Protein Synthesis Summary

1. Protein Synthesis Summary

2. Protein Synthesis 1. The DNA double helix unwinds to expose a sequence of nitrogenous bases. (A,T,C,G) 2. A copy of one of the strands is made in a process known as transcription. The copy is made of messenger ribonucleic acid (mRNA) which, following transcription, travels out of the nucleus into the main body of the cell, where protein synthesis occurs.3. The mRNA couples with the protein synthesis apparatus (the ribosome). Another type of RNA, known as transfer RNA (tRNA), brings free amino acids to the ribosome.4. The anticodon present on the tRNA recognises the codon present on the mRNA, and the ribosome adds the amino acid to the growing chain of linked amino acids (polypeptides), cleaving it away from the tRNA. This process is known as translation.5. As the polypeptide chain grows, it folds to form a protein. http://www.youtube.com/watch?v=983lhh20rGY

3. ENERGY RELATED ORGANELLES Mitochondria - The Cell's Chemical Furnaces • contains its own DNA, support for Endosymbiosis Theory • singular is "mitochondrion“ • 2 membranes, one smooth outer membrane, and an inner membrane folded into layers called cristae • Cristae has two compartments: the matrix and the inter membrane space

4. function to store energy for cell use. Energy is stored in the form of ATP - adenosine triphosphate • (Made by cellular respiration… which we will learn later!)

5. Figure 4.17

6. Chloroplasts - Where Photosynthesis Takes Place • only found in plant cells • has its own DNA, like mitochondrion • functions to convert light energy to carbohydrates • carbohydrates then broken down in mitochondria to produce ATP

7. consists of grana, closed compartments that are stacked • thylakoids are the individual disk shaped compartments that make up the grana (stack of thylakoids) • stromais the fluid surrounded the thylakoids

9. *Chloroplasts are a type of plastid Chromoplasts – red, yellow and orange pigmentLeucoplasts – colorless (potatoes)

10. Endomembrane System • Many of the different membranes of the eukaryotic cell are part of this system which carry out a variety of tasks in the cell. i.e. synthesis of proteins, metabolism and movement of lipids, & detoxification of drugs and poisons • The membranes of this system are related either through physical continuity or by the transfer of membrane segments as tiny vesicles (sacs made of membrane) • This system includes: nuclear envelope, the endoplasmic reticulum, golgi apparatus, lysosomes, various vacuoles, and the plasma membrane

11. Endomembrane System

12. Endoplasmic Reticulum • Extensive network accounting for more than half the total membrane in eukaryotic cells • Consists of a network of membranous tubules and sacs called cisternae • The ER membrane separates the internal compartment of the ER, called the ER lumen (cavity) or cisternal space, from the cytosol. • The ER membrane is continuous with the nuclear membrane

14. ER cont… Two types of ER:smooth and rough • Smooth ER – lacks ribosomes and involved in diverse metabolic processes such as lipid synthesis, metabolism of carbohydrates, and detoxification of drugs and poisons • Rough ER – has ribosomes and is involved in protein synthesis

15. Figure 4.10a

16. Golgi Apparatus -- Delivery System   • flattened stacks of membranes • functions in collection, packaging and distribution of molecules made in the cell and used elsewhere • front end (cis) faces the ER, and the back end (trans) faces the cell membrane * folded stacks are called cisternae

17. unprocessed proteins enter the Golgi apparatus from ER and proteins are packaged and exported to the nearest membrane

18. Jobs of the Golgi Apparatus              (aka Golgi Complex) 1. separates proteins according to their destinations 2. modifies proteins (adds sugar and makes glycoproteins) 3. packages materials into vesicles which are exported outside the cell  -  secretion

19. Summary of Endomembrane System See Handout*

20. Lysosomes - Intracellular Digestion Centers • vesicles that are used to digest • contain high levels of degrading enzymes – low pH(to "lyse" means to dissolve) • recycle old and worn out cell parts • "suicide sac" -  apoptosis (wikipostHWK) • digest other particles taken in by phagocytosis http://www.youtube.com/watch?v=m6qJ69wcSnc • found in animal cells TAY-SACHS disease – missing an enzyme of the lysosomes that breaks down a fatty substance.  Over time this fat builds up in the brain and nervous tissue, smothering the cells.  Results in degeneration and death.

21. Vacuoles Types: • Food vacuoles – formed by phagocytosis http://www.youtube.com/watch?v=W6rnhiMxtKU • Contractile vaculoes – pump excess water out of the cell http://www.youtube.com/watch?v=kkPiRT2ewVA 3. In plants & Fungi – Central vacuole: stores food, nutrients, water and waste…maintains turgor pressure (prefer a hypotonic state)

23. 1.  What part of the cell produces vesicles for export? 2.  What part of the cell makes proteins? 3.  What part of the cell produces ATP? 4.  What part of the cell transports materials throughout the cytoplasm? 5.  What part of the cell has a cis and a trans face?   Mini Quiz

24. a.  ________________ b.  ________________ c.  _________________ d.  _________________ e.  _________________ f.  __________________ f.

26. What is this structure? 

27. Figure 4.7b

28. What is this structure? Figure 4.10a What is this structure?

29. Describe the processes occurring in this image. Figure 4.11

30. Figure 4.13

31. What is this structure? Figure 4.16b

32. What is this structure? What is its function?  

33. Find the: a.  Nucleolus b.  Centriole c.  Vesicle d.  Smooth ER e.  Lysosome

34. Summary Video Clip http://www.youtube.com/watch?v=3jWV568GpkU