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Protein Synthesis Making proteins – one of the jobs of genes.

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Presentation on theme: "Protein Synthesis Making proteins – one of the jobs of genes."— Presentation transcript:

1 Protein Synthesis Making proteins – one of the jobs of genes.

2 Ribosomes Cell organelle that is the site of protein synthesis. In the cytoplasm Linked by endoplasmic reticulum to vesicles that release/secrete the protein the ribosome made.

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4 Two problems – location and structure The code for the protein is in the chromosomes. The chromosomes are in the nucleus. How does the info get from the chromosomes in the nucleus to the ribosomes in the cytoplasm?

5 Two problems location and structure The code is written in nucleotide bases and proteins are built out of amino acids. How does the chromosome alphabet get changed into structures that join up to make proteins?

6 Each group of 3 nucleotide bases in the DNA is called a triplet. The triplet can’t leave the nucleus, so another nucleic acid comes to the nucleus to read it.

7 Transcription (using the same code) This messenger is called mRNA. The three bases that match the DNA triplet are called a codon. E.g DNA TGC GGA CCG GAG mRNA ACG CCU GGC CUC Manual pg 85.

8 Translation (changing to a new code) At the ribosome- The codon comes in and brings the code. The tRNA reads the codon and goes off to get the right Amino Acid. The Amino Acids are linked together inside the ribosome to form the protein. Manual pg 86, 87.

9 DNA is transcripted to make messenger RNA (mRNA) mRNA is translated to make a polypeptide

10 How does the mRNA know when to start and when to stop reading? Special codons that tell them Manual pg 71. The genetic code.

11 Polypeptides and proteins A long chain of amino acids is called a polypeptide (many peptide bonds!). Sometimes a protein is made of several polypeptides joined together. This will require information from the same number of genes.

12 One chromosome has many genes in the exon sections. Each gene codes for one polypeptide chain. The group of genes that code for the protein are called a transcription unit. Michael pg 84 introns and exons.

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14 Whole picture Manual pg 78. Protein synthesis and Replication together Manual pg 79.

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