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Define cell?
The basic structural and functional unit of the body
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Chemically, cells are composed chiefly composed of what?
- carbon, hydrogen, nitrogen, oxygen and
- trace elements.
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With a Trillon cells in the body how many different cell types are they? How do they vary?
200 different cell types that differ in shape, size and function.
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Why do cells differ in structure?
Because they differ in function
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Describe the shape of fat cells, red blood cells, nerve cells and kidney cells?
- Spherical fat cells
- Disc shaped red blood cells
- Branching nerve cells
- Cube like kidney cells
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Describe the function and characteristics of the Plasma membrane? What is another name for it?
- Defines boundary of the cell and regulates passage of
- substances into and out of the cell.
- Cell membrane (phospholipid bilayer) or
- Plasmalemma
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If you poke a needle into an ovum what happens?
The plasma membrane seals itself immediately.
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What is the function of Proteins in the plasmalemma?
- Guard
- Transport channels
- Receptor sites
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Name the three parts of the plasmalemma?
- Proteins
- Cholestrol
- Cytoskeleton
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The cytoplasma is a different composition then what fluid within the cell?
Extracellular fluid
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Why is cholestrol important to the plasma membrane?
Makes the membrane more stable and maintains it's fluidity
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What are the functions of the plasma membrane?
- 1.Physical isolation
- 2.Regulation of exchange with the environment (cell membrane permeability)
- 3.Sensitivity (homoeostasis)
- 4.Structural support
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The cell membrane is selectively permeable, name two passageways into the cell and define them?
- Passive (no energy expenditure)
- Active (ATP)
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Name the passive mechanisms?
- Diffussion
- Osmosis
- Facilitated diffusion
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Name the active mechanisms?
- Endocytosis
- (pinocytosis, phagocytosis, receptor mediated)
- Exocytosis
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Because all cell membranes are not alike the permeability of a cell membrane varies depending on what factors?
Organization and characteistics of membrane lipids and proteins
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Define cytoplasm and name it's two components?
- All material within the cell membrane
- liquid (cytosol)
- structures (organelles)
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Define and describe the characteristics of cytosol?
- Liquid portion of cytoplasm
- High concentrations of potassium ions, dissolved and suspended proteins
- Small quantities of carbohydrates
- Large reserves of amino acids and lipids
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What are organelles?
Structures within the cytoplasm
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Define cytoskeleton?
- Internal protein framework that gives cytoplasm strength and flexibility
- also necessary for cell division and transport of materials and organelles around the cell
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What are the 4 major components of the cytoskeleton?
- In order of smallest to largest:
- Micro filaments
- Intermediate filaments
- Thick filaments
- Microtubules
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What do groups of Microtubules form?
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Define Microvilli? What is there function?
- Finger-shaped projections of the cell membrane (not cytoskeleton)
- Increase surface area. Microfilaments (cytoskeleton) gives it's structure
- Used in absorption
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What is the function of the nucleus? Describe some characteristics?
- The control center for cellular operations
- Stores all the information to control the synthesis of about 100,000 different proteins in the body
- Largest structure in the cell
- Contains genes (23 pair of chromosomes) DNA and Histomes usually in the form chromatin(non dividing cell)
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What is the nuclear envelope connected to?
Endoplasmic Reticulum
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Nuclear pores communicate between what two areas of the cell?
Nucleus and Cytosol
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What is the function of the nucleolous?
Synthesize the components of ribosomes
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What is the function of Ribosomes?
Site where protein is manufactured
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Where are Ribosomes manufactured, describe a characteristic of them?
- Instructions come from DNA in the nucleus
- Two subunits interlock
- Small and dense. They look granular
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Where do free ribosomes send their protein too?
proteins go into the cytosol
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Where do fixed ribosomes send their protein too?
- Attached to the endoplasmic reticulum proteins
- go into the ER lumen and are modified & packaged
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What is the importance of protein in the body?
- Proteins are extremely important because proteins form enzymes
- That control all the chemical reactions going on in the cells and therefore in your body
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Describe where ribosomes are manufactured and where they journey from their.
- Components of ribosomes are manufactured
- In the nucleolus of the nucleus and pass
- Through nuclear pores to the ER
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Describe the characteristics of the ER? Name it's function.
- Network of interconnected tubes within the cytoplasm
- Synthesis of carbohydrates (CHO), lipids and proteins
- Storage
- Transport
- Detoxification
- Carbs and lipids are manufactured in the membrane
- ER holds synthesized molecules and absorbed substances from the cytosol
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At the ER proteins are packaged for export to where?
At the ER the proteins are packaged for export to the Golgi apparatus
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What is a rule about protein manufactoring?
Proteins are manufactured only were there are ribosomes
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What is the function of the Golgi Apparatus?
- Traffic director for cellular proteins
- Has flattened disc called CISTERNAE
- Packaging secretions
- Package enzymes used by cell (proteins)
- Renew cell membrane
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Within the Golgi Apparatus, name the two vesicles that modified proteins are packaged into?
- Secretory vesicles – exocytosis
- Lysosomes - use within the cell
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Define Lysosomes, what are it's functions?
- Digestive enzymes
- •Essential cleanup and recycling inside the cell “Demolition crew”
- Fuse with the membranes of damaged organelles or vesicles
- Containing bacteria or organic debris
- Break down the contents of the vesicle
- AUTOLYSIS– enzymes destroy the proteins and organelles of
- the cell = “suicide packets
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What is the function of Mitochondria?
- Provide energy for cellular functions “Power Plants
- Number of mitochondria depends on cells energy demands
- Energy is in the form of ATP (Adenosine triphosphate)
- Break down glucose------water + carbon dioxide + ATP
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What are the three types of cell junctions? What is their function?
- Tight junctions: Block passage of water or solutes
- Gap junctions: Narrow passageway for ions and small molecules
- Desmosomes: Weld spots or lines
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What are characteristics of Demosomes? Where can they be found?
- Desmosomes are very strong and can resist twisting and stretching
- They are found in the outer layer of the skin or the
- Neck of the uterus that is stretched in childbearing
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How many cell junctions can be found on a cell?
- You can have more than one type junction on a cell.
- Can have all of them
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