introduction to cells and the microscope. brief history of cells… 1665 hooke sees “cells” in...
TRANSCRIPT
Introduction to Cells and the Microscope
Brief history of cells…
1665 Hooke sees “cells” in cork
1674 Van Leeuwenhoek observes living cells in water
1838 Schleiden theorizes all plants are made up of cells
Early Microscopes
1839 Schwann theorizes all animals are made up of cells
1855 Virchow theorizes all cells are “born” from other cells
Cell theory completed…
STOP HERE
The Cell Theory
1. All living things are composed of cells.
2. Cells are basic units of structure & function in living things 3. Cells come from preexisting cells.
The Microscope = produces enlarged image with detail
• Magnification = increase in object's size
• Led to the discovery of cells
• Resolution = power to show clear detail
Compound Light Microscope - light passes through specimen; magnifies up to ~400 times
Advantages: inexpensive; specimens alive or dead
Disadvantages: not powerful; poor resolution
Transmission
Scanning
Cell Diversity
• Cells vary in:
1. Size
2. Shape
3. Internal organization
1. Size – surface area-to-volume ratio keeps cells small
• As cells grow, volume increases faster than surface area
• If cell continued to grow, it would burst
2. Shape – reflects function of cell
Ex: nerve cells, red blood cells
3. Internal Organization • Organelle = cell component that performs a specific function for the cell
Types of Cells:
“Pro”= before; “kary”= nucleusa. DNA, ribosomes, cytoplasm & cell membrane
1.Prokaryote – simple cells (no nucleus or membrane-bound organelles)
b. unicellular (bacteria)
2.Eukaryote – complex cells “Eu”= true; “kary”= nucleus a. has nucleus & membrane bound organelles
c. Two types of eukaryotes:
1) Animal2) Plant
b. unicellular or multicellular
Eukaryotic Cell Structures
• Organelle = cell component that performs a specific function for the cell
2. Cytoplasm – space within cell
a. gel-like fluid that suspends organelles
a. STRUCTURE: Bilayer (2 layers) of PHOSPHOLIPIDS
1. Cell (plasma) Membrane = thin layer surrounding cell
Outsideof cell
Insideof cell(cytoplasm)
Cellmembrane
Proteins
Proteinchannel
Lipid bilayer
Carbohydratechains
3. Nucleus – controls all activities of cell
Three major parts:a. Nuclear membrane/ envelope = allows certain materials into & out of nucleus through pores
c. DNA (chromatin) – hereditary info.
b. Nucleolus = makes ribosomes
4. Mitochondria – makes ENERGY (ATP) for cell
b. Inner, folded membrane = CRISTAE
a. Has its own DNA
5. Ribosomes – makes PROTEINS (directed by nucleus)
a. free floating in cytoplasm
b. attached to endoplasmic reticulum
6. Endoplasmic Reticulum (ER) – TRANSPORT materials from ribosomes to Golgi complex
a. Rough ER = ribosomes attached; transports PROTEINS
b. Smooth ER = no ribosomes; makes & transports LIPIDS
7. Golgi apparatus (bodies) – MODIFIES, PACKAGES & SECRETES PROTEINS to inside & outside of cell
a. packages proteins into VESICLES [small bubbles]
8. Lysosomes –BREAK DOWN wastes, food & old cell parts using enzymes
9. Cilia – short hair-like projections for MOVEMENT
10. Flagella – long, whip-like structure for MOVEMENT
11. Vacuoles – fluid-filled pouch that STORES water, food & some wastes
a. very LARGE in PLANT Cells; small in animal cells
12. Cell wall – rigid structure outside cell membrane for STRUCTURE, SUPPORT & PROTECTION
a. made of CELLULOSE
b. Only in PLANT cells
13. Chloroplast – converts LIGHT energy to CHEMICAL energy (photosynthesis)
a. contain CHLOROPHYLL [pigment that captures light]
b. Only in PLANT cells
14. Centrioles –make spindle fibers in cell division
a. only in ANIMAL cells
15. Cytoskeleton – protein filaments that helps a cell MAINTAIN ITS’ SHAPE.
a. Acts as the skeleton for a cell.
b. Made from microfilaments and microtubules.
Organelle Poster
** Get in to groups of 2 or 3** Pick an organelle** Grab a poster and supplies** YOU CAN ONLY USE 5 WORDS ON YOUR POSTER!!!** Describe your organelle on your poster with SKETCHES or SYMBOLS
Poster Presentation• You will get about 5 mins to rehearse what you will
say in your 2 min presentation• EVERY student MUST participate to get full credit!• Questions to answer for the presentation:
• What is my organelle?• What is the function of my organelle?• How do my sketches describe the function of my organelle?• How can I describe the function of my organelle in a way
that the class will remember it for the quiz?• Does my organelle work with other organelles in the cell?
Quiz Tomorrow!!!
Ask yourself this…• Can I label the structures and functions of a
compound microscope?• Will I be able to describe the early history of cells and
microscopes from the notes?• Do I understand the Cell Theory?• Can I describe the function of ALL the organelles we
discussed in class?• IF YES…THEN YOU WILL DO GREAT!