Topic 2 Flashcards
What is Fick’s law?
Rate of diffusion ∝ (area of diffusion surface x difference in concentration)/(thickness of diffusion surface)
When will the rate of diffusion double?
If the area of diffusion doubles
If the difference in concentration doubles
If the thickness of the diffusion surface halves
What do lungs allow to happen?
Rapid gaseous exchange
How have mammalian lungs adapted to increase the rate of gas exchange?
Lots of alveoli to increase the surface area
The alveolar epithethelium and capillary endothelium are one cell thick to decrease the distance of diffusion
Breathing refreshes the air in the alveoli to maintain a high concrentration gradient
What is the general structure of amino acids?
H2N-C(R)(H)-COOH
What does the R represent in the general structure?
The variable group that changes depending on the amino acid
How are polypeptides formed?
When two or more amino acids joined together in condensation reactions, with peptide bonds between the amino acid residues
What’s another name for polypeptides?
Proteins
Name the four levels of protein structure
Primary, secondary, tertiary, quaternary
Explain what the primary structure of proteins involves.
The primary structure is the flat sequence of amino acids in a polypeptide chain
Explain what the secondary structure of proteins involves.
Hydrogen bonds form between amino acid residues to make the chain coil into an alpha helix or into a beta pleated sheet, which makes the structure 3D
Explain what the tertiary structure of proteins involves.
The secondary structure is coiled and folded further. Hydrogen and ionic bonds form. If sulfur is present in any R groups, disulfide bridges form
When is the tertiary structure the final structure of a protein?
If the protein is made from a single polypeptide
Explain what the quanternary structure of proteins involves.
When several polypeptides are bonded together to form a protein
What are the different bonds that hold proteins together?
Peptide bonds in the primary structure
Hydrogen bonds in the secondary structure
Ionic bonds, hydrogen bonds, disulfide bridges, hydrophobic and hydrophilic interactions in the tertiary structure
All of the above in the quanternary structure
Explain what globular proteins are, giving an example
Round, compact structure made up of multiple polypeptide chains
Soluble because the hydrophilic parts of the proteins are on the outside and the hydrophobic parts are on the inside.
Haemoglobin is an example of a globular protein
Explain what fibrous proteins are, giving an example
Long insoluble proteins that are tightly coiled to form a rope like shape.
There are lots of bonds that hold the multiple chains together, making them strong- often supportive tissue
Collogen is an example of a fibrous protein
What are the main features of a cell membrane?
Phospholipid bilayer, protein molecules present, such as glycoproteins, glycolipids, and cholesterol
How is the the phospolipid bilayer arranged?
The hydrophilic ‘head’, the phosphate group, face towards the outside of the membrane, where the water is. The hydrophobic ‘tail’, two fatty acid groups, are inside the membrane, so as to get as far away from water as possible.
What does in mean that the cell membrane is partially permeable?
Small, uncharged molecules can diffuse through through gaps in the bilayer. Larger molecules and ions can only pass through channel proteins or carrier proteins
Define osmosis
The diffusion of free water molecules across a partially permeable membrane from an area of high concentration of water to an area of low concentration
What is facilitated diffusion?
Larger molecules and charged molecules can’t diffuse directly through the cell membrane. Instead, carrier proteins/channel proteins in the membrane allow these molecules to pass through the membrane
