Flashcards in B1.7 Genetic Variation Deck (29)
What does the information genes carry result in?
It results in plants and animals having similar characteristics to their parents
How are genes passed on?
In sex cells (gametes) from which the offspring develops
What is asexual reproduction used for?
Producing individuals that are genetically identical to their parents
How do genes operate?
They operate at a molecular level to develop characteristics that can be seen
Where are chromosomes found?
In the nucleus
What are most characteristics determined by?
Genetic and environmental factors
What is genetic variation caused by?
The combining of genes from two parents
What is environmental variation?
Any difference that has been caused by the conditions something lives in
Describe sexual reproduction.
The fusion of male and female gametes, resulting in mixing of the genetic information from two parents and variation in the offspring
Describe asexual reproduction
The production of genetically identical clones from a single parent as there is no mixing of genetic information so no variation in offspring.
What are the advantages of sexual reproduction compared to asexual reproduction?
- The offspring inherits stronger genes
- If an environmental change (e.g new disease) comes, not all will be wiped out
What are the disadvantages of sexual reproduction compared to asexual reproduction?
- More risk
- Animals have to make effort to reproduce
- Some reproduction is dangerous
What are chromosomes made up of?
What are genes made up of?
What are the two ways plants can be cloned?
- Tissue culture
Describe the process of cloning from cuttings
1) Remove a small piece of plant
2) Grow in the right conditions
3) Roots and shoots will form to give you a small complete new plant
What conditions do plants from cuttings need to be grown in and why?
- Large leaves are removed : reduces water loss
- Rooting powder is used : contains root growing hormone (auxin) and fungicide to keep back fungus root
- Soil is kept warm : to keep shoot humid to reduce water loss
- Leaves are kept cool : stops fungus disease spreading in leaves and water loss
- Compost has a high proportion of sand in it : creates air spaces so new growing roots have oxygen for respiration
What are the advantages to cutting cloning?
Describe the process of cloning using tissue culture
1) A small piece of tissue taken
2) Placed in substance to help it grow (e.g on a agar plate with nutrients and hormones e.g auxin to stimulate growth of roots and stems)
3) After about 12 weeks roots and stems start to appear
4) The new organisms are planted
What are advantages of cloning with tissue culture?
- Very space
- Can be grown all year
Describe the process of cloning with embryo transplants
- Sperm cells and egg cells are added to each other
- Artificial fertilisation occurs
- The fertilised egg develops an embryo
- The cells of the embryo are split apart before they specialise
- Each cell develops into an individual embryo
- The surrogate mother is giving hormones to ensure readiness for pregnancy
- The embryo is implanted into her womb
Describe the process of adult cell cloning.
- Egg cell removed from female's ovary
- Nucleus removed from the egg cell
- Nucleus from male adult body cell removed and inserted into empty egg cell
- Egg cell stimulated by an electric shock, making it divide to form body cells
- Before the dividing cells specialise they are implanted into the surrogate mother to grow into a clone of the male body cell
What are the advantages of cloning?
- Study of animal clones could lead to greater understanding of embryo development and aging (e.g age related disorders)
- Could help endangered species
- Produces "ideal" offspring for farming
What are the disadvantages of cloning?
- Clones may not be as healthy as normal e.g Dolly the sheep had arthritis early
- Reduced gene pool, higher risk of a species being wiped out
- Ethical/moral problems
Describe the process of genetical engineering.
- The useful gene needed is cut out of an organism's chromosome (or a bacteria's plasmid) using an enzyme
- Enzymes are used to split open another organism's chromosome/plasmid and insert the useful gene
What are four uses of genetic engineering?
- GM crops : crops with genes modified to make them resistant to herbicides, insects and viruses
- Sheep genetically engineered to produce substances e.g drugs in their milk to treat human diseases
- Gene therapy: genetic disorder sufferers e.g cystic fibrosis can have working genes inserted
- Bacteria can be genetically engineered to mass produce insulin
What are the advantages to GM crops?
- Increases crop yield, so more food
- People in developing countries lack certain nutrients - crops can be engineered to produce contain them
- GM crops are already being grown with no problems
What are the disadvantages to GM crops?
- Reduced farmland biodiversity : reduced numbers of weeds and flowers and therefore insects
- Possible risk to humans eating them (we don't know long term effects)
- Transplanted genes can get out into the natural environment e.g weeds picking up herbicide resistant gene