2. What is the meaning of “life”?
• Primitive humans lived close to
nature. Every day they were
occupied with animals and plants,
as gatherers, hunters, or herdsmen.
And death – of infants and elders,
women in childbirth, men in strife –
was forever present. Surely our
earliest ancestors must have
wrestled with the eternal question,
“What is life?”
from This is Biology (Chapter One). Ernst Mayer. Harvard University
3. 1. Unique biochemistry
• The study of the molecular nature of
life’s processes is BIOCHEMISTRY.
• Six key elements found in all living
things:
– CHNOPS
– The study of carbon-containing
compounds is ORGANIC CHEMISTRY.
• Fundamental biochemical
similarities:
– Carbohydrates, lipids, proteins, nucleic
acids, ATP
– All life has a genetic program
4. 2. Organization & Cells
•Organization: Degree of order within an organism’s
internal and external structure & how it interacts with the
environment.
•Cells: Smallest unit that can perform all life’s
processes.
a. Unicellular= 1 cell (ex: bacteria)
b. Multicellular= Multiple cells (ex. trees, fish, you)
5. 3. Response to Stimulus
•A physical or
chemical change in
the internal or
external
environment.
Examples:
Dilating eyes in response
to change in light.
Pulling hand away after
touching hot stove.
Sneezing in response to
dust or allergies.
Leaves changing colors
during Fall.
6. 4. Homeostasis
• Maintaining a stable internal
environment even when environmental
conditions change.
• Example: Your body temperature is
maintained at approximately 98°F.
• When your body heats up, your sweat glands
secrete water to cool your skin.
• When you are cold, your body constricts the
skin (goosebumps) to conserve heat.
7. 5. Metabolism
• Sum of all chemical reactions that
involve taking in and transforming
energy & materials from the
environment.
• Purpose of metabolism is to obtain
energy for repair, movement, and
growth.
• Example: Plants, algae, and bacteria
use the sun’s energy to generate sugar
(food) through photosynthesis. You
depend on other organisms to obtain
energy.
8. 6. Growth & Development
• All living things grow which means
increase in size
– by enlarging
– by the cells dividing
• All living things change to form
fully functional mature forms.
• All living things have a lifespan.
9. 7. Reproduction
• Production of new organisms.
• Reproduction, unlike the other
characteristics, is not essential to the
survival of an individual organism. It is
essential for the survival of the species.
• During reproduction, organisms pass on
genetic information (DNA) to their
offspring.
• Sexual: hereditary information is combined
from 2 organisms of the same species.
• Asexual: hereditary information from
different organisms is not combined ~ the
original organism and new organism are
genetically the same. Ex) bacteria
10. 8. Adaptation and Evolution
• Although individual organisms
experience changes during their
lifetime, their basic genetic
characteristics do not change.
Populations of living
organisms evolve or change
over long periods of time in
order to survive in a
changing environments.
Example: MRSA
Editor's Notes
All life forms represent a dualism not found in the inanimate (nonliving) world. This dualism arises from the fact that organisms possess both a genotype (nucleic acids-DNA) and a phenotype (the product of the instructions from the genotype). There are phenomena specific to living things that result in specific characteristics attributed to being “living.”
To be considered alive, an object must exhibit ALL of the characteristics of living things.
All living things are made of one or more cells.
Living things have an orderly structure; they possess certain structures for certain functions.
Organization = complex patterns and arrangements
*Living things are made up of the same atoms/elements as inanimate matter. However, the molecules responsible for the development and functioning of living organisms (organic chemistry and biochemistry) are NOT found in inanimate nature.
**CHNOPS
Living things have parts that work together. (The whole is greater than the sum of its parts.)
In most multicellular organisms, cells and groups of cells are organized by their FUNCTION. Different types of cells have different jobs/roles within an organism.
Environment = surroundings, including air, water, weather, temp, other organisms, etc.
Stimulus = any condition in the environment that requires and organism to adjust
Response = reaction to a stimulus
Coordination and regulation of internal processes = control mechanisms to maintain a steady state of the system
Allows for organisms to ADJUST to their surroundings.
Transport
All living things need and use energy.
Living things take in substances and organize/reorganize them.
Autotroph = self-feeder; produce their own food (photosynthesis, chemosynthesis)
Heterotroph = other-feeder; get food from other organisms
Nutrition
Respiration
Synthesis
Excretion
Being open systems, living things are not subject to the limitations of the second law of thermodynamics (disorder, entropy)
Growth = an increase in the amount of living material and the formation of new structures.
Growth = cell division and cell enlargement
Development = all of the changes that take place during the life of an organism; go through stages to become fully functional “adults”
Development includes DIFFERENTIATION – cells become different from one another; specialized
The process by which an adult organism arises is called development.
Living things have a lifespan.
Reproduction = production of offspring (the next generation)
Organisms don’t live forever. All life forms have a start and an end. They grow and develop in various ways from species to species, but the end result is the continuation of the species via reproduction.
Evolved Programs – These are the genetic programs of 3.8-4 billion years of evolutionary history. All development, behavior, and other activities of living organisms are controlled by the genetic information accumulated throughout the history of life.
Evolution
Adaptation = any structure, behavior, or internal process that enables an organism to respond to stimuli and better survive in an environment
MRSA = Methicillin-resistant Staphylococcus aureus
