World of The Cell Chapter 4 How big is a cell? The smallest cell is a Mycoplasmas (very small bacteria are barely bigger) Bacteria are just bigger than a single organelle of a animal cell Plant and animal cells are bigger, you can see them with a but not the naked eye! 1
Why can t cells be huge? All entrances and exits are controlled by the which is responsible for, etc for the cell Upper limit If the cell is too big it needs too much stuff done and the membrane can t keep up Just like baby sitting But not too small Lower limit: Holding the vitals A cell can t get too small because it must be able to hold, and other otherwise it can t function First seen by looked through the FIRST compound microscope (which he invented) described the cells in cork plant cells 2
How do we even know What the eye cannot see itself we make tools to see Light Microscope: Uses a series of lights and mirrors to magnify and object, it can magnify an object times without losing Electron Microscope: Use highly charged to create images of very small things (much smaller than a cell) Can magnify up to times : runs electrons along the surface of a object doesn t destroy it : sends electrons crashing through it destroys the specimen ** either one the specimen must be long dead ways to see really small stuff SEM of a bug that was found on a daddy long legs 3
All cells by way of the Animal cell The animal cell is the flagship cell all other cells can be described easily in relationship to it So we will start with the animal cell Animal Cell Statistics Animal cells is (True Nucleus) Because of it s large size (for a cell) it divides its daily responsibility among its parts ( ) Like animals divide jobs among organs/ organ systems 4
Broken into 3 categories 1. Plasma Membrane 2. Nucleus 3. Cytoplasm 5
Protective covering of the cell Made of a Also contains / intercalated proteins that serve various functions Plasma membrane Inside the membrane The lipids do not make up the whole membrane. There are important proteins with various jobs intercalated or within the lipids 6
extracellular environment one layer of lipids one layer of lipids cytoplasm membrane protein Fig. 4.4, p. 53 Membrane Specialization: Junctions Tight junctions: so tight that they bind the cells together like sheets ie. Small intestine to keep food from leaking out Desmosomes: junctions that keep cells from falling apart ie. Skin cells Gap Junctions: allow between cells Especially in nerve cells and developing tissue 7
free surface of epithelial tissue different kinds of tight junctions gap junction basement membrane (extracellular matrix) adhering junction Fig. 4.23, p. 67 Nucleus Holder and protector of genetic information : outer covering : Ribosome assembly : The DNA/protein association within the nucleus Chromosomes: densely packed chromatin during 8
The rest of the cell that includes the : the working components of the cell kind of like your organs Inclusions: the that come in and out of the cytoplasm they exist in: the gel like coating the and nucleus Cytoplasm 9
Ribosomes Dark staining organelles made of protein and Sometimes attach to the ER, making it ER Endoplasmic reticulum The cells circulatory system that accounts for of the cells membranes Rough ER: membrane factory/ producer Smooth ER: synthesis/breakdown 10
Also known as the golgi body Near the nucleus The protein traffic director, takes proteins the and them to where they belong (in secretory vesicles) Golgi Apparatus The makes that are to the Golgi (in transport vesicles), where they are and sent out of the cell ( vesicles) or float within the cell to kill off invaders ( ) BIG PICTURE BREAK 11
Lysosomes Bundles of digestive enzymes packaged by the Golgi digest, invaders or (phagocytosis) Can kill the cell itself if it lacks essential things such as oxygen, or vitamin A http://highered.mcgraw-hill.com/olc/dl/120067/bio01.swf Peroxisomes dangerously reactive free radicals in the body First they convert them to H 2 O 2 and then to H 2 0 Abundant in and cells Replicate through, not produced by the Golgi 12
Mitochondria POWERHOUSE bound organelle probably originally a free living prokaryote it The membrane of mitochondria is the site of the electron transport chain Busy cells have many mitochondria Cytoskeleton Protein structure that extends though the cytoplasm acting as the cells skeletal/ muscular system Intermediate filaments: strong and stable. Form (anchor junctions) : motility and shape change (actin and myosin) Microtubules: overall shape and organelle arrangement ( ) Naturally clear but can be stained with fluorescent markers. Their presence/ absence/ structure has proved useful in identifying and of cells The eukaryotic cytoskeleton. Actin filaments are shown in red, microtubules in green, and the nuclei are in blue. 13
Centrioles Made of these form the spindle fibers responsible for chromosome partitioning during cell division Also aid in the formation of and Cilia and Flagella Cilia and flagella are formed when push out against the cell membrane forming a projection move things along the surface of the cell I.e. cilia move particles along and out of the lungs propel the cell itself Human sperm move via flagella 14
Contractile Vacuole Some cells use contractile vacuoles for and Paramecium (one celled animal) uses contractile vacuoles for both protecting it from exploding it when it pushes out the water it propels it forward What s different in a Plant Cell? There are 3 additional structural features that Plant cells need 1. 2. 3. 15
Central Vacuole Storage facility created from the merging of smaller vesicles that can promote growth Stores (helps w/ growth/ movement) Vital chemicals (food) to protect a plant from being eaten! It can also act as a getting rid of foreign invaders Chloroplasts Plants are : meaning they make their own food Do so from sunlight in a complex process called Chloroplasts are the for photosynthesis 16
More on Chloroplasts Between inner and outer membrane is the intermembrane space (membrane) and all contain is where photosynthesis takes place in structures called granum Cell Wall: protective covering Plant cells need to be extra strong helps them deal with and other stresses Helps circulate water and nutrients Made of, pectin and all strong structural carbohydrates Render plant cells motionless shared by neighboring cells to increase adhesion 17
Prokaryotes: how they re different No true nucleus Contain there DNA in circular bundles called or in bundles in a nucleoid region Have to help make proteins Have a membrane and a help maintain shape. even more covering that help the prokaryote stick Prokaryotic anatomy 18
Prokaryotes: what they do Many prokaryotes live off of other cells ( ) Need help adhering capsule and pili Pili are that anchor the prokaryote into its host Need to find something to mooch off of in the first place BioFilms Often live together and work together to colonize areas. These associations are called. One common type of biofilm is that that exists on your teeth and solidifies as plaque 19