MGD Flashcards
To cover some aspects of the Molecules, Genes and Disease course for ESA 1 Note: This is not all the content required for MGD, just the shit I struggled with I take no responsibility for any of the flashcards featured here...mistakes/shit happens.
What is the name given to diseases caused by improper polypeptide folding?
Amyloidoses
What type of bonds are involved in the primary structure of proteins?
Covalent (peptide) bonds
What type of bonds are involved in the secondary structure of proteins?
Hydrogen bonds
What type of bonds are involved in the tertiary/quaternary structure of proteins?
- Hydrogen bonds
- Van Der Waals
- Hydrophobic Interactions
- Covalent (Disulphide)
- Ionic Interactions
What are the main features of the alpha helix?
- 3.6 amino acids per turn
- 0.54nm pitch
- Right handed helix
What are the main features of the beta pleated sheet?
- Extended conformation
- Parallel or antiparallel
- Multiple inter-strand H-bonds
Which organelles are important for detoxification reactions?
- Endoplasmic reticulum
- Golgi body
What is the function of the plasma membrane of a eukaryotic cell?
- Cell morphology and movement
- Transport of ions and small molecules
Give two benefits of a molecule being hydrophobic as opposed to hydrophilic?
- Can pass through lipid bilayers
- Can be stored anhydrously
What is a zwitterion?
A zwitterion is a neutral molecule that has both positive and negative charge
When does a zwitterion become deprotonated?
When the pH > pKa of an Amino Acid
What is the isoelectric point of a protein?
The isoelectric point is the pH at which the protein has no overall charge.
What two small amino acids are strong helix formers?
Alanine and Leucine
Why is proline considered to be a helix breaker?
The rotation around the N-C bond is impossible.
Why is glycine considered to be a helix breaker?
The tiny R-group supports other conformations.
What effect does 2,3-bisphosphoglycerate (BPG) have on the binding of O2 to haemoglobin? Which way does it shift the oxygen dissociation curve?
It decreases the affinity for oxygen binding and shifts the curve right
In what two cases is the concentration of BPG increased?
- High altitudes
- In highly metabolising tissues
What effect do carbon dioxide and protons have on the binding of O2 to haemoglobin? What is this effect called?
They decrease the affinity for oxygen binding known as the Bohr effect
What type of oxygen binding does myoglobin exhibit?
Hyperbolic O2 binding
What type of oxygen binding does haemoglobin exhibit?
Sigmoidal O2 binding
What two states can deoxyhaemoglobin exist in?
- Tense state (doesn’t bind oxygen that readily)
- Relaxed state (binds oxygen easily)
What is a fibrous protein? Give three examples of what a fibrous protein is used for.
One repeating primary structure. Proteins for structure, support, protection
What is a globular protein? Give two examples of what a globular protein is used for.
Several types of secondary structure structure. Enzymes and regulatory proteins
What causes sickle cell anaemia?
It’s an autosomal recessive genetic disorder resulting in the substitution of hydrophilic Glutamate to hydrophobic Valine in the β-subunit of Hb
What is the pathological progress of sickle cell anaemia?
A ‘sticky hydrophobic pocket’ formed by Val allows deoxygenated Hbs to polymerise, causing sickle shape. This leads to premature destruction of RBCs and blockage of the cell microvasculature.
What are Thalassaemias?
A group of genetic disorders where there is an imbalance between α and β subunits.
What is Km?
The substrate concentration that gives half the Vmax
What is Vmax?
The maximum rate when the enzyme is saturated with substrate
List the 5 major regulatory mechanisms that control enzyme activity
- Covalent modification
- Proteolytic activation
- Allosteric control
- Substrate/product concentration
- Enzyme concentration
How does proteolytic activation work?
An enzyme secreted as an inactive protein precursor (zymogen) and cleaved by proteases create the active enzyme when needed
What type of regulatory mechanism controls phosphofructokinase activity? What activates and inhibits it?
Allosteric regulation:
- Activators are AMP, fructose-2,6-bisphosphate
- Inhibitors are ATP, citrate and H+
What is the zymogen of pepsin?
Pepsinogen
What is the zymogen of trypsin?
Trypsinogen
What is the zymogen of elastase?
Proelastase
How many rings does a purine have? What bases are purines?
Two rings (A and G)
How many rings does a pyrimidines have? What bases are pyrimidines?
One ring (C, U and T)
Which end of the DNA chain has a free phosphate?
5’ end
Which end of the DNA chain has a free -OH group?
3’ end
Briefly outline the three main steps of DNA replication.
- Initiation
- Elongation
- Termination
What is the direction of chain growth in DNA replication?
5’ to 3’
What is the genotype?
The genetic make-up of an individual
What is the phenotype?
All observable characteristics of an individual or the expressed trait as a result of the genetic make-up
Which phase of the cell cycle is all the genetic information duplicated in?
S phase
What is the function of the G1 phase of the cell cycle?
Cellular content is duplicated
What is the function of the G2 phase of the cell cycle?
Double checking everything is correct
What is a gene?
A unit of heredity; a length of DNA on a chromosome that contains the code for a protein
What is an allele?
An alternative form of a gene; each individual has two alleles for every gene, which can either be the same or different
Briefly describe the process of initiation during transcription
- Recognition at 5’TATA3’ box
- Transcription factors bind at this point
- Attract RNA polymerase
Briefly describe the process of elongation during transcription
RNA polymerase travels along forming a complimentary RNA strand
Briefly describe the process of termination during transcription
- Capping - a methyl-guanine ‘cap’ to the 5’ end
- Tailing - polyadenylated - lots of Adenine nucleotides are added
Outline the process of initiation during translation
- Binding of 40s sub-unit of Met-tRNA to the 5’ cap of mRNA
- Codon 5’AUG binds to anticodon 5’CAU
- 60S subunit then binds
Outline the process of elongation during translation
- Met-tRNA occupies p site of ribosome and then another aminoacyl-tRNA occupies the A site using GTP
- Formation of peptide bond between amino acids via peptidyl transferase, making the tRNA in P site uncharged (without amino acid)
Outline the process of termination during translation
- Stop codon on mRNA reached and no tRNA can bind to it
- Peptide and tRNA are hydolysed to release the protein into the cytoplasm
How can mutations outside the coding region affect gene expression?
Mutations to promoter regions where transcription factors bind can affect gene expression
What is regulated secretion?
-Proteins packaged into vesicles but not released until a signal (hormone)
E.g. Insulin
What is constitutive secretion?
-Proteins packaged into vesicles and release continuously by exocytosis.
E.g. Albumin