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What is central dogma? From DNA to Protein

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Presentation on theme: "What is central dogma? From DNA to Protein"— Presentation transcript:

1 What is central dogma? From DNA to Protein
All proteins consist of polypeptide chains A linear sequence of amino acids Each chain corresponds to the nucleotide base sequence of a gene

2 What is the first step? 1. Transcription: Enzymes uses base sequence of a gene as template to make strand of RNA Two DNA strands unwind in a specific region RNA polymerase assembles strand of RNA Covalently bonds RNA nucleotides (adenine, guanine, cytosine, uracil) according to nucleotide sequence of exposed gene

3 What is the second step? 2. Translation
Information in the RNA strand is decoded (translated) into a sequence of amino acids

4 Prokaryotes and eukaryotes
In prokaryotic cells (no nucleus) Transcription and translation occur in cytoplasm In eukaryotic cells Genes are transcribed in the nucleus Resulting mRNA is translated in the cytoplasm

5 Three types of RNA Messenger RNA (mRNA)
Carries protein-building codes from DNA to ribosomes Ribosomal RNA (rRNA) Forms ribosomes (where polypeptide chains are assembled) Transfer RNA (tRNA) Delivers amino acids to ribosomes

6 RNA and DNA compared DNA exists as double-stranded molecules
hereditary information double helix contains deoxoyribose sugar RNA Disposable copies of hereditary information and some are catalytic exists as a single stand. contains ribose instead of deoxyribose contains uracil in place of thymine

7 RNA Modification: Alternative Splicing
Before mRNA leaves the nucleus: Introns are removed Some exons are removed along with introns; remaining exons are spliced together in different combinations Poly-A tail is added to 3’ end of new mRNA

8 What is the genetic code?
Messenger RNA (mRNA) carries DNA’s protein-building information to ribosomes for translation mRNA’s genetic message is written in codons Sets of three nucleotides along mRNA strand

9 Codons Codons specify different amino acids
A few codon signals stop translation Sixty-four codons constitute a highly conserved genetic code

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