Week 2

Question 1

Lipid bilayer - general

Answer 1

• Lipid Bilayer fundamental structure of membrane
• Define cell and limit what can get in and out
• There is a lot more inside membrane proteins carries out most membrane functions

Question 2

Intergral proteins

Answer 2

• Integral part of structure of membrane regulates homeostasis
• Drive how cell will function
• Allow cells to create action and graded potentials

Question 3

Peripheral proteins

Answer 3

• Appear on either side of cell (OUTSIDE)
• Generally there for different cell processes – e.g. hormone may be a peripheral protein attached itself, make cell do things then leave

Question 4

Transport protein

Answer 4

• Protein that spans the membrane may provide a hydrophilic channel across the membrane
• Some transport proteins hydrolyse ATP (energy source) to actively pump substances across the membrane

Question 5

Receptors for signal transduction

Answer 5

• Lots of things cells need to do without moving things inside the cell
• Membrane protein exposed to the outside of the cell may have a binding site that fits the shape of a specific chemical messenger (i.e a hormone)
• When bound, chemical messenger may cause a change in shape of protein that initiates a chain of chemical reaction in the cell

Question 6

Attachment of protein to cytoskeleton

Answer 6

• Act as anchorage point (cytoskeleton can be anchored into the cell)
• Thus, cytoskeleton can change shape (e.g muscle cells)

Question 7

Enzymatic activity in membrane proteins

Answer 7

• Membrane protein may be an enzyme with its active site exposed to substances in the adjacent solution
• A team of several enzymes in a membrane may catalyse sequential steps of a metabolic pathway as indicated (left to right)

Question 8

Intracellular joining (membrane proteins)

Answer 8

• Membrane proteins of adjacent cells may be hooked together in various kinds of intercellular junctions
• Some proteins provide temporary binding sites that guide cell migration and other cell-cell interactions

Question 9

Cell-cell recognitions

Answer 9

• Some glycoproteins (proteins bonded to short chains of sugars) serve as identification tags that are specifically recognised by other cells
• Allowing cells a level of specificity, exchange information, having cells recognised by other cells

Question 10

Cell junctions (general)

Answer 10

• Links to functions within membrane
• Functions predominantly about anchorage –> connect cells with other cells
• 3 types

Question 11

Tight junction

Answer 11

• binding connection between membrane of one cell and membrane of another
• eliminates extracellular space –> make semipermeable layer