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AQA GCSE Biology B1.6 Genetic
Variation and its control
- Inheritance
- The information that
results in plants and
animals having similar
characteristics to their
parents is carried by genes,
which are passed on in
gametes from which the
offspring develop
- The nucleus of a cell contains chromosomes.
- The chromosomes carry the genes that control the characteristics of the body.
- Different genes control the development of different characteristics of an organism
- Differences in the characteristics of individuals of the same kind may be due to differences in:
- The genes that they have inherited
- The conditions in which they have developed
- or a combination of both
- or a combination of both
- The conditions in which they have developed
- The genes that they have inherited
- Differences in the characteristics of individuals of the same kind may be due to differences in:
- Different genes control the development of different characteristics of an organism
- The chromosomes carry the genes that control the characteristics of the body.
- The nucleus of a cell contains chromosomes.
- The information that
results in plants and
animals having similar
characteristics to their
parents is carried by genes,
which are passed on in
gametes from which the
offspring develop
- Reproduction
- There are 2 forms of reproduction:
- Sexual Reproduction~ the fusing of male and female gametes
- The mixture of the genetic information from two parents
leads to variation in the offspring
- This is important for survival as some
characteristics may give offspring a better chance
of survival.
- This is important for survival as some
characteristics may give offspring a better chance
of survival.
- The mixture of the genetic information from two parents
leads to variation in the offspring
- Asexual reproduction ~ no fusion of gametes and
only one individual is needed as the parent
- There is no mixing of genetic information and so
there is no variety in offspring.
- These genetically identical individuals are known as clones
- These genetically identical individuals are known as clones
- There is no mixing of genetic information and so
there is no variety in offspring.
- Sexual Reproduction~ the fusing of male and female gametes
- There are 2 forms of reproduction:
- Cloning
- Modern cloning techniques include:
- Tissue Culture ~ Taking small groups of cells from a
part of a plant and growing them under special
conditions.
- Taking cuttings from older plants and growing them.
- Embryo transplants ~ An embryo with unspecialised cells is split
into smaller groups of cells, then the identical embryos are
transplanted into host mothers.
- Adult cell cloning
- The nucleus of an adult cell e.g a skin cell is removed.
- The nucleus from an unfertilised egg cell (ovum) is removed
- The nucleus from the adult body cell is inserted into the empty ovum
- A small electric shock causes the egg cell to begin to divide to form an embryo
- The embryo cells contain the same genetic info as the adult skin cell (as its nucleus was used)
- When the embryo has developed into a ball of cells it is placed into the womb of an adult female to continue its development
- Dolly the sheep was produced by adult cell cloning in 1997
- Benefits of it are:
- Could produce genetically
engineered cloned animals to
have valuable proteins in their
milk. These have uses in
medicine.
- Could be used to save animals from extinction
- Disadvantages of it are:
- Concerns about the ethics of it
- Cloning limits the variation in a population (limits the gene pool)
- Could cause problems for natural selection if the environment changes
- Concerned about using the technique to clone humans in the future
- Concerned about using the technique to clone humans in the future
- Could cause problems for natural selection if the environment changes
- Cloning limits the variation in a population (limits the gene pool)
- Concerns about the ethics of it
- Disadvantages of it are:
- Could be used to save animals from extinction
- Could produce genetically
engineered cloned animals to
have valuable proteins in their
milk. These have uses in
medicine.
- Benefits of it are:
- Dolly the sheep was produced by adult cell cloning in 1997
- When the embryo has developed into a ball of cells it is placed into the womb of an adult female to continue its development
- The embryo cells contain the same genetic info as the adult skin cell (as its nucleus was used)
- A small electric shock causes the egg cell to begin to divide to form an embryo
- The nucleus from the adult body cell is inserted into the empty ovum
- The nucleus from an unfertilised egg cell (ovum) is removed
- The nucleus of an adult cell e.g a skin cell is removed.
- Adult cell cloning
- Embryo transplants ~ An embryo with unspecialised cells is split
into smaller groups of cells, then the identical embryos are
transplanted into host mothers.
- Taking cuttings from older plants and growing them.
- Tissue Culture ~ Taking small groups of cells from a
part of a plant and growing them under special
conditions.
- Modern cloning techniques include:
- Genetic Engineering
- Involves changing the genetic makeup of an organism
- In genetic engineering genes from humans and other organisms are 'cut out' using enzymes.
- The gene is then placed in the chromosome of another organism.
- Genes can also be transferred into the cells of animals,
plants or microorganisms in an early sate of development
so that they develop with desired characteristics
- New genes can be transferred to crop plants.
- Crops that have their genes modified in this way
are called Genetically modified crops (GM crops)
- GM crops may be insect or herbicide-resistant and usually have increased yields.
- GM crops may be insect or herbicide-resistant and usually have increased yields.
- Crops that have their genes modified in this way
are called Genetically modified crops (GM crops)
- New genes can be transferred to crop plants.
- Genes can also be transferred into the cells of animals,
plants or microorganisms in an early sate of development
so that they develop with desired characteristics
- The gene is then placed in the chromosome of another organism.
- In genetic engineering genes from humans and other organisms are 'cut out' using enzymes.
- Involves changing the genetic makeup of an organism
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