The Endomembrane System

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The Endomembrane System

• Do Now 11/9
• Take out homework ?
• What are the 4 levels of protein structure?

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General Cell Terminology

• Everything between the nucleus and the cell
  membrane is called CYTOPLASM.
• CYTOPLASM is
• All of the organelles like mitochondria, etc.
• The CYTOSOL, which is the aqueous solution
  everything else floats around in

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I. The Nucleus
The nucleus is a small sphere that holds all of a
cells DNA.
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The nucleus is surrounded by a lipid membrane
called the nuclear envelope, which is very
similar to the cell membrane. It has openings
called nuclear pores that allow things in and out
of the nucleus.
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Most of the inside of a nucleus is made up of
chromatin, which is a mix of DNA and certain
proteins.
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The nucleolus is a small dark part inside a
nucleus where ribosomes are made.
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II. The Endomembrane system

• The endomembrane system is a series of folded
  lipid membranes where protein production takes
  place. It includes
• The nuclear envelope
• The rough and smooth endoplasmic reticulum
• The Golgi bodies
• vesicles
• PROKARYOTES have NO INTERNAL MEMBRANES. Protein
  production occurs in the cytoplasm

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The Endoplasmic Reticulum

• Structure The endoplasmic reticulum is a large
  series of folded membranes attached to the
  outside of the nucleus.
• Function Nucleic acids and proteins travel
  through the tubes and folds during the process of
  protein production.

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Two Parts of the ER

• The first part has RIBOSOMES attached to it, and
  is therefore called the ROUGH endoplasmic
  reticulum
• The second part has no ribosomes and is called
  the SMOOTH ER.

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About those SUPER IMPORTANT ribosomes

• Very important function
• RIBOSOMES MAKE PROTEINS!
• Structure
• Two pieces of RNA stuck together

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More on Ribosomes in the Future

• Well learn more about how ribosomes make
  proteins when we study molecular genetics. The
  ribiosome basics
• Made of rRNA
• thousands per cell.
• Use the information in mRNA to build a
  polypeptide from amino acids.
• Found in all cell types.

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Do Now 11/29 Protein Production

• Copy and complete the list of the steps
  eukaryotic cells go through to make protein,
  including the organelles involved. (use
  flowchart!). NOTE Leave 5-7 blank for now.
• DNA in the nucleus stores instructions for
  building proteins.
• Lipids and other substances are produced in the
  smooth ER.
• Active proteins arrive at their final locations,
  ready to work.

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Rough then Smooth

• The rough ER is where polypeptides are built.
• The smooth ER has several functions
• Most importantly
• Lipid synthesis (for membranes)
• Home to many enzymes.

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Golgi

• Structure folded membranes
• Function Proteins are finished
• folded into correct conformations quarternary
  structures
• Modified chemically
• Addition of chemical groups (e.g. heme in
  hemoglobin, etc.)
• Modified amino acids
• label proteins so they get delivered to the right
  places.
• What might they be labeled with?

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Smooth Endoplasmic Reticulum
Amino Acids
Transport Vesicle
Mito- chondria
Rough Endoplasmic Reticulum
Golgi Apparatus
mRNA
Ribosome
Outgoing Transport Vesicles
Nucleus (DNA)
Lysosome