Biochemical Basics Flashcards
Describe how protein conformation relates to enzyme action and how factors such as temperature and pH affect it.
the conformation of the protein determines the enzyme produced. this structure can be altered by a change in pH as it can affect the bonds in the protein. A temperature change affects the vibration of the bonds and can also lead to denaturing
Describe how enzymes catalyse reactions through lowering the free energy of chemical reactions as a consequence of the interactions between the substrate and the enzyme at the active site.
the energy needed to form the high energy intermediate is reduced. it is in this position that bonds are maximally strained.
Describe how the catalytic activity of enzymes can be explained by the nature of the amino acids present at the active site and how vitamins are modified to produce coenzymes and increase the diversity of reactions that enzymes catalyse.
the side chains of the amino acids at the active site bind to the substrate. substrate binds through hydrophobic, electrostatic interactions & hydrogen bonds. the active site is the cleft or crevice of a polypeptide chain
coenzymes activate enzymes or can carry electrons or molecular groups. little activity without the presence on an enzyme
Describe how the kinetic properties of enzymes are described by the Michaelis Menten equation and know the meaning of the terms S, V, Vmax and Km. (You do not have to be able to derive the equation).
S - substrate
V - velocity
Vmax - reaction rate when the enzyme is fully saturated by substrate
Km - michaelis menten constant, half inital rate of Vmax
Describe how enzyme activity can be represented in a graphical form (The Michaelis Menten Curve and the Lineweaver Burk plot).
the lineweaver burk plot is used to find Km and Vmax
competitve inhibition - Km increased, Vmax the same
uncompetitve inhibition - Km reduced, Vmax reduced
non-competitve inhibtion - Km the same, Vmax reduced
Describe how enzyme inhibitors change the kinetic parameters of an enzyme catalysed reaction and how these changes can be used to identify how an inhibitor acts on the enzyme
inhibitors decrease reaction velocity, inhibitors can be synthesised as theraputic agents. inhibitors can bind covalently or non covalently. can be competitive, non-competive or uncompetative.
Describe a simple structure for a 5 minute medical interview.
greet patient, explain purpose of interview, get consent for interview, ask for description of presenting complaint, obtain medical and drug history, social and family history, get patients ideas, concerns an expectations, summarise info and close session
Describe how the structure and kinetic properties of allosteric enzymes differ from other enzymes and how these properties are altered by positive and negative effector molecules.
allosterically regulated enzymes are composed of multiple subunits. the allosteric effector changes the catalytic site to complement substrate, inhibitor decreases enzyme activity. inhibitor changes shape of catalytic site so it is no long complementary.
Describe how the physiological role of enzymes can be explained in terms of their kinetic properties.
some enzymes can acheive a higher maximum rate such as catalase, which nears the hypothetical highest rate. the amount of substrate that can bind to enzymes is determined by what their use is in the body, such as the rate of production of a product
Understand the simple presentation of data.
guassian distribution - symmetric about the mean. It shows that data about the mean are more frequent than data far from the mean. Appears as a bell curve. 95% of data is within two standard deviations of the mean.
Understand the importance of statistical testing.
it helps us to know if our null hypothesis is extremely unlikely or likely. this can be used to find risk factors with diseases.
Define hazard ratio.
The ratio of the hazard rates corresponding to conditions described by two levels of an independent variable. Comparison of risk to control group.
Apply the concept of ‘reference range’ to clinical data.
the range of values that is deemed normal for a physiologic measurement in healthy persons
Suggest some reasons for elevated serum AP, GGT and LD enzymes.
AP - The highest concentration of AP is present in liver and bone; an elevated AP concentration is therefore generally attributed to either liver or bone disease.
GGT - liver diseases, hepatitis or cirrhosis, congestive heart failure, diabetes, or pancreatitis. They may also be caused by alcohol abuse or use of drugs that are toxic to the liver.
LD - Anemia, kidney disease, Liver disease, Muscle injury, Heart attack, Pancreatitis, Infections, including meningitis, encephalitis, and infectious mononucleosis (mono), Certain types of cancer, including lymphoma and leukemia.
To be able to discuss the nature of membranes in a biological system
lipid structures, phospholipid bilayer, flexible, self sealing, selectively permeable, separate environments
To describe the basic structure of mammalian cell membranes
phospholipid bilayer with polar hydrophillic heads facing outwards and non-polar hydrophobic tails facing inwards. integral and peripheral proteins. cholesterol to maintain membrane stability
To understand the Fluid Mosaic model
fluid - lipids can move laterally
mosaic - proteins spanning membrane, and attached to membrane, glycocalyx attached via glycoproteins and glycolipids
To recognise the basic structure of fatty acids, phospholipids and cholesterol
fatty acids - carboxylic acid with hydrophobic hydrocarbon chain, can be saturated or unsaturated
phospholipids - phosphate group, 2 fatty acids and a glycerol molecule
cholesterol - 4 rigid, fused hydrocarbon rings, one hydroxyl group, not very water soluble
To understand the role of lipids and proteins in cell membranes
lipids can be used to store energy and for cell communication.
proteins - receptor proteins relay signals between cell’s internal and external environment, transport proteins move molecules and ions across membrane, cell adhesion molecules allow cells to interact
Identify the psychological demands that a long term condition may place on an individual.
shock, anger, anxiety, detachemtn realisation, changing family roles, finacial concerns, loss of control, adjusting to symptoms
Describe factors which may modify the impact of a chronic illness.
social support, social class, environment, finances, prognosis, visibility, emotional regulation, health related quality of life. adjustment (or lack thereof).
Outline coping strategies likely to influence patients’ responses to illness and treatment.
religion and spirituality, emotion-focused, problem-focused, familial support, postive reframing, avoidance
Describe different methods of measuring and describing disease in populations, including prevalence and incidence, risk and rates
prevelance- the amount of people who have a disease at a specific point in time
incidence - the amount of people who catch a disease in a give time period
risk - the number of new cases of disease in a time period ÷ number of people initially disease free.
rate - the number of new cases of disease ÷ total person time at risk.
Describe the design, strengths and limitations of ecological studies
design - using available information to find trends, such as birth ceritificates and population sizes
strengths - quick and cheap, no ethical approval
limitations - if exposure and outcome/disease are significantly correlated there are 4 possibilities: the exposure causes outcome, the outcome causes exposure, one or more confounders are responsible, or ecological fallacy.
There can be incorrect assumptions that association at population level holds at individual level and they use aggregate data, so all conclusions relate to groups, not individuals
Interpret a correlation coefficient
R is pearson correlation coeffiecient , +1 is a perfectly postive linear correlation, -1 is a perfectly negative linear correlation
Explain the concept of confounding
a confounder is a variable that influences both the dependent variable and independent variable
