Cell Physiology Lecture 1 Flashcards
Cell Surface
the part of the cell that is exposed to the outside world
What three things do all cells have
- A plasma cell membrane which surrounds the cell surface
- Cell organelles which do tasks
- Interior of the cell which consists of the nucleus and the cytoplasm
Cell organelles: membrane-bound or _________________
non-membrane bound
What is the cytoplasm
The region outside the nucleus and is composed of cytosol which is a gel like fluid in which the cell organelles are suspended
The ___________ is the largest organelle in the cell
nucleus
What are the 4 functions of the plasma cell membrane?
- Physical barrier between the Intracellular fluids (ICF) and the extracellular fluids (ECF)
- Cell to cell communication
- Structural Support
- Transport
Plasma Membrane Function:
Physical Barrier between ICF and ECF
-Keeps organelles and proteins inside cell
-Maintains difference in ion composition between ICF and ECF
-Maintains homeostasis – things may change outside the cell but inside
remain constant
Plasma Membrane Function:
Cell-to-cell communication
-Contains receptors which bind signalling molecules
Plasma Membrane Function:
Structural Support
-Contains connections composed of proteins which anchor cells to each other or to extracellular materials
Plasma Membrane Function:
Transport
-Plasma membrane is selectively permeable- some substances may
simply move across the plasma membrane but most require specific transport proteins (transporters, carriers, channels etc.) to cross. It is therefore selectively permeable, allowing certain molecules to move across but not others.
Can cell organelles have membranes? What are they called?
Yes, they are called intracellular membranes
What is the cell/plasma membrane, and the intracellular membranes surrounding organelles composed of?
a double layer of lipid molecules with embedded proteins
What is the predominant lipid in the cell/plasma membrane, and the intracellular membranes?
The phospholipid
What are biological membranes that have the predominant lipid as phospholipids called?
Phospholipid Bilayers
Phospholipid Bilayer
2 layers of phospholipids with embedded proteins
2 Types of biological membranes:
-Cell/Plasma Membrane
-Membranes surrounding organelles
Biological Membrane lipids are:
amphipathic
amphipathic:
contains polar and none-polar regions
3 types of amphipathic lipids found in biological membranes
- Phospholipids
- Cholesterol
- Glycolipids
What composes the structure of a phospholipid?
- Polar head group
- Non-polar tail
Structure of a Phospholipid: Polar Head group
-Composed of phosphate attached to glycerol, a nitrogen-containing chemical group, and glycerol backbone
-Polar head group is hydrophilic (water-loving or dissolves in water)
Structure of a Phospholipid: Non-Polar tail
-Composed of 2 fatty acid chains composed of carbon and hydrogen atoms
-Fatty acid chains may be: saturated (no double bonds) or unsaturated
(containing 1 or more double bonds)
-Nonpolar tail is hydrophobic (water-fearing or does not dissolve in water)
What happens to phospholipids when you put them in water
-They spontaneously form a bilayer
-Polar heads face aqueous environment, either the ECF or ICF (REMEMBER DOUBLE-LAYERED SO CAN BOTH)
- Nonpolar tails form hydrophobic core
-Bilayer is the structure of the plasma membrane and the organelle membranes
Cholesterol
-Steroid Lipid
-Amphipathic