Cells http://voicethread.com/share/38354/


Outline the Cell Theory
  • Living organism are composed of one or more cells
  • Cells are the smallest unit of life
  • All cells must come from pre-existing cells

Discuss the evidence for the cell theory:



State that unicellular organisms carry out all of the functions of life
  • Metabolism; chemical reactions inside the cell, including cell respiration to release energy
  • Response; perceiving and responding to changes in the environment
  • Homeostasis; keeping conditions inside the organism within tolerable limits
  • Growth; an irreversible increase in size
  • Reproduction; producing offspring either sexually or asexually
  • Nutrition; obtaining food, to provide energy and the materials needed for growth


Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit
nm = nanometer um = micrometer


  • Molecules - 1 nm
  • Thickness of membrane - 10 nm
  • Viruses - 100 nm
  • Bacteria - 1 um
  • Organelles - up to 10 um
  • Most cells - up to 100 um (three dimensional nature/shape)



Calculate the linear magnification of drawings and the actual size of specimens in images of known magnifications


  • :Drawings should show cells and cell ultrastructure.
Include:A scale bar: |------| = 1 µmMagnification: ×250To calculate magnification:
  • Magnification = Measured Size of Diagram ÷ Actual Size of Object



A phospholipid has a bilayer, on the outside there is the hydrophillic layer which means it likes water and there is the second layer on the innermost part called the hydrophobic layer. This layer does not like water. if the layer were to be seperated by breakage and exposed to water then there would be a desire of the exposed hydrophobic layer to not be touched by water. the layer would be pushed together by pressure because of its desire to stay away from water.

external image lipidbilayer.gif
Some functions of membrane proteins are that they are flexible and can reform when they are unattached. They also transport molecules in and out of the cell and gives messages for metabolism messgaes for horomnes and neurotransmitters.

Diffusion- the spontaneous tendency of a substance to move down ts concentration to a less concentrated are. Particles move from an area of higher to lower concentration.
EXAMPLE:
Oxtgen and Carbon Dioxide
oxygen is diffused into the cell, mitochondria converts oxygen and other foods into carbon dioxide and the carbon dioxide diffuses out of the cell.

Osmosis- the movement of water through the semi-permeable membrane. It is how much water moves through a cell through active or passive transport.
EXAMPLE:

external image osmosis.gif
In passive transport there is facilitated diffusion and diffusion. In facilitated diffusion the molecules are assisted through the membrane of a cell witht the aid of a protein carrier that has a specificity for that paticular substance.
EXAMPLE:


external image GB1-os19.jpg
In regular diffusion the molecules move from a higher to a lower concentration. In passive transport molecules move in and out of the cell but it uses NO ENERGY!!!!

EXAMPLE:


external image c8.7x11.diffusion.jpg

In active transport there is a reqirement for energy for the tranportation of molecules in and out of the cell. This energy vomes in the form of ATP and when one of the phosphate groups break off fro the ATP ths making it APD. The phosphate attaches to the protein pump which allows the pump to open and close.
EXAMPLE:

For a NaK pump:
3 Na ions and the phosphate from the ATP which is now ATP, attach to the pump. The phosphate gives the pump energy to open, when the pump opens the 3Na can leave and the pump now has the specififcity to allow K in the pump, since there is a desire for K in the cell since Na just left. The K enters the cell with the help from the phosphate. This moves from a high to low concentration, so it is moving against its concentration gradient.

EXAMPLE:


external image active_transport.jpg

Vesicles are little sacs that hold information that connect organelles to one another. So protein comes from the Rough ER and then though a vesicle it is transprted to the Golgi Apparatus in which the protein matures. After the proteins mature it is diffused to the different parts of the cell that needs the protein and through the vesicles the protein is transported out of the plasma membrane, which is known as exocytosis. And the taking in is called endocytosis.
EXAMPLE:


external image endocytosis_types.png


The cell membrane of a cell is made up of a phospholipid bilayer. the later cancan bend and it also breaks so that material may transfer in and out of the cell and then it can just reattach. Because of the fact that the membrane is fluidity, when it is hit it does not just burst but it absobs the shock. if cells were to break everytime they can in contact with another peole would be really unhealthy and sick because all of there cells would be popping and it would be unable to do its job. because it is fluidity it can change its shape to move from place to place and molecules may enter the cell to give it nutrients without doing damage to the cell.

EXAMPLE:


http://www.youtube.com/watch?v=LKN5sq5dtW4&feature=related


Explain the importance of the surface area to volume ratio as a factor limiting cell size.

Every cell needs a surface area large enough to support its volume or contents of the cytoplasm. These two variables must be directly proportional for the cell to function properly. If the volume of a cell proportionally exceeds its surface area, then it will not be able to exchange necessary substances fast enough to support its cytoplasmic contents. Also, the fact that a cell can only reach a certain size before dividing is important because the surface area to volume ratio sets an upper limit on cell size.

State that multicellular organisms show emergent properties.
Emergent Properties= New properties that emerge with each step up in the heirarchy of life, owing to the arrangement and interactions of parts as complexity increases.
These properties arise from the interaction of component parts. In other words, a multicellular organism develops properties based on the complex interactions between its job specific cells. It can therefore be said that an organism is more than the sum of its parts due to the fact that new properties emerge from the complexity of an organism and the relationship between its cell groups.


Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.
Contrary to unicellular organisms, multicellular organisms dont have just one cell that must fulfill all of the life processes within that singular cell. Multicellular organisms can differentiate into many different cell types which specialize on a certain set of functions for example muscle cells and nerve cells. It is much like how an assembly line works in that there are groups of workers that do a certain job and nothing else. This division of labor between cell groups results in a much greater efficiency.
How do organisms achieve this differentiation?
-Cells undergo a type of specialization in form and function.
-All cells have identicle genomes however cells within a specialized group can express their genes differently than cells in a different.
-Some genes can be turned on and others can be turned off for the desired function of the cell.


Draw and label a diagram of the ultrastructure of E. coli as an example of a prokaryote.


001.jpg

Cell Membrane= Regulates what substances enter and leave the prokaryotic cell.
Cell Wall= Gives rigidity and structure to the cell. It also protects from physical abuse and prevents the cell from bursting in a hypotonic environment.
Nucleoid= Location of the prokaryotic chromosone. Unlike eukaryotic cells, the nucleoid is not bound by a membrane.
Cytoplasm= The cytoplasm suspends the contents of the cell. Especially important in prokaryotic cells because they do not have membrane bound organelles.
Ribosomes= Organelle that floats freely in the cytoplasm of a prokaryotic cell. Facilitates the orderly linking of amino acids into polypeptide chains. In other words, they synthesize proteins.
Flagella= Locomotion appendages that are located at a concentrated point (as shown above) or scattered around the cell. They can propell the cell up to 50 times its body length per second.
Pili (pilus)= Hairlike prokaryotic appendage that is used to adhere to other cells or transfer DNA during conjugation. During conjugation or "bacterial sex", the pili are used to grasp a mate cell and pull them in. Then, a cytoplasmic bridge is formed to transfer DNA.


Identify structures in an electron micrograph of E. coli.

external image bacteriatem.gif

-The area on the very outside is the capsule of the E. coli cell.
-Directly inside of the capsule is the cell wall.
-Directly inside of that is the cell membrane.
-The lighter colored region is the nucleoid of the E. coli cell.
-The small, dark colored dots are protein synthesizing ribosomes.


Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell.
external image moz-screenshot-1.jpgexternal image moz-screenshot-2.jpgexternal image anatomy.GIF

Annotate the diagram of Ecoli with functions of each named structure

Cytoplasm-What the Organelles float around in.
Cell Wall - Structure
Pilli - Movement
Flagella - Movement
Nucleoid - Where the DNA floats around
Capsule - Protects from desiccation, and allows E coli to cling to surfaces.
Ribosomes - Produce proteins

Compare prokaryotic and eukaryotic cells

Eukaryotic cells are bigger. Eukaryotic cells have nucleuses with envelopes when prokaryotic cells just have nucleoids. Prokaryotic cells have flagella, pilla, and cilia when Eukaryotic cells don't.

State three differences between plant and animal cells

1. Plant Cells have Cell Walls
2. Plant Cells have Chloroplasts
3. Plant Cells only have one Vacuole when Animal Cells have many.

Outline two roles of extracellular components

1. Plant Cell walls keep the shape of a plant cell.
2. Plant Cell walls stop them from intaking excessive amounts of water.

Draw and label a diagram to show the structure of membranes

external image plasmamembranefigure1.jpg