introduction to cells and the microscope. brief history of cells… 1665 hooke sees “cells” in...

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.

Cytoskeleton

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!