Cells and Cell Membranes

1. Cells and Cell Membranes AP Biology

2. Why must living things be made of cells? • To have enzyme/substrate concentrations high enough so that rates of reactions are reasonable to support life (Rates of Reaction) • Rates of Diffusion • Rates of Transport • Reactions can occur without interference (conflicting reactions can happen simultaneously) • Local environments can allow different reactions to happen

3. Why we need cells continued • Specialization (different cells can do different things) • Damage can be contained • Reactions can be ordered by embedding them into membranes

4. Cell Movement • What cells move? • Embryonic, cancer, single, during cell division, healing, nerve cells (reach out filopodia – if a connection is used its strengthened – if not – its destroyed), macrophages, protozoans • Types of Movement • amoeboid, cilia, flagella, muscle contraction, intracellular transport

5. Fun Cell Facts • 250 cells fit on a period • Ridge on a finger – 20 cells wide • 1” patch of skin = million cells in top layer • Exceptions • Egg • Muscle cell – 1.5” long • Nerve – extentions spine to toes

6. Cell Membrane Structure • Phospholipid bilayer • Protein Channels (for small and charged atoms or molecules) • Open • Gated • Shape change • Active Transport channels • Receptors • Endocytose ligand • Sets off a series of chemical reactions • Opens gated channels • Turn on genes • Secrete a hormone • Marker or Signal Proteins – identifies the cell • Attachment proteins • Cell to cell attachment • Attachment to the cytoskeleton • Attachment to the ECM proteins

7. Importance of Receptor Shape

8. Water, water everywhere,And all the boards did shrink;Water, water everywhere,Nor any a drop to drink

9. Woman dies after water-drinking contest Water intoxication eyed in ‘Hold Your Wee for a Wii’ contest death A woman who competed in a radio station’s contest to see how much water she could drink without going to the bathroom died of water intoxication, the coroner’s office said Saturday. Jennifer Strange, 28, was found dead Friday in her suburban Rancho Cordova home hours after taking part in the “Hold Your Wee for a Wii” contest in which KDND 107.9 promised a Nintendo Wii video game system for the winner. “She said to one of our supervisors that she was on her way home and her head was hurting her real bad,” said Laura Rios, one of Strange’s co-workers at Radiological Associates of Sacramento. “She was crying and that was the last that anyone had heard from her.” Initially, contestants were handed eight-ounce bottles of water to drink every 15 minutes. “They were small little half-pint bottles, so we thought it was going to be easy,” said fellow contestant James Ybarra of Woodland. “They told us if you don’t feel like you can do this, don’t put your health at risk.” Ybarra said he quit after drinking five bottles. “My bladder couldn’t handle it anymore,” he added. After he quit, he said, the remaining contestants, including Strange, were given even bigger bottles to drink. “I was talking to her and she was a nice lady,” Ybarra said. “She was telling me about her family and her three kids and how she was doing it for kids.”

10. Ways Things Move Through the Cell Membrane • Diffusion – high to low due to random motion of molecules • Osmosis – diffusion of water • Simple diffusion– thru phospholipid bilayer – driven by kinetic energy of the molecules or atoms themselves • Facilitated diffusion– using the help of protein channels (open, gated, or shape change) – dependent on concentration, # of channels – driven by kinetic energy of the molecules – may also use an electrochemical gradient • Electrochemical gradient – molecules also move toward the opposite charge

12. Salt poisoning - Germany 4 year old dies by accident Just read in the paper that a woman killed her 4-year old stepchild by making her eat too much salt: Apparently, the two were preparing a pudding, and the child accidentally put in two table-spoons of salt instead of sugar. The stepmother got angry and forced the child to eat the pudding. The child died in intensive care a day later. Apparently, a court now ruled that the stepmother does not have to go to jail, because it is not general knowledge that excessive salt-consumption is fatal, so the death was considered accidental / negligent behavior.The newspaper says that consuming more than 1 g of salt per 1 kg of body weight within a short span of time is usually fatal. Any of our natural science / medicine buffs can confirm this? It's total news to me!

13. Protein Channels and Types of Movement Facilitated Diffusion Channels open gated shape change Active Transport Channels

14. Ways Things Move Continued • Active Transport– low to high movement using protein channel pump – pumps using energy (ATP) provided by the cell • Co-Transport – combo of active transport and fac. diffusion. Cells pump H+ which then binds to molecule to be transported. The H+ molecule combo then diffuses thru a fac. diffusion channel. • Exocytosis – (secretion) – wrapping molecules in a membrane vesicle inside the cell – having it fuse with the cell membrane and dump the contents outside the cell (with or against conc. Gradient – big stuff like proteins

15. Ways Things Move – Still Continued • Endocytosis– engulfing large particles with part of the cell membrane and bringing them into the cell in a vesicle. • Pinocytosis (liquids) • Phagocytosis (solids) • Receptor-Mediated endocytosis

17. Nucleus • Protects the DNA from cytosolic enzymes that would destroy it • Provides a small space to maximize enzyme/substrate concentrations so that replication and mRNA production is efficient • Provides the right environment for those chemical reactions • Organizes the DNA to control gene expression through the nuclear matrix

19. Cilia • Move stuff across cell surfaces like mucus • Moves some single-celled protozoans like paramecia • Flagella • Longer and only 1/cell – sperm or up to 6 on bacteria, also found on protozoa • For swimming

21. Mitochondria • Breakdown glucose and uses the released energy to make ATP from ADP • The inner mitochondrial membrane is in-folded to create more surface area = more e.t.c.’s so more efficient cell respiration • Have their own DNA and ribosomes, comes only from the mother • Can copy themselves and make their own proteins

23. Chloroplasts • For photosynthesis – create sugar from inorganic materials – carbon dioxide and water using the sun’s energy to excite the electrons – the excited electrons are stored in the covalent bonds shared between the C and H atoms • They also have their own DNA and ribsomes • Collecting the sun’s energy happens in the thylakoid membranes which are stacked and have huge amounts of surface area • The chemical reactions to then make the sugar happen in the stroma where the correct enzymes are

24. Vacuoles

25. Vacuoles • Animal vacuoles can store water, wastes, nutrients – small and fairly numerous • Plant vacuoles take up the majority of the cytoplasm of the cell • They can actively transport salt to the interior so water will flow in creating turgor pressure • Pigments also stored here • Protozoans have food vacuoles (from endocytosed food then fuses with lysosome) and Paramecium have contractile vacuoles to squeeze out water to keep the osmostic balance

26. Ribosomes – Protein synthesis aa are bonded together in a chain based on the sequence of mRNA copied for the DNA

28. RER • If proteins are destined for a particular location such as the cell membrane or are to be secreted, a signal sequence directs the ribosome to the RER • Protein enters the RER from the ribosome • Folds into the correct shape • Is modified – may be cut some, carbs added etc. • Is transported to the Golgi

30. Golgi • Modifies (add location signals) to the protein so it goes to where it’s supposed to) • Molecules that match specific docking proteins on the motor proteins are added to the protein so it “jumps on to the right microtubule • Packages (wraps it in a piece of its own membrane)

32. Lysosome • Has receptors for binding proteins • Fuses with old cell parts, bacteria, or macromolecules in vesicles and breaks them into components

33. Lysosomes • Digest old worn out cell parts to keep the cell unclogged and able to function normally • In macrophages, digest all of the junk that they endocytose like whole bacteria, dried blood, damaged bone, etc. • In single cells – they fuse with the endocyotic membrane and become food vacuoles

35. SER • Specialized functions in different cells • In all cells, can make phospholipids • Makes cholersterol • Makes steriod hormones • Detoxifies drugs and alcohol • Sequesters calcium in muscle cells

37. Centrioles • Duplicate and move to the cell poles and reforms the cytoskeletal microtubules into spindle fibers to separate the chromosomes • Plant cells don’t have them but do have a centrosome

38. Cytoskeleton

41. Cytoskeleton • Made out of many protein fibers (microfilaments) and microtubules • The microfilaments are for structure and shape of the cell • Microtubules act as train tracks for motor proteins to transport stuff through the cell • Determines the cell’s shape and therefore what DNA is read – must be attached to nuclear matrix and is attached to the cell membrane and ECM

42. Nucleolus • Clump or RNA and proteins that will become the ribosomes

43. Cell Wall • Plants – cellulose – helps create turgor presssure, provides structure • Bacteria - chitin

45. Cell Junctions • Tight Junctions – between epithelial cells – proteins that hook the cells together tightly so that there is no leakage between the cells • Desmosome – tight junction with extra reinforcing proteins tying the cytoskeletons of neighboring cells together – keeps cells from ripping apart • Gap Junctions – found in smooth muscle – tiny protein tunnels that ions can pass through from cell to cell

46. Animal Tissues - Epithelium • Square or rectangular • Form Leakproof Linings and barriers • Selectively secrete and absorb

47. Animal Tissues - Nervous • Big cell bodies with many short extensions to receive information and one long axon to send information • Fast signal transmission since almost touch the cells they are communicating with with their extensions

48. Animal Tissues – Skeletal Muscle • Long tube-shaped cells packed with contractile proteins and many nuclei • Tight junctions between cells – each muscle is connected to an axon for quick communication

49. Animal Tissues – Smooth Muscle • Spindle-shaped cells surrounding hollow organs to squeeze the contents to move them • Have gap junctions so contract all together

50. Animal Tissues – Connective Tissue Bone • Cells not joined – separated by ECM • Amt. and type of matrix gives the tissue it’s characteristics • Matrix is always a mix of fibrous proteins and liquid) Bone is strong and supports weight because: Bone is mostly matrix Matrix is hardened with calcium