Topic 2 Flashcards
How are the lungs adapted for gas exchange.
-contain alveoli that have a large surface area
-surrounded by capillaries that are one cell thick so short diffusion distance
-steep concentration gradient between alveoli and blood
What is Fick’s law
Rate of diffusion is quicker when there is larger surface area and concentration difference but smaller distance
Structure of amino acids
-Two amino acids= dipeptide
-Three or more amino acids= polypeptide
Describe primary structure of a protein
Two amino acids join as a dipeptide via condensation reaction with peptide bond, process repeated to from polypeptide chains. Sequence of amino acids in polypeptide chains is primary structure.
Secondary structure of a protein
Amino acid chain folds into alpha helixes or beta pleated sheets with hydrogen bonds
Tertiary structure of a protein
3D folding of secondary structure into complex shapes. Forms ionic/H+ bonds and disulphide bridges. Shape is determined by bond present.
Quaternary structure of protein
3D arrangement of more than one polypeptide, not all proteins have this
Structure of fibrous proteins
-long/parallel polypeptides
-little tertiary/quanternary structure
-insoluble
-used for structural purposes (i.e collagen)
Structure of globular proteins
-complex tertiary/quaternary structure
-souluable
- compact and spherical
-many uses (Haemoglobin, hormones,antibodies and carrier proteins)
Structure of a cell membrane
Cell membrane forms a phospholipid bilayer. Phosphate head is hydrophilic and fatty acid tail is hydrophobic.
What does the fluid mosaic model tell you and what evidence is there
Shows cell membranes are fluid and have a mosaic like arrangement of proteins.
Evidence: -Phospholipids naturally form bilayers in water
-Microscope image shows proteins on membrane
-lipid soluble substances pass more easily than water soluble
Define diffusion
Movement of molecules from high to low concentration down concentration gradient. No energy required.
Define facilitated diffusion.
Transport Polar molecules and ions across membranes using channel proteins. Down concentration gradient from high to low concentration, no energy required.
Osmosis
Net movement of water molecules from high to low concentration through partially permeable membrane, no energy required.
Active transport
Transports all types of molecules through carrier proteins that change shape against concentration gradient from low to high concentration. Requires energy supplied by ATP.
Exocytosis
Used for bulk movement of substances out of cell, vesicles fuse with cell surface membrane releasing contents.
Endocytosis
Used for bulk movement into cell, vesicles created by cell surface membrane bringing contents into the cell.
For unaffected lungs how is water removed out of mucus (too much water)
1)Na+ pumped across basal membrane
2)Na+ diffuses through sodium channels in apical membrane
3)Cl- diffuses down electrical gradient
4)water drawn out by osmosis, as high Salt in tissue fluid and low in mucus
