Topic 3- Cells & Tools Used in the Lab

What is the difference between a theory and a law? Theory- Not definite or proven, but is backed by scientific evidence. Law- Definite, proven and is supported by scientific evidence.

Cell Theory: (3 parts) All living things are composed of cells. 1. Cells are the basic unit of structure. 2. Cells are the basic unit of function. 3. Cells come from pre-existing cells MITOSIS

Levels of Organization Organelle: part of the cell Cell: basic unit of living things Tissue: made of a group of cells Organ: made of several tissues Organ System: composed of a group of organs Organism: a living thing

Levels of Organization

Cell Models: An Interactive Animation

Animal Cell

Plant Cell

Cell Organelles (Parts of the Cell) Organelles Common to BOTH Animal & Plant Cells:

1. Cell/Plasma Membrane: 1. surrounds all cells 2. regulates what goes into and out of the cell - semipermeable

The Cell Membrane is labled A in both pictures

2. Nucleus: (contains DNA/RNA) Controls the functions of the cell. It has a membrane of its own (nuclear membrane). [Brain] Letter B - Nucleus

Found within the nucleus. Allows RNA to enter the cell. 3. Nucleolus: Found within the nucleus. Allows RNA to enter the cell. Dark circle w/in B - nucleolus

4. Cytoplasm: Jelly-like fluid containing other organelles It moves in a circular motion- CYCLOSIS.

5. Endoplasmic Reticulum E.R. : Channels - Aids in transport. Can be smooth or rough Rough- contains Ribosomes

Letter B - is the Endoplasmic Reticulum

6. Ribosomes: Site of protein synthesis. Can be free or attached to the E.R. Letter C - Ribosomes

7. Mitochondria: Site of cellular respiration  ATP=ENERGY. [Powerhouse]

8. Golgi Bodies/Apparatus/Complex: Stacks of flattened tubes that package wastes in the cell. [Garbage Men]

9. Vacuoles: STORAGE Holds water or food. LARGE in a plant cell. small in an animal cell. [Storage Bin] Vacuole Letter A - Vacuole

Organelles only in ANIMAL CELLS: Lysosomes: Digests food or old, worn out parts of the cell. “Suicide Sacs” Centrioles: Aids in cell division. Come in pairs.

Organelles only in PLANT CELLS: Chloroplasts: Contains chlorophyll traps light and allows plants to make food  PHOTOSYNTHESIS Cell Wall: Non-living structure that supports and protects the cell. Composed of cellulose.

Letter C – Cell Wall Letter B – Chloroplasts - Photosynthesis

Tools & Techniques Used In the Lab:

Microscopes Image is upside down & backwards. If you need to center a specimen, move the slide in the opposite direction.

Types of Microscopes Compound Light Microscope: 2 sets of lenses (ocular & objective) Specimens must be thin & transparent

Compound Microscope

Total Magnification Eye piece x Objective lens = Total Magnification

Calculating Total Magnification What is the total magnification under low power? 10 * 15 = 150x What is the total magnification under high power? 10 * 45 = 450x

Focusing: Put slide on stage Turn to low power obj. Use coarse adj. knob to focus Turn to high power Use fine adj. knob to focus * Never use coarse adj. knob under high power  you could crack the slide

Move decimal point 3 places to the RIGHT Microscope Measurement- The unit of measurement used with the microscope is the micron (um). 1mm=1,000 um 1. When converting mm  um Move decimal point 3 places to the RIGHT 5mm=5,000 um 2. When converting um  mm Move decimal point 3 places to the LEFT 9,000um=9mm

Which neuron is the longest? How long is one cell in Micrometers?

In um, approximately how long is the paramecium?

Field of View- When you look in the ocular, it is the view you see. HIGH POWER FOV is 4x smaller than low power FOV. You will see less cells, but more detail. High power is darker than low power. LOW POWER FOV is 4x LARGER than high power FOV. You will see more cells, but less detail. Low power is brighter than high power.

Field of View (FOV)

Microscope Measurements: Q: If you can see 20 cells under low power FOV, how many will you see under high power FOV? LOW POWER  HIGH POWER ( / 4) 20 / 4 = 5 cells under High power Q. If you can see 2 cells under high power FOV, how many will you see under low power FOV? HIGH POWER  LOW POWER (X 4) 2 x 4 = 8 cells under Low power

More Tools & Techniques Used in the Lab: 1. Stereomicroscope/ Binocular / Dissecting Microscope: 2 eyepieces look at opaque objects

2. Electron Microscope - uses beams of electrons and magnets - specimens thin and dead - view inside mitochondria or ribosomes - extremely powerful

Microdissection Instruments: Dissection of cells Can be used to transplant a nucleus from one cell to another

Stains: Makes organelles more visible Iodine- yellow stain Methylene Blue (vital/living) - blue stain

Centrifuge: Spins contents at a high speed Separates contents by density Heaviest- bottom Lightest- top

Chromatography: Separates pigments/colors at different rates

Gel Electrophoresis: Used to separate substances that have an electrical charge Substance is cut using an enzyme Substances are placed into wells located at the top of the gel Substances separated based on their size and charge Small particles travel further through the gel, large particles do not Can be used to separate fragments of DNA

Gel electrophoresis