Microorganisms and Cells Explained

Life and
living
Andries Olivier p 1

Andries Olivier p 1
Microorganisms

Andries Olivier p 1
The existence of microorganisms
Living
organisms
which are
too small to be
seen with the
naked eye.
You need a

Andries Olivier p 1
Extremely small in size.
Numverous. Numverous. Numerous.Numverous. Numverous. Numerous.Numverous. Numverous.
Numerous.Numverous. Numverous. Numerous.Numverous. Numverous. Numerous.Numverous. Numverous.
Numerous.Numverous. Numverous. Numerous.Numverous. Numverous. Numerous.
Numerous
Extremely
important to ü

Andries Olivier p 1
They play an important role
in the decomposition of
dead plants and animals,
causing dead matter to
decay and spoil.

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Some are useful, others are
harmful.
Cause diseases in
animals, humans and
plants.

Andries Olivier p 1
There are three main types:
viruses
bacteria
fungi

Andries Olivier p 1
Viruses
Smaller than fungi and bacteria.
You need a powerful electron
microscope to see them.
They are not true cells: they cannot
reproduce on their own.
They can only reproduce once they
are inside a hosts' cells.
This causes the host to become ill
because their cells become
damaged.
Influenza
Measles
Common cold
Chicken pox
Fever blisters
AIDS

Andries Olivier p 1
Bacteria
Bigger than viruses, but still VERY small.
Found everywhere.
Most are harmless to humans and play
important roles in food webs.
Those that do, cause disease enter human
cells and use the cells to feed while giving
off poisons.

Andries Olivier p 1
Fungi
Fungal cells 10 – 100 times bigger than bacteria
cells.
Many different types, shapes and sizes.
Yeast – small, unicellular: used to bake bread.
Mould – very thin threads (furry/woolly): grows
on stale bread and overripe fruit.
Mushrooms and toadstools – larger and grow in
soil or in compost.

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Reproduction
Make replicas of themselves and
multiply in minutes/seconds.
They damage the hosts' cells or give
off toxins.
Only after many cells have been
damaged, or large amounts of toxins
have built up, does the host get sick.

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Role
Maintain soil fertility
Purify water
Digest food in humans and animals

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Useful microorganims
Decomposing bacteria help to break
down animal and plant material.
Nutrients return to the soil.

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Useful microorganims

Andries Olivier p 2
Useful microorganisms
Some ruminants have bacteria in their stomachs
that help to digest grass.
Also used to produce dairy products.
Yeast = unicellular fungi. Used in baking bread.
One adds yeast to the dough, which respires and
forms small bubbles of CO2. (Which allows the
bread to rise.)
Yeast also ferments alcoholic drinks such as beer
and wine.

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Antibiotics
...are manufactured by using microorganisms.
...used to destroy other disease-causing bacteria
or prevent them from reproducing.
...containing penicillin are produced using penicillin
fungus.
Certain antibiotics originate from bacteria.

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Antibiotics
...can cause allergic reactions in some people.
Everyone has 'good' bacteria in their digestive
systems – it helps to destroy dangerous/harmful
bacteria.
Dangerous bacteria can affect the digestive
system, causing an upset tummy.

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Harmful organisms
Once inside the body, they multiply quickly.
Can cause disease in two ways:
Destroy cells
Give off poisonous chemicals called toxins
The effect of microorganisms on the body are
called symptoms.
Microorganisms which cause diseases are
called pathogens.

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HIV and AIDS
HIV infects a person when they have unprotected sex
with an infected person of when blood from and infected
person enters the body of another person.
An infected mother can pass HIV to her unborn child, or
through breastfeeding.
If someone is infected with the HI virus we say that they
are HIV positive.

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HIV and AIDS
HIV attacks the body's immune system. (The bodies'
defence system, protecting the body by fighting
diseases.)
HIV enters the cells of the immune system (called T
cells), destroys the cells and weakens the immune
system.
The immune system cannot combat diseases when it is
weakened.
The person will be ill more often.

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HIV and AIDS
Over the years the virus attacks so many cells that the
immune system eventually no longer works and is no
longer able to protect the body against serious illnesses.
At this point we say the person has AIDS.
TB and pneumonia are bacterial infections which often
affect people with AIDS.
It can take a few years for the HI virus to weaken a
person's immune system, so the person can appear
healthy for a long time although they are HIV positive.

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Resistance to medicines
Harmful microorganisms can be destroyed by white blood
cells.
White blood cells can:
Ingest and digest microorganisms.
Produce antibodies that attach microorganisms.
These destroy or collect them which enables them to be
engulfed quicker.
Destroy toxins manufactured by harmful organisms.

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White cells also produce “memory cells”, which stay in
the blood for a very long time, and can recognise
pathogens which enter the body. These cells helps a
person to attack the disease quickly, so that person does
not suffer the same symptoms again. A person is now
immune.
Each type of antibody is specialised. When a mixture of
organisms infects a body, many different antibodies are
required to help with healing.
Medical remedies are used to help combat
microorganisms. However, microorganisms can mutate,
developing resistance to the medicines, so they spread
much quicker.

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The structure of
living things

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Cells and systems
All living things consist of really small particles called
cells.
Cells are the basic unit of
which living organisms
consist.

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Cells and systems
All cells have the same basic structure,
but differ according to their function,
and from which part of the organism
they originate.
Groups of cells with the same structure
and function are known as tissues.

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Cells and systems
So the progression is:
Atoms → Molecules →
Cells → Tissues →
Organs → Systems →
Organism

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Cells and systems
Since cells are very small,
we need to use a
microscope to see cells.

Andries Olivier p 8
Microscope

Andries Olivier p 9
Microscope
Also ocular: Lens where
you put your eye, enlarges
the object (10x).
Holds objectives with low-
and high-power lenses
rotating disc.
Lenses of the objectives
help to enlarge the image.
Also platform: Supports the
microscope slide opening
which transmits light from
the mirror or electric light
source below.

Andries Olivier p 9
Microscope
Controls the amount of light
directed onto and passing
through the object; focuses
light rays from the mirror or
light source onto the object.
Reflects light upwards
through the condenser
towards the opening in the
stage.
Used for final focus to get a
clear image.

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Microscope
tube
arm
Coarse
adjustment
knob

Andries Olivier p 9
Microscope
Magnification: If the magnifying power of the eyepiece
is 10x and the objective is 40x, the the total
magnification of the object being viewed is 10 x 40; or
400x
Microscope slide: Consists of a glass slide, the object
(specimen and a cover-slip.

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Cell structure
Cell membrane: covers the cell
Cytoplasm: the living
substance, contains all
organelles. Viscous liquid.
Nucleus: controls the
functions of the cells.
Largest organelle in the
cell.
Vacuole: organelle with a
membrane that holds liquid.

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PLANT CELLS
Firm shape because of a
cell wall.
One or two large, permanent
vacuoles.
The green pigment called
chloroplasts.
ANIMAL CELLS
Flexible shape because it has
no cell wall.
Many small vacuoles, in any
at all.
No green pigment called
chloroplasts.

Both types of
cells
have...
cytoplasmcell
membrane a nucleus

Life processes
and systems

Parts and systems
Digestive
system Mouth
Oesophagus
IntestinesNutrition

Parts and systems
Respiratory
system Trachea
Lungs
DiapraghmRespiration

Parts and systems
Excretory
system Kidneys
Lungs
SkinRespiration

Parts and systems
Reproductive
system Penis and testes
(males)
Vagina, ovaries and
uterus (females)Reproduction

Parts and systems
Nervous
system Brain
Spinal cord
Sense organsSensitivity

Parts and systems
Locomotory
system Bones
Muscles
Movement

Parts and systems
Circulatory
system Heart
Blood vessels
Transportation

Nutrition

The process by which
living organisms take
in food and use it for
energy, growth and
repair.

Required
growth energy
K
health
N Repair and replacement
of worn and damaged
tissue

Nutrient Function
Proteins Growth and repair building blocks
Carbohydrates Instant energy source
Fats Reserve energy source and insulation
against the cold
Vitamins Ensures normal growth and
development. Health.
Minerals Ensures normal growth and
development.
Water Main ingredient of your body. Supplies
fluid medium for metabolic processes.
Fibre Prevents constipation and certain
cancers.

Digestion
Breaking down of organic food
compounds to their simplest forms.
Food is made up of really large molecules
which cannot be absorbed into the blood
or cells because of their size.
Cells need protein to be made smaller –
into amino acids, carbohydrates into
glucose and fats into glycerol and fatty
acids.

Digestion
Mechanical digestion:
Teeth tear, chew, grind
Stomach stir, grinds and mixes
Chemical digestion:
Digestive enzymes break food down
chemically

Human digestive system
Made up of:
Mouth
Oesophagus
Stomach
Small intestines
Large intestines

Teeth
Biting, chewing
grinding food
Tongue
• Keep food
between teeth
• Mixed food with
saliva
• Moulds food into
bolus
• Assists with
swallowing
Salivary glands
Secrete saliva
• Keep food moist
• Form a bolus
Oesophagus
Peristalsis: pushes bolus to stomach by
means of peristalsis – no digestive function.
Stomach
• Muscular wall grinds food finely
and mixes it with digestive
juices (mechanical digestion).
• Stomach juices start breaking
down proteins (chemical
digestion).
Liver
• Produces bile
• Bile digests fatty
acids
Gall bladder
Temporarily stores bile
Pancreas
Produce digestive
juice with enzymes
that break down
proteins, fats and
carbohydrates.
Small intestine
• Secretes intestinal juice containing
enzymes
• Enzymes digest food substances
• Contains villi
• Absorbs digested food substances
Large intestine
• Stores undigested
food temporarily.
• Absorbs water,
mineral salts and
some vitamins.
• Bacteria
decompose
digested food to
faeces which leaves
the body through
the anus.

Teeth functions
Incisors and canines:
Bite and tear food
Premolars and molars:
Grind the food

Tongue functions
Contains taste buds – is a taste
organ.
Helps with chewing – moves food
under teeth, makes a bolus, assists
in swallowing.

Salivary glands

Salivary glands types
Parotid glands (ear salivary glands)
Submaxillary glands (lower jaw
glands)
Sublingual glands (under tongue
salivary glands)

Salivary glands functions
Contains ptyalin (enzyme) digests
cooked starch.
Slimy – smooths the finely chewed
food, makes swallowing easy.
Alkaline and neutralises food and
helps with the prevention of food
decay.

Oesophagus

Stomach
Takes 3 hours
for food to
change into
chyme.
Chyme = grey
coloured liquid mass
of food that has been
changed as a result of
the grinding and
breaking down
digestive processes.

Stomach - functions
Store food temporarily
Grind food even finer
Stomach walls secrete gastric juices to
break down food to smaller forms
Pyloric valve allows small amounts of
chyme to go to small intestine
Some food that are already small
enough is absorbed

Small intestine
Elastic, muscular tube, approximately 5 m
long folded up.
Held in place by membranes attached to
the walls of the abdominal cavity.
Divided into three regions:
Duodenum
Jejenum
Ileum

Small intestine - function
Glands secrete intestinal juices (enzymes).
Not fully digested food are completely
digested.
Absorption of digested food takes place
here.

Large intestine
1,5 m long and 70 mm wide
Caecum leads into the appendix –
causing appendicitis.
Colon forms the largest part. Stores
food
Rectum ends in the anus from where
faeces is expelled.

Large intestine - functions
Stores faeces temporarily
Glands in the wall secrete mucous to
assist the movement of the faseces.
Water, mineral salts and certain
vitamins are absorbed from the
contents

Balanced diet

Malnutrition
Incorrect nutrition
Poor people – undernutrition
Rich people – overnutrition

Undernutrition
When someone does not take up
enough of one or more of the food
groups.
Sometimes caused by traditional eating
habits, excessive strict diets or of pure
ignorance.

Deficiency
diseases
Symptoms Causes
Rickets Bones soften and break
Shortage of vit. D.
Scurvy Bleeding gums, low
resistance to infectious
diseases.
Shortage of vit. C.
Night
blindness
Inability to see in poor light.
Shortage of vit. A.
Beri-beri Nerve and heart problems.
Weakened muscles;
paralysation.
Shortage of vit. B1
.
Goitre Enlarged thyroid gland.
Shortage of
iodine.
Anaemia Tiredness, weakness,
decreased oxygen supply.
Shortage of iron.

Deficiency
diseases
Symptoms Causes
Kwahiorkor Bloated stomach and swollen
cheeks. Skin cracks and
peels.
Shortage of
proteins.
Marasmus Loss of muscle and the body
becomes thin and weak.
Drastic loss of mass,
diarrhoea.
Diet low in
kilojoules and
proteins.
Starvation.
Pellagra Cracked, dry skin (especially
cheeks), digestive diseases.
Shortage of B-
group vitamins.
In young children due to malnutrition

Other illnesses
Anorexia nervosa
Bulimia nervosa
Overnutrition

Microorganisms and Cells Explained

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