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Deoxyribonucleic Acid ( DNA )
The heredity molecule controlling the
activities on the cell.
The DNA Line-up
What’s So Special About DNA?
DNA is one of the most boring macromolecules imaginable - its made of only four building blocks and has a perfectly monotonous structure.
Worse yet, DNA just sits there - it doesn’t catalyze reactions or build the cell or organism.
So, what’s so good about DNA?
The answer lies in DNA’s ability to store and copy information.
Structure
• The double helix structure of DNA was first described in 1953 by James Watson & Francis Crick.
• This was marked one of the most significant discovers of the twentieth century.
Winners of the Race to Learn DNA’s Structure – Watson and Crick 50 Years Ago
NucliotideThe building block of the DNA ladder
• Composed of:• Phosphate
• Deoxyribose sugar
• Nitrogen base
Building DNA Building Blocks
There are Four kinds of Nitrogen Bases
• Purines Pyrimidines• Adenine-----------------Thymine• Guanine-----------------Cytosine
• (Hydrogen bonds)• A always pairs with T• G always pairs with C
• Made of Two Rings Made of One Ring
Matching DNA Nitrogen Bases
G
Matching DNA Nitrogen Bases
A AC TT C G AAT CC CC C
G
G GG TT A
Matching DNA Nitrogen Bases
A AC TT C G AA
AA TTT T
T CC CC C
G GG GGGG
G GG TT
C C CA A A
A
GC T
Key words of DNA shape
• Double stranded ladder shape sides of sugar and phosphate rings of bases coil into (double helix)
Replication
Making an exact copy of a DNA molecule (self doubling)
DNA Replication
DNA perfectly illustrates the relationship between structure and function.
Simple As It Is in Principle, DNA Replication Requires Many Enzymes That Work Coordinately
First and foremost are the DNA polymerases
Protein Synthesis• The Process of making proteins
• Transcription – The process of copying the DNA pattern into messenger RNA
• Messenger RNA – Brings coded information from DNA to the ribosomes
• Ribosomes – The protein factories in the cell
Protein Synthesis
• Translation – The process of changing the information of messenger RNA into proteins
• Transfer RNA – The TNA that carries the amino acids to the ribosomes and pairs them with mRNA
• Codon – Combination of 3 bases on mRNA that determines the order of amino acids
RNA Differences
• Ribose sugar
• Uricil instead of Thymine
• Single stranded helix
• mRNA, tRNA, rRNA
• Found in nucleus and in the cytoplasm
• Smaller in size
ACGTGTGAGTCGTAGCTGGTA
and label the codon with its appropriate Amino Acid.
Transcribe the following strand of DNA to a strand of mRNA:
How Do Genes Work?
The answer is the purview of molecular genetics.