Chapter 2 the cell
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The basic structural and functional unit of the body
Chemically, cells are composed chiefly composed of what?
- carbon, hydrogen, nitrogen, oxygen and
- trace elements.
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.
Why do cells differ in structure?
Because they differ in function
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
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
If you poke a needle into an ovum what happens?
The plasma membrane seals itself immediately.
What is the function of Proteins in the plasmalemma?
- Transport channels
- Receptor sites
Name the three parts of the plasmalemma?
The cytoplasma is a different composition then what fluid within the cell?
Why is cholestrol important to the plasma membrane?
Makes the membrane more stable and maintains it's fluidity
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
The cell membrane is selectively permeable, name two passageways into the cell and define them?
- Passive (no energy expenditure)
- Active (ATP)
Name the passive mechanisms?
- Facilitated diffusion
Name the active mechanisms?
- (pinocytosis, phagocytosis, receptor mediated)
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
Define cytoplasm and name it's two components?
- All material within the cell membrane
- liquid (cytosol)
- structures (organelles)
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
What are organelles?
Structures within the cytoplasm
- Internal protein framework that gives cytoplasm strength and flexibility
- also necessary for cell division and transport of materials and organelles around the cell
What are the 4 major components of the cytoskeleton?
- In order of smallest to largest:
- Micro filaments
- Intermediate filaments
- Thick filaments
What do groups of Microtubules form?
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
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)
What is the nuclear envelope connected to?
Nuclear pores communicate between what two areas of the cell?
Nucleus and Cytosol
What is the function of the nucleolous?
Synthesize the components of ribosomes
What is the function of Ribosomes?
Site where protein is manufactured
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
Where do free ribosomes send their protein too?
proteins go into the cytosol
Where do fixed ribosomes send their protein too?
- Attached to the endoplasmic reticulum proteins
- go into the ER lumen and are modified & packaged
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
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
Describe the characteristics of the ER? Name it's function.
- Network of interconnected tubes within the cytoplasm
- Synthesis of carbohydrates (CHO), lipids and proteins
- Carbs and lipids are manufactured in the membrane
- ER holds synthesized molecules and absorbed substances from the cytosol
At the ER proteins are packaged for export to where?
At the ER the proteins are packaged for export to the Golgi apparatus
What is a rule about protein manufactoring?
Proteins are manufactured only were there are ribosomes
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
Within the Golgi Apparatus, name the two vesicles that modified proteins are packaged into?
- Secretory vesicles – exocytosis
- Lysosomes - use within the cell
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
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
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
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
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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