Chapter 8

Transcription

1 Chapter 8

2 Cell membrane Cytoplasm Ribosomes ALL cells have DNA cytoplasm In prokaryotes the DNA is in the. nucleus In eukaryotes the DNA is in the.

3 Function protects the cell and helps move substances and messages in and out of the cell Structure a phospholipid bilayer embedded with proteins Semipermeable only certain substances are able to pass through the membrane

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5 Phosphate heads is polar & hydrophilic (water loving) Fatty acid tails (lipids) are nonpolar, repel water, & hydrophobic (water fearing)

6 Hydrophilic Phosphate group Hydrophobic Fatty Acid Tails

7 Only small, nonpolar substances can pass directly through the membrane (like CO 2 and O 2 ) Ions (like Na + /K + ) & polar molecules (like H 2 O) are repelled by the fatty acid tails and must enter/exit via proteins Macromolecules must enter/exit via vesicles

8 How does the cell membrane help the cell maintain homeostasis? By regulating what materials move in and out of the cell, the cell membrane controls the cell s internal environment

9 Cell-surface markers proteins with carbohydrate chains that act like a name tag to identify the type of cell Liver cells have different markers than heart cells

10 Receptors receive chemical messages from other cells They allow the cell to detect and respond to changes in the environment.

11 Enzymes speed up chemical reactions at the cell s surface

12 Transporters help move molecules across the membrane Some require energy to work and others do not

13 BR Copy and answer the question. In the cell membrane, the fatty acid tails of phospholipid molecules point. a) away from each other b) toward each other c) toward the cytoplasm d) toward the extracellular fluid

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15 Equilibrium a state that exists when the concentration of a substance is the same throughout a space. Substances will naturally move toward equilibrium. Draw picture

16 Concentration gradient a difference in the concentration of a substance across a distance (cell membrane) When a substance moves from an area of higher concentration to an area of lower concentration, it is moving down or with the concentration gradient.

17 When a substance moves from an area of lower concentration to an area of higher concentration, it is moving agains the concentration gradient.

18 Does not require energy to move substances across the membrane No ATP needed Substances move down the concentration gradient From HIGH concentration to LOW concentration ATP

19 DIFFUSION the movement of substances directly across the membrane Only small, non-polar substances can cross directly through the membrane (O 2 and CO 2 ) Draw picture

20 Moving molecules across the membrane with the help of a protein Moves polar molecules and ions that cannot pass through the membrane Draw picture

21 OSMOSIS the diffusion of water across a semipermeable membrane Osmosis is the movement of WATER ONLY! Requires help from a protein to cross the cell membrane because water is polar. Draw picture

22 Hypo low Cells swell and may burst!!! Concentration inside the cell Solute = High Water = Low Concentration of the Solution Solute = Low Water = High Water will flow INTO THE CELL. Example: A cell placed in pure water.

23 Iso - same No change to cell! Concentration Inside the Cell Solute = same as in the solution H 2 O = same as in the solution Concentration of the Solution Solute = same as in the cell H 2 O = same as in the cell Water will flow IN AND OUT EQUALLY. Example: Blood cells in plasma.

24 Cell Shrivels!!! Hyper - higher Concentration inside the cell Solute = Low Water = High Concentration of the Solution Solute = High Water = Low Water will flow OUT OF THE CELL. Example: A cell placed in a salt water.

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26 Moves substances against the concentration gradient which requires energy ATP required Moving from LOWER concentration to HIGHER concentration ATP

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28 Membrane proteins that require energy to operate Example: Sodium Potassium Pump Requires energy to move sodium and potassium against the concentration gradient

29 The cell membrane pinches to form a vesicle which brings its contents into the cell. Macromolecules cannot cross through the membrane so they must enter by vesicles. Draw picture White blood cell chasing bacteria Amoeba eating paramecium for lunch

30 The vesicle fuses with the cell membrane and empties its contents outside the cell. Macromolecules cannot cross through the membrane so they must exit by vesicles. Draw picture Paramecium & Exocytosis

31 Follow all lab safety rules. DATA TABLE EGG Original Mass (g) Final Mass (g) Difference in Mass (g) Appearance (Shape/Color) A Vinegar B Vinegar A Distilled Water B Corn Syrup LAB QUESTIONS

32 Label the cups EGG A and EGG B and put your lab group number and class period. Use the Petri dish and mass the eggs with the electronic balance & record in the data table. Carefully place the raw eggs into the cups & cover the eggs with vinegar. (Vinegar will dissolve the shell around the egg.) Put your cups in the center of your table. Answer the Day 1 Question. What happened when you put the egg in the vinegar? Push in your stools. Put your paper in the basket. Go back to your seat.

33 You will lose points if you: Do not clean up your table Spray and wipe it down! Throw away all cups and paper towels in the trash. Mutilate your eggs! Throw the whole, unpopped egg into the trashcan on the front lab table!

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35 WORD BANK ATP Diffusion (simple) Facilitated diffusion Glucose High (2) Into Large (2) Low (2) Osmosis Out of Protein Proteins Vesicles (2) The proteins on the back go in order from left to right. Channel Carrier Pump