Cell Membrane (PPT 5-7) (U1) Flashcards
About how thick is the plasma membrane?
- Around only 8nm thick
nm= nanometers
The function of the cell membrane is too…
- Isolate the cytoplasm from the external environment.
- Control what moves in and out of the cell.
- Cell to cell recognition.
What cells have a cell wall?
- Bacteria
- Fungi
- Plant
What is the membranes structure?
Hint= Fluid mosaic model
A double layer of phospholipids which are arranged with the hydrophobic tails facing inwards.
The double layer is fluid, with proteins floating within it.
Glycoproteins, glycolipids and cholesterol are an integral part of the membrane structure.
Define Hydrophobic and Hydrophilic?
Hydrophobic= Water hating end
Hydrophilic= Water loving end.
Why is it fluid mosaic?
Fluid because the components can move
Mosaic because the proteins embedded create a mosaic tile look.
Phospholipids create a —– to —— soluble ——-. (Fill in the blanks).
1- barrier
2- water
3- molecules
What type of molecules will Phospholipids let through the membrane?
- Lipids (as they are soluble in lipids)
- Hydrophobic molecules. (Water hating)
—— molecules like —– cannot cross. (fill in the blank)
1- Large
2- Proteins.
Are phospholipids stationary?
No, they can move and do so frequently.
It is the phospholipids ability to —- that makes the membrane fluid. This is crucial because ————? (Finish the sentence)
1- move
2- it allows the embedded proteins to move where they are required.
What does semi-permeable mean?
Semi-permeable means they allow some things through, but not all.
What are the two types of membrane proteins?
1- Integral proteins (transverse the membrane)
2- Peripheral proteins (stuck on the inside or outside of the membrane)
What is the structure and function of Integral proteins?
S= Generally span both phospholipid layers.
F= Transport of molecules. Signal transduction Cell to cell communication Joining of cells Anchorage (attachment to cytoskeleton).
Glycoproteins and glycolipids are a… (finish the sentence)
Short chain of carbohydrates attached to proteins and lipids on extracellular side of the membrane.
What is the structure and function of Cholesterol molecules?
S= Within the phospholipid layers, providing stability without affecting its fluidity.
F= Increase strength. Increase flexibility, Increase the rigidity of the membrane.
Assist with changing temperatures.
Membranes are also found ——- ———– cells as part of the ——- of membranous ———. (Fill in the blank)
1- within
2- eukaryotic
3- structure
4- organelles
What are the two ways substances are moved across the plasma membrane?
- Passive (not requiring energy)
- Active (energy requiring)
Give examples of passive transport.
- Diffusion
- Facilitated diffusion
- Osmosis
Give examples of active transport.
- Ion pumps
- Cytosis
What is diffusion?
- Diffusion is a passive transport process, does not require energy.
- The movement of molecules from high concentration to low concentration. (Across the concentration gradient).
Each type of diffusing molecule moves across….
Its own concentration gradient. The bigger this concentration, the faster the diffusion.
What is facilitated diffusion?
- When a substance is aided across a membrane by selective protein channels.
What is the upside to facilitated diffusion?`
- Transport is quicker than diffusion.
- The channels are specific for particular molecules.
- Does not require energy.