Chapter 7

Part 3

•In this section, we will cover the specifics of PROKARYOTES or PROKARYOTIC CELLS

Two Basic Types of Cells page 173

•With the development of better microscope, scientists observed that all cells contain small, specialized structures called ORGANELLES

• Each organelle has a specific function for the cell and many, not all, are surrounded by a membrane

• Cells can be divided into two broad groups:–1. those that contain membrane bound

organelles- classified as EUKARYOTIC CELLS (“eu” means “true”)–2. those that DO NOT contain membrane

bound organelles- classified as PROKARYOTIC CELLS (Greek word for “before nucleus”)

• Examples of EUKARYOTES:–Plants, animals, protists, fungi,

algaeExample of PROKARYOTES:•Bacteria and archaebacteria

Prokaryotes: Quick Facts

• 3 groups: archaeobacteria, cyanobacteria, true bacteria• No membrane bound nucleus• Chromosomes located in “nucleoid” or “plasmid”• Have a cell wall and a cell membrane• unicellular• Have appendages such as fimbriae, pili, and flagella• Smaller than eukaryotes• About 1-2 micrometers in diameter and 10 micrometers

long)• Reproduction is always asexual

Prokaryote Structure

Prokaryote Structure

1. A cell membrane, usually surrounded by a cell wall and sometimes by an additional outer layer

2. An internal cytoplasm with ribosomes, a nuclear region, and in some cases granules and or vesicles

3. A variety of external structures, such as capsules, flagella, and pili

Prokaryote Size

• Among smallest of all organisms• Large surface to volume ratio• Large SA:V means no internal part of the cell is

very far from the surface and that nutrients can easily and quickly reach all parts of the cell

External structures

• about ½ of bacteria are motile• 1. Flagella- long, thin, helical appendage. A

bacteria can have one, two or many flagella.

External structures cont…..

• Pili- tiny, hollow projections that attach bacteria to surfaces and are not involved in movement

• Glycocalyx- polysaccharide containing substance external to the cell wall– Capsule- protective structure

– Slime layer- protects against drying, traps nutrients, enables bacteria to adhere to surface, connects cells together. This is how plaque forms on our teeth

Chemotaxis and phototaxis

• Chemotaxis- bacteria moving toward or away from substances in their environment by a non random process as a response to the concentration of solutes in their surrounding

•Phototaxis- bacteria moving toward or away from light

Prokaryote shapes

• 3 basic shapes

• Spherical, rodlike, and spiral• Spherical called a coccus• Rodlike called a bacillus• Spiral are called vibrio, spirillum

or spirochete

Prokaryote Classification

• Science uses a 5 kingdom classification system• “5 kingdoms of life”• Plantae, Fungi, Animalia, Protista, Monera• Some taxonomists have recommended the

creation of a 6th kingdom for archaeobacteria and renaming Monera as eubacteria

Kingdom Monera

• Otherwise known as kingdom Prokaryotae• All prokaryotic organisms• Includes true bacteria (eubacteria),

cyanobacteria, archaeobacteria

Cyanobacteria

• Formerly known as blue green algae• Photosynthetic• Process of Nitrogen fixation• Responsible for algae blooms• No harm to humans

Archaeobacteria

• Primitive prokaryotes• Adapted to extreme environments• Environments such as excessively salty

environments, hot, or acidic environments

Factors affecting growth

• pH- microorganisms have an optimum pH- the pH at which they grow best. Most do not grow at a pH more than 1 pH unit above or below their optimum pH

• Temperature-

Bozeman Biology

• http://www.youtube.com/watch?v=sv2q1t9YjsM

• Answer questions with this 9 min. video

Antibacterial Products

• An anti-microbial is a substance that kills or inhibits the growth of microorganisms[1] such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes (microbiocidal) or prevent the growth of microbes (microbiostatic). Disinfectants are antimicrobial substances used on non-living objects or outside the body

Hand washing

• Hand washing has been the primary method of controlling the spread of infectious disease for over 100 years.

Antibacterial cont……..

• Do antibacterial products do more harm than good?• Research shows that these products can cause

bacterial resistance, thus decreasing the effectiveness of antibiotics. Antibiotics kill more than the disease causing bacteria to which they are directed. They kill any other susceptible bacteria. Once the ecosystem is cleared of susceptible bacteria, resistant bacteria can multiply and dominate the environment due to lack of competition.

Infants and Bacteria

• Antibacterial cleaners may hurt a baby’s immune system rather than keeping him or her healthy.

• Exposure to bacteria is essential for development of an infant’s immune system

• A baby must be exposed to germs during its first year in order to develop the antibodies needed to fight infection later in life

Cleaners….

• Strong antibacterial cleaners are needed only when someone in a household is seriously ill or has low immunity. CDC suggests using antibacterial products if you work with food, childcare, or health care situations

• Soap, hot water, alcohol, chlorine bleach, and hydrogen peroxide are sufficient for most purposes

Triclosan

• The most common ingredient in antibacterial products is triclosan, which is used in surgical scrub and has bacteria-fighting properties

• Found in toothpaste, acne creams, deodorants, lotions, and liquid soap

• What are the environmental effect s of chemicals like triclosan? (research has shown that 95% of products containing triclosan are disposed of through residential drains)

Triclosan Dangers

• Must stay on a surface for 2 minutes to be effective. Most people rinse it off before then

• Triclosan can react to chlorine in drinking water and form chloroform, which is a carcinogen

• When triclosan reacts with light, it forms poisonous dioxins

• Majority of women are now showing traces of triclosan in their breast milk

Safer antibacterial alternatives

• Regular soap and water• Alcohol rubs• Friction- rub hands long enough when

washing or using alcohol rubs• Most common diseases are viral in nature and

therefore not prevented by antibacterial products

Beneficial Bacteria in our Body

• In our gut- A substantial part of our immune system depends on these healthy flora

• humans cannot fully utilize starches without outside help

• gut flora outnumber the cells of our bodies by 10 to 1). There are around 10 trillion cells that make up the human body, and we have around 100 trillion bacteria cells in our digestive tracts.

Gut Bacteria

• Tiny organisms, mostly bacteria, who live in our GI tract, help us to digest food, aid nutrient absorption, produce certain key vitamins, prevent disease, and much, much more. These tiny organisms actually make up three to five pounds of our total body weight!

Probiotics

Antibiotics

• Antibiotics are generally used to treat bacterial infections.

• prolonged use of certain antibiotics can decrease the number of gut flora, which can have a negative impact on health. Some recommend that, during or after prolonged antibiotic use, one should consume probiotics and eat reasonably to replace destroyed gut flora.

Penicillin

• Alexander Fleming in 1928• At the time, however, the importance of Alexander

Fleming's discovery was not known. Use of penicillin did not begin until the 1940s when Howard Florey and Ernst Chain isolated the active ingredient and developed a powdery form of the medicine.

• Penicillin is one of the earliest discovered and widely used antibiotic agents, derived from the Penicillium mold.

• many types of bacteria are now resistant

Harmful Bacteria and their Diseases

• E. Coli

E coli

• Escherichia coli • The harmless strains are part of the

normal flora of the gut, and can benefit their hosts by producing vitamin K2,and by preventing the establishment of pathogenic bacteria within the intestine.

• fecal-oral transmission is the major route through which pathogenic strains of the bacterium cause disease.

• Gram negative• Rod shaped• Have flagella

• Salmonella

Salmonella

• cause illnesses like typhoid fever, paratyphoid fever, and foodborne illness

• Salmonella can survive for weeks outside a living body

• To protect against Salmonella infection, it is recommended that food be heated for at least ten minutes at 75 °C (167 °F) so that the centre of the food reaches this temperature.