Bacteria science#6(showas5)

Chapter 7 Section 1

BACTERIA

* A pathogen is a disease-causing organism – a living microbe that can make a person sick.

* Bacteria are unicellular (one-celled) organisms- a bacterium is a prokaryotic cell – a cell with no

membrane-bound structures

- Bacteria are found in almost every environment

- Bacteria are microorganisms because they are so small they cannot be seen without a microscope

INSIDE A BACTERIUM:

• A typical bacterial cell contains:- cytoplasm- cell membrane- cell wall- one chromosome- free ribosomes

They are much simpler than eukaryotic cells

• Many bacteria that live in moist conditions have flagella, which are whip-like tails that help them move.

• Bacteria reproduce by a process called fission

- fission produces two new cells with genetic material identical to each other and to the original cell

- fission is the simplest form of asexual reproduction

http://www.youtube.com/watch?v=DY9DNWcqxI4

• Bacteria take in nutrients in a variety of ways, depending on the type of bacteria it is.

- Some bacteria contain chlorophyll and make food using energy from the sun

- Some use energy from chemical reactions

- Some are producers, organisms that can make their own food, while others are consumers, which cannot make their own food

- Some consumer bacteria are parasites, absorbing nutrients from a living host

• An aerobe is an organism that uses oxygen for respiration

• An anaerobe lives without oxygen

• Some bacteria are aerobic; others, such as the bacteria that live in the human intestinal tract, are anaerobic.

• Many bacteria are helpful.

- probiotics are bacteria used in dietary supplements that are good for digestive health

- Lactobaccilus Acidophilus (L. Acidophilus) are bacteria used in making yogurt cultures

- The anaerobic bacteria in the intestines aid in digestion

• Harmful bacteria include:- E. coli- Salmonella- Streptococcal bacteria- Bacteria that cause pneumonia

• Antibiotics are bacteria that limit the growth of other bacteria; an antibiotic weakens or kills the illness-causing bacteria

• A vaccine can be made from either bacterial or viral pathogens