Cool Cats Don’t Run

ytoplasmytoplasm ellmembraneellmembrane NANA ibosomesibosomes

DNA 1/27/16 Take out quiz photo and corrected responses for acct check. Write analogies (like in yesterday’s activity) for the following organelles. Continue on the same sheet of paper from yesterday, so they are all in one place: 1.Ribosome 2.Mitochondria 3.Cell Wall

Nucleus Nucleolus (made up of DNA)

Endoplasmic Reticulum Vacuole Ribosomes

Mitochondria Chloroplast

Cell Membrane Cell Wall

1.What are some things that you bring into your home because you need them? 2.What are some things that are not wanted in your home so you keep them out? 3.What are some things that are sent out of your house? Share with Your Partner

The Cell Membrane: The Gatekeeper of the Cell

What does Alice have to do with Cell Membranes?

Class Brainstorm What properties could the cell membrane use to distinguish between molecules? Physical Properties Chemical Properties

What is the cell membrane? Every cell is surrounded and protected by a plasma membrane (aka cell membrane) The cell membrane is made mostly of lipids, carbohydrates, and some protein channels

What does the cell membrane do? The cell membrane has two main jobs: 1. It separates the inside of the cell (the intracellular space) from the outside of the cell (the extracellular space) 2. It acts as a gatekeeper by only allowing certain molecules in or out

Components of the Cell Membrane The cell membrane is made of special lipids called phospholipids Phospholipids have two parts: – Hydrophilic (water- loving), or polar heads – Hydrophobic (water- fearing) or nonpolar tails

Drawing out phospholipids

DNA 1/28/16 Draw a phospholipid. Label the two parts of phospholipids that make up the phospholipid bilayer. Which part of the phospholipid is hydrophobic? Which part is hydrophilic?

Announcements Tomorrow = last day of plant data collection Case study paragraphs due tonight at 11:59 PM. Plant data section due Tues at beginning of class. (hard copy in class for peer review. No turnitin submission)

Today! There is a hiring symposium that I am sneaking away to watch. Here is what to do: 1. Collect and record plant data. 2. Work on case study paragraphs (peer revise all paragraphs in your group to make sure that the reasoning makes sense for all 4!! Use the rubric!) 3. Make revisions to intro and methods section of plant lab. (If I have not written your feedback yet, look at someone’s feedback within your group. There were a lot of common errors)

Other parts of the cell membrane Several types of proteins are embedded in the cell membrane. Two major ones are: Protein channels: proteins that allow a passage way into and out of the cell Protein receptors: Binds to a signaling molecule outside of the cell that causes a reaction inside of the cell

Other parts of the cell membrane The cell membrane also has carbohydrates on the outer surface that play a role in cell recognition and cholesterol around the lipid tails to regulate membrane fluidity

Activity: Modeling the Cell Membrane Work together with your shoulder partner to make a model of the cell membrane Make sure you READ each step carefully and WORK together! Cotton ball = nucleus Straw = Protein channel Q-tip = Phospholipid Candle = protein receptor Cholesterol String = carbohydrate

Step 1: Identifying the phospholipid First identify which parts of the q-tip are the polar phosphate head and the nonpolar lipid tail Which part does not want to come into contact with water? Q-tip = Phospholipid

Step 2: Building the cell membrane Imagine that the surface of your desk is made up of water. Arrange your q-tips in a way so that the minimum number of hydrophobic (nonpolar regions) are exposed to water.

Step 3: Building the cell membrane Arrange your q-tips in a way that results in an inner compartment that can also have water. Water inside

Step 4: Building the cell membrane Add your protein receptor and channels to the membrane to allow things to communicate and enter/exit the cell. Straw = Protein channel Candle = protein receptor

Step 5: Adding cholesterol and carbohydrates Snugly pack the cholesterol strands between the lipid tails. These cholesterol molecules help maintain membrane fluidity Add carbohydrates to the outer layer of phospholipids. These carbohydrates allow the cells to be recognized by other cells and molecules (and viruses yikes!) Cholesterol String = carbohydrate

Step 6: Nucleus Add your nucleus to the cell. Is this cell a eukaryotic or prokaryotic cell? How do you know? What does the nucleus hold in these cells? Cotton ball = nucleus

Drawing out our cell membrane

What does the cell membrane do? The cell membrane helps cells maintain homeostasis by allowing SOME things to enter/exit the cell and not others – it is SEMI- PERMEABLE

Questions: If ANYTHING could freely move in and out of the membrane, would it still be called semi-permeable? If NOTHING could move in and out of the membrane, would it still be called semi-permeable?

Semi-permeable Semi = Partially Permeable = Allowing things to pass through Semi-permeable means that some things can enter and leave while other things cannot