Reproduction and cloning Flashcards
What are the traits of asexual reproduction?
Only one parent is required as cells divide in two
There is no gamete fusion or mixture of chromosomes
There is no genetic variation between the parent and offspring
Why is lack of genetic variation a bad thing?
The lack of genetic variation means that a whole species could
be vulnerable to and wiped out by a disease
What are the traits of sexual reproduction?
Parents produce gametes which fuse and create an offspring
The offspring are genetically different to parents and each other (excluding identical twins)
Each gamete contains half the required chromosomes
How can plants be cloned?
Cutting and tissue culture
How do you clone by taking cuttings?
- A small cutting with a new bud is taken from the parent plant
- They are kept in moist conditions until they can be planted
What are the advantages of taking cuttings?
It is quick
It is cheap
What are the disadvantages of taking cuttings?
You can only take a few from one parent plant or you risk causing damage
How do you clone by tissue culture?
Put plant cells in a growth medium of hormones
What are the advantages of cloning by tissue culture?
It is quick
It does not take up much space
They can be grown all year
How are embryo transplants performed?
- Gametes are taken from the parents and are artificially fertilised
- The embryo that forms is split to form clones
- These clones are implanted into surrogates and produce baby calves who will be genetically identical to one another
- This allows for hundreds of ideal offspring to be produced yearly
How else may strong traits be passed on for ideal offspring?
Selective breeding
What type of cloning was Dolly the sheep produced from?
Adult cell cloning
What is adult cell cloning?
When the nucleus is removed from an egg cell and the nucleus from an adult body cell is implanted into it
What are the steps of adult cell cloning?
- The nucleus is removed from an unfertilised egg cell
- The nucleus from an adult body cell is placed inside
- The cell is shocked and is stimulated to divide
- When the embryo becomes a ball of cells, it is implanted into a surrogate mother
What are the disadvantages of cloning?
The reduced gene pool leads to the presence of fewer alleles, making a population susceptible to disease
It is speculated that cloned animals are less healthy than normally produced ones
There is not always success, and if scientists went on to clone humans, it can be assumed that this would follow many unsuccessful attempts with unethical products
