Protein synthesis process
1. The DNA unzips and is used as a template for mRNA. Base pairing ensure it's complementary. This is called TRANSCRIPTION.
2. The mRNA strand moves out of a nuclear pore and joins with a ribosome.
3. Amino acids that match the mRNA codes are brought to the ribosome by tRNA.
4.The ribosome sticks together the amino acids to create a polypeptide; this includes triplets of bases that are called 'codons'. This step in called TRANSLATION.
Mutations can be harmful, benficial or neutral.
HARMFUL: A mutation can cause a genetic disorder; e.g Cystic Fibrosis.
BENEFICIAL: A mutation can cause a characteristic that is benficial to the organism; e.g mutation in plasmids can cause resistance to antiboitics.
NEUTRAL: A mutation has neither harmful/benficial effects; e.g. they dont affect a proteins function.
ENZYMES ARE BIOLOGICAL CATAYSTS THAT SPEED UP A REACTION WITH BEING CHANGED OR USED UP.
- DNA REPLICATION - enzymes help copy a cell's DNA before it divdes by mitosis/meiosis.
- PROTEIN SYNTHESIS - they hold together the amino acids and form bonds between them.
- DIGESTION - enzymes are hidden into the gut to digest different foods.
They have special shapes so they can catalyse reactions.
The substrate is the molecule changed in the reaction. Every enzyme has an active site that joins on to the subsrate to catalyse a reaction; they usually highly specific for their type of substrate.
This is because, for the enzymes to work, they need the substrate to fit into the active site. If the shape does not match, it will not catalyse the reaction. This is called the 'lock and key mechanism'.
More on enzymes
What affects the rate on an enzyme-catalysed reaction:
- TEMPERATURE: If you increase the temperature, the rate of reaction also increase; this is due to the fact that the substrate particles having more energy so they're more likely to join with their active site. However, if it gets too hot, the bonds break and the enzymes denature. The maximum temperature for human enzymes are about 37 degrees.
- pH LEVELS: If it is too high or too low, it interfers with the bonds which may change the shape of the active sites and denature the enzymes. Usually, pH.
- SUBSTRATE CONCENTRATION: The higher the substrate concentration, the faster the reaction. It is only true up to a ppint, after, it has no difference.
The Human Genome Project
This is where thousands of scientist collaborated to try and identify every single type of genes.
- Predict and prevent diseases - if doctors were aware what genes caused what diseases, it could help manufacture genetically tailored advice.
- Develop new and better medicines - knowing how a disease affects makes it possible to design more effective treatments.
- Acurate diagnoses - some diseases are hard to test for so knowing the genetic cause can make testing a lot easier.
- Improve forensic science - can accumalte a DNA fingerprint of their biological traits.
- Increased stress - if someone was aware from an early age the problem that might occur, it can lead to panics.
- GENE-ism - Can come under pressure to not have children
- Discrimination - life insure woukd be really expensive and employers may not want to employ someone who may become ill.
Moving useful genes from one organism's chromosomes into the cells of another.
A useful gene is cut - using restriction enzymes - out from one organism's chromosomes, these are then inserted into an empty chromosome. These create GM bacteria.
- Reduce Vitamin A defieceny - Beta-carotene makes vitamin A, if there is a lack of it, a BC gene can be inserted into rice. This is called Golden Rice and this can means fewer peole will suffer from Vitamin A deficiency.
- Produce human insulin - human insulin gene can be inserted into bacteria to produce human insulin. This is a quick and easy method to treat diabetes.
- Increasing crop yield - insert gene that makes plants resistant to herbicide so when plants are growing spraying herbicide on them will not kill them. This can make more food.
Reduces farmland biodiveristy as there are less weeds/flowers. Not everyone is convinced it is safe. It may create a 'superweed' if it gets out into the natural environment.
Mitosis and Meiosis
Mitosis makes new cells for growth and repair. Human cells are diploid - they have 46chromosomes. When the cell divides it makes two cells excatly identical, this divides by mitosis.
Asexual reproduction also uses mitosis;
No genetic variation
Meiosis creates gentically variated offspring.
1.An adult body cell is taken from the organism being cloned. It has a full set of 46 chromosomes.
2. An unfertilized egg cell is enculated - has it nucleus removed.
3. The body cell is placed into the egg cell and given a shock; this activated mitosis.
4. It is then emplanted into a surrogate and it grows into a zygote.
- Can help with shortages of transplant
- Can lead to a greater understanding of age related disorders
- Help preserve endangered species
- Leads to a reduced gene pool
- May live a short ife
- Many failures, genetic defects, more dieseases.
1. To start with, cells are all the same (undifferentiated); these are embryonic stem cells.
2.They able to divde to produce stem cells or dfiferent types of specialised cells.
3. Differentiation is the process becoming specialised. It is where the embryo starts to develop a human body, e.g organs and systems.
4.Animals lose this stage early on, however, plants are able to do this forever.
FOund in the bone marrow.