B2 Cell transport systems Flashcards
Define diffusion?
The movement of a substance from a high concentration to a lower concentration
Give two differences between active transport and facilitated diffusion.
Active transport requires energy/ATP whereas facilitated diffusion is passive. Active transport moves substances against the concentration gradient whereas facilitated diffusion moves substances down the concentration gradient.
Give a similarity between active transport and facilitated diffusion.
Both use carrier proteins.
Which type of molecule can diffuse across the phospholipid bilayer?
Non-polar or lipid soluble molecules.
Through what structure do water soluble molecules cross the membrane?
Through channel proteins/aquaporins
Which part of the phospholipid is hydrophobic?
Fatty acid tail.
Protein molecules found on the surface of the membrane are called …
Extrinsic proteins
Give 2 differences between a triglyceride and a phospholipid.
Phospholipids contain a phosphate group whereas triglycerides do not.
Phospholipids have 2 fatty acids whereas triglycerides have 3 fatty acids.
What is the function of the carbohydrates found on the outer surface of the membrane?
Antigens
Each carrier protein can transport …. type of molecule.
One
Name the two carbohydrate containing chemicals found in cell membranes.
Glycoproteins and glycolipid.
What effect does cholesterol have on the fluidity of the membrane?
Reduces the fluidity/movement of phospholipids in the membrane.
How can the structure of the membrane be changed to make the diffusion of water soluble molecules more rapid?
Increase number of channel proteins Increase surface area.
Give three ways in which the rate of gas exchange can be increased.
Increase the surface area.
Increase the concentration gradient.
Decrease the diffusion pathway/distance Increase the temperature
Why is the term fluid mosaic used to describe the model for membrane structure?
Fluid - phospholipid move within the membrane.
Mosaic - proteins form blocks on the surface of the membrane.
Define osmosis
Net movement of water from a high water potential to a lower water potential through a selectively/partially permeable membrane.
Name a chemical that moves by osmosis into cells.
Water
Name 2 molecules that move into cells and are used in respiration.
Oxygen and glucose
What happens to ATP during active transport?
It is hydrolysed.
A phosphate group is removed. Allowing the release of a small amount of energy.
Name the components of a cell surface membrane
Phospholipids
Proteins (extrinsic and intrinsic)
Glycoproteins
Glycolipids
Cholesterol
What are the functions of the phospholipids in the cell membrane
Allow non-polar molecules cross the membrane
Prevent polar molecules crossing the membrane
Makes membrane flexible and self healing
What are the functions of proteins in the cell membrane?
Provide structural support
Act as channels to transport polar molecules/facilitated diffusion
What is the function of cholesterol in the cell surface membrane?
Reduces lateral movement of molecules in the membrane
Acts as a buffer against temperature changes
Prevent leakage of water and dissolved ions from the cell
What are the functions of glycoproteins in the cell surface membrane?
Act as recognition sites for hormones and neurotransmitters
Help cells attach and form tissues
What happens to red blood cells if placed in pure water?
Swell and burst/undergo lysis
What happens to a red blood cell placed in a strong sugar solution?
Shrinks
Define active transport
The movement of molecules or ions against a concentration gradient using ATP and carrier proteins.
What is the role of ATP in active transport?
Provide the energy needed to transplant a molecule against its concentration gradient.
ATP binds to carrier protein, ATP is hydrolysed causing the protein to change shape, allowing the entry of the molecule/ion
Name the molecule shown in the diagram
Triglyceride
Name the components of this triglyceride
Glycerol
3 Fatty acids
Name the structure shown on the diagram
Phospholipid bilayer
Name the molecule shown on the diagram
Phospholipid
Name the components of a phospholipid
Glycerol
2 fatty acids
1 phosphate
Describe the structure of this fatty acid
Monounsaturated fatty acid
One Carbon carbon double bonds in the hydrocarbon
Describe this phospholipid
Polyunsaturated
More than one carbon carbon double bond in the hydrocarbon
Name the structure shown on the diagram
Cell membrane
OR
Plasma membrane
Name structure G
Channel Protein
Name structure F
Extrinsic protein
OR
Carrier protein
Name structure E
Cholesterol
Name structure B
Glycolipid
Name the molecule shown in the diagram
Steroid
OR
Oestrogen
Name two steroids
Oestrogen
AND
Testosterone
Give three functions of lipids in humans
Energy storage
Heat insulation
Protection of vital organs eg kidney
Name two ways in which red blood cells can be classified
ABO system
AND
Rhesus system
Proteins and lipids in membranes can be glycosylated.
What does this mean?
Carbohydrates are added to them.
