molecular genetics€¦ · 1) dna contains all the genetic information about an organism. 2)...
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MOLECULAR GENETICS
● what is DNA?● 23 and me ☺
History (1):The transforming principle
History (2):Hershey & Chase Experiment
Central Dogma of Molecular Biology
DNA → RNA → protein
1) DNA contains all the genetic information about an organism.
2) Regions on DNA that code for specific attributes are called genes.
3) In order for the information within a gene to be useful, it has to be translated into proteins.
The end proteins determine individual traits!
What makes good genetic material?
● Stable source of information
● Ability to replicate accurately
● Capable of change
DNA
-DNA Stands for DeoxyriboNucleic Acid
-DNA is the hereditary material inherited from past generations
-The vast majority ( >99%) of your DNA is in the nucleus of your cells
DNA Structure-double helix.
- sugar-phosphate backbone with nitrogenous groups attached
-monomers that make up nucleic acid
Three components
1. Pentose sugarDNA = deoxyribose
2. Nitrogenous base
3. Phosphate group attached to 5’ carbon
Nucleotides
Four bases:
Adenine and guanine are known as purines
Cytosine and thymine are known as pyrimidines
-Nucleotides are linked by phosphodiester bonds
Phosphodiester bond
- covalent bond between the phosphate group (attached to 5’ carbon) of one nucleotide and the 3’ carbon of the sugar of another nucleotide.
-very strong: DNA is remarkably stable- can be boiled without degrading!
● The DNA helix is composed of two ANTIPARALLEL strands
5’: phosphate3’: OH of sugar
5’ and 3’● the ends of the DNA chain are not the
same● One end of the chain has a 5’ carbon
(bound to phosphate group) and the other end has a 3’ carbon (bound to OH group)
- New nucleotides are added only at the 3’ end: 5’ → 3’ extension
5’ end
3’ end
COMPLEMENTARY BASE PAIRING● Polynucleotide chains join together
through hydrogen bonding◦ A forms 2 hydrogen bonds with T
◦ C forms 3 hydrogen bonds with G
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