DNA Flashcards
(23 cards)
What is DNA?
DNA is a double-stranded molecule twisted into a spiral called a double helix and is made up of twisted strands of the bases A, T, C and G.
What are enzymes?
Enzymes are large molecules that speed up the chemical reactions inside cells.
What does A always bond with?
T
What does G always bond with?
C
What is aerobic respiration?
Most of our energy comes from the process of aerobic respiration, which takes place inside the mitochondria of cells.
What are the two strands in DNA held together by?
The two strands in DNA are held together by hydrogen bonds between pairs of bases.
What happens when a cell divides?
When a cell grows and divides into two, it first has to make a duplicate copy of each DNA molecule. This is done by the bonds breaking between the two strands, the strands unwinding, and then new bases joining each old strand to make new strands.
What is complementary base pairing?
Complementary base pairing is the arrangement where the two strands of a DNA molecule are joined together through their bases.
What is good about the hydrogen bonds being weak?
With the hydrogen bonds being weak, it means that they are easily broken enabling a DNA molecule to separate into two strands.
What is a codon?
The sequences of three bases is called a codon.
What was Rosalind Franklin and Maurice Wilkins’ role in the discovery of DNA?
In 1952, Franklin and Wilkins used X-ray crystallography to discover the arrangement of the atoms of DNA molecules.
What was James Watson and Francis Crick’s role in the discovery of DNA?
In 1953, Watson and Crick used Franklin and Wilkins information to propose that the structure of a molecule of DNA is a double helix.
What were the aims of the Human Genome Project (HGP)
- To work out the order or sequence of all the three billion base pairs in the human genome
- To identify all the genes
- To develop faster methods for sequencing DNA
What are the differences between genetic engineering and cloning?
- Cloning produces exact products where as genetic engineering produces a unique set of genes.
- In cloning genes are copied within the same species where as in genetic engineering, genes can be swapped across species.
How does genetic engineering work?
Certain enzymes can cut pieces of DNA containing a particular gene from one organism, and join them into a gap in the DNA of another organism. This means that the new organism with the inserted genes has the genetic information for one or more new characteristics. For example, the organism might produce a useful substance, or be able to carry out a new function. We say that the organism has been genetically modified.
What is the biggest problem with genetic engineering?
The risks that come with doing it.
What is GM insulin?
Natural insulin can be taken from the pancreas of a pig or cow. It is used to treat diabetes but is limited in supply and doesn’t suit all people.
What are the advantages of using GM insulin?
- It is cheap to produce in large quantities.
- It is human insulin, so users experience no allergic reactions or intolerances.
- It does not use animal products and so it no a problem for certain religious groups or vegetarians.
What are the advantages of using GM crops?
- they can grow in places with low rainfall
- they produce their own chemicals to kill insects that damage them
- they resist diseases
- they resist the effects of herbicides; farmers can then destroy competing weeds without destroying the crop
- they produce their own fertiliser.
What are the disadvantages of using GM crops?
- it’s not natural
- eating GM food may affect our health
- GM crops may harm wildlife
- pollen from crops modified to resist herbicides may transfer to weeks
What is golden rice?
Golden rice is a variety that has been genetically modified to produce more beta-carotene in the rice grain. This is converted to vitamin A in our cells.
What are the arguments for using golden rice?
- Human cells convert beta-carotene into vitamin A very efficiently.
- Golden rice is not meant to be the only solution to the vitamin A problem.
- We are only trying to deal with a part of the bigger problem of making a healthy balanced diet available to poor people.
What are the arguments against using golden rice?
- Aiming for a balanced diet is a better solution to vitamin A deficiency.
- Trying to deal with the vitamin A problem with a single GM solution is too limiting.
- Golden rice has never undergone trials to check that it is safe for people to eat.
