CH 3 Flashcards
List the main component of the plasma membrane and what it is made out of. List the property of each part as well as the component as a whole.
Phospholipids. They have a phosphate head and two fatty acid tails. Phospholipids are amphiphilic. The phosphate head is hydrophilic and polar and the fatty acid tails are hydrophobic and non polar
What is the plasma membrane
Plasma Membrane - phospholipid bilayer and embedded proteins which separate the intracellular environment from the extracellular environment.
What are the phosphate heads and fatty acid tails made up of?
Phosphate heads - Made up of Glycerol and Phosphate Group
Fatty Acid Tails - Made up of long chains of carbon and hydrogen.
Describe the differences between hydrophobic, hydrophilic, amphipathic/amphiphilic, nonpolar and polar molecules.
Hydrophilic – having the tendency to be attracted to and dissolve in water.
Hydrophobic - having the tendency to repel and be insoluble in water.
Amphipathic/ Amphiphilic - describes molecules with both hydrophilic and hydrophobic components. (Such as phospholipids)
Polar - describes a molecule with both a positive end and negative end. These tend to be hydrophilic.
Nonpolar - describes a molecule without a clearly positive or negative end. These tend to be hydrophobic.
List and describe the three types of proteins.
Integral Protien – proteins that are a permanent part of the membrane.
- Transmembrane Protien – integral proteins that go through the entire bilayer.
Peripheral Protien – protiens that are temporarily attached to the plasma membrane and only interact with the phosphate heads of phospholipids.
List the 4 functions of proteins
Transport –channels or pumps in a protein that control what enters and exits the cell, making the plasma membrane selectively permeable.
Catalysis – speeding up chemical reactions with the help of a protein group called enzymes.
Communication – receive signals or recognise cells and molecules. Often attached to the cytoskeleton to transmit signals into the cell.
Adhesion – stick to other cells, the extracellular matrix, or the cytoskeleton.
What is the function and structure of a Carbohydrate? Also describe the two types of carbohydrates.
Structure:
-Chain structure that extends outside the cell that is rooted in the membrane.
-Glycolipids – a carbohydrate bound to a phospholipid.
-Glycoprotien - a carbohydrate bound to a protein.
Function:
-Aids with cell-to-cell communication, signalling, recognition of self or non-self (foreign) molecules, and adhesion.
What is the function and structure of a Cholesterol? Also what is cholesterol?
Cholesterol – a steroid-alcohol that regulates fluidity in plasma membranes.
Structure:
-A lipid steroid that embeds itself between the fatty acid tails of the phospholipid bilayer in animal cells. Other kingdoms have similar molecules with similar functions.
What is the function of cholesterol?
Function:
-Regulates the fluidity of the membrane.
-At higher temperatures, the cholesterol keeps phospholipids bound together as cholesterol has hydrophobic regions which can increase nonpolar interactions with the tails.
-At lower temperatures, cholesterol disrupts the fatty acid tails, stopping phospholipids from becoming a solid boundary by taking up room in the membrane which prevents it from packing too tightly.
What is the Fluid Mosaic model and explain each part.
Fluid Mosaic Model - the theory of how the plasma membrane is structured.
‘Fluid’ Explains that:
-Phospholipids continuously move. This allows the plasma membrane to be fluid.
-Phospholipids can rotate, move laterally or transverse.
‘Mosaic’ Explains that:
-Protein and Carbohydrates embedded in the membrane are able to move around fluidly in the bilayer.
-Scientists imagine that it would look like mosaic pictures.
What are two words to describe membrane fluidity and explain what they mean.
-Saturated - fatty acid chain with only single bonds between carbon atoms. This allows phospholipids to pack together tightly as the tails have no kinks.
-Unsaturated - fatty acid chain with at least one double or triple bond between carbon atoms. This pushes phospholipids apart as the tails have many kinks.
What is passive transport?
Passive Transport - the movement of molecules through a semipermeable membrane and down the concentration gradient, without an input of energy.
Diffusion vs Simple Diffusion.
Diffusion - the passive movement of molecules from areas of high concentration to areas of low concentration (down the concentration gradient) due to kinetic energy.
Simple Diffusion – small and nonpolar molecule diffusion through a phospholipid bilayer (e.g., oxygen and carbon dioxide)
-Once equilibrium is reached the solute moves equally in both directions.
List 2 Factors that affect simple diffusion and define an ion.
Size – small, nonpolar molecules are able to slip through the bilayer. Highly charged molecules such as ions are not able to cross despite their size.
Polarity: nonpolar, uncharged, or hydrophobic molecules are able to cross as the plasma membrane is mostly nonpolar due to the fatty acid tails that attract them.
Ion – atom or particle with an electric charge due to the loss or gain of electrons.
Solute vs Solvent
Solute - a substance dissolved in the solvent.
Solvent - a liquid in which a solute is dissolved, forming a solution.
What is Facilitated Diffusion?
Facilitated Diffusion - a type of passive transport where molecules move through a phospholipid bilayer with the aid of a membrane protein. These proteins are specific to the type of molecule they transport. Some small or nonpolar molecules (e.g., water) also have dedicated protein channels.
