Daily Science Discussion review with Miss Hager about requirements of life

Bacteria Biology I

Bacteria Basics All bacteria are single-celled organisms. Bacteria are prokaryotes. Typically range in size between 1-5 micrometers. 1 micrometer = 10-9 meters

Bacteria Types Eubacteria Archaebacteria/Extremophiles Live almost everywhere (fresh water, salt water, land, and living organisms). Most common type of bacteria. Archaebacteria/Extremophiles Most live in extremely harsh environments. Believed to be the ancestors of eubacteria and eukaryotes.

Bacteria Shapes & Arrangements Bacteria are usually classified by their arrangement and shape. Shapes include: Rods (bacilli, plural bacillus) Spheres (cocci, plural coccus) Spirals (spirillium, plural spirilla) Arrangements include: Pairs (diplo) Chains (strepto) Irregular, grape-like clusters (staphylo)

Bacteria Arrangements - Examples Staphylococcus

Bacteria Arrangements - Examples Streptococcus

The Ways Bacteria Move Some bacteria never move. Some bacteria move with flagella. Flagella – a whip-like structure that moves back and forth. Other bacteria lash, snake, or spiral forward. Some bacteria even glide along a layer of slime-like material that they secrete from their body.

Bacteria Metabolism Heterotrophs – cannot make their own food. Humans and animals are examples of heterotrophs. Autotrophs – can make their own food. Plants are examples of autotrophs.

How Bacteria Release Energy Obligate Aerobes – require oxygen to live. Example: Mycobacterium tuberculosis Obligate Anaerobes – cannot live in oxygen. Example: Clostridium botulinum Facultative Anaerobes – do not require oxygen, but are not harmed by its presence. Example: Escheria coli

A Planet Covered in Bacteria! Bacteria reproduce at astonishing rates. Some bacteria can reproduce as often as every 20 minutes! If unlimited food and space were available: One single bacterium that divided every 20 minutes would reach a mass approximately 4,000 times that of Earth in just 48 hours!

Growth & Reproduction Binary Fission Occurs when a bacterium grows to nearly double its original size. The bacterium makes a copy of its DNA and divides in half, producing two “daughter” cells. There is no exchange or recombination of genetic material (asexual reproduction).

Growth & Reproduction Conjugation Some bacteria can exchange genetic information. A hollow bridge forms between two bacterial cells and the genes pass from one cell to the other. This increases the genetic diversity of bacteria populations (sexual reproduction).

Growth & Reproduction Spore Formation Occurs when growth conditions become unfavorable. The bacteria form structures called spores. The spores can remain dormant for months or even years while waiting for more favorable conditions. Once conditions improve, the bacterium will grow again. Allows bacteria to survive harsh conditions like extreme heat, dryness, or lack of nutrients that might otherwise kill them.

The Importance of Bacteria While many bacteria can be harmful or cause disease, bacteria are vital to maintaining the living world!!!

Importance of Bacteria Decomposers When every living thing dies, it leaves behind a supply of raw materials that need to be broken down so that other living things can use them. Some bacteria act as decomposers and help the ecosystem recycle important nutrients. Example: when a tree dies, armies of bacteria attach and digest the dead tissue, releasing it into the soil. Bacteria also decompose sewage, discarded food, and chemical waste.

Importance of Bacteria Nitrogen Fixers Plants need nitrogen to make amino acids (long chains of amino acids are proteins). There is nitrogen in the air (N2), but plants cannot directly use N2. Bacteria living in the soil (and sometimes in the roots of the plant itself) convert the nitrogen gas (N2) into ammonia (NH3), which the plants can use.

Importance of Bacteria Humans use bacteria in a variety of ways. Foods and beverages. Cosmetic products. Cleaning up small oil spills. Purifying water. Make medicines and chemicals. Symbiotic relationships. Example: E. coli live in the intestines of humans and make a number of vitamins that the body cannot produce by itself (in exchange for a warm home with plenty of food).