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Notes Chap 3, Sect 3
Organelle – specialized structures within the cell
The following organelles are found in both plant and animal cells:
Nucleus – controls most of the cell functions
Nuclear envelope / nuclear membrane – double layer (2 lipid bilayers)
Nuclear pores – small channels scattered over/through membrane
Substance made in nucleus pass through these
Nucleolus – ribosomes partially assembled here
DNA: contains hereditary information; stored in nucleus
(eukaryotic DNA wound tightly around proteins)
Ribosomes – proteins made on these
Made up of dozens of different proteins and RNA
There are free ribosomes floating in the cytosol. TRUE or FALSE
Endoplasmic Reticulum (ER) – extensive system of internal membranes that move substances
through the cell
Membrane: made of lipid bilayer with embedded proteins
(just like cell membrane)
Rough ER – has ribosomes attached
helps transport proteins made by its ribosomes
Smooth ER – no ribosomes attached
makes lipids & breaks down toxic substances
Vesicle – small, membrane bound sac
ER pinches off part with completed proteins
Golgi apparatus – flattened, membrane bound sacs; packing and distribution center of cell
Receives and modifies proteins (enzymes inside GA help)
Lysosomes – help breakdown – small organelles that contain digestive enzymes
What 3 things work together to process proteins?
Vesicles, golgi apparatus & lysosomes
Steps for processing of proteins:
1. Proteins from ribosomes are packaged into vesicles.
2. Vesicles transport proteins from rough ER to golgi apparatus.
3. In golgi apparatus, proteins are modified, processed and repackaged in new vesicles.
4. some vesicles move to cell membrane and release contents outside of cell.
5. some vesicles remain and become lysosomes to digest and recycle the cell’s unused
components – break down proteins, carbohydrates and lipids.
Mitochondria – known as the “powerhouse” of the cell
Harvest energy from organic compounds to make ATP
ATP – main energy currency in cells.
Mitochondrion membrane: 2 membranes: outer membrane = smooth, while inner
membrane = folded (here reactions take place to produce ATP)
Mitochondrial DNA – mitochondria have their own DNA and ribosomes
Similar to circular DNA of prokaryotes
Plant cells have 3 structures unique to them:
Cell wall – provides support, protection and shape
Made up of proteins and carbohydrates (including cellulose)
Chloroplasts – use light energy (sun) to make carbohydrates from carbon dioxide and water
Membrane: has 2 membranes (like mitochondria)
DNA: has its own (like mitochondria)
Also found in: algae
Central Vacuole – large, membrane bound space
Stores water and ions, nutrients, or waste
When it is full, it makes cell rigid (plants stand upright)_.