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Science year 9


... by spreading spores Can be ... Disease Gaze SJ Agents that cause infectious diseases can be transmitted in many ways. Through the air Through contaminated food or ... – PowerPoint PPT presentation

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Title: Science year 9

Science NCEA L1 1.11 Micro-organisms and humans
Living and non-living organisms
Biology is the study of living things A living
object is an object that caries out life
functions A non-living object is an object that
has not been alive A 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
Life functions of living organisms
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
GZ Science resources
All living organisms are made of cells
Animal Plant Bacteria Virus
Enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. gtsmall vacuoles, no chloroplasts, no cell wall. Similar to the animal cell, but gtdoes not have centrioles, lysosomes, cilia, or flagella. gtIt 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.
All living organisms are organised into Domains
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
Prokaryotes and Eukaryotes
Prokaryotes Eukaryotes
gtlack cell nucleus gtDNA/RNA material stored in a single loop in an area called the nucleoid gthave no membrane bound organelles. gtreproduce asexually by binary fission gthave membrane bound nucleus containing genetic material gtDNA stored on Chromosomes gthas membrane bound organelles (mitrochondria respiration, Chloroplasts photosynthesis) gtusually reproduce sexually by meiosis
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
Types of Micro-organisms
Yeast (fungi)
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 its 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.
Examples of Viruses
Rabies virus
Influenza virus
Bacteriophage virus
Viruses can take numerous forms
Virus Structure
All viruses contain gt Nucleic acid, either DNA
or RNA (but not both), gt A protein coat
(capsid), which encases the nucleic acid. gt Some
viruses are also enclosed by an envelope of fat
and protein molecules.
Function of the Virus Components
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
  • 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.

Culturing Viruses
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 hens 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).
Reproduction of 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 Th
e 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 T
he newly created virions break through the cell
wall (killing it) and proceed to infect other
Lysogenic Cycle
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.
Targeted Cells
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.
  • There are three requirements that must be met to
    ensure successful infection of a virus
  • sufficient virus must be present
  • the cells must be susceptible and permissive
    (matching) to the virus,
  • and local defenses (immune system) must be

HIV Virus
1. 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.
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.
Are microscopic Are made up of one cell Are
round, long thin, or spiral shaped Need food
and warmth to grow Use enzymes to digest food
Bacterial cell
They have no mitochondria, the cell membrane is
the site of energy release. The DNA is in a
single loop rather than chromosomes Outside the
cell membrane is a cell wall and often a slime
capsule for protection There may be a flagellum
to help the bacterium move. size they are much
smaller All bacteria are prokaryotes they have
no nucleus membrane, just an area that the DNA
Cell Structure of Bacteria
Absence of nucleus
No organelles in cytoplasm (except ribosomes)
Examples of Bacteria
Streptococcus pyogenes These 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)
Bacteria nutrition
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.
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 (
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.
Anaerobic respiration
harmful useful
gtGangrene - foul-smelling discharge, dead tissue, and gas formation within the tissue gtyoghurt production gtproduction of biogas gtwaste processing gtelectricity generation
Aerobic respiration
harmful useful
gtFood rotting sour milk gtNitrogen fixing bacteria gtCheese production gtGE insulin production
Bacteria excrete waste products. Sometimes these
are harmful and are known as toxins. A
disease-causing bacterium is called a pathogen.
Bacterial reproduction
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
Conditions required for bacterial growth
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.
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 HYPHAE Parasites
or decomposers Spread by spores Fuzzy- looking
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.
Fungi Structure
Fungi Structure
gtSpores, 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) gtSporangium or
fruiting body. The visible part of the fungi that
produces and distributes the spores. gt 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.
Fungi Reproduction
  • Can be ASEXUAL by spreading spores
  • Can be SEXUAL where two hyphae touch

Fungi Reproduction
Fungi Asexual 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.
Fungi Sexual 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
Fungi Nutrition
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
Extra-cellular digestion
  • Steps to feeding
  • Enzymes are released from the hyphae.
  • The food material outside the hyphae is digested.
  • The food molecules are small enough to diffuse
    into the hyphae.

Fungal hypha
Smaller food particles absorbed
Enzymes secreted to break up large particles
Large food particle
Fungi Respiration
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.
Sugar alcohol
carbon dioxide C6H12O6
( 2ATP)
Fungi Excretion
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.
Helpful vs Unhelpful Fungi
  • 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
  • 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
  • However, Penicillin is an important antibiotic

Making a culture
  • Collect a swab and petri dish
  • Wash your hands - to avoid contamination of
  • 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

Identifying Microbes
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 Fungi How
you can identify it fuzzy

Using Fungi to make wine and beer
  • The microbe used in beer wine making is a
    fungus called YEAST
  • The YEAST makes alcohol by anaerobic respiration
  • 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

Food production
Micro-organisms play essential roles in the
manufacture of such foods as bread and cheese,
and also in the brewing and wine making
Using Bacteria to make Yoghurt
  • From milk that has had bacteria added to it
  • When bacteria feed on the Lactose (sugar) in the
    Milk and makes LACTIC ACID and water

Stages in yoghurt production
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!
Yoghurt Production
The milk is pasteurised for 10 minutes at 95C.
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 43C. 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
22C. Fruit and flavour may be then added then
the yoghurt is packaged. It is then cooled and
stored in a fridge at 5C. storage at this
temperature slow down the activity of any
bacteria in the yoghurt so it lasts longer.
Complete the following table to describe the key
steps in the yoghurt making process
Key step Description of what happens in each step
Pasteurised 10 minutes at 95C, kills harmful bacteria already in the milk
Homogenised Shaken up so milk doesnt separate out in its parts (water, cream, fat etc) Cooled and kept at 43C
Inoculation A starter culture of useful bacteria is added to the milk
Incubated Kept warm at 43C for 4 to 6 hours which is the ideal growing conditions for the bacteria
Packaged Cooled down to 22C, fruit and flavour added and put into packs for selling
Stored Kept in a fridge at 5C so bacteria does not grow any more and the yoghurt lasts longer
Stages in wine production
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 doesnt do anything in this step.
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.
Transmission of Infectious Disease
  • Agents that cause infectious diseases can be
    transmitted in many ways.
  • Through the air
  • Through contaminated food or water
  • Through body fluids
  • By direct contact with contaminated objects
  • By animal vectors such as insects, birds, bats,

Courtesy of VOA Chinese students wearing masks
during a SARS outbreak
Courtesy of CDC Aedes aegypti mosquito Known to
transmit Dengue fever
Classification of infectious diseases
By duration Acute 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
How pathogens cause disease
Production of poisons, such as toxins and
enzymes, that destroy cells and tissues. Direct
invasion and destruction of host
cells. Triggering responses from the hosts
immune system leading to disease signs and
Courtesy of CDC Human Immunodeficiency Virus.
HIV-1 virions can be seen on surface of
Reducing the spread of infectious diseases
Vaccines Antimicrobial drugs Good personal
hygiene and sanitation Protection against
mosquitoes Quarantine