1. 4-1 Protein Synthesis Is a Major Function of Cells

2. DNA mRNA Amino Acid chain, a Polypeptide Protein Transcription Translation Takes place in the nucleus Takes place on a ribosome The general steps in protein synthesis

3. 4-3 Figure 4.7 Function of ribosomes Transcription Translation

4. 1.Transcription is the process of copying the DNA sequence of a gene into a mRNA transcript Takes place in the nucleus 2.Translation is the process of copying the mRNA transcript into a sequence of amino acids which will eventually become a protein The mRNA than moves to a ribosome, either attached or free Free ribosomes are found in the cell’s cytoplasm Produces proteins for use within the cell Attached ribosomes are found on the endoplasmic reticulum Produces proteins for use in the cell membrane or is exported outside of the cell

5. The pathway for proteins being used for the cell membrane or for export out of the cell 1.Nucleus → site of transcription: DNA → mRNA 2.mRNA travels to a ribosome on the endoplasmic reticulum: RER 3.RER → site of translation: mRNA → amino acid sequence: a polypeptide 4.The polypeptide then travels through the RER into the Smooth ER and then to the Golgi body 5.The polypeptide is modified by the SER and Golgi body 6.A vesicle forms on the outside of the Golgi body and then pinches off 7.The vesicle moves through the cytoplasm and fuses with the cell membrane

6. 4-6 Figure 4.9 Golgi apparatus (gray- green) and transport vesicles

7. 4-7 Figure 4.14 The organelles of the endomembrane system

8. The general steps in protein synthesis

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