Download 2 Cells A

Every cell has three things in common:
1. Metabolic functions (using sugars, oxygen, etc)
2. Responds to its environment
3. Capable of maintaining homeostasis within itself and within the body.
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HOMEOSTASIS is maintaining a constant and appropriate internal
environment, such as temperature, pH, glucose levels, etc.
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Plasma membrane (actually, a type of organelle)
Cytoplasm and cytosol
Nucleus
Organelles (a membranous or membrane-bound compartment that
carries out particular functions)
Ribsomes (little factories that take amino acids and make proteins out of them)
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CYTOPLASM: watery liquid found inside and outside the organelles, but
outside the nucleus.
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CYTOSO: Lanother liquid that is thicker than water, and is NOT inside the
organelles. It is only found outside of the organelles and nucleus.
Contains the following:
a. Mostly water
b. Things dissolved in water (amino acids, sugars like glucose,
nucleic acids, and ATP, which is a molecule used for energy).
c. Cytoskeleton
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Cytoskeleton: made up of long protein fibers, extend throughout cytosol.
Function of cytoskeleton:
1) Maintains cell shape
2) Movement (such as muscle cell contraction, organelles within the cell, or
the cell itself moving around).
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ORGANELLES: those that are surrounded by a membrane
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PLASMA (CELL) MEMBRANE
ENDOPLASMIC RETICULUM (ER): a network of channels.
o ROUGH ENDOPLASMIC RETICULUM (endoplasmic =
within
o SMOOTH ENDOPLASMIC RETICULUM (no ribosomes)
GOLGI COMPLEX
VESICLES (vacuoles)
MITOCHONDRIA
NUCLEUS
CENTRIOLES
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PLASMA (CELL) MEMBRANE
Surrounds the entire cell.
Functions of the Plasma Membrane:
a. Movement of materials into and out of cell, acts as a barrier to
the external environment
b. Acts as a site for receiving signals from the rest of the body
c. Acts as a site for holding the cell in place
The plasma membrane is made up of two layers of molecules =
PHOSPHOLIPIDS (Phospho-lipied Bilayer)
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RIBOSOMES
Ribosomes make proteins.
Ribosomes are not organelles because they do not have a plasma membrane.
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ENDOPLASMIC RETICULUM (ER): a network of channels.
• Two types:
• Rough ER: contains ribosomes
• Function of ribosomes is to make proteins.
• Smooth ER: no ribosomes
• Function is to detoxify chemicals that enter the cell.
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ROUGH ENDOPLASMIC RETICULUM (endoplasmic = within
cytoplasm; reticulum = network; rough = surface of membrane covered with
ribosomes. This is an organelle, but the ribosomes are not.
Function of RER is the synthesis (making) of certain kinds of proteins:
a. Membrane proteins
a. Proteins for export (such as digestive system enzymes)
b. Proteins for use within the cell
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SMOOTH ENDOPLASMIC RETICULUM (no ribosomes)
Function of SER
a. SER is continuous with the rough ER, but lacks ribosomes and
functions primarily in lipid production
b. Involved in metabolism (makes/ breaks) of carbohydrates (sugars)
and lipids.
c. Stores calcium (necessary for every cell)
d. Detoxifies harmful substances (alcohol, drugs, etc)
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GOLGI COMPLEX
Functions of Golgi complex:
a. Packages the proteins made by the RER and sends them
where they need to go (like a FedEx center!)
a. Sometimes proteins are modified in the golgi
complex. Therefore, this structure receives materials
from the rough ER and “packages and ships” them.
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VESICLES (vacuoles): a sphere of membrane with something in it. Bubblelike containers for various substances. This is an organelle. Some are created
by the end of the Golgi complex: a piece of membrane pinches off, leaving a
protein in the vesicle, which carries the protein to the cell membrane, where
it merges with the cell membrane, pops, and releases its contents outside of
the cell.
Many types.
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Lysosomes
Transport vesicles
Storage vesicles
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LYSOSOMES: are sacs of powerful digestive enzymes to dissolve an old
organelle, etc, or to commit cell suicide = APOPTOSIS (programmed cell
death).
- Specialized vacuoles that contain digestive enzymes and acids that
dissolve foreign bodies that enter the cell.
- When bacteria enter a cell, the lysosome will fuse w/the bacteria and
release its enzymes on them to destroy them.
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TRANSPORT VESICLES: when material needs to move from RER to
Golgi complex, or from Golgi complex to cell membrane, etc.
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STORAGE VESICLES
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MITOCHONDRIA
 Function of mitochondria is to make ATP, which is cellular energy
(ATP is an energy source).
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NUCLEUS
NUCLEUS
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NUCLEOLUS
 Within a nucleus there sometimes are areas that are darker. These
are regions of condensed RNA.
 The nucleolus is NOT an organelle, but the nucleus is. Don’t get
“nucleolus” mixed up with the word “nucleus” on the test. The
nucleolus does not contain the DNA; the nucleus does. The nucleolus
is within the nucleus, but it does NOT contain DNA.
 The nucleolus makes ribosomes and stores RNA (RNA is made in
the nucleus). RNA is important for protein synthesis.
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TRANSCRIPTION is the process of DNA communicating with
RNA.
• This occurs in the nucleus.
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TRANSLATION is the process of RNA communicating with a
ribosome to tell it what type of protein to make. Therefore, translation
is characterized by PROTEIN SYNTHESIS.
• This occurs in the cytoplasm.
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CENTRIOLES
Centrioles are filaments within the cell that function during mitosis.
• When the cell goes from metaphase to anaphase of mitosis, the
chromatids separate and follow the spindles of the centrioles towards
the opposite ends of the cell.
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FLAGELLUM
• Some cells have a flagellum, which is a whip-like tail used to help
them move.
• An example is a sperm cell.
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MICROVILLI
• Some cells have microvilli, which increase the surface area of cells
by approximately 600 fold, thus facilitating absorption and secretion.
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CILIA
• Some cells have cilia, which are small, hair-like structures that can
wave back and forth, causing substances to move along across the
top of the cell.
• For example, the cells of the lungs are lined with cilia,
which move mucous up from the lungs so it can be
coughed up and swallowed.
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STEM CELLS: A population of cells are always available to replace the
cells that died
 Muscle stem cells give rise to new muscle cells.
 Bone marrow stem cells give rise to new blood cells.
 Embryonic stem cells give rise to any type of cells, including neurons
(adults don’t have neural stem cells) and pancreatic cells (diabetics
don’t have pancreatic stem cells).
 Stem cells are named by type + suffix: BLAST
 Erythrocyte = RBC. Erythroblast = stem cell that gives rise to
erythrocyte.
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Too many cells can be a TUMOR (an abnormal growth). Two types of
tumors:
1. BENIGN (“harmless”, although can cause harm by pressing on vital
structure)
2. MALIGNANT (cancerous). These are dangerous because the
cells in the tumor METASTASIZE (leave original site, go
elsewhere and grow).
Cancer is hundreds of diseases, each with a different cause, symptoms,
treatment, and prognosis. Any cell type can become malignant, producing
different types of cancer.
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THREE TYPES OF CANCER
1. CARCINOMA: epithelial tissue
2. SARCOMA: Connective tissue
3. LEUKEMIA: Blood or blood-forming tissues
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