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Chapter 3 Notes (cont.) (10/27/08)

II.  Cytoplasm – the substance between the plasma membrane and the nuclear membrane.  The matrix is where the organelles are found:

-         Thick, semitransparent

-         Elastic fluid containing suspended particles and a series of microtubules and filaments

-         Cytoskeleton – gives the cell its shape and support

-         Cell is 75% - 90% water

-         Proteins, carbs, lipids, and inorganic substances make up the solids

-         Some chemical rxn’s take place

-         Raw materials that are unusable

-         Decomposition rxn’s – H2O  à  H2 + O2

 

A. Organelles: structure and physiology

·        Cell contains compartmentalized structures called organelles

·        They have specific shapes and specific roles in growth, maintenance, repair, and control.

·        Types of organelles:

1.   Nucleus – spherical or oval

·        largest organelle

·        contains hereditary information

·        most cells only have one

·        RBC’s do not have one

·        seperated from cytoplasm by a double membrane (nuclear envelope)

·        perinuclear cisternae – has tiny pores for communication           

Inside is gel-like substance called Karyolymph (nucleoplasm)

·        nucleolus is found inside the nucleus and is non-membrane bound

·        breaks apart during cell division, and it makes RNA and proteins

·        DNA is not seen when spread out in the thread-like form called chromatin and is the only time that it can replicate itself for cell division.

·        Proteins are called Histones

·        see diagram from class for coiling methods.

 

2.  Ribosome – made of 2 subunits a large and a small

           main purpose is to make proteins

           Amino Acids join them one at a time to make a chain

           some are free (proteins for inside)

           some attached to organelles (outside)

 

3.  Endoplasmic Reticulum –

           Double membrane channels called cisternae

           channels are external of nuclear membrane

2 Types of ER 

a. Granular (Rough) ER

b. Agranular (Smooth) ER

           maintain stability and distribution of cytoplasm

           it is the transportation system of cell

           storage area for synthesized molecules

           Rough ER –synthesize proteins

           Smooth ER – synthesize lipids and release of Ca2+ for muscle contraction

 

4.  Golgi Complex – principle function is to process, sort, package, and deliver proteins to various parts of the cell.

           its near the nucleus

           consists of 4-8 flattened sacs with expanded areas at the ends (cisternae – divided into cis, middle, and trans)

           fuses with cis

           golgi puts proteins in its vesicles

           goes from cis à middle à trans its transfored into specific functions (see diagram from class)

           2 types of vesicles for secretory granules and lipid secretion

 

5.  Mitochondria – small, spherical, rod-shaped, and filamentous

           is the powerhouse of the cell

           energy made from glucose à ATP (Adensosin triphosphate)

           consists of 2 membranes (like plasma membrane)

           outer membrane smooth (shorter)

           inner made of a series of folds called cristae (longer)

           center space is the matrix

           have ability to self replicate

           inner membrane (see diagram from class)

    

6.  Lysosomes (lysis-dissolution; soma – body)

           made by golgi with single membrane

           powerful digestive enzymes

           Ty-Sacchs – deficiency of lysosomes

           WBC’s destroy harmful substances

           primary lysosome is inactive until fusion with vacuole

           vacuole temporary storage area

           engulf, digest it until small enough to go thru membrane

           engulf worn out organelles and those materials are put back into cytoplasm for reuse (autophagy)

           Autolysis (self-distruction) (suicide packets)

 

7.  Peroxisomes – similar to lysosomes

           abundant in liver

           rid of peroxides that are toxic to us

           2H2O   à  2H2O  +  2O2

 

8.  Cytoskeleton – network of microfilaments that give cells support and structure

           microfilaments – made up of protein called actin

           microtubules – made of protein called tubulin

           contain channels for movement

           assist in movement of pseudopodia

           forms flagella and cilia, centrioles, and mitotic spindles

           

9. Centrosome and Centrioles

           located by nucleus

           made of a pair of centrioles

           each centriole is made up of 9 triplet cluster of microtubules (see diagram from class)

 

10.  Flagella and Cilia – used for locomotion

           flagella – usually few of them and long

           contain cytoplasm connected to membrane       

           cilia – usually many and short

           ciliated hairs of respiratory to move mucus

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