Science NCEA L11.11 Micro-organisms and

humans

Living and non-living organisms

Biology is the study of living thingsA living object is an object that caries out life functionsA non-living object is an object that has not been aliveA dead object is an object that was once alive

All living organisms are composed of cells. A cell is a small, membrane-bound compartment that contains all the chemicals and molecules that help support an organism's life.GZ Science resources

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Life function Gives us the ability to….

Movement move through space

Respiraton obtain energy through biochemical reactions

Sensitivity respond to stimuli

Circulation move nutrients, oxygen, heat and water around the body

Growth increase in size

Reproduction create more living things

Excretion dispose of waste chemicals

Nutrition extract useful chemicals from the environment

Life functions of living organisms

GZ Science resources

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Animal Plant Bacteria

Virus

Enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles.>small vacuoles, no chloroplasts, no cell wall.

Similar to the animal cell, but >does not have centrioles, lysosomes, cilia, or flagella.>It does have a rigid cell wall, central vacuole, and chloroplasts.

Does not have nucleus or organelles (except ribosomes).

Not considered living or consisting of cells but contains genetic material (RNA/DNA) similar to all other living things.

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All living organisms are made of cells

Recent advancements in Science have lead biologists to develop a revised classification system, grouping organisms into domains.The Prokaryotes are divided into Bacteria and the more ‘primitive’ Archaea. These were once combined as the Monera kingdom. The Eukaryotes share similar cell structure with organelles and a nucleus. These were once divided into the Fungi, Protist, Plant and Animal kingdoms

All living organisms are organised into Domains

Prokaryotes Eukaryotes

>lack cell nucleus>DNA/RNA material stored in a single loop in an area called the nucleoid >have no membrane bound organelles.>reproduce asexually by binary fission

>have membrane bound nucleus containing genetic material>DNA stored on Chromosomes >has membrane bound organelles (mitrochondria – respiration, Chloroplasts – photosynthesis)>usually reproduce sexually by meiosis

Prokaryotes and Eukaryotes

Micro-organisms (or microbes) are very small organisms, which are usually only visible with the aid of a microscope. Sometimes a colony of micro-organisms can be seen with the naked eye.

Micro-organisms which have single cells are unicellular. Those made of many cells are multicellular. Some have no cells at all – viruses.

Micro-organisms

Living Non-living

Viruses

Yeast (fungi)

Protista

Types of Micro-organisms

Bacteria

Daphnia (animal)

Relative size of Micro-organisms

Viruses are not living organisms because they are unable to carry out all of the characteristics of living organisms without invading a living cell and ‘hijacking’ it’s processes. Viruses do not posses cells or cell components of their own.

They cannot synthesise proteins, because they lack ribosomes. Viruses cannot generate or store energy.

Because viruses can not survive without cells, scientists predict that they originated from rogue pieces of DNA/RNA strand. Gaz

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Viruses

Rabies virus

Bacteriophage virus

Influenza virus

Viruses can take numerous forms

Examples of Viruses

All viruses contain:

> Nucleic acid, either DNA or RNA (but not both),

> A protein coat (capsid), which encases the nucleic acid.

> Some viruses are also enclosed by an envelope of fat and protein molecules.

Protein Coat

RNA/DNA strands

Example – HIV Virus

Spikes

Lipid layer

Virus Structure

Nucleic Acid - Just as in cells, the genetic material (DNA or RNA) of each virus encodes the genetic information for the synthesis (creation) of all proteins. While the double-stranded DNA is responsible for this in prokaryotic and eukaryotic cells, only a few groups of viruses use DNA. Most viruses have single-stranded RNA. The genetic material can only make protein when it is slotted into the DNA of a host cell.

Function of the Virus Components

Capsid - The capsid is the protein shell that encloses the nucleic acid; The capsid has three functions:

1) it protects the genetic material from digestion by enzymes.

2) contains special sites on its surface that allow the virus to attach to a host cell.

3) It may contain spike proteins that enable the virus to penetrate the host cell membrane and, in some cases, to inject the infectious nucleic acid into the cell's cytoplasm.

Function of the Virus Components

Viruses will not grow on agar (jelly made from seaweed with nutrients) because they cannot feed.

They need living cells to reproduce in and are often grown in fertile hen’s eggs.

The introduction of micro-organisms onto agar or into living cells is known as inoculation.

It is to dangerous to grow viruses in the school laboratory as all viruses are Pathogens (harmful to living organisms).

Culturing Viruses

Absorption

Viruses can enter an organism through any cavity or broken surface of an organism. Once inside, they find a host cell to infect.

Entry

The Virus attaches to a specific cell type and ‘injects’ its genetic material.

Replication

The viruses genetic material joins into the cell DNA and viral protein is made.

Assembly

Various pieces of viral protein are constructed into individual viral particles (or virions).

Release

The newly created virions break through the cell wall (killing it) and proceed to infect other cells.

Reproduction of Viruses

Once inside the host cell, some viruses, such as herpes and HIV, do not reproduce right away. Instead, they mix their genetic instructions into the host cell's genetic instructions. When the host cell reproduces, the viral genetic instructions get copied into the host cell's offspring. The host cells may undergo many rounds of reproduction, and then some environmental or predetermined genetic signal will stir the "sleeping" viral instructions. The viral genetic instructions will then take over the host's machinery and make new viruses as described above. This cycle, called the lysogenic cycle, is shown in the figure above.

Lysogenic Cycle

There are three requirements that must be met to ensure successful infection of a virus:

1. sufficient virus must be present

2. the cells must be susceptible and permissive (matching) to the virus,

3. and local defenses (immune system) must be absent.

The virus attaches to the target cell, usually through specific protein-protein interactions between capsid and cell surface receptors.Only then can the genetic material be taken into the host cell.

Targeted Cells

HIV Virus1. Binding and Fusion: HIV begins its life cycle when it binds to a CD4 receptor and one of two co-receptors on the surface of a lymphocyte (white blood cell). The virus then fuses with the host cell. After fusion, the virus releases RNA, its genetic material, into the host cell.2.Reverse Transcription: An HIV enzyme called reverse transcriptase converts the single- stranded HIV RNA to double-stranded HIV DNA.3. Integration: The newly formed HIV DNA enters the host cell's nucleus. The integrated HIV DNA is called provirus. The provirus may remain inactive for several years, producing few or no new copies of HIV.4.Transcription: When the host cell receives a signal to become active, the provirus uses a host enzyme called RNA polymerase to create copies of the HIV genomic material, as well as shorter strands of RNA called messenger RNA (mRNA). The mRNA is used as a blueprint to make long chains of HIV proteins.5. Assembly: An HIV enzyme called protease cuts the long chains of HIV proteins into smaller individual proteins. As the smaller HIV proteins come together with copies of HIV's RNA genetic material, a new virus particle is assembled.6. Budding: The newly assembled virus pushes out ("buds") from the host cell. During budding, the new virus steals part of the cell's outer envelope. This envelope, which acts as a covering, is studded with protein/sugar combinations called HIV glycoproteins. These HIV glycoproteins are necessary for the virus to bind CD4 and co- receptors. The new copies of HIV can now move on to infect other cells.

Are microscopicAre made up of one cellAre round, long & thin, or spiral shapedNeed food and warmth to growUse enzymes to digest food

Bacteria

Bacteria are sufficiently different to be classified within their own domain, separate from the plants, fungi, protists and animals. Bacteria have a vast variety of different lifestyles and survival methods.

Bacterial cell

They have no mitochondria, the cell membrane is the site of energy release.The DNA is in a single loop rather than chromosomesOutside the cell membrane is a cell wall and often a slime capsule for protectionThere may be a flagellum to help the bacterium move. size – they are much smallerAll bacteria are prokaryotes – they have no nucleus membrane, just an area that the DNA occupies

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Absence of nucleus

No organelles in cytoplasm (except ribosomes)

Cell Structure of Bacteria

Streptococcus pyogenesThese spherical bacteria are common inhabitants of the throat. Sometimes they can cause strep throat or even more serious disease like necrotizing fasciitis (commonly called flesh-eating bacteria)

Examples of Bacteria

Bacteria may be parasitic (feeding off other organisms) or saprophytic. Bacteria feed by extra-cellular digestion. They secrete enzymes outside their cell membrane and cell wall. The enzymes digest the food into small particles that can be absorbed through the cell membrane. This is similar to fungi feeding.

Bacteria nutrition

Respiration is the process of obtaining energy by chemically breaking down food, In animals and plants, oxygen is needed to break down the food into carbon dioxide, water and energy. This is called aerobic respiration. Most bacteria respire aerobically, while others do not need oxygen (and may even be killed by it). This type of respiration is called anaerobic respiration.

Oxygen + Sugar → Carbon dioxide + Water (+ Energy)

Respiration

Anaerobic respiration

harmful useful

>Gangrene - foul-smelling discharge, dead tissue, and gas formation within the tissue

>yoghurt production >production of biogas>waste processing >electricity generation

Aerobic respiration

harmful useful

>Food rotting – sour milk

>Nitrogen fixing bacteria>Cheese production>GE insulin production

Respiration is the process of obtaining energy by chemically breaking down food, In animals and plants, oxygen is needed to break down the food into carbon dioxide, water and energy. This is called aerobic respiration. Most bacteria respire aerobically, while others do not need oxygen (and may even be killed by it). This type of respiration is called anaerobic respiration.

Respiration

Bacteria excrete waste products. Sometimes these are harmful and are known as toxins. A disease-causing bacterium is called a pathogen.

Excretion

Happens when one bacteria cell reaches its maximum size and divides into two identical cells

This division is called BINARY FISSION

Some bacteria can divide every fifteen minutes

Parent cellParent cellParent cellParent cell DNA copiedDNA copiedDNA copiedDNA copied Cell dividesCell dividesCell dividesCell divides

Two Two identical identical new cells new cells are madeare made

Two Two identical identical new cells new cells are madeare made

Bacterial reproduction

Bacteria need the following conditions for growth:

Energy – in the form of food

Moisture

Warmth – cooling bacteria reduces their growth rate, but does not usually kill them. Refrigerators and freezers preserve food by slowing down the growth of bacteria.

Conditions required for bacterial growth

Oxygen – For aerobic bacteria only. Oxygen may kill anaerobic bacteria.

pH – bacteria grow better under the right conditions of pH (acidity or alkalinity). Bacteria grow well on the human skin, as it is slightly acidic.

Made of tangled threads called HYPHAEParasites or decomposersSpread by sporesFuzzy- looking

Fungi

Fungi can either be multicellular such as mushrooms and mould or unicellular such as yeast.

The Fungi have their own Kingdom but share similarties with both plants – do not move around, and animals – can not make their own food.

Fungi are either parasitic – feeding off live hosts or saprophytic – feeding off dead organisms.

Fungi make up an important part of the food chain as decomposers – breaking down dead organic mater and returning the nutrients so they are available to other organisms. Gaz

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Fungi

Fungi Structure

>Spores, haploid (only half the chromosomes) used for reproduction – both asexual (growing into an exact copy) or sexual (when combining with a spore from another fungus)

>Sporangium or fruiting body. The visible part of the fungi that produces and distributes the spores.

> Hyphae, the feeding threads. A mat of hyphae is called a mycelium. The hyphae can also be involved in sexual reproduction when they come in contact with hyphae from another fungus.

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Spores

Sporangium

Stalk

hyphae

Fungi Structure

• Can be ASEXUAL – by spreading spores• Can be SEXUAL – where two hyphae touch

Fungi Reproduction

Fungi Reproduction

1.Special spore capsules or cases called sporangia develop and produce the spores. These spores are haploid – they have only half the number of chromosomes. They can be either + or – strains. (rather than male or female).

2. Millions of spores are released to float in the air

3. When spores land on tissue they germinate, sending out hyphae that rapidly branch and invade the new host.

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Fungi Asexual reproduction

1. Fungi form a gamete producing area called a Gametangia.

2. Gametangia from a + strain and a – strain join – but still from the same species of fungi.

3. The 2 gametes (haploid) fuse to form a diploid zygote with a full set of chromosomes.

4. The zygote grows to produce spores (haploid)

5. This process allows the fungi to produce variation amongst the offspring

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Fungi Sexual reproduction

Multicellular fungi are made up of a mass of very fine threads called hyphae, which invade the tissue of the host organism or dead matter.

Fungi feed like bacteria by releasing digestive enzymes onto food, then reabsorbing the nutrients. This is called extra-cellular digestion.

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Fungi Nutrition

Steps to feeding;

1. Enzymes are released from the hyphae.

2. The food material outside the hyphae is digested.

3. The food molecules are small enough to diffuse into the hyphae.

Fungal hypha

Large food particle

Enzymes secreted to break up large particles

Smaller food particles absorbed

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Extra-cellular digestion

Sugar alcohol + carbon dioxide

C6H12O6 CH3CH2-OH

+ 2CO2 (+ 2ATP)

This can be aerobic (with oxygen) or anaerobic (without oxygen). Bread and wine yeasts respire anaerobically, producing carbon dioxide and alcohol. This is important in wine making, brewing of beer and rising of bread. The process is called fermentation.

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Fungi Respiration

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Carbon dioxide and alcohol (ethanol) are waste products of yeasts. Other fungi may produce different waste products including toxins.

Toxins excreted by fungi that kill or stop the growth of bacteria are known as antibiotics.

Humans have made use of the antibiotics produced by fungi to fight harmful bacteria in their bodies. The most commonly used antibiotic is produced by the penicillin sp. of fungi.

Fungi Excretion

UNHELPFUL:

• Mould is a fungus that is unhelpful when it gets on food like bread and spoils it

• Yeast is a fungus that is unhelpful to humans when it causes infections like “Thrush”

• Penicillin is a fungus that looks really bad for you

HELPFUL:

• However, humans eat some moulds like the “blue” in blue cheese!

• However, yeast is useful in fermentation to make beer, wine and ginger beer and for making bread rise

• However, Penicillin is an important antibiotic medicine

Helpful vs Unhelpful Fungi

• Collect a “swab” and petri dish

• Wash your hands - to avoid contamination of plate

• Swab area you have been asked to investigate

• Lift up side of petri dish lid without taking it off - to avoid contamination

• Swab agar hard enough to leave microbes on - take care not to tear agar

• Close lid and tape sides of the petri dish - so you can still see your cultures

• Write your name and place you swabbed in small writing on bottom of dish - so you can still see your cultures

Making a culture

Name: M. luteus (type of bacteria)How you identify it: bright yellow, shiny, & smooth

Name: Staphylococcus aureus (type of bacteria)How you identify it: large & cream-colored

Name: Streptococcus pyogenes (type of bacteria)How you identify it: smaller than staphylococcus & white

Name: Corynebacteria (type of bacteria)How you can identify it: dry and crinkly

Name: FungiHow you can identify it: fuzzy

Identifying Microbes

• The microbe used in beer & wine making is a fungus called YEAST

• The YEAST makes alcohol by anaerobic respiration or FERMENTATION

• In WINE-MAKING, the YEAST uses the SUGAR in the fruit for FERMENTATION

• In BEER-MAKING, the YEAST uses the SUGAR in the malted barley for FERMENTATION

GLUCOSEGLUCOSE CARBON DIOXIDECARBON DIOXIDE + WATER+ WATER+ OXYGEN+ OXYGEN

Using Fungi to make wine and beer

Micro-organisms play essential roles in the manufacture of such foods as bread and cheese, and also in the brewing and wine making industries.

Food production

YOGHURT IS MADE:

From milk that has had bacteria added to itBy BACTERIAL FERMENTATIONWhen bacteria feed on the Lactose (sugar) in the Milk and

makes LACTIC ACID and water

Using Bacteria to make Yoghurt

STEP PROCESS WHAT MICROBE DOES

1 Milk is pasteurised This is to reduce the amount of unhelpful bacteria in the milk

2 Milk is cooled and bacteria are added

Two yoghurt-making bacteria are added

3 Yoghurt is incubated

This is to encourage the bacteria to grow and divide by binary fission

4 Flavour is added The lactic acid made by the bacteria gives the yoghurt its “tangy” taste… just add fruit!

Stages in yoghurt production

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The milk is pasteurised for 10 minutes at 95°C. This kills the bacteria in the milk. The milk is then homogenised to make sure none of the parts of milk separate out. The milk is then cooled and kept in a fermentation tank at 43°C. Yoghurt starter culture containing the two bacteria, streptococci and lactobacilli is added. This is called inoculation.

The mixture is incubated at this temperature for 4 to 6 hours. During this time the bacteria grow, reproduce and use lactose sugar for respiration. They excrete lactic acid as a waste product of their respiration. The lactic acid changes the flavour of the yoghurt and coagulates the proteins in the milk to form yoghurt.

When the amount of lactic acid in the yoghurt gets to 0.9% the tank is cooled down to 22°C. Fruit and flavour may be then added then the yoghurt is packaged. It is then cooled and stored in a fridge at 5°C. storage at this temperature slow down the activity of any bacteria in the yoghurt so it lasts longer.

Yoghurt Production

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Complete the following table to describe the key steps in the yoghurt making processKey step Description of what happens in each step

Pasteurised 10 minutes at 95°C, kills harmful bacteria already in the milk

Homogenised

Shaken up so milk doesn’t separate out in its parts (water, cream, fat etc) Cooled and kept at 43°C

Inoculation A starter culture of useful bacteria is added to the milk

Incubated Kept warm at 43°C for 4 to 6 hours which is the ideal growing conditions for the bacteria

Packaged Cooled down to 22°C, fruit and flavour added and put into packs for selling

Stored Kept in a fridge at 5°C so bacteria does not grow any more and the yoghurt lasts longer

STEP PROCESS WHAT MICROBE DOES

1 Grapes crushed

Yeast on the grape skins is mixed in with the juice of the fruit

2 Juice & skins are left at 25oC.

Yeast on grape skins uses the sugar in the fruit juice to make alcohol and carbon dioxide gas - fermentation

3 Wine is stored in barrels for up to 18mths

Fermentation stops before the wine is put in barrels so the microbe doesn’t do anything in this step.

Stages in wine production

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Disease – a pathological condition of body parts or tissues characterized by an identifiable group of signs and symptoms.

Infectious disease – disease caused by an infectious agent such as a bacterium, virus, protozoan, or fungus that can be passed on to others.

Infection – occurs when an infectious agent enters the body and begins to reproduce; may or may not lead to disease.

Pathogen – an infectious agent that causes disease.Host – an organism infected by another organism.

Virulence – the relative ability of an agent to cause rapid and severe disease in a host.

Disease

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Agents that cause infectious diseases can be transmitted in many ways.Through the airThrough contaminated food or waterThrough body fluidsBy direct contact with contaminated

objectsBy animal vectors such as insects, birds,

bats, etc.

Courtesy of VOA

Chinese students wearing masks during a

SARS outbreak

Courtesy of CDC

Aedes aegypti mosquito Known to transmit

Dengue fever

Transmission of Infectious Disease

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By durationAcute – develops and runs its course quickly.Chronic – develops more slowly and is usually less severe,

but may persist for a long, indefinite period of time.Latent – characterized by periods of no symptoms between

outbreaks of illness.By location

Local – confined to a specific area of the body.Systemic – a generalized illness that infects most of the

body with pathogens distributed widely in tissues.By timing

Primary – initial infection in a previously healthy person.Secondary – infection that occurs in a person weakened by

a primary infection.

Classification of infectious diseases

Production of poisons, such as toxins and enzymes, that destroy cells and tissues.

Direct invasion and destruction of host cells.

Triggering responses from the host’s immune system leading to disease signs and symptoms.

Courtesy of CDC

Human Immunodeficiency Virus. HIV-1 virions can

be seen on surface of lymphocytes.

How pathogens cause disease

VaccinesAntimicrobial drugsGood personal hygiene and sanitationProtection against mosquitoes Quarantine

Reducing the spread of infectious diseases