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Animal Cells
Most human cells, like most animal cells, have the following parts:

Plant Cells
Plant cells have all the features of a typical animal cell, but they also contain features
that are needed for their very different way of life
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Sometimes cells
become so specialized that they only have one function within the body
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Red blood cells
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Contain haemoglobin which combines with oxygen and transports it to other cells
and around the body
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Their shape also allows cells to
squeeze through capillaries and provide oxygen
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Mature red
blood cells also lack mitochondria
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They need to move to reach the egg and then
burrow inside
The tail of the sperm cell enables it to swim to the ovum and fertilise it
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The middle section is packed with mitochondria to power movement
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When a sperm cell fuses with the egg, the egg then forms a strong membrane to
prevent other sperm from entering
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In humans,
this gives a total of 46 chromosomes
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It is made up of cytoplasm surrounded by a
membrane and a cell wall
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Unlike animal, plant and algal cells, bacteria cells don’t have a nucleus
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Microorganisms which cause disease are called pathogens
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Bacteria are very small cells that can cause disease
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Bacteria divide (binary
fission), and they are usually genetically identical
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Fortunately, your body has several ways to prevent pathogens from getting inside
and doing damage
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In spite of this, some pathogens can evade these
barriers and enter the body
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Producing antibodies:
Every cell has unique molecules (antigens) on its surface
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A unique antibody is produced for each type of pathogen
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This is termed
‘immunity’ and is the principle on which vaccines work
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Antibiotic Resistance
Common medications that people take when they have an infection, like paracetamol
and ibuprofen, don’t affect the pathogen causing the illness
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Antibiotics, such as penicillin exert their effects on bacterial cells without harming
your own cells
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Antibiotics can stop working as bacteria develop random mutations
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These antibiotic-resistant bacteria then
multiply, following the principles of natural selection
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Natural selection is a process that results in the adaptation of an organism to its
environment by means of selectively reproducing advantageous changes in its
genotype or genetic constitution
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To help prevent
antibiotic resistance, patients should always finish the course of antibiotics and
medics should avoid prescribing them unnecessarily
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Bacterial and viral infections can cause similar symptoms, however, they are dissimilar
in the way they respond to medications
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Thus antibiotics should not be used for viral infections

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