Download You and your Genes.

You and your Genes.
By
Helena Cowling
Genes, Chromosomes and DNA
•
•
•
•
Genes are parts of
chromosomes and
chromosomes are
made up from DNA.
The chromosomes are
found in the nuclei of
cells.
Genes are there to
make proteins.
DNA has a double
helix shape.
Genes, chromosomes and DNA
continued..
• Both of the strands of
DNA are made up from
smaller molecules.
• four of these molecules
are called bases.
• Bases always pair up in
the same way to connect
the strands of DNA
together.
• the order of these
bases gives instructions
on how to make a
particular protein.
Inheritance
• The Egg and sperm
cells are called sex
cells.
• The sex cells only
have 1 copy of each
chromosome.
• When the sperm cell
fertilises the egg, the
nuclei from each
connects so that the
egg has two copies of
every gene.
Inheritance continued…
• Chromosome genes carry
the same genes in the
same place.
• Different versions of
genes are called alleles.
• two alleles in a cell may
be the same or different.
• If a cell has one
dominant allele and one
recessive allele then the
characteristics coded in
the dominant allele will
be inherited.
Babies and children
• Babies may be similar to
there parents in some
way.
• Brothers and sisters may
be different to each
other but they could also
be very similar.
• There are two
chromosomes that
determine a gender. A
male has a X and Y
chromosome and a female
has two X chromosomes.
Genetic Diseases
• Some diseases are caused by
faulty genes.
• These diseases are called
genetic diseases.
• Some examples of these arecystic fibrosis, Huntington’s
disease and Haemophilia
• If a person has one recessive
allele then they will not have
the disease, but they will be
a carrier. They could pass
this allele onto there
children.
• People can check if they are
a carrier of a genetic
disease.
Family Trees
• Using family trees can help
people see if they are likely
to get a genetic disease or if
they will be a carrier or not.
• You can also use Punnett
squares or genetic cross
diagrams to see what chance
H= Dominant gene (Faulty gene)
there is of someone having
h= Recessive gene (Good gene)
the disease.
Mum
• What is the chance of a
child having Huntington's
disease?
///// H
h
• There is a 50% chance of the
h
Hh
hh
Dad
child having Huntington’s
disease.
h
Hh
hh
Genetic testing.
• Even though genetic
testing can be helpful, it
can also be wrong
sometimes.
• However it is
controversial whether or
not it should be allowed.
• If someone is pregnant
and they find out their
child has a genetic
disease they could decide
not to have the child.
Genetic modification.
• In the future, genetic
modification could be used
to treat or prevent genetic
disease.
• They could do this by
putting normal alleles into
the cells with the faulty
alleles.
• Genetic modification could
also be used to make
designer babies.
• There are different ethical
issues about this and many
people are against it, but
some people support the
idea.
Natural Cloning
• Some bacteria, simple
animals and plants can
reproduced on its own.
• This is called asexual
reproduction.
• Animals and plants with lots
of cells have specialised
cells. These do certain jobs.
• Some plant cells are
unspecialised. These can
then develop into any cell
that the plant needs.
• When gardeners take
cuttings of plants it is the
unspecialised cells that are
used to grow new roots.
Cloning.
• It is very difficult to clone
animals or humans.
• To do this you need to –
Take an egg cell.
Take out the nucleus.
Take the nucleus from a
normal cell.
Put the new nucleus into the
egg cell.
• There are different ethical
issues with this and lots of
people are against it,
especially religious groups.