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Title: DNA Notes
Description: Extensive notes on matters pertaining to DNA such as its components, function and uses as well as the processes of transcription and translation in the formation of polypeptides and the DNA replication. As well as the steps of DNA transfer from gene to vector.
Description: Extensive notes on matters pertaining to DNA such as its components, function and uses as well as the processes of transcription and translation in the formation of polypeptides and the DNA replication. As well as the steps of DNA transfer from gene to vector.
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DNA Notes
Deoxyribonucleic acid (DNA) carries genetic information that is important for cellular functions, e
...
cell
division
...
A segment of DNA is a gene that stores information
used to make a single polypeptide, which is used to make proteins that determine the characteristics of
an organism
...
Each DNA
molecule consists of two strands twisted around each other to form a double helix
...
During cell division, chromatin threads coil
tightly to form chromosomes inside the nucleus
...
DNA is made up of two pairs of antiparallel (run in
opposite directions) polynucleotide chains
...
o
Nucleotide Basic Unit of DNA
▪
Sugar Phosphate Backbone Provides structural support for the DNA
...
However, the
phosphate group is connected to the deoxyribose sugar of the previous
nucleotide at the 3’ carbon atom
...
●
▪
Phosphate Group
Nitrogencontaining base Complementary bonds are such that one pyrimidine
pairs with one purine
...
Cytosine and Guanine pair using 3 Hydrogen bonds
...
Thus, for a base, there is an equal
amount of bases to complement it
...
The template is the antisense strand
...
Formation of Polypeptides
Transcription is when the template is used to make a messenger RNA (mRNA) in the nucleus
...
The mRNA is then carried out of the nucleus to
the cytoplasm, where ribosomes translate the sequence of codons on the mRNA into a polypeptide,
through translation
...
These
ribosomes are attached to the RER or are free in the cell
...
tRNA
“translates” or matches a codon on the mRNA to a specific amino acid, which are free in the cytoplasm
...
Each anticodon unit is specific and is complementary to specific codons on mRNA
...
1
...
The two DNA strands are separated
...
2
...
3
...
4
...
The anticodons on the tRNA bind to the complementary codon on the mRNA
...
As the ribosome moves along the mRNA, the polypeptide produced gets longer as
more amino acids are joined together by peptide bonds
...
Amino acids are continually attached until the STOP codon is reached
...
Upon encountering the
STOP codon, the ribosome detaches and the polypeptide is released
...
RNA is used in the replication of DNA
...
A sequence of polynucleotides with different bases makes up a gene
...
DNA consists of many genes
...
In
each gene, one chain makes up the template for DNA
...
The nucleus in every cell in the body contains all the genes necessary to construct the human body
...
DNA replication follows a semiconservative model
...
Each new helix is made of one old
strand and one new strand
...
Topoisomerase unwinds DNA at a “bubble”, reducing torsional strength
...
Helicase breaks Hydrogen bonds between Base pairings and separates the two strands
...
Singlestrand binding proteins prevent the strands of DNA to join back together into a double
strand
...
DNA Replication occurs in the opposite direction of the strand it is replicating
...
g
...
DNA replication is continuous when replicating the 3’ to 5’
strand but is discontinuous when replicating the 5’ to 3’ strand
...
RNA Primase adds a short length of RNA attached by base pairing complementing the existing
DNA strand’s template and this makes a short RNA Primer
...
DNA Polymerase III starts replication next to the RNA Primer and adds nucleotides
...
DNA polymerase I replace RNA primer with DNA and a nick is left where two nucleotides are
unconnected
...
Ligase joins together DNA fragments by making another sugarphosphate bond
...
Genetic engineering is used to transfer genes from one organism to another
...
The transferred
gene can be expressed in the recipient organism
...
A vector can be another DNA molecule, a bacterium or a
virus that is used to carry the genes of one organism to another
...
g
...
Gene Transfer
E
...
inserting human insulin gene into bacteria
1
...
Cut the gene
using a restriction enzyme
...
Each ‘sticky end’ is a single strand sequence of nucleotides
...
2
...
Cut the plasmid with the same restriction enzyme
...
3
...
The human insulin
gene will bind to the plasmid by complementary base pairing between their ‘sticky ends’
...
The plasmid is now known as a
recombinant plasmid
...
Mix the recombinant plasmid with E
...
Apply heat that will open up pores in the cell
membrane of the bacterium for the recombinant plasmid to enter
...
The transgenic bacterium will use the new gene to make insulin
...
As not all bacteria will take up the recombinant plasmid, the bacteria mixture is grown in
antibiotic ampicillin, which will kill off all the bacteria that didn’t take in the recombinant plasmid
...
•
Insects that feed on GM crops my develop resistance to the toxins in the crops and may
subsequently develop resistance to pesticides
...
Economic hazards
•
GM seeds can be legally protected against piracy through patenting
...
•
Companies have engineered crop plants that produce seeds that cannot germinate (terminator
technology)
...
•
In poorer societies, farmers may not have the financial capacity to buy these seeds
...
•
Genetically modifying plants could result in alteration in metabolic processes within the plants
and cause production of toxins
...
•
Some people may create new combinations of genes for chemical or biological warfare
...
This gene could mutate and affect the offspring of the patient
...
•
Some religions do not approve of genetic engineering as it may not be appropriate to alter the
natural genetic makeup of organisms
Title: DNA Notes
Description: Extensive notes on matters pertaining to DNA such as its components, function and uses as well as the processes of transcription and translation in the formation of polypeptides and the DNA replication. As well as the steps of DNA transfer from gene to vector.
Description: Extensive notes on matters pertaining to DNA such as its components, function and uses as well as the processes of transcription and translation in the formation of polypeptides and the DNA replication. As well as the steps of DNA transfer from gene to vector.