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Nucleus
“Brain”
Description:
1. Most prominent cell structure.
2. Round shape surrounded by a double membrane called the
nuclear envelope.
3. Nuclear side of the nuclear envelope is lined with nuclear
lamina which gives the nucleus its shape and support.
4. Part of the endomembrane system.
5. Makes cells eukaryotic – plant, animal, fungi, “protists”
Functions:
1. Stores DNA in the form of chromosomes (coiled DNA
around histone proteins) and chromatin (uncoiled DNA).
2. Protects the DNA from hydrolytic enzymes in the cytoplasm.
3. Holds the nucleolus.
4. Directs the activities of the cell.
5. Location of DNA Replication (DNA is copied) and
Transcription (DNA  mRNA).
6. Can have ribosomes attached to the outer membrane to
synthesize proteins.
Nucleolus
“rRNA Factory”
Description:
1. Located inside the nucleus.
2. Most cells usually have more than one nucleolus – nucleoli
3. Eukaryotic cells only – plants, animals, fungi, “protists”
Functions:
1. Synthesizes rRNA from DNA.
2. Assembles proteins with rRNA to form large and small
ribosomal subunits.
3. Subunits exit the nucleus via the nuclear pores to form
ribosomes in the cytoplasm where they become free
(cytoplasm) or bound ribosomes (RER or nucleus).
Ribosomes
“Protein Factories”
Description:
1. Particles made of rRNA and proteins.
2. Large and small subunit.
3. Not a membrane bound organelle.
4. Found in all prokaryotes and eukaryotes.
5. 2 forms: free (cytosol) and bound (RER or nucleus)
Functions:
1. Read mRNA to synthesize proteins from amino acids.
2. Free: produce proteins such as enzymes that function inside
the cytoplasm.
3. Bound: produce proteins for outside the cytoplasm such as:
the cell membrane, specific organelles, or for secretion from
the cell (export).
Endoplasmic Reticulum
“Highway”
Description:
1. Network of dynamic membrane tubules and sacs called
cisternae.
2. Inside of the ER is called the lumen.
3. Outer membrane of the nucleus is continuous (attached) with
the lumen of the ER.
4. Rough (RER) has ribosomes attached to the outer cisternae
and Smooth (SER) does not have ribosomes attached.
5. Part of the endomembrane system.
6. Eukaryotes only – plants, animals, fungi, and “protists”
Functions:
1. Rough ER:
2. Smooth ER:
Produces secretory proteins (usually
glycoporteins) at the ribosomes.
Creates membrane proteins (such as transport
proteins) and phospholipids.
Synthesizes lipids – oils, phospholipids, and
steriods
Metabolizes carbohydrates
Stores calcium ions (Ca 2+)
Breaks down toxins (drugs and poisons) –
enzymes add hydroxyl groups to the toxins
to make them more polar and water soluble
so the body can transport and excrete them.
Vesicles
“Transporters”
Description:
1. Sacs made of membranes.
2. Part of the endomembrane system.
3. Eukaryotes only – plants, animals, fungi, “protists”
Functions:
1. Transport molecules within the endomembrane system where
the system is not directly (physically touching) connected.
Golgi Apparatus
“Shipping and Receiving Center”
Description:
1. Flattened membrane sacs – cisternae
2. Has a “cis” side located near the ER and a “trans” side which
faces out into the cytoplasm.
3. Material is transferred from stack to stack via vesicles.
4. Part of the endomembrane system.
5. Eukaryotes only – plants, animals, fungi, “protists”
Functions:
1. Cis side receives from the ER
2. Trans side ships out into the cytoplasm via vesicles.
3. Modifies proteins and phsospholipids.
4. Makes lysosomes.
5. Most vesicles fuse with the cell membrane.
Lysosomes
“Digestive Compartments”
Description:
1. Sac made of a membrane that contains acidic hydrolytic
enzymes.
2. Hydrolytic enzymes are made by the RER.
3. Eukaryotes - Not common in plant cells.
4. Part of the endomembrane system.
Functions:
1. Digest macromolecules from polymers to monomers.
2. Performs phagocytosis (engulfs and destroys)
3. Recycle organic material within the cell - autophagy
Vacuoles
“Maintenance Compartments”
Description:
1. Membrane enclosed sacs
2. Part of the endomembrane system
3. Types: Food Vacuoles (protists), Contractile Vacuoles
(freshwater protists), and Central Vacuole (plants).
4. Common in eukaryotic plant cells and “protists”.
Functions:
1. Food Vacuoles: works with lysosomes to digest food via
phagocytosis.
2. Contractile vacuoles: pump excess water out of cells.
3. Central vacuoles: storage of “cellular sap” – water, waste,
food, proteins, ions etc.
Mitochondria
“Energy Converter”
Description:
1. Enclosed in a double membrane.
2. Outer membrane is smooth.
3. Inner membrane is convoluted – folds – cristae – increase
surface area.
4. Inside inner membrane – mitochondrial matrix
5. Between the inner and outer membrane – intermembrane
space.
6. Not part of the endomembrane system.
7. Many in a cell. – more mitochondria in more active cells.
Functions:
1. Cellular respiration – converts chemical energy (organic
compounds) into ATP using oxygen
Plastids
“Pigmented Organelles”
Description:
1. Enclosed in a double membrane.
2. Not part of the endomembrane system.
3. Eukaryotic plant and algae organelles.
4. Types: Amyloplasts, Chromoplasts, and Chloroplasts.
5. Chloroplasts: inside contains thylakoid stacks – grana and
empty space called stroma.
Functions:
1. Amyloplasts: store starch (amylose).
2. Chromoplsts: have pigments that give fruit and flowers color.
3. Chloroplasts: photosynthesis - convert light energy into
chemical energy (organic compounds) using H2O and CO2.
Peroxisomes
“Oxidizers”
Description:
1. Single membrane sac.
2. Contains oxidizing enzymes.
3. Usually located close to chloroplasts and mitochondria.
4. Not part of the endomembrane system.
Functions:
1. Produce H2O2 in metabolic processes.
2. Catalase then converts the toxic H2O2 to water.
Cytoskeleton
“Supporter”
Description:
1. Network of fibers in the cytoplasm
2. Microtubules – thickest - hollow tubes made of tubulin
(protein).
3. Microfilaments – thinnest - made of 2 actin (protein) strands
4. Intermediate filaments – middle - supercoiled proteins
(keratin)
Functions:
1. Supports the cell and give it shape.
2. Interacts with motor proteins to cause movement in the cell.
3. Microtubules: shape and support the cell, serve as tracks for
organelle movement, move chromosomes during cell division
(centrioles in animal cells).
4. Microfilaments – Actin filaments – cellular contraction –
works with myosin in muscle cells.
5. Intermediate filaments – reinforce shape of cell – hold
organelles in permanent places.
Cilia and Flagella
“Movers”
Description:
1. Made of microtubules – “9+2” arrangement and dynein
proteins
2. Attaches to the cell at a basal body (centriole structure)
3. Cilia – short and lots
4. Flagella – long and few
5. Unicellular eukaryotes and some multicellular – protists,
some plant cells, and some multicellular animal cells (ex:
respiratory cells)
Functions:
1. Propulsion – either entire cells or substances over the surface
of a cell.
2. “Walking” – microtubules move or bend from side to side.
Cell Wall
“Protector”
Description:
1. Extracellular structure – outside of cell.
2. Primary cell wall - thin
3. Secondary cell wall - thick
4. Middle lamella – gap between cell walls of 2 cells
5. Prokaryotes (peptidoglycan) and Eukaryotes – Plants
(cellulose) and Fungi (chitin) – NOT IN ANIMAL CELLS
Functions:
1. Protection
2. Shape
3. Prevents bursting from water uptake.
Extracellular Matrix
“ECM”
Description:
1. Mostly an extracellular structure.
2. Glycoproteins that extend from the cell membrane – collagens
and fibronectans
3. Contains surface receptor proteins – integrins that span the
membrane and connect to microfilaments in the cytoskeleton.
4. Proteoglycans – little protein core with lots of carbs attached
5. Eukaryotes - Animal cells
Functions:
1. Communication - regulates the cells behavior with regard to
the external cellular conditions – integrins.
2. Coordination – cells grouped together as tissues must behave
similarly.
Intercellular Junctions
“Cell Communicators”
Description:
1. Plasmodesmata – perforated holes in the cell walls of plants
2. Tight junctions – proteins that link cell membranes together –
animal cells
3. Desmosomes – keratin protein and intermediate filaments –
“anchoring junctions” - animal cells
4. Gap junctions – membrane proteins that form a hole in the
cell membranes of cells – “communicating junctions” –
animal cells
Functions:
1. Plasmodesmata – cellular communication - passageway for
cytosol containing chemicals and solutes – plant cells only.
2. Tight Junctions – seals the cells to prevent leakage from
tissues – animal cells only.
3. Desmosomes – hold cells together as tissues – animal cells
only
4. Gap junctions – cellular communication within a tissue –
passageway for sugars, ions, amino acids and other small
molecules – animal cells only
Cell Membrane
“Protector”
Description:
1. Surrounds ALL cells – prokaryotic and eukaryotic.
2. Made of lipids (phospholipids and cholesterol), proteins
(glycoproteins and membrane proteins), and carbohydrates.
Functions:
1. Selective permeability – controls what enters and leaves the
cell.
2. Cell communication – cells join together to form tissues
because of the carbohydrates on the outside of cell
membranes.