Transcript membranex
WARM UP: WEEKLY FORMATIVE ASSESSMENT Complete the chart covering viral vs. bacterial pathogens! 5 minutes WHAT IS ONE CRITICAL THING THESE PEOPLE DO IN ORDER TO “PLANK” ON AN OBJECT? CHECK THIS OUT!!! THESE PEOPLE ARE CRAZY! http://youtu.be/tRHnTFesv7c PLANKING: An act of BALANCING your body on any given object. *You must keep your arms down to your sides and your head down. Raise your hand…. Predict what you think HOMEOSTASIS means for a cell. Look at your notebooks… Which ORGANELLE is responsible for maintaining homeostasis?!! (hint: it does this by controlling what enters and leaves the cell) What if I told you… You are made of mostly water! IN and OUT of your cells is water-based. The cell membrane has both waterLOVING and water-FEARING properties so it must be shaped a certain way! Today we are building a cell (plasma) membrane! Cut and organize the pieces of the cell membrane in the placement you predict. Put it in the MIDDLE of the notebook, across two pages: 30-31 DON’T GLUE YET! HINT: THE WATER-FEARING PARTS WILL FACE EACH OTHER! Fluid surrounds the membrane. Label “INTRACELLULAR” and “EXTRACELLULAR”. What side of the membrane do you predict the organelles to go? DRAW and LABEL these organelles where they belong: nucleus, ribosomes, mitochondria Fluid surrounds the membrane. If AQUEOUS means made of mostly WATER… Which part of the cell should be AQUEOUS, inside or outside the cell? Or both? LABEL “AQUEOUS (WATER-BASED) ENVIRONMENT” where it belongs! So… We talked about digestion last six weeks. After the polymers get broken down into monomers in the digestive system…..What happens to these molecules after they are absorbed? Where do these molecules go? HOW DO THEY GET INTO OUR CELLS?! Cell transport Every multi-cellular organism is made of specialized cells (Red blood cells, muscle cells, nerve cells) Each cell must perform an important life function The cell membrane is important. The cell membrane will allow things to enter and leave the cell. This is called CELL TRANSPORT. This is where homeostasis plays a role Have you ever wondered why your dog pants on hot days? It's because your dog is trying to maintain homeostasis. Homeostasis is a word used to describe how a living organism regulates its internal environment to maintain stability (equilibrium = balance). How do living things maintain homeostasis? When your body temperature begins to rise, what happens? *You begin to sweat. *Sweating is your body's way of cooling down = Dogs….. do not have sweat glands SO they pant. Dogs have just a few sweat glands in their paws, so no matter how much they sweat; sweating could never cool them off. That's where the tongue-hanging out, mouthopen dog panting comes in. They are maintaining balance Cell Membrane characteristics: The cell (plasma) membrane regulates what enters and leaves the cell (like a body guard) It is responsible for maintaining homeostasis in that way. There are a few ways to describe the membrane: phospholipid bilayer semi permeable Fluid mosaic model Cell Membrane characteristics: phospholipid bilayer : the membrane is composed of TWO layers of phospholipids, forming a bilayer. The tails face each other. semi (selectively) permeable: the membrane only allows certain particles to pass through, not others. Fluid mosaic model: the membrane looks “fluid-like” because it is flexible. What is a PHOSPHOLIPID? A lipid molecule with a PHOSPHATE head and TWO FATTY ACID tails. The phosphate heads are HYDROPHILIC and love water. The fatty acid tails are HYDROPHOBIC and hate water, so they face each other when forming the layer! On your membrane, LABEL: THE PHOSPHATE HEADS FATTY ACID TAILS Hydrophilic zone hydrophobic zone Cell Membrane Structure Label your cell membrane! Proteins Carbohydrate chains Phospholipids Protein channel Lipid bilayer What molecules are the cell membrane composed of? * Proteins – Aid in transport * Phospholipids – make up the double layer *Surface carbohydrates – allow for cell recognition & signaling