Cellular Video

Plant Cells vs Animal Cells

Animal cells lack a large vacuole, chloroplasts, and a cell wall. Plant cells lack centrioles. Because animal cells lack chloroplasts, they have to acquire energy through eating other beings. Plant cells can use photosynthesis to make their own energy and "food." The lack of a cell wall and vacuole also make animal cells less rigid and more "fluid."

Components of the Endomembrane System

Signal Hypothesis:
Prediction that proteins bounds for the endomembrane system have a "zip code" analogous to the nuclear localization signal. The idea is that first amino acids act as a signal that brings the protein into the lumen of the ER, called the ER Signal Sequence (20 amino acids).

Endomembrane System:
The main function of the Endomembrane system is to produce protein through the use of the nucleus for the "data," the rough ER for the production, and the Golgi Apparatus to be "finished." The proteins help the cell and other cells. Endomembrane System also makes lipids going through the smooth ER instead of the rough ER. This is important because lipids make up membranes and are the number one ingredient in cells.

Nuclear Envelope:
Material can get in and out of the nucleus through a protein trnasporter, the nuclear pore complex. Molecules can get through the nuclear pore complex by having a "zip code" chemical, nuclear localization signal. The protein is integrated in the nuclear envelope which give protection of the DNA and chromosomes.







Rough ER:

• Structure:

1. Single Membrane, integrated proteins
2. Ribosomes
3. Lumen, interior of the sac-like structure
   

• Function:

1. Protects the production of proteins and supports the structure of rough ER
2. Ribosomes are embedded on the outside of the organelle and are key in the production of the protein.
3. Lumen is where the protein is folded and other types of processing

Smooth ER:

• Structure:

1. Single membrane, integrated proteins
2. enzymes
3. sac like branches

• Function:

1. Protection of lipid synthesize
   
2. Catalyze reactions to produce lipids and phospholipids
3. Help keep interior structure for the smooth ER

Smooth ER also contain enzymes that convert drugs, posions, and toxic by-products of cellular metabolism into more tolerable substances that can be managed.




Golgi Apparatus:

• Strucutre:

1. Single membrance, receptors of products of the rough ER
2. Flattened cisternae, stacked on top of another

• Function:

1. Protects the finishing products of protein and pinch off into vesicles that deliver the products

Cell Structure

Plasma Membrane:

• Structure:

1. Single Membrane, phosopholipid bilayer
2. Integrated transported and receptor proteins

• Function:

1. Selective permeability allows osmosis and diffusion for small molecules and ions and keeps cell stability and structure
2. The integrated proteins allow the transportation of impermeable molecules and allow the cell to live.

Cell Wall:

• Structure:

1. Carbohydrate fibers that are held together by hydrogen bonds and polypeptide bonds that create a strong wall

• Function:

1. Protection of the cell and structural support in the plant, e.g. wood

Cytoskeleton:
The cytoskeleton system of the cell is a complex organization of dense fibers, actin filament, intermediate filament, and microtubules. These fibers help give structural support for the cell by keeping the cell a certain size and holding the nucleus and organelles in their designated areas. The system also moves the cell itself, the actin filament, and move objects in the cell.

Actin Filament:

• Strucuture:

1. Fibrous material of globular protein, actin
2. Double helix
3. Myosim

• Function:

1. Maintain cell shape by resisting tension, similar to steel rods in concrete
2. Creates the ability to have both cellular and inner cell movement by rotating
3. Myosin is the motor protein which is key in the transformation of ATP into mechanical energy which causes the actin to "slide"
4. The combination of Myosin and actin filament create 3 important jobs in the cell: cellular movement (actin acts as a muscle and causes contractions and other motions that create a 3 step process from motion), cell division (actin filament pinches the plasma membrane), and cytoplasmic streams in long or large cells in which diffusion will take to long.

Intermediate Filaments:

• Structure:

1. Defined by shape, not material, but are fibers configured into a large cable

• Function:

1. This filament acts purely as a beam which holds the cell in it's particular shape and helps keep the nucleus and other organelles in their assigned locations.

Microtubules:

• Structure:

1. a hollow tube of helices of a-Tubulin adn b-Tubulin dimer
2. kinesin
3. Centrosome
4. Centriole

• Function:

1. The microtubules act just like the actin filament, however the microtubules are larger in diameter. They give support to the cell and allow for movement of molecules and nutrients.
2. The kinesin is the motor protein in microtubules that moves objects around. But unlike myosin, kinesin moves when the ATP is added and the protein creates the mechanical energy by "walking" up and down the microtubules.
3. This is the center for which microtubules are created and grow from this region.
4. Still have an unknown reason.

• Microtubules also help in cell division by forming cell plates during plant cell division and form the new cell wall. They also move chromosomes during division, along with organelles.
  

Energy Organelles

The Endosymbiant Hypothesis:

The hypothesis is a proposal discussing the present mitochondria and chloroplast stating that they were bacteria themselves that helped support other prokaryotic cells and eventually lost some of their organelles and became dependent on the host cells and the host cells remained dependent on it.

Mitochondria: (also contains chromosome (super coiled DNA) and manufactures ribosomes)

• Structure:

1. Double-bond membrane (Outer and inner)
2. Cristae are sac-like and are in a series. Connected to the inner membrane
3. Mitochondrial matrix is "fluid" or the cytoplasm
   

• Function:

1. Outer membrane supports and seperates the organelle from the cell and the inner gives internal support
   
2. Enzymes are embedded in the cristae or floating in the matrix, and help form ATP

Chloroplasts: (also contain seperate chromosome (super coiled DNA))

• Structure:

1. Double bound membrane (outer and inner)
2. Thylakoids (flat membrane bound vesicles)
3. Grana- stacks of thylakoids
   
4. Stoma

• Function:

1. Separate the the Chloroplast from the cytoplasm and give integrity to the organelle
2. Many of the pigments, enzymes, and molecular machines are embedded in the thylakoid which are grouped together, compartmentalization.
   
3. Other important enzymes are located i nthe stroma, "fluid."
   

Cellular Containers

Lysosomes:

• Structure:

1. Single Membrane
   
2. Integrated with transporters (Proton Pumps)
   
3. Many digestive enzymes on the inside

• Function

1. Houses the decomposition of Macromolecules
2. Allows for protons to enter the system and create an acidic environment of 5.0 pH
   
3. Acidic environment allows for optimum performance of enzymes to break down macromolecules into their monomers for waste or recycling

Peroxisomes:

• Structure:

1. Single Membrane, integrated transporters
2. Enzymes
   
3. Catalase

• Function: (dependent on the cell type, e.g. liver, kidney, plant)
  

1. Houses oxidation reduction (RedOx) reactions
2. These RedOx reactions breakdown special molecules and make safe products for trash or recycling and hydrogen peroxide
3. An enzyme that converts a product of RedOx reactions, hydrogen peroxide, into water and oxygen.

Vacuoles:

• Structure:

1. Single Membrane
2. Integrated transporters
3. Enzymes for specialized digestion
4. Ions and proteins

• Function:

1. Stores water to give structural support for the plant cell and houses other chemicals
2. Allow for entry of ions or exit of protein monomers, or other chemicals
3. Enzymes can break down certain chemicals (specialized vacuole) but seeds have vacuoles that contain enzymes and protein, in which the protein is broken down into monomers allowing growth for the plant.

Vesicles:

• Structure:

1. Membrane bounded bubbles

• Function:

1. Carry (transport) material around the cell, located mostly near the endomembrane system.
   

Prokaryotic Cells vs Eukaryotic Cells

Prokaryotic cells contain very little of an internal membrane structure, if at all. The Eukaryotic cell contains many membrane bounded organelles that are as complex as the prokaryotic cell.

Prokaryotic:

1. Cell Wall
2. Plasma Membrane
   
3. Flagellum
   
4. Plasmids
5. Ribosomes
6. Cytoplasm
7. Chromosome (Super-coiled DNA strand)
8. Nucleoid (non-membrane bound)
9. Cytoskeleton (small compared to the Eukaryote)
10. Glycolipids

Eukaryotic Cells (Animal & Plant)

1. Nucelus: Nuclear Envelope, Nucleolus, Chromosomes
2. Centrioles
3. Rough Endoplasmic Reticulum
   
4. Smooth Endoplasmic Reticulum
5. Ribosomes
6. Peroxisomes
7. Golgi Apparatus
8. Lysosome (Vacuole)
   
9. Mitochondria
10. Cytoskeletal structure
11. Plasma Membrane
12. Cell Wall
13. Chloroplast
14. Cytoplasm

Compartmentalization

2 Advantages:

1. Separation of Chemical Reactions to help maintain productivity of the cell by separating in compatible reactions.
2. Chemical Reactions increase in efficiency due to being kept together and organized by which products of one reaction "pop out" beside the enzyme necessary for another life sustaining reaction.

Nucleus

Structure:

1. Complex Double Membrane (Nuclear Envelope)
2. Nuclear Pores
3. Nuclear Lamina
4. Nucleolus

Function:

1. Protection of DNA and Chromosomes
2. Allow entry and exit of products and reactants, respectively
3. Cytoskeletal-like structure which maintains the integrity of the nucleus and keeps chromosomes in their "assigned" place
4. House for manufacturation of RNA molecules into Ribosomal subunits