Sem 1 Flashcards
Features of competitive inhibitors
- structural resemblance to substrate
- no reaction but blocks substrate from entering active site
- can be reversed by an increase in [s]
Features of non-competitive inhibitors
- allosteric site
- changes shape of active site
- substrate is blocked from entering
- can no be reversed by increasing [s]
Structure of CNS
Made up of brain and spinal cord :
Frontal lobe - reasoning, planning, movement, emotion and problem solving
Occipital lobe - processing visual information
Temporal lobe - perception and recognition of sounds, memory and speech
Function of CNS
Receives and processes information and coordinates organ function
Function of peripheral nervous system
Sends information from organs eg blood pressure , fullness of stomach into the CNS
(Connects the CNS to the organs, limbs and skin)
Somatic nervous system
Regulate contraction of skeletal muscle - voluntary
Autonomic nervous system
Regulate function of internal organs - involuntary
Structure of neurons
Cell body - organelles which carry out cellular functions eg protein synthesis, energy production
Dendrites - receive input from other neurons via synapses
Axon - nerve fibre transmits action potential towards postsynaptic neuron or the effector organ
What are the 5 phases of an action potential
1- resting potential 2-threshold 3-rising phase 4-falling phase 5-recover phase
- action potential arise from a change in membrane potential
- ions move down an electrochemical gradient
- movement of NA+ and K+ results in an action potential
3 Amine neurotransmitters and their functions
Serotonin - influences mood
Dopamine - reward pathway
Acetylcholine - CNS neuromuscular function
Main functions of the ER
- translocation of proteins
- glycosylation of proteins
- assembly of lipids
Lysosome function in cellular digestion
- fuse with food vacuoles
- polymers digested into monomers
- pass to cytoskeleton to become nutrients of cell
what is Apoptosis
Auto-destruction process where lysosome break open and kill cell
Main functions of Golgi body
- Protein modification
- protein processing
- protein sorting and localization
3 stages of converting food energy into ATP (mitochondria)
Stage 1.
Large molecules broken down into smaller subunits
Stage 2.
Numerous small molecules converted to a few molecules which play a central role in metabolism
Stage 3.
Oxidation to produce ATP
Mitochondrial ATP synthesis
- The energy from the high energy electrons is used to pump protons across the inner mitochondrial membrane from the matrix and into the inter membrane space
- The protons then flow back down the gradient and this energy dribbles coupled ATP synthesis
Function of cytoskeleton
Provides a supporting framework for the cell and gives the cell its particular shape
Cytoskeleton and its associated motor proteins organisms and moves the cytoplasmic contents
what are the 2 types of stroke
- ischemic stroke (most common)
- hemorrhagic stroke
Causes of an ischemic stroke
- Blood vessels occluded (clot or plaque)
- lack of nutrients, o2 , cell death
Where are the 2 regions of a stroke
- umbra- centre
2. penumbra - periphery
Treatment of ischemic stroke
Tissue-type plasminogen activator (alteplase)
Treatment of hemorrhagic stroke
Surgery in order to remove the clot
Cause of Parkinson’s disease
Idiopathic - don’t know the exact cause
Dopaminergic neurons - loss of these neurons that produce dopamine
Affects of Parkinson’s disease
Dopamine coordinates fine movement so a loss of dopamine results in tremors -uncontrolled movement
Treatment of Parkinson’s disease
Cannot simply use dopamine because it can’t cross the brain cloud barriers so levodopa which looks very similar is used
Cause of Alzheimer’s disease
Caused by the abnormal build-up of proteins in and around brain cells
Treatment of Alzheimer’s disease
No affective medicine for the disease itself so treatment is focused on symptoms
Function of GABA
Main inhibitory neurotransmitter in CNS.
Binding of GABA to receptor inhibits transmission of an action potential
What is hyperpolarization
Accumulation of negative charge inside neuron
NA+ channels don’t open, no influx of NA+ so no transmission of action potential
Causes of schizophrenia
Excessive neurotransmission (action potentials) caused by dopamine
Treatment of schizophrenia
Treated with antipsychotics -
Bind to dopamine receptors - reduces action potentials, reduces neuronal activity in the brain , reduces anxiety
Function of the GI system
- digestion of food
- absorption of nutrients, and drugs
- Elimination
- mechanical and chemical breakdown of food
4 regions of the GI tract
Mouth - breaks up food particles
Esophagus - transport of food to stomach via sphincter
Stomach - secretion of gastric juices for chemical digestion
Small intestines
4 accessory organs
- salivary gland
- liver
- gallbladder
- pancreas
Role of gastric juices in food and drug absorption
HCI (controlled by vagus nerve and hormone gastrin) and digestives enzymes -> initiate s the digestion of proteins
Role of mucus coating in food and drug absorption
Lubricates and protects epithelial surfaces
Role of gastric emptying in food and drug absorption
Moves food in the stomach to small intestine
Features of the small intestine
- large surface are and high perfusion
- exposure to enzymes and solubilizes
- receives secretion from liver and pancreas
Why is large surface area so important for drug absorption after oral administration
Dissolved drugs absorbed here
Main role of the liver in digestion
- Main site of metabolisms xenobiotics
- secretes bile
- stored in gallbladder between meals
- important for digestion of lipids
Role of pancreas in digestion
- proteolytic enzymes
- lipase for digestion of lipids
- HCO3 stomach acid neutralizing
Digesting carbohydrates
Starch (amylase) -> disaccharide -> monosaccharide - transported across intestinal epithelium into blood
Digestion of proteins
Peptide (pepsin) -> peptide fragments -> amino acids - active transport to epithelial cells
Digestion of lipids
Emulsification ( bile salts, pancreatic lipase , Michelle formation - transport of lipids — completed in small intestine )
Role of large intestine in absorption
- Reabsorption of water and salts from chyme
- Absorption of drugs minimal compared to small intestine
- mixing and propulsion of contents
- indigestible residue and liquid eliminated as facial waste
Anatomy of the gut
Caecum -> ascending colon -> transverse colon -> descending colon -> sigmoid
Sign and symptoms of IBS
Symptoms include stomach cramps, bloating, diarrhea and constipation. These come and go and can last for days, weeks or months at a time. Usually a lifelong problem with no cure.
Treatment for IBS
- change to diet or lifestyle
- IBS friendly diet - low FODMAP diet
- exercise and reducing stress
- probiotics
Two main forms of IBD
- Ulcerative colitis - inflammatory disease that affects the mucus a of the colon and rectum
- Crohn’s disease - inflammatory disease that affects the gut (Small and large intestine)
Signs and symptoms of IBD
- diarrhea sometimes mixed with food, mucus and pus
- cramping
- malaise fever
- loss of appetite and weight
Treatment of IBD
- antibiotics
- corticosteroids
- biologics
3 stages of protein synthesis
- initiation
- elongation
- termination
Protein synthesis: initiation
Small subunit complexes with initiation factors and base parings occurs - start codon of mRNA is positioned in the ribosomal P site and tRNA joins
Protein synthesis: elongation
The ribosome has 3 sites where tRNA can bind:
The A site, P site and E site.
Only 2 of these are occupied at one time.
The ribosome moves 1 codon towards the end of the mRNA so that the growing peptide chain moves from the A to the P site. This means that unloaded tRNA moves to the E site. The A site is now empty -> then it all happens again
Protein synthesis: termination
-synthesis continues until a stop codon is reached (UAA, UGA OR UAG)
3 ways antibiotics block bacterial ribosomes
- inhibition of initiation
- prevention of tRNA binding to the A site
- blocking the exit tunnel
Tetracycline
Prevents tRNA binding to the A site - most common current use is in the treatment of severe acne
Chloramphenicol
Inhibition of peptide bond formation
Erythromycin
Blocking the exit tunnel of the ribosome
What is PTM
Post-translational modification:
The enzymatic modification of a protein after its translation
5 types of PTM
- Lipidation
- phosphorylation
- Glycosylation
- Acetylation
- methylation
Alpha helix features
- R group extend on the outside
- one complete turn every 3.6 amino acids
- twists clockwise
Amphipathic helix
Helix with hydrophilic and hydrophobic faces.
Amphipathic helixes posses hydrophilic amino acids on one side and hydrophobic residues on the other; such alpha helices in some case can be used to associate a protein or peptide to a membrane
Complex helices
Alpha helices can wind around each other to form “coiled-coils”
Features of a beta sheet
- R group point up and down
- Strands held by H bonds between backbone
- H bonds connect an amino acid in one chain with two from another chain
Turns and bends in secondary structure
Turns and bends used to change direction in which sheets or helices run
Loops and turns - protein tertiary structure
Found on protein surfaces controls the size and shape:
Loops - contains stretches of hydrophilic residues thus found on surfaces of proteins. Used to connect alpha helixes and beta sheets
Turns - same as loop but with less than 5 residues
Structure of lipid bilayer
Made up of two layers of phospholipids that are amphipathic compounds. Phospholipid molecule are arranged into two layers form a lipid bilateral
Function of cholesterol in bilayer
Present in the space among the hydrophobic tails of phospholipids in the lipid bilayer to regulate the fluidity of the cell membrane. The role of cholesterol is temperature dependent. At high temperatures, it decreases the mobility of phospholipid molecules while at a lower temperature, it promotes their mobility
Function of glycolipids
Glycolipids serve to stabilise the cell membrane. They’re are also responsible for cell to cell interactions. Some also serve as cell surface receptors
What are transmembrane proteins
A transmembrane protein has the following structure:
- A hydrophilic domain that interacts with the molecules present in the cytoplasm of the cell
- A hydrophobic domain that is responsible for anchoring the protein in the cell membrane
- another hydrophilic domain that interact with molecules in the surrounding environment of the cell
Anchored proteins
Proteins that are not in contact with the cell membrane. Attached to a lipid residue that is inserted into the lipid belayer of the cell membrane. Present either in the cytoplasm or in the extracellular fluid
Peripheral proteins
Proteins that are present on one side of the cell membrane. These are temporary proteins and lose their association with the cell membrane as soon as they have preformed their function
Carbohydrates in the lipid bilayer
They are involved in cell to cell recognition and other inter-cellular interactions
Cell membrane anchoring the cytoskeleton
Cytoskeleton is anchored to the the cell membrane via linker proteins such as integrin. Kept anchored to the cell membrane vials these anchoring proteins
Cell membrane and cell to cell recognition
This function is preformed by glycolipids and glycoproteins present on the outer surface of cell membranes -> can be recognised by partner cells but not by the cells of the other tissues
Endocytosis
The membrane of the cell extends around the large substance to form an endocytic vehicle. This vehicle is later taken in by the cell as it breaks from the cell membrane.
Exocytosis
The preformed vesicles fuse the cytoplasmic surface of the cell membrane. The vehicle becomes a part of the membrane while the substance is dumped into the extra cellular fluid
Active transport proteins
Two main families of transport proteins use ATP hydrolysis to pump molecules across membranes
- P class transporters (ion pumps)
- ABC transporters
ABC transporters
Called abc because they contain two highly conserved ATP-Binding-Cassettes
Used for export in eukaryotes
