Lecture 11

Front 1

1. What cells have a plasma membrane? (Eukaryotic, prokaryotic or both?)

Back 1

ALL cells have a plasma membrane

Front 2

2. What cells have membrane-bound organelles? (Eukaryotic, prokaryotic or both?)

Back 2

Eukaryotic cells ONLY have membrane bound organelles

Front 3

3. What is the advantage of having membrane-bound organelles? Explain.

Back 3

Membrane-bound organelles are compartmentalized allowing for greater complexity of structure and function -> specific functions compartmentalized

Front 4

4. What are the main components of membrane structure?

Back 4

Amphiphatic lipid bilayer
Membrane proteins, sugars, and cholesterol
Cytosolic sub-membrane protein meshwork

Front 5

5. Why is the lipid bilayer called amphipathic?

Back 5

Amphiphatic has both hydrophilic and hydrophobic components

Front 6

6. What is the main function of the lipid bilayer?

Back 6

Provides hydrophobic barrier to most molecules while allowing a select few to diffuse across -> semi-permeable

Front 7

7. What type of molecules can pass through the membrane rapidly?

Back 7

Small, hydrophobic (non-polar) molecules (CO2, N2, O2 -> gasses)

Front 8

8. What type of molecules cannot easily pass through the membrane?

Back 8

Small, uncharged, polar molecules pass slowly through (H2O, urea, glycerol)
Steroid hormones
Charged or strongly polar molecules (ions, sugars, proteins)

Front 9

9. What is the basic structure of a phospholipid?

Back 9

Hydrophilic polar head (phosphate group) with hydrophobic carbon tails (lipids/fatty acids)
One tail is saturated (C-C), the other unsaturated (at least one C double bond C)
Two layers of this, heads facing out, tails facing each other

Front 10

10. Why are membrane proteins so critical?

Back 10

They provide for specific membrane functions
Associate with membranes in many ways

Front 11

11. What are the different ways proteins can associate with membranes? (Understand the differences of each.)

Back 11

Transport: move molecules across membrane
Enzymatic activity: substrate binding to protein alters substrate
Signal transduction: proteins bind signaling molecules
Cell-cell recognition: communication between cells
Intercellular joining: allows for cell to join with another cell
Attachment to cytoskeleton and ECM

Front 12

12. What are the different functions of transmembrane proteins?

Back 12

Transmembrane protein functions: nutrient uptake, waste elimination, pH and osmolarity maintenance, and electrical gradient maintenance

Front 13

13. What is the difference between passive and active transport?

Back 13

Passive transport occurs via as diffusion, facilitated diffusion, or conformational protein change w/out needing energy
Active transport requires ATP as energy to facilitate transport

Front 14

14. Why is transport across the membrane important for cellular function?

Back 14

Cells cannot function if they cannot maintain their electrical gradient, dispose of wastes, regulate their internal environments, and take up nutrients

Front 15

15. Is the protein to lipid ratio the same for all membranes?

Back 15

No, the protein to lipid ratio varies between membranes on different organelles, depending on that organelle’s function

Front 16

16. What molecules in the membrane are sugars found on? What is their primary function? What is a specific example of this function?

Back 16

Sugar side chains are found on proteins and lipids embedded in the membrane
Sugar moides function in cell recognition
Differences in cell-surface sugars are the molecular basis for different blood groups

Front 17

17. What side of the membrane are sugars found on? Why are sugars in glycoproteins found on this side of the membrane?

Back 17

Sugars on proteins/lipids are found on non-cytosolic side (INSIDE) of the membrane
Sugars on glycoproteins are found on the non-cytosolic side (INSIDE) of the membrane (because they are added to proteins in the ER lumen & golgi lumen (INSIDE cell) -> when transport vesicles fuse with plasma membrane -> needs to be in same orientation to wind up in lumen)

Front 18

18. What is cholesterol and what is its function?

Back 18

Sterol (steroid alcohol) with a polar head group, a non-polar tail, and a rigid ring structure
It provides rigidity to the membrane

Front 19

19. What is the submembrane protein meshwork? Where is it found? What is its function?

Back 19

Peripheral proteins and cytoskeletal components
Found on cytosolic face of membrane (OUTSIDE cell)
Allows membrane to communicate with the rest of the cell

Front 20

20. What are the principle functions of cell membranes?

Back 20

Compartmentalization of cell functions, defense and integrity of contents, selective permeability in two directions, regulation of internal activity, attachment and movement, and response to from outside.

Front 21

21. What are the key functions of the nucleus and ER?

Back 21

Nucleus: store, protect, transcribe DNA
ER: protein synthesis and membrane integration, lipid synthesis and membrane integration, detoxification of dangerous materials, and calcium sequestration

Front 22

22. What are the key functions of the endosomal system?

Back 22

Delivers molecules to the lysosome for degradation
Lysosome recycles membrane components

Front 23

23. What are the key functions of mitochondria and chloroplasts?

Back 23

Cellular power plants: generate most of cell’s ATP
Store, protect, express their own DNA

Front 24

24. What are the key functions of the peroxisome?

Back 24

Detoxification: metabolism of ROS, lipid synthesis, breakdown of long-chain fatty acids

Front 25

25. What are the key functions of the vacuole?

Back 25

Water storage, maintaining turgor, exporting harmful materials/waste products, maintaining pH

Front 26

26. What organisms have vacuoles?

Back 26

All plants and fungi have vacuoles
SOME protists and bacteria have vacuoles