DNA notes
D. DNA, RNA
D1. Structure: DNA & RNA are polymers of nucleotides.
synthesis
NUCLEOTIDES ---------------> NUCLEIC ACID (DNA / RNA)
<--------------
hydrolysis
Nucleotide - nucleotides are composed of 3 parts:
Nucleotide - nucleotides are composed of 3 parts:
BASE: DNA: Adenine RNA: Adenine
Thymine Uracil
Guanine Guanine
Cytosine Cytosine
The bases are single or double ring structures that contain some nitrogen
- "Nitrogenous bases"
Thymine Uracil
Guanine Guanine
Cytosine Cytosine
The bases are single or double ring structures that contain some nitrogen
- "Nitrogenous bases"
ADENINE THYMINE
GUANINE CYTOSINE
Purines and pyrimidines
Adenine, Guanine: Purine (Double ring bond) -larger
Thymine, Cytosine: Pyrimidines (Single ring bond) -smaller
GUANINE CYTOSINE
Purines and pyrimidines
Adenine, Guanine: Purine (Double ring bond) -larger
Thymine, Cytosine: Pyrimidines (Single ring bond) -smaller
- A 2 Ring Base always bonds with 1 Ring Base.
4. Complementary base pairing
The nucleotides string together (Synthesis) by joining the sugar of one nucleotide to the phosphorous of the adjacecent nucleotide. This forms a sugar - phosphorous backbone .
The bases stick towards the centre and form hydrogen bonds with the bases of the adjacent strand.
The two strands twist, forming a spiral shaped molecule called a double heliX
Complementary Base Pairing:
4. Complementary base pairing
The nucleotides string together (Synthesis) by joining the sugar of one nucleotide to the phosphorous of the adjacecent nucleotide. This forms a sugar - phosphorous backbone .
The bases stick towards the centre and form hydrogen bonds with the bases of the adjacent strand.
The two strands twist, forming a spiral shaped molecule called a double heliX
Complementary Base Pairing:
- Sugars & Phosphorous of
nucleotides bond, forming the "Sugar
Phosphorous backbone "
Bases bond toward the centre
- The double spiral shape:
-Double Helix
D2. Replication
- When a cell divides, it must make an exact copy of the DNA. There are 3 basic steps:
- any mistakes in copying is a MUTATION .
- each cell receives 1/2 mother (old) DNA and 1/2 new DNA (semi- conservative )
- the entire process invoves many enzymes
D3. Recombinant DNA
Recombinant DNA is the use of various techniques and enzymes to recombine DNA from different organisms. Genes from one species can be cut out and inserted into the DNA of an entirely different species. The new gene can then be expressed by the recipient species.
Recombinant DNA involves the use of special enzymes (called restriction enzymes) that cleave DNA at specific sites, and other enzymes such as DNA polymerase, Ligase, Reverse transcriptase.
D4. Uses for recombinant DNA
There are many possibilities for uses of recombinant DNA.
D5. Compare and Contrast DNA and RNA
DNA: - Deoxyribose (5 C sugar with one less oxygen)
- Bases: Adenine, Guanine, Thymine, Cytosine
- Strands: Double Stranded, with base pairing
- Double helix shaped
- Only found in Nucleus
- Longer than RNA
- 1 Kind
RNA: - Ribose (5 C. sugar with one more oxygen)
- Adenine, Guanine, Uracil, Cytosine
- Single Stranded
- Not double helix shaped
- Found in nucleus and cytoplasm
- Shorter
- 3 Kinds (messenger - mRNA, transfer - tRNA, ribosomal - rRNA)
nucleotides bond, forming the "Sugar
Phosphorous backbone "
Bases bond toward the centre
- The double spiral shape:
-Double Helix
D2. Replication
- When a cell divides, it must make an exact copy of the DNA. There are 3 basic steps:
- - DNA "unzips" at the hydrogen bonds between the bases. (Enzyme)
- - Free floating nucleotides line up with their exposed complementary bases. - complementary base pairing New hybrogen bonds form between the complementary bases.
- - An enzyme runs down the bases and bonds the sugar / phosphorous backbone. DNA Polymerase
- any mistakes in copying is a MUTATION .
- each cell receives 1/2 mother (old) DNA and 1/2 new DNA (semi- conservative )
- the entire process invoves many enzymes
D3. Recombinant DNA
Recombinant DNA is the use of various techniques and enzymes to recombine DNA from different organisms. Genes from one species can be cut out and inserted into the DNA of an entirely different species. The new gene can then be expressed by the recipient species.
Recombinant DNA involves the use of special enzymes (called restriction enzymes) that cleave DNA at specific sites, and other enzymes such as DNA polymerase, Ligase, Reverse transcriptase.
D4. Uses for recombinant DNA
There are many possibilities for uses of recombinant DNA.
- Protein production.
It is possible to isolate a gene from one organism (say Human insulin), and using recombinant DNA techniques, insert that gene into a different organism (say E. coli bacteria). The new organism can then produce that protein. By culturing large quantities of the bacteria it is possible to collect large amounts of Human insulin inexpensively. Many other useful human proteins are being produced in this manner (interferon, Growth Hormone, interluekins etc.)
- Gene therapy
It is possible to correct genes in individuals that have non-functional (mutated) genes. For example, the corrected gene for the protein that causes Cystic fibrosis has been inserted into a virus that infects human lung cells. The virulent part of the virus genes has been deactivated. The virus then injects the corrected cystic fibrosis gene into the cells of the cystic fibrosis patient, and their symptoms are greatly reduced!
- Transgenic organisms (have a foreign gene inserted into them)
Selected genes can be inserted into a plant to give it features that were not possible through breeding. For example, a bacterial insect toxin gene can be inserted into a plant (eg. potatoe) so the plant is now toxic to insects, and fewer insecticides are needed in order to grow it!
D5. Compare and Contrast DNA and RNA
DNA: - Deoxyribose (5 C sugar with one less oxygen)
- Bases: Adenine, Guanine, Thymine, Cytosine
- Strands: Double Stranded, with base pairing
- Double helix shaped
- Only found in Nucleus
- Longer than RNA
- 1 Kind
RNA: - Ribose (5 C. sugar with one more oxygen)
- Adenine, Guanine, Uracil, Cytosine
- Single Stranded
- Not double helix shaped
- Found in nucleus and cytoplasm
- Shorter
- 3 Kinds (messenger - mRNA, transfer - tRNA, ribosomal - rRNA)