2: Cell membranes Flashcards
The cell membrane is ___ permeable.
selectively
Functional differences between cell types are due to variations in the composition of the ___ ___.
cell membranes
What are the two main components of cell membranes?
Lipids
Proteins
Phospholipid heads are (hydrophilic / hydrophobic).
Heads are hydrophilic
Phospholipid tails are (hydrophilic / hydrophobic).
hydrophobic
Due to the hydrophilic/phobic nature of the phospholipid heads and tails respectively, the lipids arrange themselves into a ___.
bilayer
The cell membrane consists of embedded ___ and a phospholipid ___.
proteins , bilayer
Is the phospholipid bilayer fluid or rigid?
Fluid
All phospholipids are constantly ___.
moving
What molecule helps to stabilise the fluid phospholipid bilayer?
Cholesterol
What kind of molecule can pass through the phospholipid bilayer?
Small, uncharged polar molecules
Water soluble substances (can / cannot) pass through the phospholipid bilayer.
cannot
Name some substances which can pass through the phospholipid bilayer.
O2
H2O
CO2
What are the two classes of membrane protein?
Integral
Peripheral
What is another name for integral protein?
Transmembrane protein
What is peripheral protein?
Protein which is not embedded in the membrane - adheres to cytoplasm instead
What is integral protein?
Protein which spans the membrane one or more times
Give some examples of types of integral protein.
Ligand-binding receptors
Adhesion molecules
Pores and channels
Carriers
Pumps
Enzymes
Which cellular process do docking-marker acceptors help with?
Exocytosis of vesicles
Apart from lipids and protein, what other molecule can be found on cell membranes in small amounts?
Carbohydrate
When carbohydrate is bound to a) protein and b) lipid, what are those molecules called?
a) glycoproteins
b) glycolipids
What layer is formed by glycoproteins and glycolipids on the surface of the cell membrane?
Glycocalyx
What do membrane carbohydrates serve as on the cell membrane?
Self-identity markers
What kind of molecule makes up self-identity markers on the cell membrane?
Carbohydrate
Self-identity markers have an important role in cell-to-cell ___ and cell ___.
interactions , growth
What are tight junctions?
Structures which join the lateral ends of epithelial cells together
What are desmosomes?
Structures which anchor cells which stretch (e.g cardiac muscle, skin)
What are gap junctions?
Communication junctions which allow the passage of ions between cells
a) Structures which anchor stretchy cells
b) Structures which join the lateral ends of epithelial cells
c) Communication structures which allow for the passage of ions between cells
Match these definitions to tight junctions, desmosomes and gap junctions.
a) Desmosomes
b) Tight junctions
c) Gap junctions
Overall, what are the three main molecules involved in the structure and function of the cell membrane?
Phospholipids (forming a bilayer)
Proteins
Carbohydrates
