Endoplasmic reticulum (ER)

General Structure
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System of interconnected folded membranes (cisternae)
forming a maze of enclosed spaces
Largest internal membrane
General function
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Used as intracellular highway!
Molecules move through the cell by the ER
All those folds create channels and connections for molecules
to move
Two types of ER
Rough ER
Smooth ER
Structure
• Has ribosomes
attached to it
• Looks pebbly
• No ribosomes
attached to it
• Smooth surface
Function
Ribosomes here are
the site of protein
synthesis for proteins
leaving the cell
Also stores and
regulates protein
levels, detoxifies
drugs/alcohol, site of
lipid synthesis rxns
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Location:
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Continuous with nuclear membrane
Expands from the nuclear membrane through the cytoplasm
Takes of a large part of the cytoplasm
Both plant and animal cells

Rough ER
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Pancreatic cells have large amount
Smooth ER

Liver cells have large amount
ER
ER
Golgi apparatus
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Structure
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Function
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Flattened folded membrane sacs
Has vesicles fusing with/budding from it
Processing, packaging, secreting
Used to activate proteins (make them functional!) or alter
lipids
Location

Both plant and animal cells
Golgi apparatus
How do proteins get from the
ribosomes to the outside of the cell?

Production line model:
1. Proteins leaving the cell are made at the ribosomes bound to
the ER (dehydration synthesis!)
2. They are released into the internal compartment of the RER.
3. They are transported through the ER in vesicles to the
receiving end of the Golgi
4. They are modified and packaged by the Golgi.
5. They leave from the migrating end of the Golgi in vesicles.
6. The vesicles fuse with the cell membrane.
7. The contents are released externally by exocytosis.
Ribosomes

Structure

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RNA and proteins
2 subunits – made separately in nucleolus and move into
cytoplasm through nuclear pores where they are put together
Do not have membrane (so they’re found in prokaryotes, too)
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Function (general)
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Site of protein synthesis (where a.a. are linked together in
dehydration synthesis)
Location
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Both plant and animal cells, most numerous structure
Free ribosomes – floating in cytoplasm
Bound ribosomes – attached to ER
2 types of ribosomes and their functions:


Free = makes proteins that will be used by that cell
Bound = makes proteins that will be exported out of the
cell to another cell
Ribosomes are not surrounded by a phospholipid
bilayer (membrane); therefore, they are found in
prokaryotic cells, too!!!
Mitochondria

Structure

Bean shaped organelle made of an internal and external
membrane

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Outer membrane = smooth, protects mitochondria
Cristae = folded surfaces of inner membrane; area where most
ATP is made; folds ↑ S.A. so more surface for chemical rxns
Mitochondria have their own DNA! It’s a circular piece
of DNA like prokaryotes have (evidence supporting
endosymbiotic theory)
Mitochondria

Function
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Site of cellular respiration (energy is made in the form of ATP)
Remember… ATP is chemical energy for the cell and this
energy will drive all cellular reactions
Which cells will contain a lot of
mitochondria?

Location

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Both plant and animal cells
Highly active cells need lots of mitochondria because they
need a lot of energy

Muscle cells
Picture
Lysosome

Location


Structure

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ANIMAL cells ONLY
Spherical, membrane bound
Bud from Golgi
Function
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Contain digestive enzymes and can digest ALL organic molecules
Can digest food particles, microorganisms (bacteria), damaged or
worn out cells or organelles
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Autophagy = digests worn out organelles
Autolysis = destroys own cell
Interesting fact:You have separate fingers and toes because of
lysosomes during embryonic development!
Cilia / Flagella
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Location
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ANIMAL cells
Extend from surface of cell
Function

Assist in movement (either of cell itself or to move substances
in the organism)
Differences? Fill in the T chart under
picture.
Cilia
Flagella
-short
-hair-like
-numerous
-long
-whip-like
-usually one or a
few
Internal composition?

Made up of an arrangement of microtubules in a 9+2
arrangement
Basal bodies

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Anchor cilia/flagella to cell; organize development of
cilia/flagella
Located just below surface of cell