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Eukaryote Cell: Organelles - Membrane Bound 

Membrane bound organelles include the  plasma membrane, endoplasmic reticulum, Golgi complex, lysosomes, vacuoles, plastids and mitochondria. These organelles consist of cell membrane, may contain specific enzymes to carry out various functions, and may be used to transport material within the cytoplasm or to the exterior of the cell.  The Cell's Membrane System includes the plasma membrane, endoplasmic reticulum,  Golgi complex  and lysosome because these structure are interrelated. You may want to go back to review membrane structure. Click here.  click Identify the membrane bound  structures

 
B = smooth ER,   C = rough ER,   E = cell membrane,  F = mitochondrion, H = food vacuole, J = lysosome, K = Golgi, O = nuclear membrane 
 
In your  notes draw a figure of a cell and label the organelles which are made of membranes.

Read the pages indicated by B-10, study the figures showing the various cellular organelles. Study behavioral objectives 7 and 8

Endoplasmic Reticulum: This includes a major network of internal membranes in all plant and animal eukaryote cells. It  is continuous with the outer membrane of the nuclear envelope which invaginate inward forming a double membrane structure (canal) running throughout  the cytoplasm. There are two type of ER, smooth ER and rough ER. 

Rough ER differs from smooth ER in that it is covered with ribosomes. Rough ER is the site for synthesis of membrane proteins (by the attached ribosomes)  and proteins to be secreted outside the cell or into the vacuoles. 

Smooth ER functions as a major site of lipid synthesis and membrane assembly. In your notes draw a figure showing the location and differences between the two types of ER. Write the function for these two types of ER in a working cell. 
          Endoplasmic Reticulum  

The figure above shows a nuclear membrane (C) attached to rough ER (B) which has ribosomes attached to its surface synthesizing proteins (hydrolytic enzymes) (E)  which may flow down the smooth ER (A) where they are surrounded by  membrane forming a lysosome (F). 

Golgi Body: These are cup shaped stacks of many membrane sacs derived from the ER. To the figure you drew above, add two Golgi bodies showing their relationship with the ER. 
  

The Golgi may receive molecules from vesicles, rearrange the molecules and release the new product formed in a different vesicle. If these vesicles contain digesting enzymes they are called lysosomes. The lysosomes can in turn fuse with other vesicles or food vacuoles and hydrolyze the macromolecule into their monomers so they can be recycled. Study the figure indicated by B-11. In your notes write a description for each of the steps indicated by numbers. Learn how Golgi are used in specialized cells in the storing and releasing of secretions by reading the pages indicated by B-12  (search for digestive secretin, hair follicle secretions) 
 

 You will be tested over the figure above later. G = Golgi body, H = ER (rough).
  I = ER (smooth) 


Lysosomes: These are vesicles containing hydrolytic (digesting) enzymes that may digest worn out cell organelles, macromolecule is food vacuoles or entire cells (cell death). Learn how lysosomes function in organisms by reading the pages indicated by  B-13 (search for Tay-Sachs disease - lipid breakdown, unicellular digestion, selective cell death). In your notes write a paragraph how lysosomes are used during these processes. 
 
 
 
 
 
 

Vacuoles: These are single membrane structures formed by pinocytosis or phagocytosis. This was discussed earlier in this miniunit. 
 
 

 

E = lysosome,  D = food vacuole 
 
 

 

1. Explain the various processes (A-J) occurring in the figure above by using the following terms and descriptions. 

(golgi which processes many chemicals and synthesize new molecules, ER (rough) with ribosomes synthesizing protein (hydrolytic enzymes) ,  food particle,  mitochondrion, ER (smooth) synthesizing lipids and forming membranes, vacuole with proteins which need further processing, cell membrane, phagocytosis, food vacuole, lysosome) 

Press here to check answer.  press 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 


Mitochondria: Mitochondria are the organelles which contain the enzymes that carry out cellular respiration. Respiration is an oxidative process where energy rich molecules (glucose)  is broken down into energy poor molecules (carbon dioxide and water) with the energy being released in the form of biological energy (ATP).  ATP are molecules that living organisms  use to transport energy from one reaction to another. 

Mitochondria are double membrane organelles which  vary in shape from spherical to tubular, but they all have a smooth outer membrane and a highly convoluted inner membrane. The inner membrane folds are called cristae.  Read the pages indicated by B-14. Study behavioral objective 9. Draw in you notes a figure showing the following structures in a mitochondrion: inner and outer membrane, matrix, cristae, mitochondrial DNA. Write in your notes a paragraph describing the function of the mitochondrion (include the following terms - ATP, aerobic, anaerobic, oxygen, food molecules). 
 

 
 
 
 
Plastids: Plastids are double membrane organelles found only in plant cells. There are three main types of plastids: chloroplast, leucoplast and chromoplast. 
 

Leucoplasts are double membrane structures which stores carbohydrates formed during photosynthesis (glucose) in the form of starch grains. These are the main starch storing organelles found in the cells of root and stem of plants  (example - potato). 

Chromoplasts are also double membrane organelles. They contain colored pigments (orange, red, yellow) in the cells of many fruits and flowers. 

Chloroplasts  are the plastids which contain the enzymes that carry out photosynthesis. Photosynthesis is a reductive  process where energy poor molecules (carbon dioxide and water) are synthesized into  energy rich  molecules (glucose). During this process light energy is absorbed and transferred into biological usable energy (ATP) which is utilized to form energy rich molecules from energy poor molecules. This light energy is absorbed by chlorophyll molecules located in the membranes of the chloroplasts.  Chloroplasts  are double membrane organelles which  vary  in shape from spherical to tubular, but they all have a smooth outer membrane and  highly convoluted inner membranes. The inner membranes are called thylakoids and a stack of thylakoids forms a granum..  Read the pages indicated by  B-15.  Study  behavioral objective 9. Draw in you notes a figure showing the following structures in a chloroplast: inner and outer membrane, stroma, thylakoids, grana, chloroplast  DNA. Write in your notes a paragraph describing the function of the chloroplasts (include the following terms - light energy, ATP, chlorophyll, food molecules,  oxygen). 
  

2. Identify A - E by one of the following descriptions: inner membrane, outer membrane, stroma, granum, stroma thylakoids, grana thylakoids. 

Press here to check answer.  press 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
 
 


Extracellular structures: Cells may secrete substances outside of the cell membrane which form various structures for specific functions. Some examples are protein hair shafts in mammals, protein claws or nails in mammals, cell wall in all plant cells. 

Cell walls are found in plant, fungi and bacteria cells. Only plant cells contain cell walls consisting  of cellulose. Animal cells lack a cell wall. Read the pages indicated by B-16 concerning cell walls and study behavioral objective 16.  In your notes draw two joined plant cells and label the following: primary cell wall, secondary cell wall, pectin, middle lamella.  Explain when and the secondary cell wall is formed.  Read the pages indicated by B-17  to study different types of plant cells with primary cell walls only compared to plant cells with primary and secondary cell walls (compare parenchyma cell walls with sclerenchyma cell walls) 
 
 
 
3. Identify the structures in the above figure. 

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