Protein synthesis occurs on ribosomes in the cytoplasm
The code needed to produce a protein is carried from the DNA to the ribosomes by a molecule called mRNA
Proteins are: Made
up from long chains
of amino acids and
can be structural,
hormones, carrier
molecules or
enzymes
Mutations can
lead to the
production of
many different
proteins. This is
because a
change in bases
in DNA can
change the
amino acid
sequence.
Chromosomes
are long coiled
up molecules of
DNA, divided up
into regions
called genes
Enzymes work
by a lock and
key mechanism
Enzymes activity is affected
by pH and temperature. This
is due to: lower collision rates
at lower temperatures,
denaturing at extreme of pH
and high temperatures
Proteins are coded
for by DNA: The
base sequence
codes for the order
of amino acids, each
amino acids is coded
for three bases
Cell division and cell growth
In meiosis, the
chromosome number is
halved and each cell is
genetically different
There are a number of
differences between
plant growth and animal
growth
Growth can be
measured by a
change in wet mass,
dry mass or length.
each method has
advantages and
disadvantages but
dry mass is the best
measure
Gametes are produced
by meiosis
New cells for
growth are
produced by mitosis
The new cells made by mitosis are
genetically identical
Being multicellular allows
organisms to: be larger, use
cell differentiation
Undifferentiated cells called
steam cells can develop into
different cells, tissues and
organs
Respiration and circulation
the symbol equation for aerobic respiration is:
Red blood cells carry
oxygen around the body
and are especially
adapted for this function
The heart has four chambers
and is part of a double
circulatory system
Anaerobic respiration takes place during
hard exercise when there is insufficient
oxygen avaliable
Anaerobic respiration produces lactic acid,
which: Builds up muscles causing pain and
fatigue, acts as oxygen debt and has to be
broken down in the liver after exercise
Arteries have thick elastic walls
and carry blood away from the
heart, Veins have large lumens
and valves, and carry blood back
to the heart
Changing genes and cloning
Gene therapy involves changing a
person's genes to try and cure
disorders
Genetic engineering
can be used to produce
useful products but
raises some ethical
issues