Year 11 Term 2 Flashcards
What does genetic engineering involve
Changing the genetic material of an organism
What is the first step of genetic engineering
Insulin gene is cut out of DNA by an enzyme and plasmid is taken out of bacterium and split open by a restriction enzyme
What’s a restriction enzyme
They recognise specific sequences of DNA and cut the DNA at these points. The cut leaves one of the DNA strands with unpaired bases, this is called a sticky end
What is the second step of genetic enginerring
The insulin gene is inserted into plasmid by another enzyme, then this plasmid is taken up by the bacterium. The bacteria then multiplies many times, the insulin gene is switched on and the insulin is harvested
What are other examples of genetic engineering
Genes can be cut out of the DNA of one plant and inserted into rice genes, enzymes are still used in this process
In animals, plants and microbes, when does genetic modification usually take place
Genes are often transferred at early stage of development so that the organism develops with the desired characteristics
GM of golden rice
Genes in the pathway for better carotene production are obtained and introduced to the white rice genome, resulting in golden rice which increases the vitamin A content almost 25 fold
Arguments for GM (genetically modified) crops
Higher crop yields Can be resistant to herbicides Reduces pesticide use Safe for human consumption Preserves habitats as less land needed to grow crops Better shelf life
Arguments against GM cops
Unknown long term health risks
Could affect wildlife as killing weeds
Increasing yields means a distribution problem
GM crops are often infertile
What is another name for meiosis
Reduction division
Where is the only place meiosis occurs
Only in the cells of the reproductive organs and produces gametes (sex cells) in the ovaries and testes or then anther and ovule of a plant
What does haploid mean
Half the number of chromosomes
What does diploid mean
Full sets of chromosomes e.g. 46 or 23 pairs
Why do gametes only have one copy of each chromosome
So that when gametes fuse at fertilisation, the zygote has the normal amount of chromosomes. The zygote then divides by mitosis to produce more cells that differentiate as the embryo develops
What happens during meiosis
Chromosomes replicate then shorten and thicken. The pairs line up at centre of cell and spindles attach these pairs separate into 2 new cells and nucleus reforms, spindles attach to the duplicates of chromosomes and are pulled apart into separate cells
What is left at the end of meiosis
4 new cells have formed each having 2 chromosomes (23) they are haploid cells and each one contains different genetic material to the others
What is asexual reproduction
Only 1 parent, no fusion of gametes so offspring genetically identical, happens by mitosis, only genetic variation is random mutations
What are the several types of asexual reproduction
Binary fission (bacteria)
Production of spores (fungi)
Strawberry (runners)
Potato (tuber)
What is sexual reproduction
Mixing of genetic info from 2 organisms, offspring genetically different to parents, male and female gametes produced by meiosis fuse, nuclei of cells are haploid and unite at fertilisation forming diploid zygote
Ads and Disads of sexual reproduction
Increases chance of survival if circumstances change, there is genetic variation however a partner needs to be found
Ads and Disads of asexual reproduction
Only needs 1 parent, no time/energy wasted finding a mate, produces large amount rapidly however susceptible to disease and no genetic variation
Malaria sexual and asexual reproduction
Malaria caused by parasite that’s spread by mosquitoes. The parasite reproduces sexually when it’s in the mosquito and asexually when it’s in the human host
Fungus sexual and asexual reproduction
These fungus species release spores which can become new fungi when land in a suitable place. a.s produced spores form genetically identical fungi to parent fungus. s produced spores introduce variation and produced in response to a change in the environment, increasing the chance of the fungi surviving the change
What does DNA stand for
Deoxyribonucleic acid