Describe: Viruses, Prions, & Viroids...Examples of each

Virus- Depends on the host cells that they infect to reproduce. Viruses exist as a protein coat or a capsid, when found outside the host cells. The genetic material found in viruses can be DNA or RNA, but not both. It can be single or double stranded. The virus can insert its genetic material into the host cell, when the genetic material is inserted it can cause uncontrolled growth of the cell, and eventually leads to a tumor formation.

Examples of viruses are:

• Tobacco Mosaic Virus(TMV)




• T4 bacteriophage




• Human Immunodeficiency Virus(HIV)

http://www,ucmp.berkeley.edu/alllife/virus.html

http://www.accessexcellence.org/RC/VL/GG/examples_of_viruses.php

Prions- An infectious protein particle similar to a virus but lacks nucleic acid: thought to be the agent responsible for scrapie and other degenerative diseases of the nervous system.

An example of a prion is:

• CJD(Creutzfeld-Jacob Disease)

http://www.wordnetweb.princeton.edu/per/webwn?s=Prion

http://www.sourcewatch.org/index.php?title=Prion

Viroids- Or virusoid, the smallest of viruses; A plant virus with its RNA arranged in a circular chromosome without a protein coat.

Examples of viroids are:

• Potato spindle tuber viroid- first viroid discovered(1967)


• Coconut cadang- cadang viroid-samll (246 bases) but most virutent.

http://www.wordnetweb.princeton.edu/per/webwn?s=Viroid

http://www.micro.siu.edu/micr302virus.html

Describe the characteristics necessary for life?

Some characteristics of life are:

1. Composed of cells
2. Organization
3. Use energy(need food)
4. Response
5. Growth
6. Reproduction
7. Adaption
8. Genetic Material(DNA)
9. Metabolism
10. Homeostasis

Explain why transport is essential for life?

Transport is essential for life because without it the cells can't import or export materials or maintain life-sustaining activities.

Compare & Contrast Passive & Active Transport

• Something that distinguishes active and passive transport is the use of metabolic energy and the direction of the flow of materials.


• Passive transport does not expand metabolic energy, and also the flow of materials is down the concentration gradient. In passive transport the materials move to reach equilibrium.


• On the other hand active transport uses metabolic energy and also the material flow is against the concentration gradient. And in active taransport materials accumulate on one side of the membrane.

Discuss Cellular Transport

Two types of transport move materials across the Plasma Membrane: Passive & Active Transport.

An examples of Passive Transport are: Diffusion, Osmosis, & Facilitated Diffusion.

Diffusion is the movement of substances with the concentration gradient.

Osmosis & Facilitated Diffusion are kinds of Diffusion.

Osmosis is the movement of water through a semipermeable membrane. Water moves from high to low concentration, that is towards the area where there is more solute, so that means, less water. Less water is: Hypotonic Solution, & more solute is: Hypertonic Solution. If the semipermeable membrane separates the hypotonic from the hypertonic solution, the water will move across the membrane from the hypotonic to the hypertonic solution. NO metabolic enenrgy is involved.

Facilitated Diffusion is the diffusion of a substance across a membrane. It is called "Facilitated" because a transport protein in the membrane enhances the transport of the substance across the membrane.

Active transport uses energy(in the form of ATP), and the materials flow against the concentration gradient. Carrier-mediated active transport systems use energy & membrane proteins to "pump" certain substances against the concentration gradient.

Compare & Contrast Eukaryotic & Prokaryotic Cells

Compare

1. Similar basic metabolism.


2. Both very diverse in forms.


3. Both have DNA as their genetic materials.


4. Both have ribosomes.

Contrast

Prokaryotic

1. No membrane bound organelles.


2. No nuclear membrane or nucleoid region.


3. Found only in Kingdoms: Archabacteria & Eubacteria.


4. Size: 0.1um-10um.

Eukaryotic

1. Has membrane bound organelles.


2. Definite membrane bound nucleus.


3. Found only in Kingdoms: Animal, Plant, Fungi, & Protista.


4. Size: 10um-100um.