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Slide 1

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Cell division is necessary for the Mitosis results in two
growth of an organism, or for repair
identical cells being produced
if tissues are damaged. from the original cell. A copy
of each chromosome is made
before the cell divides and
one of each chromosome goes
into each new cell.
Stem cells are unspecialised. They
can develop (differentiate) into
many different types of
specialised cell. Stem cells are
found in the embryo and bone
Many embryonic stem cells that
we carry research out on are
aborted embryos or `spare'
embryos from IVF. This results
in ethical issues and much
debate as it can be argued you
Cells in reproductive organs are destroying life to obtain
divide to form gametes. these stem cell for research.
Meiosis: Before division a However there is huge
copy of each chromosome is potential for stem cells. The
made. The cell now divides use of bone marrow stem cells
twice to form four gametes. is still limited by the number of
Each gamete has only one different types of cells we can
chromosome from the original develop them into.
pair. All the cells are Sexual reproduction results in variation
different from each as the gametes from each parent fuse.
other and the parent So half the genetic information comes
cell. from the father half from the mother.…read more

Slide 2

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Mendel was a monk who worked out
how characteristics were inherited.
His ideas were not accepted for
many years.
Genes are short lengths of DNA
which make up chromosomes and
control our characteristics.
Genes code for combinations
of specific amino acids, which
make up proteins.
Humans have 23 pairs of
chromosome. One pair are
the sex cells females are XX
males are XY (the Y
chromosome is shorter than
the X).
If an allele `masks' the effect
of another it is said to be
`dominant'. The allele where
the effect is `masked' is said
to be `recessive'.
Genes controlling he same characteristic
are called alleles.
Huntington's disease is a disorder of the
nervous system. It is caused by a
dominant allele, so even if only one parent
has the disease it can be inherited by a
Record your Cystic fibrosis is a disorder of the cell
results as membranes. It is caused by a recessive allele so
percentages. parents must both be carriers so there is a
chance of having a child with cystic fibrosis.…read more


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