- Slides: 23
Cell Structure The Microscope
Introduction - Microscope l l Discovery of Micro-organisms Allows us to look at cells Has lead to discoveries in many diseases Cytology - the study of cells Light Microscope Electron Microscope Beams of Light Beams of electrons X 1500 X 500, 000
The Light Microscope You Must be able to label a microscope & state its functions
Functions of Microscope l l l l Eyepiece lens - magnifies the image Course adjustment - rough adjustment Fine adjustment - precise focusing Nosepiece - revolves lens into position Objective lens - magnifies image Stage - holds the slide Light source - sends light through the slide Clips - hold the slide in place
Basic Cell Structure Plant or Animal Cells? ? ?
Cell Ultra – Structure (Animal)
Cell Ultra – Structure (Plant)
Cell Membrane Phospholipids and proteins bi-layer FUNCTIONS: • Controls movement of substances in & out of cell. • Production of anti-bodies • Support • Structure
Cell Wall l l Only found in plant cells. Made by the cytoplasm. Made of cellulose Fully Permeable Middle Lamella: Functions 1. Support 2. Protection • A chemical material which 'glues' plant cells together. • It is produced during cell division.
The Nucleus The nucleus is the control centre of the cell. Structure l Nuclear membrane l Nuclear pores l Nucleoli - manufacture proteins l Chromosomes/chromatin
The Nucleus The nucleus is the control centre of the cell. Functions l Cell division - mitosis/meiosis l Protein synthesis l Controls activities of the cell
Mitochondria • Most are found in active cells like muscle cells, nerve cells etc… matrix • Used in plant and animal cells for respiration. cristae • Produces a large number of enzymes.
Chloroplasts • Only found in plant cells • Contain pigment chlorophyll • Used during photosynthesis to absorb sunlight
Ribosomes l l l Produced by the nucleolus in the nucleus. Tiny, but very numerous. Either floating freely in cytoplasm or attached to endoplasmic reticulum. Protein synthesis. Sometimes they may be attached together in a group called a 'polysome'.
Centrioles l l Mainly found in animal cells. Occur in pairs near the nucleus. Function l Cell division
Vacuole l l Mainly in plant cells. Found in some animal cells such as Amoeba. Controls the water content of the cell. Contains food/excretory products (sap)
Endoplasmic Reticulum l l A network of canals in the cells which serves as a transport system. Store food materials such as proteins, fats, carbohydrates, vitamins and minerals. Sometimes there are ribosomes attached to the outside of the E. R. - these are called Rough Endoplasmic Reticulum. When there are no ribosomes attached they are called Smooth Endoplasmic Reticulum.
Golgi Apparatus: l l Sometimes called Golgi Bodies. Functions are bile production, mucous and synovial fluid secretion, eye pigment, enamel, keratin (nails and hair protein) and the production of cell membranes
Differences in Plant & Animal Cells Plants Animals Cell Walls No Cell Walls Chloroplasts No chloroplasts Chlorophyll No chlorophyll Large Vacuoles Small (if any) vacuoles
Prokaryotic and Eukaryotic Cells Eukaryotic cells l cells that contain a nucleus bound by a nuclear membrane. l They also contain many membrane bound structures called organelles.
Prokaryotic and Eukaryotic Cells Prokaryotic cells l l l Cells that do not have a nucleus bound by a nuclear membrane. Instead of having DNA fixed on chromosomes their genetic information is on a circular loop called a plasmid. Example - bacteria cell.
Mandatory Experiments To prepare an examine a plant cell, stained & unstained using a light microscope a. Plant cell – onion, get the thin epidermis between layers of the onion to allow light pass through b. Stain – iodine, shows up membranes c. Apply cover slip at an angle to prevent air bubbles d. Start the procedure at low power to find the cell and prevent damage to the microscope e. Be able to draw the results
Mandatory Experiments To prepare and examine an animal cell using a light microscope a. b. c. d. e. f. Animal cell – cheek cell Spread the cells out thinly to allow the light to pass though Dye – methylene blue, stains the nucleus dark blue Apply cover-slip at an angle to prevent air bubbles Start with low objective lens Use fine focus on the high power to prevent damage to the microscope g. Be able to draw results