LIFE SCIENCES

CHARACTERISTICS OF LIVING THINGS

Organisms are HIGHLY ORGANIZED. All organisms are made up of the same basic components, kind of building blocks: CELLS. (ORGANISM is an entire and independent living thing)

CELLS ARE THE UNIT OF STRUCTURE AND FUNCTION OF LIVING THINGS. CELLS CONTROL AND REGULATE THEIR OWN ACTIVITY.

CHARACTERISTICS OF ALIVE BEINGS

1. They have a complex, organized structure mainly made of organic molecules.

2. They respond to stimulation from the environment that surrounds them.

3. They keep actively their complex structure and their intern environment; this process is called homeostasis.

4. They obtain and use materials and energy of it’s environment and turn them in different forms.

5. They grow.

6. They reproduce, using a molecular pattern called DNA.

7. They generally posses the capacity to evolve and adapt.

IRRITABILITY: Organisms respond to stimuli in different ways.

REPRODUCTION: Process by which organisms produce more of their own.

HOMEOSTASIS

Organisms are able to maintain a nearly constant internal environment, although the surrounding may change. Homeostasis is the regulation of an organism’s internal environment to maintain conditions suitable for life.

Prokaryotes

Prokaryotes are organisms without a cell nucleus, or any other membrane-bound organelles. Most are unicellular, but some prokaryotes are Multicellular organisms.

The prokaryotes are divided into two domains: the bacteria and the archaea. Archaea or Archaebacteria are a newly appointed kingdom of life. These organisms were originally thought to live only in inhospitable conditions such as temperature, pH-extremes, and radiation, but have since been found in all types of habitat.

From Old Greek pro - before + karyon nut or kernel, referring to the cell nucleus, + suffix –otos.

KIND OF CELLS

Eukaryotes

Animals, plants, fungi, and protists are eukaryotes, organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. The most characteristic membrane bound structure is the nucleus. In the nucleus the genetic material, DNA, is arranged in chromosomes. Many eukaryotic cells also contain membrane-bound organelles such as mitochondria, chloroplasts and Golgi bodies. Eukaryotes often have unique flagella made of microtubules in a 9+2 arrangement.

from the Greek ευ, meaning good/true, and κάρυον, meaning nut, refering to the nucleus

DNA

Short for Deoxyribonucleic acid

All genetic information as well as the instructions for making proteins is contained here

Its structure was discovered by James Watson and Francis Crick

DNA structure

Is composed of two strands of nucleotides forming a double helix

Nucleotides are composed of a simple sugar called deoxyribose, a phosphate group and a nitrogen containing base.

Concentration gradient: difference in concentration of a substance between one region and another

Diffusion: process by which molecules move randomly from regions of high concentration to regions of low concentration

Osmosis: movement of water through a differentially permeable membrane. Responds to concentration gradient

CONCEPTS

How does substances move across membranes?

Passive transport :Substances move down concentration gradient. There’s no energy expenditure.

Active transport. Use energy to move substances against a concentration gradient

Osmosis

“Pure” water has higher concentration of water molecules than other water solution with any substance added.

A differentially permeable membrane has pores just large enough for water to pass through but small enough to be impermeable to any other molecule.

What is a Population?

A population is one species living in a specific area.

For example, all foxes living in an area form a population.

Another example, all dandelions growing in an area form another population.

What is a Community? A community is formed from all living

populations found in an area. All the foxes, dandelions, grasshoppers,

snakes, hawks, deer, and skunks living in one area each form their individual populations, but together make up a community.

What is a Ecosystem? An ecosystem is formed by the

interactions between all living and non-living things

What is Ecology?Ecology is how living and non-living things affect each other in their environment.

The geography of ecosystems