Monera (bacteria)



|3.1 Diversity of Organisms |Objectives |

|3.1.3 Monera |Describe the distribution of bacteria and fungi. |

| |Explain the structure of each type, including plasmids. |

| |Name 3 main types of bacterial cells. |

| |Explain reproduction of bacteria. |

| |Explain nutrition of bacteria. |

| |State the factors affecting growth of micro-organisms. |

| |Define the term: Pathogenic |

| |Define the term: antibiotics |

| |State the role of antibiotics. |

| |Outline the potential abuse of antibiotics |

| |Name two Beneficial and two harmful bacteria |

| |Define the terms: saprophytic & parasitic. |

|3.1.9.H Nature of Bacteria &|Explain the prokaryotic nature of bacteria |

|Fungi |Explain the eukaryotic nature of fungi |

|3.1.10.H Growth Curves |Discuss the growth curves of micro organisms |

| |Compare Batch and Continuous Flow Food Processing |

Microbiology is the study of microorganisms e.g. bacteria and fungi.

Distribution of bacteria and fungi

Bacteria – terrestrial and aquatic. Fungi mostly terrestrial.

Basic structure of a bacterial cell

[pic]

Microscopic (1000 bacteria in a full-stop!)

Cell wall - made of sugars and protein, gives shape and protection.

Nuclear material = 1 circular chromosome of DNA and maybe 1 or more plasmids - small loops of DNA . Plasmids contain genes that are responsible for bacterial resistance to antibiotics.

No organelles (except ribosomes) i.e. no nucleus, mitochondria, chloroplast.

( Flagella: movement

( Capsule: slimy protective coat ( chlorophyll

Bacterial types

Classified according to shape.

Round e.g. in pairs eg. pneumonia, in chains e.g.sore throats, in clusters e.g. skin boils & food poisoning,

Rods e.g. tuberculosis, E. coli (found in human intestines and therefore sewage), tetanus(lockjaw), botulism,

Spiral e.g. cholera, syphilis, Weil’s disease

Reproduction

Asexual reproduction - by binary fission. The chromosome is replicated and the cytoplasm divides to form two daughter cells, each with an identical chromosome. Under suitable conditions a bacterium may reproduce itself every 20 minutes. This leads to large population numbers of identical daughter cells (clones).

[pic]

*The rapid rate of bacterial reproduction has important consequences.

Wounds become heavily infected very quickly.

Mutations mean that antibiotic-resistant bacteria can appear in large numbers.

Bacteria can transfer plasmids to other bacterial species and so transfer antibiotic immunities.

Bacteria can give very efficient returns of product in industry.

Endospores

The bacterium replicates its chromosome. One copy is surrounded by a tough cell wall. The outer cell breaks down. Endospores can remain dormant for decades. When conditions are suitable the endospore germinates to form a single cell.

Note - When food is placed in a freezer many bacteria respond by producing spores. These can survive the cold temperature and germinate when food is thawed. Thawed food must be cooked and eaten without delay. Fast freezing restricts spore formation.

[pic]

Nutrition

(a) Autotrophic – make their own food

(i) Photosynthetic - use light and hydrogen sulfide to make food e.g. purple sulfur bacteria

(ii) Chemosynthetic - use energy from chemical reactions e.g. nitrifying bacteria.

(b) Heterotrophic – take in food.

(i) Saprophytic - feed on dead organic matter e.g. bacteria of decay

(ii) Parasitic - feed on living host causing it harm e.g. sore throats, tetanus

Factors affecting growth of bacteria

Temperature Usually 20 - 30oC for most bacteria, but range from 0oC to 80oC – hot springs.

Oxygen

Aerobic bacteria require oxygen for respiration e.g. streptococcus bacteria in sore throats.

Anaerobic bacteria do not require oxygen e.g. Clostridium which causes tetanus or botulism

Facultative anaerobes can respire with or without oxygene.g E. coli in intestines.

Obligate anaerobes can only respire in the absence of oxygen e.g. Clostridium tetanii.

pH (most bacterial enzymes prefer a neutral pH of 7, bacterial enzymes are denatured in an unsuitable pH.

*Helicobacter if found in the stomach (pH2) of about half the Irish population. It can cause stomach ulcers.

External solute concentration affects the bacteria because water is gained or lost by osmosis. If gained the cell wall prevents it from bursting, if lost the dehydration stops enzymes from working.

*Bacteria in Dead Sea can survive high salt concentration

Pressure - the growth of most bacteria is inhibited by high pressure because the cell walls are not strong enough. Some bacteria can withstand high pressure e.g. those found in deep-sea vents.

Growth curve

[pic]

A. Lag phase:

Numbers are low (constant) because:

• bacteria are adapting to their new environment e.g. they may be producing new enzymes to digest nutrients on which they are to grow.

.

B Log phase:

Bacterial numbers increase rapidly

• because the bacteria are actively dividing (plenty of food, oxygen, moisture, space, suitable temp. and few toxins).

C Stationary phase:

The number remains high and constant (reproduction rate = death rate) because of:

• competition for food, space, moisture and oxygen

• accumulation of toxins.

D Decline phase:

Decrease in numbers (death rate ( reproduction rate)

• due to competition for resources and

• build-up of toxins.

E Survival/Death phase

Numbers low

Bacteria die and some may survive as endospores, which can remain dormant until conditions are favourable.

Antibiotics are chemical substances produced by bacteria and fungi that stop the growth of or kill other bacteria and fungi.

They are not effective against viruses. Most antibiotics work by inhibiting cell wall synthesis during cell division e.g. penicillin (Alexander Fleming 1928).

Antibiotics and Resistance

If bacteria are constantly exposed to an antibiotic they can become resistant to it. This antibiotic resistance

can be acquired by mutation, uptake of genes from plasmids, viruses or from other resistant bacteria.

These resistant bacteria increase very rapidly and spread e.g. MRSA (methicillin resistant Staphylococcus aureus) in hospitals.

Economic importance of bacteria (know two beneficial and two harmful)

Beneficial bacteria:

• Production of yoghurt and cheese by Lactobacillus

• Manufacture of some antibiotics.

• Genetically engineered bacteria e.g. E. coli, are used to produce enzymes, insulin, vitamins, antibiotics.

• Nutrient recycling in soil – bacteria of decay break down dead plants and animals.

Harmful bacteria - minority.

• Bacteria cause human disease.g. TB, whooping cough, meningitis, typhoid, cholera, salmonella food poisoning, leprosy, pneumonia, tetanus

• Animal disease e.g. mastitis, anthrax

• Plant diseases e.g. soft rot of vegetables

• Food spoilage e.g. lactobacilli cause milk to turn sour.

• Tooth decay - bacteria in mouth converts sugars to acid, which dissolves the enamel on teeth.

A pathogen is a disease-causing organism.

Bioprocessing involves the use of m/o to produce food and other products.

M/o are grown in a liquid medium in a bioreactor (vessel).

Batch cultivation e.g. antibiotics

A fixed amount of nutrients and microorganisms are added to bioreactor at start. Air is added if needed and waste gases removed. Growth is allowed up to a certain point (usually lag, log, stationary), bioreactor is emptied and product extracted. Bioreactor is cleaned and sterilised.

[pic]

Continuous cultivation e.g. single-celled protein

Nutrients are continuously added to bioreactor. Once bioreactor is set up used medium and products are continuously removed. Quicker process because there is no need to empty bioreactor etc. regularly and also get a continuous yield. By adjusting the nutrients added, the growth rate can be kept at a level (log stage) which gives the max. yield of product.

[pic]

Advantages of batch culturing

• Easier process to control.

• Products may be needed only in small amounts.

• Product may only be needed at a particular time.

• Some m/o grow well for a short period of time.

\

Nitrogen cycle

[pic]

Nitrogen fixing bacteria – found in soil or root nodules of legumes, converting nitrogen gas to nitrate

Bacteria of decay – found on dead organic matter in soil, from nitrogenous waste

Nitrifying bacteria – found in soil, convert ammonia to nitrite to nitrate

Denitrifying bacteria – found in soil, convert nitrate to nitrogen gas.

Leaving Cert Questions

Section A

2004 HL

1. (a) Name an autotrophic organism …………………………………………………………………………

SEC Sample Paper OL

2. Bacterial cells have three main shapes. Two of these are shown below. Name each shape.

[pic]

Name ………………… …………………… Name …………………………………………

Bacteria reproduce asexually by dividing in two. What term is used for this form of asexual reproduction? ………………………………………………………………………………………………………………

What do bacteria form when environmental conditions become unfavourable?

…………………………..……………………………………………………………………………………

What does the term pathogenic mean in relation to bacteria?

…………………………………………………………………..……………………………………………

2005 OL

6(b) The diagram shows the structure of a typical bacterium.

[pic]

(i) Name A, B, C, D.

A …………………………..……. B ………..…………………….

C ……………………..…………. D ………..…………………….

(ii) To which kingdom do bacteria belong? ……………………………………………

Section C

2006 HL

15. (b) Answer the following in relation to bacteria.

(i) Distinguish between photosynthetic and chemosynthetic bacteria. Give an example of each type.

(ii) Name two forms of heterotrophic nutrition found in bacteria.

(iii) What are antibiotics? For what purpose are they used?

(iv) Explain what is meant by antibiotic resistance and suggest how it may develop. (30)

2007 HL

14. Answer any two of (a), (b) and (c). (30, 30)

(b)

(v) What is an antibiotic?

(vi) Antibiotics should not be prescribed for a person suffering from a viral infection.

Suggest a reason for this.

2008 HL

15. (c) The diagram shows a bacterial growth curve.

[pic]

(i) A and B represent the labels on the axes. What does each of them stand for?

(ii) What term is applied to the part of the curve labelled x? What is happening during x?

(iii) What term is applied to the part of the curve labelled y? What is happening during y?

(iv) Copy the diagram into your answer book and continue the curve to show the next phase. Explain why you have continued the curve in this way.

(v) Distinguish between batch and continuous flow food processing using micro-organisms in the food industry.

2010 HL

12.

(i) To which kingdom do bacteria belong?

2010 HL

15.

(c) Suggest a biological explanation for each of the following observations:

(ii) Doctors are reluctant to prescribe antibiotics to patients suffering from common cold-like

symptoms.

2013 HL

12.

(b) (i) Name the kingdom to which bacteria belong.

(ii) Draw a large diagram of a bacterial cell to show:

1. The relative positions of the cell wall, cell membrane and capsule.

2. A plasmid.

Label each of the above structures.

(iii) 1. Under what circumstances does a bacterial cell form an endospore?

2. Describe briefly how an endospore forms.

(iv) Name two types of heterotrophic nutrition used by bacteria.

(c) (i) Distinguish clearly between antibodies and antibiotics by writing a note about each.

(iii) Using your knowledge of antibiotics and bacteria, suggest why a person is more likely to pick up an infection in hospital than at home.

2007 OL

13. (a) The diagram shows a typical bacterial cell.

[pic]

(i) Some bacteria have a layer outside the cell wall (labelled A in diagram).

Name this layer and state its function

(ii) Name a structure, other than A, which is not found in all bacteria. (9)

(b) The table below shows ways in which bacteria obtain their food. Study the table and then answer the questions that follow.

|Autotrophic |Heterotrophic |

|Photosynthetic |Parasitic |

|Chemosynthetic |Saprophytic |

(i) Distinguish between autotrophic and heterotrophic nutrition.

(ii) What is saprophytic nutrition?

(iii) Why are saprophytic bacteria important in nature?

(iv) Briefly explain chemosynthesis.

(v) What term is used for the organism from which a parasite obtains its food?

(vi) Give examples of two harmful bacteria. (24)

2009 OL

12. (b) The diagram shows the structure of a typical bacterial cell.

[pic]

(i) Name the bacterial cell parts A, B and C.

(ii) What is the function of C?

(iii) Name any two of the main bacterial types (shapes).

(iv) By which method do bacterial cells reproduce?

(v) Some bacteria are anaerobic. What does this mean?

(vi) What are pathogenic bacteria?

(vii) Give two example of the economic importance of bacteria.

2010 OL

13. (a)

(ii) Distinguish between autotrophic nutrition and heterotrophic nutrition. (9)

2012 OL

13. (a) All organisms may be classified (grouped) into five kingdoms.

(i) Suggest one advantage of classifying organisms.

(ii) Name the kingdom to which bacteria belong.

(iii) Give one example of the economic importance of bacteria. (9)

(b) (i) Draw a large labelled diagram of a typical bacterial cell.

(ii) Bacteria may be classified by their shape.

Name any two bacterial shapes.

(iii) Name the method by which bacteria reproduce.

(iv) What are pathogenic bacteria?

(v) State two factors affecting the growth of bacteria. (27)

Answers

2004 HL Sample Q1

|1. | |5(4) |

| |(a) |protection/ boundary/ bears antigens/ controls exit and entry of substances | |

2004 OL Sample Q2

|2. | | | |5(4) |

| | | |Rods (Bacillus) Spheres (Cocci) | |

| | | |Binary fission | |

| | | |Spores (Endospores) | |

| | | |Disease causing | |

2005 OL Q6

|6. |10 answers |2(6)+8(1) |

| |(a) |(i) |A = contractile/ vacuole | |

| | | |B = cytoplasm / endoplasm | |

| | | |C = pseudopod / false foot | |

| | | |D = nucleus / organelle | |

| | |(ii) |Protista / Protoctista | |

| |

| |(b) |(i) |A = flagellum | |

| | | |B = DNA /chromosome/ nucleoid) not nucleus | |

| | | |C = cell wall / Membrane | |

| | | |D = capsule (slime layer) | |

| | |(ii) |Monera (Prokaryotae) | |

|2006 HL Q15(b) |

| |(b) |(i) |using light to make food or obtain energy |3 |

| | | |Make food or obtain energy using a chemical reaction |3 |

| | | |[accept ‘from chemicals’] | |

| | | |Example 1: role or implied role e.g. volcanic pools |3 |

| | | |Example 2: role or implied role e.g. in soil |3 |

| | |(ii) |parasitic / saprophytic |2(3) |

| | |(iii) |substances produced by bacteria or fungi [accept micro-organisms] |3 |

| | | |treat infections or correct example |3 |

| | |(iv) |resistance: bacteria or fungi not killed by or inhibited by or | |

| | | |immune to (antibiotic) |3 |

| | | |how develops: natural selection has occurred or surviving | |

| | | |strains multiply or misuse comment or plasmid transfer |3 |

|2007 HL Q14(b) |

|14 |b |(v) |substance produced by micro-organisms / that kills (some) microorganisms or bacteria or |2(3) |

| | | |fungi | |

| | |(vi) |(antibiotics) have no effect (on viruses) or promote resistant bacteria |3 |

|2008 HL Q15(c) |

| |(c) |(i) |A = population (size) of or number (of bacteria) |3 |

| | | |B = time |3 |

| | |(ii) |X = lag (phase) |3 |

| | | |adapting to environment or low reproductive rate |3 |

| | |(iii) |log or exponential (phase) |3 |

| | | |reproducing rapidly |3 |

| | |(iv) |curve showing flattening or falling |3 |

| | | |reproduction slows or some limiting factor mentioned or toxin builds | |

| | | |up or space limitations |3 |

| | |(v) |(batch) fixed amount of nutrients added at beginning or (bioreactor) |6 |

| | | |emptied at end of production and (continuous) nutrients continuously | |

| | | |fed into bioreactor or product removed continuously | |

2010 HL Q12

|12 |(b) |(i) |Monera or Prokaryotae |3 |

2010 HL Q15(c)

|15 |c |(ii) |Common cold is a viral disease / antibiotics do not affect viruses / (overuse of antibiotics) may |2(3) |

| | | |lead to antibiotic resistance in bacteria (in patients) | |

| | | |Any two | |

2013 HL Q12

|12 |(b) |(i) |*Monera |3 |

| | |(ii) |1 + 2 |Diagram: wall + membrane + capsule + plasmid shown |5, 3, 0 |

| | | | |Labels: |4(1) |

| | |(iii) |1. |Harsh conditions or example |3 |

| | | |2. |DNA replicates / thick wall (or described) / encloses / shrinkage (or water loss) / of |2(3) |

| | | | |cytoplasm | |

| | |(iv) |*Saprophytic |3 |

| | | |*Parasitic |3 |

| |

| |(c) |(i) |Antibodies – proteins / produced by body / in response to antigen (or to infection) | |

| | | |Antibiotics – produced by micro-organisms / kill (or destroy or stop growth of) other micro-organisms / |4(3) |

| | | |do not affect viruses | |

| | |(iii) |Antibiotic resistance strains / more pathogens / more people (or poor hygiene) / patients weaker |2(3) |

2007 OL Q13

|13. | | |

| |(a) |(i) |capsule or slime layer or mucilage |3 |

| | | |protection |3 |

| | |(ii) |flagellum or plasmid |3 |

| |

| |(b) |(i) |autotrophic nutrition – makes own food |3 |

| | | |heterotrophic – uses food already made (made by other organisms) |3 |

| | |(ii) |feed on dead matter |3 |

| | |(iii) |decompose dead organisms or recycle nutrients |3 |

| | |(iv) |obtain energy (make food) from chemical reactions |3 |

| | |(v) |host |3 |

| | |(vi) |TB/ syphilis/ cholera/ tetanus/ sore throat/ names of bacteria/ etc. |2(3) |

| |

2009 OL Q12

|12 |(b) |(i) |A = Cell Wall / Cell Membrane / Capsule |3(1) |

| | | |B = DNA / Chromosome / Genetic material | |

| | | |C = Flagella (allow tail) | |

| | |(ii) |Movement |3 |

| | |(iii) |Rod / Coccus / Spiral |2(3) |

| | | |Any two | |

| | |(iv) |(Binary) Fission / allow asexually |3 |

| | |(v) |Do not use Oxygen |3 |

| | |(vi) |Disease causing |3 |

| | |(vii) |e.g. Causes crop diseases / causes human diseases / biotechnology |2(3) |

| | | |Any two | |

2010 OL Q13

|13 |a |(ii) |Autotrophic nutrition: Food synthesised from simple molecules or produces own food | |

| | | |(Either point answered) | |

| | | |Heterotrohic nutrition: Already synthesised food consumed from other organisms or food from other | |

| | | |sources | |

2012 OL Q13

|13 | | | |7 + 2(1) |

| |(a) |(i) |EG. Identification |(1 pt) |

| | |(ii) |Monera |(1 pt) |

| | |(iii) |EG. Food Production |(1 pt) |

| |

| |(b) |(i) | |D. 5,2,0 L.2(1) |

| | | |Diagram to include: | |

| | | |Cell Memb/Cytoplasm + one other. | |

| | | | | |

| | | |Labels: Any two valid labels | |

| | | | | |

| | | | | |

| | | | | |

| | |ii-v | Pr |2(6) + 4(2) |

| | |(ii) |Bacillus or rod shaped / Coccus or spherical (Round) / Spirillum or spiral shaped |(2 pts) |

| | |(iii) |Binary Fission or asexual [Not Mitosis] |(1 pt) |

| | |(iv) |Disease-causing |(1 pt) |

| | |(v) |Temp / O2 (allow air)/ water/ food /pH / Waste |(2 pts) |

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Name:

Diagram:

All three = 5

One absent = 2

Two absent = 0

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