biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Biology 2201 Unit 2 Chapter 5

5.1­ Kingdom Bacteria (Eubacteria) and Kingdom Archaea (Archaebacteria)

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Kingdoms Archaea and Bacteria

• Kingdom Archaea and Kingdom Bacteria used to be classed as one kingdom (Kingdom Monera). However, it has been recently discovered that these two groups are very different genetically and biochemically.

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Kingdom Bacteria­ General Characteristics

• all members of this kingdom are prokaryotic and unicellular • most live as single cells but some live in colonies • some members move by their flagella, but others do not move • some bacteria cause disease, but this is a small number. Most bacteria play vital roles in the environment, such as decomposers. • bacteria are classed using different characteristics: • Shape• Cell wall structure • nutrition

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Bacterial Shapes• different bacteria have different shapes • a. Cocci – round • b. Bacilli – rod-shaped • c. Spirilli – spiral –shaped

• There are also different names for different arrangements of bacteria • diplo = in pairs • staphylo = arranged in clusters • strepto = in a chain

• The arrangement and shape are commonly combined into the genus name of a species of bacteria in order to describe it• Ex. Staphylococcus aureus

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Cell wall structure in bacteria• There are 2 different basic cell wall structures found in bacteria. Scientists use a special stain called Gram stain to tell them apart. This stain highlights basic differences between the arrangements in amino acids and sugar molecules. These two types are: • a. Gram-positive – have thick cell walls made of peptidoglycan (made of carbohydrate and protein). Gram-positive bacteria stain purple. • b. Gram-negative – have 2 cell walls; the inner wall is thin and made of peptidoglycan. These bacteria stain pink. This group is larger and more diverse.

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Cell wall structure in bacteria (pics)

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Nutrition in Bacteria• Different species of bacteria can obtain energy from very different sources. This is one reason why bacteria can be found nearly everywhere. • a. Autotroph – organism that can produce organic molecules from simple inorganic molecules and thus make its own food; there are 2 types: • i. Photoautotroph – uses sunlight (plants, some algae) • ii. Chemoautotroph – uses energy from chemicals like ammonia and hydrogen sulphide (some bacteria)

• b. Heterotroph – organism that must derive some of its nutrients from organic molecules formed by autotrophs; there are 2 types • i. Photoheterotroph – uses light to help break down organic compounds (some bacteria) • ii. Chemoheterotroph – directly breaks down organic compounds from autotrophs (most animals, fungi, bacteria)

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How Bacteria Reproduce ­ Asexual• There are 2 main methods that bacteria use to reproduce: • 1) Asexual reproduction – means reproduction with no distinct sexes. Offspring come from one parent.

• Binary fission – the asexually reproductive process of cell division in bacteria (see fig 5.4, p. 134) • Steps: • as the bacterial cell grows, it makes a copy of its chromosome (DNA) • when the cell reaches a certain size, it elongates and separates the two chromosomes • the cell then builds a partition (wall) between the two chromosomes • the original cell splits into two cells, with identical genetic material

• This process is very quick (~ 20 minutes) and can produce large numbers of bacteria very quickly. This is the main method of reproduction in bacteria.

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Binary Fission ­ diagram

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How Bacteria Reproduce ­ Sexual• sexual reproduction – means reproduction with two separate sexes contributing towards the offspring. • Conjugation – a form of sexual reproduction in bacteria. During conjugation, bacterial cells become linked through structures called pilli that transfer some genetic material from one cell to the other. The receiver cell then undergoes binary fission. • Some bacterial species form endospores to help protect their offspring. • Endospore – small-seed like structures that contain bacterial DNA and a small amount of cytoplasm surrounded by a protective outer coating. When conditions are favourable, the endospores lose their coat and begin to develop into a normal cell

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Conjugation ­ pics

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Bacteria and Human Health

• some bacteria are harmful to people • ex. Clostridium botulinum causes botulism (food poisoning that can cause death)

• bacterial infections can be controlled using antibiotics over time. However, bacteria can become resistant to antibiotics. Hence, it is wise not to overuse antibiotics

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Bacteria and the Environment• several key processes in nature depend on bacteria such as the carbon and nitrogen cycles • photosynthetic bacteria produce a lot of oxygen • bacteria are important decomposers, which is important for recycling of nutrients

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Kingdom Archaea • General characteristics of Kingdom Archaea: • all unicellular and prokaryotic • cell walls do not have peptidoglycan and they have unusual lipids (they remain stable over very high temperatures) • there are cocci, bacilli, and spirilli shapes as well as triangular and square shapes • some archaea move by flagella while others do not • reproduction is either by binary fission or conjugation

biology 2201 ch 5.1 notes.notebook

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October 08, 2011

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Classification in Kingdom Archaea• Archaea are classed based on where they can be found and their metabolism: • 1) methanogens – live in oxygen-free environments such as under swamps and marshes. They give off methane gas and use carbon dioxide, nitrogen, or hydrogen sulphide as an energy source • 2) halophiles – found in extremely saline (salty) environments. Salt concentrations can reach up 15% (normal ocean water is 3.5%). Some of these are photoautotrophs, most are chemoautotrophs (aerobic cellular respiration) • 3) thermoacidiophiles – live in extremely hot and acidic environments, such as in volcanoes. Some are chemoautotrophs, most are chemoheterotrophs (anaerobic cellular respiration)