Chapter 7: Cellular Structure & Function

1. Chapter 7: Cellular Structure & Function 7.1 Cell Discovery and Theory 7.2 The Plasma Membrane 7.3 Structures and Organelles 7.4 Cellular Transport

2. 7.1 Cell Discovery & Theory • Objectives: • Relate advances in microscope technology to discoveries about cells. • Compare compound light microscopes with electron microscopes. • Summarize the principles of the cell theory. • Differentiate between a prokaryotic cell and a eukaryotic cell.

3. History of the Cell Theory • 1665. ____________ looked at cork (oak bark) and saw box-shaped structures. • Called them cellulae. • ____________ is the basic structural and functional unit of all living organisms.

4. The Cell Theory • Three Principles: • All living organisms are composed of one or more __________. • Cells are the basic unit of structure and organization of all living organisms. • Cells arise only from previously existing cells, with cells passing copies of their ____________________________onto their daughter cells.

5. Microscope Technology • Microscopes have made it possible to see things even smaller than just cells. • Compound light microscopes: typically ______ lenses • Objects cause light to ______________, which blurs images • Max magnification: ~1000X

6. Electron Microscopes • Transmission: (TEM) uses _____________ to aim a beam of electrons at thin slices of cells • 500,000X, dead, very thin, stained with heavy metals • Scanning: (SEM) directs electrons over the surface producing 3D images • Still must be _____________. • Scanning Tunneling: (STM) 3D computer images. Can be ___________ specimens!

7. Basic Cell Types • All have one thing in common: the ____________________________!! • Special boundary that helps control what enters and leaves cell. • Most cells have genetic material that provides instructions for making substances the cell needs. • Break down molecules to generate ___________ for metabolism. • Prokaryote v Eukaryote cells: eukaryotes have _______________ and are one to 100x larger.

8. Eukaryotic Cells • Contain a nucleus and other ________________. • _____________________: specialized structures that carry out specific cell functions. • ______________: distinct central organelle that contains the cell’s genetic material in the form of DNA.

9. Prokaryotic Cells • No nucleus • No membrane-bound organelles. • Most unicellular organisms are prokaryotes. • ___________________. • Many scientists believe prokaryotes are similar to the first organisms on Earth.

10. 7.2 The Plasma Membrane • Objectives: Describe how a cell’s plasma membrane functions. Identify the roles of proteins, carbohydrates, and cholesterol in the plasma membrane. • Function of the Plasma Membrane • Responsible for __________________________. • Selective permeability: membrane that allows some substances to pass through while keeping others ____________.

11. Structure of the Plasma Membrane • Phospholipid bilayer: two layers of phospholipids are arranged ______________________. • Polar head and Nonpolar tail. Polar head _______ water. Nonpolar tail _______ water. Arrangement allows it to exist in a watery environment. • Phosphate group is what makes the ______ polar. • Water-soluble substances do not move easily through the plasma membrane because they get stopped by the nonpolar middle.

12. Other Components of plasma membrane • Cholesterol, proteins, and carbohydrates. • __________________: can be receptors that transmit signals to the inside of the cell; on the inner surface they anchor the membrane to the cell’s internal support structure; if they span the entire membrane, they can be transport proteins—move needed substances or waste materials through the plasma membrane

13. Other components continued… • _______________________: positioned among phospholipids because it’s nonpolar. Helps prevent the fatty-acid tails of the phospholipid bilayer from sticking together, which contributes to the fluidity of the plasma membrane. • _______________________: Stick out from the membrane to define the cell’s characteristics and help cells identify chemical signals.

14. Fluid mosaic model • All of the components can move throughout the membrane itself. • The phospholipids can move. • Proteins can move around within the phospholipid bilayer.

15. 7.3 Structures and Organelles • Objectives: Identify the structure and function of the parts of a typical eukaryotic cell.Compare and contrast structures of plant and animal cells. • Cytoplasm & Cytoskeleton: • __________________: semifluid material inside the plasma membrane • ___________________: supporting network of long, thin protein fibers that form a framework for the cell and provide an anchor for the organelles inside the cells.

16. Cell Structures • _________________: Cell’s managing structure. Contains most of the cell’s DNA. • Surrounded by nuclear envelope that has nuclear pores that allow larger-sized substances to move in and out of nucleus. • ___________________: organelles that help manufacture proteins. Made of two components—RNA and protein—not bound by a membrane like other organelles. • __________________: site of ribosome production within the nucleus.

17. More Cell Structures • ____________________________: ER, membrane system of folded sacs and interconnected channels that serves as the site for protein (RER) and lipid (SER) synthesis. • __________________________: flattened stack of membranes that modifies, sorts, and packages proteins into sacs called vesicles. These vesicles can fuse with the plasma membrane to release proteins to the outside environment.

18. More Cell Structures • ____________________: Temporary storage of materials within the cytoplasm. • In plant cells: stores food, enzymes and other materials needed by the cell. • Most animal cells do not have vacuoles, but if they do, they are smaller than plant ones. • _________________: vesicles that contain substances that digest excess or worn-out organelles and food particles. Also digest bacterial and viruses that enter the cell.

19. More Cell Structures • _________________________: powerhouse of the cell. Converts fuel particles (mostly sugars) into usable energy. • Contains its own DNA. This is why we have maternal DNA. • ______________________: organelles that capture light energy and convert it to chemical energy through a process called photosynthesis. • ____________________: a thick, rigid, mesh of fibers that surrounds the outside of the plasma membrane in plant cells. Made of cellulose and allows the plants to stand up!

20. More Cell Structures • ___________: short, numerous projections that look like hairs. Motion is similar to oars in a rowboat. • Human respiratory tract. • _________________: longer and less numerous. Move with a whiplike motion. • Composed of microtubules. • In prokaryotes, these structures contain ___________________ and are enclosed by the plasma membrane.

21. Comparing Cells • Plant versus Animal • ________________ contain chloroplasts that have chlorophyll and are able to convert sun energy into chemical energy (make sugar). • ____________ have large vacuoles whereas ____________ cells typically have no vacuoles or only really small ones. • Finally, _____________ cells have cell walls, and ________________ cells do not.

22. Organelles at Work • Transcription and Translation • DNA is transcribed into mRNA in the nucleus and then it goes to the ER where ribosomes translate the mRNA into proteins. These proteins are sent to the golgi packages them in vesicles and transports them to other organelles or outside of the cell.These proteins can be used to carry out cellular processes.

23. 7.4 Cellular Transport • Objectives: Explain the processes of diffusion, facilitated diffusion, and active transport. Predict the effect of a hypotonic, hypertonic, or isotonic solution on a cell. Discuss how large particles enter and exit cells. • _____________________: Net movement of particles from high to low concentration.

24. More on Diffusion • __________________________: condition where there is continuous movement of particles but no overall change. • 3 factors that affect the rate of diffusion • _________________________: higher concentrations allow diffusion to go quicker • _______________________: the higher the temp, the faster the diffusion • __________________: higher pressure means higher diffusion rates.

25. Facilitated Diffusion • Uses ___________________________to move other ions and small molecules across the plasma membrane. • Still uses a concentration gradient…from high to low, so no energy is needed. • Also known as _________________________.

26. Osmosis • Diffusion of ______________ across a selectively permeable membrane. • You cannot learn biology by the process of osmosis!!!! • Concentration is defined as the amount of solute per unit solvent. • Therefore, water will move to an area of higher solute concentrate to dilute that solution and strengthen the original solution.

27. Active Transport • Movement of substances across the plasma membrane ______________ the concentration gradient. • Requires energy. • Uses carrier proteins commonly called pumps. • Helps maintain homeostasis. • Example: sodium potassium ATPase pump. • Three sodium from inside the cell bind, then uses ATP to change the shape, allowing sodium to leave, then potassium binds, a phosphate is released from the protein, it changes shape, and the potassium is now in the cell.

28. Isotonic Solutions • Iso is Greek for ________________. • The cell is in a solution with the same concentration of solutes and water. • This cell is at equilibrium and there is no net movement of water across the plasma membrane.

29. Hypotonic Solution • Hyp-O-tonic: think about it blowing up! • Cell is placed in a solution with a lower concentration of solute. • Therefore, water floods into the cell. • In RBCs, __________________ can occur. (The cells can actually burst.) • In plants cells, it creates ____________________, and the plant cells become firmer.

30. Hypertonic Solution • The concentration of the solute outside the cell is higher than inside the cell. • Therefore, the net movement of water is _______ of the cell. • In RBCs, ___________________ occurs. The cells shrivel up. • In plant cells, the cells shrink smaller than the cell wall and _____________________ occurs. The plant wilts.

32. Endocytosis & Exocytosis • ____________________ is the process by which a cell surrounds a substance in the outside environment, enclosing it in a portion of the plasma membrane, and brings it into the cell. • ________________________ is the secretion of materials at the plasma membrane. The vesicle fuses with the plasma membrane and the contents are released outside of the cell.