chapter 17 monerans or prokaryotic cells. what are monera? remember from our classification notes...
TRANSCRIPT
Chapter 17
Monerans
Or Prokaryotic Cells
What are monera?
• Remember from our classification notes that one of the five kingdoms is the kingdom monera.
• Consists of the smallest organisms on the planet.
• They are mostly prokaryotic– Meaning they don’t have a nucleus
Classification of Monerans: (four phyla)
1. Eubacteria: “true” bacteria– Contains the most number of species of all the
monera phyla– Usually referred to as bacteria– Consist of a cell wall made of complex
carbohydrates (protects bacterium from injury– Cell membrane surrounding cytoplasm (some have
two cell membranes)– Some have long whip-like flagella which protrude
from the membrane through the cell wall (used for movement)
– Different jobs: nitrogen fixers, photosynthetic, and disease causers in other organisms
Classification of Monerans: (four phyla)
2. Cyanobacteria: photosynthetic bacteria – AKA blue-green algae –but now we only use
algae for eukaryotes– Those that are blue-green in color contain a
blue pigment called phycocyanin and also chlorophyll-a which is green.
– The presence of other pigments may change the color to yellow, brown and even red.
Classification of Monerans: (four phyla)
– Contain membranes that carryout the light reactions of photosynthesis.
• These membranes are quite different from and simpler than chloroplasts in plant cells.
– Found throughout the world in fresh water and salt water and on land
– Few species can survive in extremely hot water, others can even grow on snow
– They are often the first species to recolonize after a natural disaster –ex a volcanic eruption.
Classification of Monerans: (four phyla)
3. Archaebacteria – Includes organisms that live in extremely harsh
environments– Example: one group lives in oxygen-free
environments such as mud or digestive tracts of animals. These are called methogens because they produce methane gas
– Other species live in extremely hot environments such as hot springs which can reach almost the boiling point of water.
Classification of Monerans: (four phyla)
4. Prochlorobacteria– Photosynthetic organisms that contain both
chlorophyll a and b – More like the chloroplast of green plants
than to cyanobacteria. – AKA prochlorophyta –phyta means plants-
to emphasize this similarity.
– Only two species have been discovered.
Identifying Monerans
1. Cell Shape: there are three basic shapes• Rods –called “bacilli”• Sphere – called “coccus”, like streptococcus which
causes strep throat• Spiral –called “spirilla”
2. Arranging themselves in a distinct way:• some grow in colonies• others (like streptococcus) form large chains• others form large clumps or clusters.
Identifying Monerans
3. Cell walls• some have a double membrane others have a
single• Gram staining
4. Kinds of movement:• propelled by one or more flagella • others lash, snake or spiral forwards• others glide slowly along a layer of slimelike
material that they secrete themselves.• Some do not move at all.
Identifying Monerans
5. How they obtain energy:a. Autotrophs: can make their own food.
• Phototrophic autotrophs. Ex: cyanobacteria and some photosynthetic eubacteria
• Chemotrophic autotrophs: live in harsh environments and obtain energy from inorganic molecules (hydrogen sulfide, nitrites, sulfur and iron)
• Ex: Nitrosomonas –uses ammonia and oxygen to produce energy
Identifying Monerans
b. Heterotrophs: need to get food from other sources.• Chemotrophic heterotrophs: take organic
molecules and then break them down. Ex: salmonella from raw meat, which also release poisons into the food they are eating—food poisoning.
• Phototrophic heterotrophs: use sunlight for energy, but they also need organic compounds for nutrition
Bacteria Growth and Reproduction
Methods:
1. Binary Fission: the equal division of a bacteria into two daughter cells
– Replicates its DNA and divides in half
– Asexual reproduction (no mixing of DNA)
– Ex: E.coli
Bacteria Growth and Reproduction
2. Conjugation: (fig 17-14) • A form of sexual reproduction
(the exchanging of genetic material)
• A long bridge of protein forms between and connects two bacterial cells
• Genetic info from one cell is transferred to the other cell.
• The new combinations of genes enhances the genetic diversity in that population of bacteria. –enhancing the chance of survival.
Bacteria Growth and Reproduction
3. Spore formation: Figure 17-15– Asexual – Some produce an endospore (a thick internal wall
that encloses its DNA and a portion of its cytoplasm).– This thing can remain dormant for months or even
years waiting for more favourable conditions for growing.
– When conditions are better the endospore will open up and the bacterium will grow again.
– Technically not reproduction but rather a sophisticated defense system.
Quiz Next Class
• Differentiate between the three methods of bacterial reproduction.
• Be sure to include – the type of reproduction
• Sexual or asexual
– A brief description of each type– What is happening with respect to the DNA
Importance of Monerans:
• We use products made by monerans every day for example:– Cheese– Yogurt– Buttermilk– Sour cream– Pickles– Sauerkraut– Vinegar from wine
Importance of Monerans:
• Bacteria are also used in industry for example:– One type can digest petroleum (useful in
cleaning up small oil spills) – Some remove waste products and poisons
from water– Others help mine minerals from the ground– Synthesizing drugs and chemicals through
techniques of genetic engineering (i.e. insulin, factor C, etc.)
Symbiotic relationships
• Bacteria form symbiotic relationships with other organisms, that is both the bacteria and the other organisms benefit from the relationship.
• For example our intestines are inhabited by large numbers of bacteria, including E. coli. (called “coli” because they were found in the colon) – Inside the intestines, the bacteria get a warm, safe
home, plenty of food, and free transportation.– In turn, we get help in digesting are food and
production of vitamins that we cannot produce on our own.
Symbiotic relationships
• Another example: Cows need bacteria to digest cellulose (fiber) which is found in grass and hay.
Bacteria in the Environment:
Bacteria are necessary for three major jobs that help maintain life as we know it:
1. Nutrient Flow: Bacteria recycle and decompose, or break down, dead material• Example: form the moment a tree dies, armies
of bacteria attack and digest the dead wood, breaking it down into simpler substances. The result is the tree nutrients are recycled, enriching the soil in which it grew.
Bacteria in the Environment:
2. Sewage Decomposition:– Humans take advantage of the ability of bacteria to
decompose material in the treatment of sewage.– Bacteria is added directly to waste water, and they
grow rapidly. As they grow, they break down the complex compounds in the sewage into simpler compounds.
– This process produces purified water nitrogen gas and carbon dioxide gas, and leftover products that can be used as crop fertilizers.
Bacteria in the Environment:
3. Nitrogen Fixation:– All organisms on our planet are totally dependent on
monerans for nitrogen.– All green plants need nitrogen to make amino acids and
because animals eat plants, plant proteins are ultimately the source of proteins for animals.
– Our atmosphere is 80% nitrogen gas, but this form of nitrogen is useless to plants
– They require that nitrogen be “fixed” chemically in the form of ammonia (NH3) and related nitrogen compounds.
– Cyanobacteria and other monerans are the only organisms that can fix nitrogen
– Example: soybean plants and Rhizobium form a symbiotic relationship to fix nitrogen
Bacteria and Disease:
• Some of the diseases caused by pathogenic bacteria include:– Diphtheria– Tuberculosis– Typhoid fever– Tetanus– Hansen disease– Syphilis– Cholera
Bacteria and Disease:
• Two general ways that bacteria cause diseases:
1. They may damage the cells and tissues of the infected organism directly by breaking down its living cells to use for food
2. They release toxins that travel throughout the body, interfering with the normal activity of the host.
Bacteria and Disease:
• How to fight against bacterial infections in the body:
1. stimulate the immune system with vaccines
2. a number of drugs
3. antibiotics
Bacteria and Disease:
• Methods of controlling bacteria:1. Sterilization: Through great heat or
disinfectant chemicals
2. Food Processing: including refrigeration, boiling, frying, or steaming. Placing food in salt, vinegar