Flashcards in L1 - Amino acids and proteins Deck (41):
What is a basal body?
An organelle made up of a centriole and short cylinder configuration of microtubules
Name 5 specialised cell types
Epithelial cells, muscle cells, nerve cells, adipocytes and erythrocytes
What is the most prolific cell in the body?
Name three differences between eukaryotes and prokaryotes
1. Bacteria do not have a separate nucleus
2. Bacteria have a cell wall and a plasma membrane
3. Bacteria lack most organelles
What is the difference between the bonds that hold macromolecules/ complexes together and those that hold Monomeric units together?
Macromolecules are held together by non-covalent interactions whereas Monomeric units are held together with covalent bonds
Name four types of non-covalent interactions
1. Hydrogen bonds
2. Ionic interactions
3. Van Der Waals interactions
4. Hydrophobic interactions
Which atoms can form hydrogen bonds?
A hydrogen atom attached to an electronegative atom (O,N or F) which therefore has a partial positive charge and an electronegative atom with a partial negative charge
What makes a molecule soluble or insoluble in water?
Whether the molecule is polar and can form hydrogen bonds with water and dissolve, or whether it is non-polar and cannot form hydrogen bonds and therefore can't dissolve
What is the meaning of Amphipathic?
Molecules that have polar and non-polar regions
Describe some roles of protein in the body
Catalysts - enzymes
Transporters (O2, Fe)
Structural support (e.g. Collagens in skin and bone)
Machines (muscular contraction and motion)
Immune protection (Ig's)
Ion channels (allow charged molecules across PM)
Receptors (for hormones and neurotransmitters)
Ligands in cell signalling (growth factors etc.)
What intrinsic factors of the polypeptide chain determine protein structure?
The chemical and physical properties of the amino acids
What is a zwitterion?
A neutral molecule which has an even number of positive and negative charges
What does an amino acid structure look like in water?
It forms its ionised form:
But still has an overall neutral charge - it's a Zwitterion
How do you determin whether an amino acid is an L- or D- isomer?
Rearrange the amino acid so that the hydrogen atom is facing directly towards you and the carboxyl group is facing straight up. Read the amino acid like (CO)(R)(N) - if you read it clock-wise it is the L-isomer, if you read it anti-clockwise it's the D-isomer
What is the protein sterechemical isomer found in the body?
What are the three groups that amino acids are classified into by their side-chains?
1. Non-polar amino acids (hydrophobic)
2. Polar, uncharged amino acids (hydrophilic)
3. Polar, charged amino acids (hydrophilic)
Also aliphatic vs aromatic
How many naturally occuring amino acids are there in the body?
Which is the smallest amino acid?
Why is histidine an honorary member of polar, charged amino acids when it is uncharged?
Due to its pKa it is charged at physiological PH
Lysine has a pKa of 10.5, will its side chain be charged or uncharged at physiological PH?
Glutamate has a pKa of 4.3, will its side chain be charged or uncharged at physiological PH?
What about at PH 4.3?
Negatively charged at physiological PH
Neutral at PH 4.3
Draw a peptide bond forming between two amino acids
Remember to draw this occuring at physiological PH, therefore COO- and NH3+
Describe the characteristics of a peptide bond
1. It's planar: C(alpha), C, O, N, H and C(alpha) all lie in the same plane
2. C-N bond has partial double-bond characteristics, therefore will not rotate
Therefore the peptide bond is rigid and planar
What is meant by the isolelectric point (pI) of a protein?
The PH at which there is no overall NET charge
How would describe the pI of basic proteins?
PI>7, so they contain many positively charged amino acids at physiological PH
How would you describe the pI of acidic proteins?
What is a conjugated protein?
A protein that has covalently linked chemical components in addition to amino acids e.g. Lipids, carbohydrates, phosphate groups, metals etc...
What is the function of mitochondria?
What is the function of the Golgi complex?
Export of proteins
What is the function of the Endoplasmic reticulum?
Export of proteins
Lipid and steroid synthesis
What is the function of the nucleus/ nucleolus?
DNA synthesis and repair
RNA processing and ribosome assembly (nucleolus)
What is the function of lysosomes?
What is the function of the plasma membrane?
Cell morphology and movement
Transport of ions and small molecules
What is the function of the cytoplasm?
Fatty acid synthesis
Metabolism of carbohydrates, amino acids and nucleotides
What is the function of the ribosome
At pH 7.4 what is the concentration of H+ ions?
PH= -log10 [H+]
7.4 = -log10 [H+]
Give TWO definitions of pH
1. A measure of the concentraion of H+ in solution
2. PH= -log10[H+]
Why do metabolically active tissues cause a localised fall in blood pH?
Metabolically active tissues make a lot of acidic substances that will lower the pH of the blood close to them. Examples include lactate, H+, CO2.
Using the Hendersson-Hasselbalch equation (PH=pK+log [A-/HA]), what is the pH of a solution of carbon dioxide and bicarbonate of 1.2mM and 24mM?
Considering the bicarbonate buffer system:
HCO3-+H ions H2CO3 H2O and CO2
And knowing that pK of bicarbonate buffer=6.1
PH= 6.1 + log [24/1,2}
PH=6.1 +log 
Explain how hyperventilation can cause an increase in blood pH
1. Hyperventilation decreases the partial pressure (concentration) of CO2 in the lungs.
2. This concentration of CO2 dissolved in the blood is proportional to the partial pressure of CO2 gas in the lungs and therefore CO2 blood concentraion falls.
3. This means that the equilibrium position of the bicarbonate buffering reaction in the blood moves to favour the reaction of H+ + HCO3- -> CO2 and H2O. This decrease H+ concentraion in the blood and therefore blood pH rises above its normal 7.4 value.