasm from the outside
• Semi permeable which means it only allows certain substances through the membrane. It allows movement of water by osmosis
• Support the cell
Cytoplasm
• Watery substance that contains all the organelles within the cell
Nucleus
•Contains DNA which make up genes. Genes are found on thread like structures called chromosomes
•Genes contain information to make proteins. Proteins control the function of the cell
Ultra Structure of The NucleusNuclear pore: Controls movement of substances into and out of nucleus
Chromatin contains DNA, arranged into chromosomes which are not dividing
Nucleolus contains RNA, DNA, and proteins. Makes Ribosomes
Ultra Structure of the Mitochondrion
Ultra Structure of the Mitochondrion
• Powerhouses of the cell
• Composed of inner and outer membranes
• Site of energy release (through respiration). Enzymes are attached to inner membrane. In respiration makes molecules of ATP (chemical energy)
• Cells with lots of mitochondria produce a lot of energy
Ribosomes: make proteins
Ribosomes
Ribosomes
• Each cell contains thousands
• Found in cytoplasm of cell
Use
To make proteins
Made from
Rna and Protein
A typical animal cell
The parts of a typical animal cell
Learning Check
1. All cells have a cell membrane. What are its 3 functions?
2. Label the picture
3. What is the function of
a ribosome?
4. What is the cytoplasm?
5. What is the function of the cytoplasm
Learning Check
What is this organelle?
Why are they known as powerhouses?
What type of cells would have these organelles in large numbers?
Plant Cells Plant Cells contain the following structures
can be seen under the light microscope
can be seen under electron microscope
Cell Membranes
Nucleus
Cytoplasm
Cell Wall
Vacuole
Chloroplasts
Mitochondrian
Parts of nucleus
Ribosomes
Parts of Chloroplasts
Ultra structure of an plant cellDraw
Cell wall
• Gives shape, support and strength
• Made of cellulose (structural polysaccharides)
• Fully permeable: allows all substances into and out of the cell
Vacuoles
• Provides support
• Stores water, salts, sugars/sap.
• Plant cells have large vacuoles
(Animal cells have either small or no vacuoles.)
Chloroplasts: The function of chloroplasts is photosynthesis. Contain
chlorophyll.
Ultra structure of the Chloroplast (draw)
• Have a double membrane• The membrane stacks (grana) contain the
chlorophyll which traps the sun’s energy• Have loops of DNA
A typical plant cell
The parts of a typical plant cell
http://www.youtube.com/watch?v=rABKB5aS2Zg&feature=related
Learning check
1. What organelle carries out
photosynthesis?
2. What type of cells have large vacuoles and
cell walls?
3. What is the function of vacuoles?
4. What is the function of cell walls?
5. What makes cells walls rigid?
Eukaryotes and Prokaryotes
Eukaryotes and Prokaryotes
• Prokaryotic cells: contain no true nucleus and no membrane-bound organelles. Found as bacteria
• Eukaryotic cells: contain a nucleus and other membrane-bound organelles. Found as plant and animal cells, fungi and amoeba
Comparing animal and plant cells
Can you….1. Identify the parts of a plant cell as seen under light microscope
2. Identify the parts of an animal cell as seen under light microscope
3. Give the function of each of the following parts: Cell wall, cell membrane, nucleus, cytoplasm, vacuole and chloroplast
4. Identify the ultra structure and give the function of each of the following cell parts: Cell membrane, mitochondrion, chloroplast,
nucleus, nuclear pores, ribosome and DNA
6. Draw the ultra structure of the mitochondrion and the chloroplast
7. Definition of prokaryotic and eukaryotic cells (HL)
END
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