BIOL 120 1st Edition Lecture 10 Outline of Last Lecture I Prokaryotic Cells cont a flagella II Eukaryotic Cells a nucleolus nuclear envelope nuclear pore chromatin Rough ER endocytosis pinocytosis thylakoids grana stroma III Cell to cell interactions and connections Outline of Current Lecture I Membrane Structure II Membrane Proteins III Cell division beginning Current Lecture I Membrane Structure 1 it is a phospholipid bilayer 2 Has proteins that go through the membrane i e Globular proteins 3 the environment influences the fluidity A saturated fatty acids make the membrane less fluid i straight tail forms from single carbon bonds ii Bent tail forms from double bonded carbons kinks B Most membranes contain cholesterol which can increase or decrease membrane fluidity based on temperature These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute I warmer is more fluid than cold II Membrane Proteins 1 hydrophobic interior of membrane makes it hard for molecules to pass through proteins function as transport proteins A nonpolar molecules can easily move through because phospholipids are mostly non polar and wont form bonds B Smaller polar molecules have limited permeability proteins moves these across the membrane 2 Functions A Transporters selective allow only certain molecules to move across B Enzymes perform many chemical reactions on the surface of PM membrane using enzymes attached to it 1 Cristae gives more surface area where ATP is made C Cell surface receptors Receptor proteins in PM receives chemical messages 2 Can bring chemicals molecules into the cell by binding to them to start a cell function D Cell surface identity markers PM membrane proteins which identify cell types E Cell to cell adhesion proteins Cells use specific proteins to glue them together F Attachments to the cytoskeleton Anchored to the cytoskeleton by PM proteins 3 Help keep cell shape and placement within the cell 3 Transmembranal A integral membrane proteins i span the lipid bilayer nonpolar regions are embedded in the interior and polar regions are protruding from both sides B Peripheral proteins Found on the surface of the membrane 4 Pore transporter role A a extensive nonpolar region within a trasnmembrane protein i made from beta barrel ii the interior is polar Allows water and small molecules to pass through membrane 5 Channel Proteins A ion channels act as a gate that allows ions to pass through B Gated channel open or close in response to a stimulus that can be chemical or electrical 6 Carrier Protein A transports ions and other solutes needs a concentration difference across the membrane i has a net gain of 0 ii gradient goes from high to low B has to bind to the molecule to transport it i saturation rate of transportation is limited by numbers of transporters 7 Active Transport A requires energy ATP directly or indirectly B moves substance against the concentration gradient from low to high concentrations C needs selective carrier proteins i uniporters move one molecule at a time ii Symporters move two molecules in the same direction iii Antiporters move two molecules in opposite directions one in and one out 8 Passive Transport A no energy input needed B follows the concentration gradient from high to low 9 Sodium potassium pump A uses ATP for active transport B uses antiporters to move 2 K into the cell and 3Na out of the cell i going against the gradient 10 Endocytosis A movement of substances into the cell i Phagocytosis cell takes matter in ii Pinocytosis cell takes in fluid and solutes 11 receptor mediated endocytosis A receptor proteins bond to molecules then caves in on itself to bring them into the cell B in the disease familial hypercholesterolemia receptors lack tails and cannot function correcting letting bad cholesterol build up in arteries 12 Exocytosis A the discharge of materials out of the cell B plants use export cell wall material C Animals use to secrete hormones neurotransmitters and digestive enzymes III Cell division beginning 1 Key Concepts A Eukaryotes divide to reproduce through the Cell Cycle G1 S or synthesis G2 M or mitosis i chromosomes are duplicated during the S phase from 46 to 92 ii then moved to the middle of the cell during the M phase iii chromosomes distributed to two daughter cells and cytokinesis begins division of cytoplasm iv also duplicated and divides organelles B This process produces two cells identical genetically to the parent cell i diploid 46 chromosomes 2 sets ii haploid 23 chromosomes 1 set for reproduction 2 Bacterial Cell Division A bacteria divides through binary fission no sexual life cycle reproduce by cloning B The circular bacterial chromosomes is replicated and then Septum forms to divide the cell into 2 3 Mutations A the cell cycle needs to be carefully controlled otherwise can lead to the development of cancer 4 Meiosis and Mitosis A both are followed by cytokinesis B Meiosis leads to the production of gametes egg and sperm C Mitosis leads to the production of all other cell types somatic cells 5 functions of Mitosis A Growth B Wound repair C Asexual reproduction