What is life?

[The Jays]

Theme #1 - Cells

All living things are composed of one or more cells. Different types of cells have different "jobs" within the organism. Each life form begins from one cell, which then will split. These cells split, and so on. After this has happened several times, differentiation is undergone, when the cells change so that they are not the same thing anymore. Then they are used to begin to put together the final organism, some cells, for example, as the eyes, some as the heart, etc. The only arguable exception to this is viruses. They are not composed of cells, but are said to be "living."

Theme#2 - Organization

Complex organization patterns are found in all living organisms. They arrange themselves on very small levels, grouping like things together. On larger levels, they become visible. This also has to do with differentiation, as the cells are organized in a manner that makes sense for the organism after they change to what they’ll be in the final organism.

Theme#3 - Energy Use

All organisms use energy. The sum of the chemical energy they use is called metabolism. This energy is used to carry out everything they do. Autotrophs (plants) use energy from the sun for photosynthesis, to make their own ‘food’ (glucose). Heterotrophs (animals and humans) must ingest food for this purpose.

Theme#4 - Homeostasis

All organisms have stable internal conditions which must be maintained in order to remain alive. These include temperature, water content, heartbeat, and other such things. In a way, this has to do with energy use, because a certain level of energy must be kept within the body at all times. For this, obviously, humans must then ingest food on a regular basis. Not all conditions are for the body to maintain itself; though most are.

Theme#5 - Growth

All organisms grow and change. Cells divide to form new, identical cells. Differentiation happens, as well, when cells mutate into other types of cells, making a more complex organism. Organisms growing, changing, and becoming more complex is called development. Single-celled organisms do grow as well, but they will only become slightly larger – this is nearly unmeasurable.

Theme#6 - Reproduction

All organisms reproduce in order to continue the species' life. This is combining genetic information (in sexual reproduction) or splitting into two organisms (in asexual reproduction) in order to create another of the same species. In sexual reproduction, the new organism will have some characteristics from the mother, and some from father. It may look like either of them, or it may not. In asexual reproduction, the new organism is an exact copy of the first. Sometimes, not every member of a species is able to reproduce. As long as others are (which we know they can, if they still exist today) then it does not threaten the species. (Except for mules, but don't worry about them, they are a bizarre anomoly.)

What is life?
I.
Six characteristics
a. Cells
a.
All living things are composed of one or more cells.
b.
Different types of cells have different "jobs" within the organism.
c.
The only arguable exception to this is viruses. They are not
composed of cells, but are said to be "living."
b. Organization
a.
Complex organization patterns are found in all living organisms.
c. Homeostasis
a.
All organisms have stable internal conditions which must be
maintained in order to remain alive.
b.
These include temperature, water content, heartbeat, and other
such things. In a way, this has to do with energy use, because a
certain level of energy must be kept within the body at all times.
d. Growth
e. Reproduction
a.
All organisms reproduce in order to continue the species' life.
b.
This is combining genetic information (in sexual reproduction)
or splitting into two organisms (in asexual reproduction) in order to
create another of the same species..
f. Energy Use
a.
The sum of the chemical energy-metabolism
b.
Autotrophs use energy to reduce carbon dioxide to organic
carbon
1.
Photosynthesis by plants and phytoplankton with energy
from the sun
2.
Chemosynthesis using chemical reactions that release
energy
a.
Example: Ocean vent communities where colorless
sulfur bacteria use sulfur
c.
Heterotrophs require organic matter to grow
d.
If there is air, aerobic respiration makes the most energy
e.
Anaerobic respiration occurs where there is no air
1. Very important, as by product is methane, an important
greenhouse gas
2. Autotrophic methane production- CO
2
+ 4H
2
- CH
4
+ 2H
2
O
a. Example: mud flats where H2 concentrations
high
3. Heterotropic methane production- CH
3
COOH- CH
4
+ CO
2
a.
Example: bacteria in cow guts, fermentation
4. Sources of methane in modern climate: cow farts, rice
paddies, landfills, natural gas production