CHAPTER 6 - CELLS Section 6.1 & 6.2. Importance of cells An organism’s basic unit of structure &...
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Transcript of CHAPTER 6 - CELLS Section 6.1 & 6.2. Importance of cells An organism’s basic unit of structure &...
CHAPTER 6 - CELLS
Section 6.1 & 6.2
Importance of cells
An organism’s basic unit of structure & function is the cell
Everything we do occurs fundamentally at the cellular level Thinking Moving Maintaining homeostasis
Cells discovered by Robert Hooke in 1665
Studying Cells
How do we understand cells if we can’t see them?
Microscopes allow us to see the inner workings of cells
Two main types of Microscopes Light Microscope (LM) – 1665-present Electron Microscope (EM) – 1950’s-present
Light Microscopes
Allow us to see plant & animal cells and the nucleus.
Can also see bacteria cells. Light passes through the specimen and
lenses, bends the light to magnify the image.
Magnification: ratio of an object’s image to its real size (max. about 1,000x)
Resolution: measure of the clarity of the image (max. about 200nm – size of bacteria)
Electron Microscopes
Rapidly advance our understanding of cells because we could see subcellular structures
Focuses a beam of electrons through the specimen
Two types: Scanning electron microscope (SEM)
Gives a 3D image of the surface of the specimen Transmission electron microscope (TEM)
Used to study internal stux – gives a cross section
Advantages & Disadvantages Light Microscopes
Advantage: Can study living organisms Disadvantage: Can’t see organelles in
detail Electron Microscopes
Advantage: Can see organelles in detail Disadvantage: Specimens are killed in
preparation process (not for living tissues)
Cell Fractionation
Goal: take cells apart and separate the major organelles from one another
Process: Centrifuge spins test tubes at various
speeds Cell components separate by size and
density Result:
Bulk quantity of cellular organelles to study composition and function
Section 6.2
Two types of cells Prokaryotic found in Domain _______ & _______ Eukaryotic found in Domain _______
What 4 Kingdoms contain organisms with Eukaryotic cells?
1. Animal 2. Plant 3. Protist 4. Fungi
Similarities & Differences
All Cells contain: Plasma membrane made up of a __________
Phospholipid bilayer Cytosol (cytoplasm) DNA Ribosomes
Differences: Eukaryotic cells contain membrane bound
organelles and the DNA is contained in the nucleus.
Prokaryotic cells:
DNA located in nucleoid region Prefix: pro means “before” Suffix: karyon means “kernel” (nucleus) No membrane bound organelles in
cytoplasm Smaller & simpler Cilia and flagella for locomotion Some have cell wall surrounding plasma
membrane
Prokaryotic cells
Cell Size
Cellular metabolism sets a limit on how large a cell can get
The cell needs to bring in oxygen & nutrients and needs to get rid of waste
Cell needs to maintain a high surface area to volume ratio to exchange the materials it needs to
Larger organisms do not have larger cells just more of them (we have trillions of cells!)
Surface area to volume ratio
Plasma membrane
Eukaryotic cells
Contain membrane bound organelles Larger than prokaryotic cells and more
complex Animal & Plant cells Draw a diagram of an animal and a plant
cell