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Matter 6: Cytology & Endomembrane System
Transcript of Matter 6: Cytology & Endomembrane System
The Endomembrane System
Dead White Men Who Discovered (and were made of) Cells:
The Wide World of Cells:
Discovery of Cells (1600's)
Anton van Leeuwenhoek
First person to look at biological material under a high powered (~100X) microscope
Coined the term "cells" to describe the appearance of cork under a microscope
...These are not the only 2 contributions
: The study of cells
All living things are made of cells
The cell is the basic unit of life
All cells come from pre-existing cells
Maximum Magnification- 1000X
Maximum Resolution- 10 micrometers (um)
Types of light microscopy:
Maximum Magnification- 10,000,000X
Maximum Resolution- 20 nanometers (nm)
Types of electron microscopy:
A way to isolate different components of cells for detailed study
What are the benefits & problems of the 2 different kinds of microscopy?
There are physical constraints on cell size:
Too small: Can't fit all the stuff inside
Too big: Can't exchange matter with the environment efficiently.
Cells exist in the 10 um - 1 mm size range.
"simpler" (no membrane bound organelles)
smaller (typically 10-100 um)
Much more abundant
lots of membrane bound organelles.
larger (100 um - 1mm)
2 major types
You Need To!
The Utility of Membrane-Bound Organelles
By enclosing parts of the cell in membrane, eukaryotic cells are able to SPECIALIZE!
Membranes isolate different areas of the cell, which allows the cell to have varied conditions in different regions (different pH, concentrations of different molecules, etc.)
Membranes also provide surface for various reactions (Respiration and Photosynthesis, for instance).
The specialization of cellular regions is what makes eukaryotic cells so much more complex than prokaryotic cells.
Specialization is also a prerequisite for multicellular life (why?)
So many compartments = So many options
The Life of the Cell
All cells must do the following things to stay alive:
Process matter: Molecules need to be acquired, synthesized and digested
Process energy: In order to process matter, energy must be provided. This energy usually comes from one of two places (where?)
Process information: The instructions that enable the cell to process matter and energy must be interpreted by the cellular system. Signals from the environment must also be interpreted.
Many cells will also do the following :
Reproduce: The information that runs the cell must be passed on to new generations of cells.
Communicate: Cells respond to/direct other cells.
Cells have systems to do all of these things!
2 Major Points
The Endomembrane System
Proteins are the molecules that a cell uses to do most of its work.
Here is a brief list of things that proteins do:
Carry out chemical reactions
Copy DNA & RNA
Receive and send messages to the environment/other cells
Receive and send messages to other cells
We have previously discussed protein structure.
The instructions to build proteins are stored in DNA (we can call them "
An overview of eukaryotic protein synthesis
Structure: a double membrane, with protein pore channels
Function: site of DNA storage and replication, information relay to ribosomes
flourescence image showing nuclei (yellow)
Structure: a complex of RNA and protein. 2 subunits ("large" & "small"). Eukaryotic ribosomes are larger than prokaryotic ribosomes.
Function: site of protein synthesis, using an RNA transcript of a gene
The nucleolus is the region of the nucleus where ribosomal RNA genes are concentrated.
It can be seen under magnification as a dark spot on the nucleus.
How eukaryotic cells send proteins from ribosomes to their particular destinations
2 Kinds of Ribosomes
floating in cytoplasm
make proteins that stay in the cytoplasm
Attached to Endoplasmic Reticulum ("ER")
make proteins that go into membranes, or are exported from the cell.
Ribosomes become free/bound based on the protein they are making
Structure: a network of membrane channels attached to the nuclear membrane.
rough: closest to nucleus, covered in bound ribosomes
free: farther from nucleus, no bound ribosomes
Function: Rough ER compartmentalizes the cell, provides structural support, & targeted protein synthesis. Smooth ER synthesizes lipids for the cell (for things like membrane), detoxifies compounds, breaks down glycogen.
Structure: A small compartment surrounded by membrane
Function: Various, depending on the contents.
Structure: A series of flattened, mebrane-bound sacs
Function: synthesis, modification & packaging of molecules
Structure: a phospholipid bilayer with embedded proteins.
Function: Controls transport of matter into and out of cell.
Receives/Sends messages with environment.
The Endomembrane System
Why does life require cells?
How are cells organized?
What is the advantage to having organelles?
How do the interactions of cellular components allow for life processes?
Explain the cell theory
Compare different types of microscopy.
Explain why there are no giant cells around.
Refine your contrast of prokaryotic and eukaryotic cells.
Relate the structure and function of the organelles in this presentation.
Explain the interactions of the organelles in this presentation.
Explain how the organelles in this presentation provide for essential life processes.
Make Sure You Can: