1. The Microscope

2. Learning Objectives By the end of this topic, you will be able to:
Name the parts of the microscope and their functions.
Use the microscope to observe biological specimens
Know the difference between the light microscope and the electron microscope

3. Compound Microscopes
The microscopes used in our lab are called compound microscopes because they have two magnifying lens
a. The Eyepiece Lens is the lens that you look through.
b. The Objective lens is the lens that is immediately above the specimen.

4. The Objective Lenses There are three objective lenses:
- the scanning lens with the 4X label
- the low power lens with the 10X label
- the high power lens with the 40X label

5. Parts of the Microscope

6. Parts of the Microscope
Function
Lenses
Magnification
Stage
To place the slide on
Clips
Hold the slide in place
Diaphragm
To control the amount of light
Coarse Focus Knob
To focus the image
Fine Focus Knob
To precisely focus the image
Light
To supply light to the object

7. Learning Check Label the parts of the Microscope

8. Magnification Magnification =
the magnifying power of the eyepiece lens x
the magnifying power of the objective lens.
Example:
Eyepiece lens = 10X
Objective lens = 4X
Total magnification = 10 x 4= 40X

9. Focussing The Image
The course focus knob allows for dramatic or large movement of the objective lens.
The fine focus knob allows for very slight movement of the objective lens.

10. The Stage and the Diaphragm
The stage has two metal clips to hold the microscope slide in place.
The diaphragm allows light to be focused onto the specimen through a hole in the stage.

11. ELECTRON MICROSCOPE

12. Electron Microscope Uses Electrons instead of light
Electrons have much lower wavelength than light
Resolution is much better
Magnification is much greater

13. Images from Electron Microscope
Platelet
Bacteria
Cytplasm

14. Learning Check What is the function of each of these parts of the Microscope?
Eyepiece Lens Objective Lens
Stage Clips
Diaphragm Coarse Focus Knob
Fine focus Knob Light

15. What have you learned? Can you?
Name the parts of the microscope and their functions.
Use the microscope to observe biological specimens
Outline the differences between the light microscope and the electron microscope

16. The Cell
The CELL is the smallest unit of matter that can carry on all the PROCESSES OF LIFE.

17. 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

18. Robert Hooke
Robert 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

19. Plant Cell as seen under a light microscope

20. 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.

21. Organelles
Cells contain a variety of internal structures called ORGANELLES.
An organelle is a cell component that PERFORMS SPECIFIC FUNCTIONS FOR THE CELL.

22. Organelles we need to know
Cell membrane
Nucleus
Mitochondria
Chloroplast
Ribosomes
DNA
Cell Wall
Vacuole

23. Can you name 8 organelles?
Learning Check
What are Cells?
What are organelles?
Can you name 8 organelles?

24. Animal Cells Animal Cells contain the following structures
Cell Membranes
Mitochondria
Nucleus
Cytoplasm
Only the cell membrane, the cytoplasm and the nucleus can be seen under the light microscope.

25. Cell Membrane Cell Membranes are made up of phospholipids and proteins
The phospholipids and proteins are in constant motion.
Membranes are said to be fluid

26. Functions of Cell Membranes
Separate the cell organelles and cytoplasm from the outside
Semi permeable - allows some molecules freely into and out and others to enter
Membranes give some support to the cell
Membranes recognise molecules that touch them

27. Learning Check All cells have a cell membrane.
All cells have a cell membrane.
What are its 3 functions?
      ___________________________________

28. Nucleus A large organelle near the center of the cell is the NUCLEUS.
It contains the cell's genetic information
It controls the activities of the cell.

29. Eukaryotes and Prokaryotes
Organisms whose cell contain a nucleus and other membrane-bound organelles are called eukaryotes.
Organisms whose cells never contain (or lack) a nucleus and other membrane-bound organelles are called prokaryotes.

30. Ultra Structure of The Nucleus

31. What’s in a nucleus
The nucleus is made up of a double membrane with numerous nuclear pores.
These control the movement of substances into and out of the nucleus
A nucleolus which contains RNA, DNA, and Proteins and it makes Ribosomes
Chromatin which contains DNA that is arranged into chromosomes which stores our genes

32. Fill in the blanks
The control center of the cell is called the ______.
It is enclosed by a double membrane called the ___________ __________________.
Openings in the nuclear envelope called __________ allow for movement of substances in and out of the nucleus
Structures inside the nucleus that contain DNA and proteins are called _____________.  
Since DNA cannot leave the nucleus, genetic information is copied into molecules of __________ and sent out into the cytoplasm. This information is used to manufacture ________________.

33. Mitochondria
Mitochondria supply energy to the cell in a process known as respiration
Cells with lots of mitochondria produce a lot of energy
The inner membranes of the mitochondria produce the energy

34. Mitochondrion
The more folds a mitochondrion has the more energy it produces

35. Learning Check Label the diagram What is this organelle?
Why are they known as powerhouses?
What type of cells would have these organelles in large numbers?

36. Ribosomes Ribosomes can be seen as red dots in this cell
Their function is to make proteins by joining amino acids together.
They are composed of rRNA and protein

37. Cytoplasm Cytoplasm is a clear jelly like fluid that fills the cell
ALL the organelles (excluding the nucleus) within the cell are considered the cytoplasm
It gives shape and support to
the cell
- Suspends all organelle

38. Learning Check What is the function of a ribosome?
What is the cytoplasm?
What is the function of the cytoplasm?

39. Ultra Structure of an animal cell

40. Plant Cells
Plant cells contain other organelles besides the ones in the animal cell
Cell walls
Chloroplasts
Large Vacuoles
*Animal cells do not contain these structures

41. The function of chloroplasts is Photosynthesis

42. Ultra structure of the Chloroplast
The chloroplast contain the chlorophyll which traps the sun’s energy

43. Cell wall
The cell wall is rigid and gives plant cells a very defined shape.
The cell wall is composed of cellulose fiber, polysaccharides, and proteins.
The function of the cell wall is to support and strengthen the cell

44. Vacuoles
Vacuoles are membrane-bound sacs within the cytoplasm of a cell
Vacuoles provide structural support, as well as serving functions such as storage, waste disposal, protection, and growth.
Plant cells have large vacuoles

45. Ultra structure of an plant cell

46. Learning check What organelle carries out photosynthesis?
What type of cells have large vacuoles and cell walls?
What is the function of vacuoles?
What is the function of cell walls?
What makes cells walls rigid?