Cell Structure & Function

1. Cell Structure & Function

2. Cell Theory All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from preexisting cells through cell division. Definition of Cell A cell is the smallest unit that is capable of performing life functions.

3. Prokaryotic Do not have structures surrounded by membranes Few internal structures One-celled organisms, Bacteria

4. Eukaryotic Contain organellessurrounded by membranes Most living organisms Plant Animal

5. Parts of the Cell Mitochondria Vacules Cytoplasm Nucleus Rough ER Plasma membrane Lysosomes Smooth ER Golgi Bodies Ribosomes All working together so that the cell can grow, work, repair, and reproduce

6. Surrounding the Cell Plasma Membrane • Outer membrane of cell that controls movement in and out of the cell • Double layer

7. Functions of Plasma Membrane Protective barrier Regulate transport in & out of cell Allow cell recognition Receptor proteins function in cell communication Contains the cytoplasm (fluid in cell) Provide a binding site for enzymes

8. Homeostasis • Cells must keep the proper concentration of nutrients and water and eliminate wastes. • The plasma membrane is selectively permeable – it will allow some things to pass through, while blocking other things.

9. Structure of the Plasma Membrane Lipid bilayer – two sheets of phospholipids. • Found around the cell, the nucleus, vacuoles, mitochondria, and chloroplasts. • Embedded with proteins and strengthened with cholesterol molecules.

10. What is a Phospholipid? • It’s a pair of fatty acid chains and a phosphate group attached to a glycerol backbone. • Polar (hydrophilic) phosphate heads face out & the nonpolar (hydrophobic) fatty acids hang inside.

11. Membrane Proteins Determine what particles can pass through the membrane. Serve as enzymes(may speed reactions). Act as markers that are recognized by chemicals and molecules from the inside and the outside of the cell (the immune system).

12. Phosphate Polar Cholesterol structure & support Fatty acid nonpolar Carbohydrate chains identification Membrane proteins Receptors, enzymes, crossing Extracellular (outside the cell) Intracellular (inside the cell)

13. Nucleus Directs cell activities Contains genetic material - DNA Separated from cytoplasm by nuclear membrane • Surrounds nucleus • Made of two layers • Openings allow material to enter and leave nucleus

14. Inside the nucleus Chromosomes Made of DNA Contain instructions for traits & characteristics Nucleolus Contains RNA to build proteins

15. Endoplasmic Reticulum Moves materials around cell Smooth type: cholesterol& fatsynthesis & breakdown (lipid metabolism); lacks ribosomes Rough type: the cell’s membranefactory; ribosomes embedded in surface

16. Ribosomes Make proteins Each cell contains thousands Found on ribosomes & floating throughout the cell

17. Mitochondria Produces energy Cellular respiration - chemical reactions breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates

18. Golgi Bodies Protein packaging Proof reads proteins & makes minor corrections Move materials within the cell Move materials out of the cell

19. Lysosomes Hydrolytic enzymes Breaks down molecules ‘Digests’proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal Cell breaks down if lysosome explodes

20. Vacuoles sacs for storage Also used for digestion, and waste removal Contains water solution Help plants maintain shape

21. Cytoplasm Fills cell & holds organelles Gel-like mixture -mostly water Protects & stabilizes organelles Surrounded by cell membrane

23. Cells break down food sources i.e. glucose, fats, and protein &release their stored energy. Produce energy storage molecules called ATP – adenosine triphosphate. Cellular Respiration

24. Anaerobic Processes No oxygen is required for these processes. Includes glycolysis, the breakdown of glucose, and fermentation. Some bacteria and yeast are examples of anaerobes.

25. Glycolysis Occurs in the cytoplasm. Breaks down glucose 2 molecules of pyruvate(3-carbon structures) 2 ATPmolecules are formed. 2 NADHenergy shuttles are also formed.

26. Fermentation Pyruvate can be metabolized by: Alcoholic fermentation or Lactic acid fermentation Alcoholic Fermentation produces ethyl alcohol and CO2 Lactic acid fermentation produces lactic acid.

27. Aerobic Processes Requires oxygen. Most organisms are aerobes. Equation for Aerobic respiration: C6H12O6 + 6O2  6CO2 + 6H2O + Energy

28. The Mitochondria If O2 is present following glycolysis, pyruvate is modified and enters the mitochondria. Here food is broken down completely into CO2. Energy storage molecules like NADH and ATP are produced.

29. Energy from electrons ATP ATP ATP O2 The Role of Oxygen Energy carriers like NADH drop off electrons As the electrons “fall” to oxygen energy is stored in a payload of ATP. Oxygen picks up electrons and hydrogen ions to form water. H2O

30. ATP: Adenosine Triphosphate • ATP is the cells energy currency. • Cellular work such as metabolism, transport, and movement is powered by the breakdown of ATP. • ATP Structure • Ribose – a 5-carbon sugar • Adenine – a N-base • 3 phosphate groups

31. ATP / ADP Cycle ATP is constantly being used and remade in the cell. Energy is released or stored by breaking or making a phosphate bond.

32. Summary of Cellular Respiration

34. Selectively Permeable Phospholipid Bilayer Active & Passive transport mechanisms move molecules across the membrane

35. Transport Across the Membrane Active Passive

36. Simple Diffusion Requires NO energy Molecules move from area of HIGH to LOW concentration

37. Simple Diffusion • Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural KINETIC ENERGY

38. Facilitated Diffusion Molecules will randomly move through the pores in Transport Proteins. Highconcentration of solute  Lowconcentration of solute

39. Facilitated Diffusion Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side.

40. Facilitated Diffusion Other carrier proteins change shape to move materials across the cell membrane Along the concentration gradient

41. Osmosis High water potential Diffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute) Low water potential

42. Cells in Solutions

43. IsotonicSolution HypotonicSolution HypertonicSolution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) CYTOLYSIS PLASMOLYSIS

44. Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient

45. Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. Active Transport This is how many hormones are secreted.

46. Endocytosis- moving things in Pinocytosis Phagocytosis Most common form of endocytosis. Ingestion of solid particles by endocytosis Fuses with lysosomes and the material is degraded Takes in molecules dissolved in H2O.