IMMS Flashcards
What does allosteric mean?
It is altering the activity of an enzyme by means of a conformational change induced by a different molecule
What forms the secondary yolk sac?
The hypoblast forms new cells that migrate along the exocoelomic membrane, proliferate it and gradually form a new cavity within the primitive yolk sac. This is the secondary yolk sac and it replaces the primitive yolk sac.
What does the embryoblast differentiate into?
The epiblast and the hypoblast. The two layers together form the bilaminar disc.
What does the epiblast cells do?
The epiblast cells give rise to amnioblasts that line the amniotic cavity superior to the epiblast layer
What do the hypoblast cells do?
The hypoblast gives rise to cells that line the blastocyte cavity and the inner surface of the trophoblast. They form the exocoelomic membrane. The cavity is now the primitive yolk sac/exocoelomic cavity
What does the trophoblast differentiate into?
The cytotrophoblast and the syncytiotrophoblast.
What is the syncytiotrophoblast?
The syncytiotrophoblast is the outer layer of the trophoblast. It erodes maternal tissue and is how the maternal blood enters the embryo
What is the extraembryonic mesoderm
A new population of cells appear between the inner surface of the cytotrophoblast and the outer surface of the exocoelomic membrane of the primitive yolk sac. These cells, derived from yolk sac cells, form a fine, loose, connective tissue, which is the extraembryonic membrane
What is epicenesis?
The development of an egg or seed through cell division and the formation of organs
What is preformation?
A pre-formed, miniature human is in the sperm and is planted in the female during intercourse
What is development biology?
Examining the correlations between genes and morphological changes that occur in the embryo
What is the embryonic period?
It is the time between fertilisation to the beginning of the ninth week
What does virtue ethics believe in?
It focuses on the character of the agent. It integrates reason and emotion.
What are the five focal virtues?
Compassion, discernment, trustworthiness, integrity and conscientiousness. These virtues are acquired, just like skills.
What is deontology?
It believes the features of the act themselves determine worthiness. There are hypothetical and categorical imperatives from which duties and obligations are derived.
What is utilitarianism?
An act is evaluated solely in terms of its consequences. It believes in maximising good. It considers the likely consequences and picks the best one
What is hedonistic utilitarianism?
Pleasure vs pain - simple sensory vs higher cognitive
What is preference utilitarianism?
Utility increases as preference/desire is satisfied
What is closed awareness?
The patient doesn’t know they are going to die but others do and haven’t told them
What is suspicion awareness?
The patient doesn’t know they are going to die but has their suspicions even though the health professionals haven’t confirmed anything
What is mutual pretence?
Everyone ones the patient is going to die but nobody talks about it
What is open awareness?
Everyone knows the patient is going to die and everybody talks about it openly
What is acute illness?
A disease of short duration that starts quickly and had sever symptoms
What is chronic illness?
A persistent or recurring condition. The distance, which may or may not be severe, often starts gradually and changes will be slow
What are the three health behaviours?
Health behaviour, illness behaviour and sick role behaviour
What is health behaviour?
A behaviour aimed to prevent disease
What is illness behaviour?
A behaviour aimed to seek remedy (like going to the doctors)
What is the sick role behaviour?
Any activity aimed at getting well (taking antibiotics)
What is unrealistic optimism?
Individuals continue to damage their health due to inaccurate perceptions or risk and susceptibility due to: lack of personal experience with the problem; belief it is preventable by personal action; belief that if its not happened by now, it’s not going to; belief that a problem is infrequent
What is a cohort study?
It is an observational, analytical study. Start with the population, look at if they were exposed to the variable then see if they develop the disease
What is a case-control study?
It is an observational, analytical study. Start with the cases and controls, look back at whether they were exposed to the variable
What are the five steps of evidence based practise?
- Asking focused questions. 2. Finding the evidence. 3. Critical appraisal. 4. Making a decision. 5. Evaluating performance
What is a cross-sectional study?
An observational, analytical study. It looks at association at one time point
What is demography?
The anatomy of the population
What is sociology?
The physiology of the population
What is epidemiology?
The pathology of the population
What is FAD?
It a coenzyme that carries hydrogen. It is derived from the vitamin riboflavin. It is bound to its enzyme which in turn in ‘stuck’ in the inner membrane of the mitochondrion. Each FAD is oxidised by the respiratory chain to produce 1.5 ATP molecules
What is NAD?
It is a coenzyme that carries hydrogen. It is derived from the vitamin niacin. It is involved in redox reactions. The reduced form is NADH. Each NADH is oxidised by the respiratory chain to produce 2.5 ATP molecules
How is ATP regenerated?
It requires a source of energy. A controlled series of chemical reactions including: glycolysis; the Krebs cycle; oxidative phosphorylation. This created ATP directly through substrate level phosphorylation and via electrons by oxidative phosphorylation.
What are the key functions of the sodium potassium pump?
(1) it established an intracellular environment high in K+ and low in Na+ (2) control of cell volume (3) provides an electrochemical gradient for sodium, driving other active transport systems (4) establishing a resting potential both directly and indirectly via the ion gradient
What does phosphocreatine do?
Phosphocreatine serves as a ready source of phosphoryl groups to synthesis ATP from ADP. The phosphocreatine concentration in skeletal muscle is considerably higher than in other tissues. The enzyme creatine kinase catalyses the reversible reaction.
What is Gibbs free energy?
It is the energy liberated and available for use. It depends on the difference in energy between the products and the substrates. For ATP hydrolysis it is -7.3kcal/mole
How is Gibbs free energy related to ATP?
A reaction is spontaneous if the Gibbs free energy is negative. Phosphoanhydride bonds tend to have a large negative Gibbs free energy of hydrolysis. The transfer of the phosphoryl group to a compound gives it free energy so it has more free energy to give up.
What is the structure of ATP?
It is made of adenine, three phosphate and a ribose sugar. Adenine and the sugar together is called adenosine. It has two phosphoanhydride bonds.
What are the three types of connective tissue?
Fibrous (both loose and dense). Hard (cartilage and bone) Fatty (white and brown)
What is biogenetics?
The study of energy relationships and energy transformations in living organisms.
How many types of fatty tissue are there?
2: brown and white
Describe a white fat cell
Large cells with a single fat globule in each one. They usually appear white in conventional slides.
Describe a brown fat cell
Cells with many globules of fat inside, they are found across shoulders and down the back of a newborn and is important in neonatal thermo-regulation because it gives off heat when broken down
How is collagen made?
Tropocollagen composed of a triple helix of peptides. Fibroblasts secrete tropocollagen subunits. The fibres are assembled extra-cellularly, they have variable thickness.
Name some different types of collagen
There are more than 12 types of collagen, they are often tissue specific. Type 1 is in the skin; type 2 is in the cartilage; type 3 is in the liver; type 4 is in the basement membrane; type 5 is in the placenta
Where is skeletal muscle found?
It is found in the larynx, the diaphragm and in the limbs
How are skeletal muscles formed?
Myoblasts fuse to form a multi-cells syncitium. Sarcomeres joined end to end to form myofibrils. Cytoplasm filled with myofibrils form a muscle fibre. Muscle fibres clump together to form fascicles, which are held together by connective tissue, epimycium and perimycium
What are the constituents of connective tissue?
Cells (fibroblasts and fat cells) Visible fibres (collagen, elastic and reticulin) Ground substance (hydrophilic jelly): proteoglycans, glycosaminoglycans, laminin, fibronectin
How is smooth muscle formed?
Visceral (smooth) muscle cells are fusiform cells with an oval nucleus. It is in arterial walls, the walls of the intestine and the airways of the lungs
How is cardiac muscle formed?
Cardiac muscle is branching chains of cells, straited with a central nucleus. It is found in the heart and at the base of the great vessels.
What are the three types of simple epithelium?
Squamous: single layer of flattened cells with parallel oval nucleus Cuboidal: roughly square in profile, with a round nucleus Columnar: taller than they are wide with an oval, perpendicular nucleus
What are the functions of stratified epithelial?
It has a protective function; it is continually worn down; the worn away cells get replaced from below
Where is stratified epithelium found?
It is found in areas where there is continuous abrasion, like skin, the oesophagus and vagina
What are the subtypes of stratified epithelia?
Squamous: can be keratinised, like in skin or non-keratinised, like in the mouth, oesophagus and vagina Cuboidal: found in some large ducts
What are the junctions between cells?
There are adherent (tight) junctions; desmosomes; and gap junctions.
What are adherent junctions?
Band-like fusions between cells that are impervious to most molecules
What are desmosomes?
Plaques that form physical joins between cells and connect the cytoskeletons of adjacent cells
What are gap junctions?
Electrical junctions that permit the transfer of small molecules. They can be gated channels
What does Vitamin A do?
It helps you see at day and night. It protects you from infection by keeping skin healthy. Promotes normal growth and development.
What does vitamin C do?
It helps heal cuts and wounds. It keeps the immune system healthy.
What does vitamin D do?
It increases the amount of calcium and phosphate absorbed and deposits it in bones and teeth to strengthen them.
What does Vitamin E do?
It strengthens the immune system
What does Vitamin K do?
It makes the blood clotting proteins and proteins for your blood, bones and kidneys.
What are the functions of epithelia?
It forms barriers for: protection (skin); absorption (gut); secretion (pancreas). All epithelia have a basement membrane.
What are the different types of epithelia?
Simple epithelium: it is a single layer of cells (lungs) Stratified epithelium: it is many layers of cells (skin) Pseudo-stratified epithelium: epithelia that doesn’t fit into either category
What does vitamin B1 do?
It helps with energy production in your body. It is also known as thiamin.
What does Vitamin B2 do?
It helps with energy production in your body and helps your body use other B vitamins. It is also known as riboflavin.
What does Vitamin B3?
It helps enzymes work properly and helps use protein, fat and carbohydrate to make energy
What does vitamin B6 do?
It helps form haemoglobin and helps to make and use protein and glycogen
What does iron do?
It helps energy transfer by haemoglobin and cytochromes
What does zinc do?
It helps growth, health and immune function
What does copper do?
It helps in connective tissue formation and energy transfer
What does manganese do?
It is involved with arginine, pyruvate and superoxide metabolism
What does chromium do?
It is part of the insulin receptor
What does selenium so?
It prevents peroxidation of reduced compounds such as glutathione
What is malnutrition?
A state of nutrition in which a deficiency, excess or imbalance of energy, protein or other nutrients causes measurable adverse effects on tissue/body form, body function and clinical outcome. It is screened for using the MUST screening tool
What are micronutrients used in?
Trace element and vitamins. Cofactors in metabolism. Gene expression. Structural compounds. Antioxidants
What is basal metabolic rate?
A measure of the energy required to maintain non-exercise bodily functions such as respiration, contraction of heart muscle and biosynthetic process.
What affects BMR?
BMI, hyperthyroidism, low ambient temperature, fever, caffeine, exercise and pregnancy all increase BMR. Age, being female, starvation, hypothyroidism and drugs decrease BMR.
What is F.I.S.H.?
It is fluorescence in situ hybridisation. We use DNA probes labelled with fluorochromes. They are hybridised directly to the chromosome preparation or interphase nuclei. The can count chromosomes in interphase nuclei. We can look for submicroscopic deletions using locus specific probes.
Where are dietary fats stored?
Fat: adipose tissue Carbohydrate: glycogen in liver and muscle Protein: muscle
How is the total energy expenditure spread out?
60% resting 30% activity induced 10% dietary
What are the four pathways of metabolism?
- Oxidative (catabolic) 2. Storage (anabolic) 3. Biosynthetic (anabolic) 4. Waste Disposal (catabolic)
What is the difference between anabolic or catabolic?
Anabolic is creating large molecules. Catabolic is breaking down large molecules
What is the role of cytogenetics?
Confirmation of malignancy. Classification of a disease type Prognosis Monitoring
What are acquired mutations?
-changes occur during a lifetime -restricted to malignant tissue -they are not heritable
What are constitutional mutations?
They occur at gametogenesis, it affects all cells of the body and they are heritable
What is hereditability?
The proportion of the aetiology that can be ascribed to genetic factors as opposed to environmental factors. It is expressed as a percentage. One way to calculate it is the concordance rate in monozygotic twins
What are the characteristics of multifactorial inheritance?
The incidence of the condition is greatest amongst relatives. The risk is greatest for the first degree relatives and it decreases rapidly in more distant relatives. If there is more than one affected relative then the risk increases.
What are the characteristics of X-linked inheritance?
The genes are carried on the X chromosome. Usually only makes affected, but it is transmitted (usually) through unaffected females. There is no male-to-male transmission. An affected male cannot have affected sons, but all his daughters will be carried.
What is lyonisation?
It means generally one of two X chromosomes active in each female cell, but it can be skewed
What is penetrance?
The percentage of individuals of a specific genotype showing the expected phenotype
What is the expressivity?
It refers to a range of phenotypes expressed by a specific genotype
What is anticipation?
It is when a genetic disorder affects successive generations earlier or more severely than expected
What is somatic mosaicism?
It is a genetic fault only in some tissue in the body
What is gonadal mosaicism?
It is a genetic fault in gonadal tissue
What is autosomal dominant inheritance?
It is a disease that manifests in the heterozygous state. It affects men and women in equal proportions. It affects individuals in multiple generations. Transmission by individuals of both sexes to both sexes. Don’t forget penetrance and variability
What is consanguinity?
Reproductive union between two relatives
What is autozygosity?
Homozygosity by descent. I.e. Inheritance of the same mutual allele through two branches of the same family
What are the types of genetic testing?
Diagnostic: to confirm a diagnosis Carrier: to determine if the patient is a carrier Predictive: to see if the patient will get the disease in the future
What is an autosomal chromosome?
Any chromosome, other than sex chromosomes, in pairs in diploid cells
What does recessive mean?
The disease only manifests in homozygotes
What does homozygous mean?
The presence of identical alleles at a given locus
What does heterozygous mean?
The presence of two different alleles at a given locus
What is an allele?
One or more alternative forms of a gene at a given locus
What is a locus?
The position of a gene/DNA on the genetic map
What is autosomal recessive inheritance?
A disease that manifests in the homozygous state. Males and females are affected in equal proportions. It only affects individuals in a single generation. 1/4 risk in offspring and 1/2 risk of being a carrier. It is more common consanguineous unions.
What is heterogeneity
There’s one gene, one mutation and one disease
What is allelic hetergenity?
Lots of different mutations in one gene
What is locus heterogeneity?
Mutations in different genes give the same condition
What are the types of genetic disorders?
Chromosome abnormalities Singe gene disorders Multifactorial and polygenic disorders
What are the mechanisms of allele dominance?
Loss of function mutations. Gain of function mutations. Dominant negative mutations.
What are loss of function mutations?
Only one allele is functioning, most of these mutations are recessive, unless the pathway is very sensitive
What is gain of function mutation?
Increased gene dosage or increased protein activity
What are dominant negative mutations?
Where the protein from the mutant allele interferes with the protein from the normal allele
What are the types of DNA mutations?
Duplications; deletions; slice site mutations; non-sense mutations; mia-sense mutations
What is a non-sense mutation?
Where an immature premature stop-codon occurs because of a mutation
What is a mis-sense mutation?
Where the mutation means the amino acid is replaced by another amino acid so the protein is changed
What are the functions of splicing?
It means different proteins can be made from the same gene. It allows new proteins to be made (this is useful in the immune system)
What is an out of frame deletion?
It is a deletion of one base
What is an in frame deletion?
It is the deletion of a whole codon
What inactivates genes?
-activation of repressors (RNA polymerase inhibitors) - each step of the transcription finds no longer actively produced transcription proteins -complexes do not form because of lack of phosphorylation -enzymes are no longer activated
What’s the difference between euchromatin and heterochromatin?
Euchromatin is accessible to transcription proteins and is activatable, it is unmethylated DNA. Heterochromatin is inaccessible to transcription factors.
What are the three types of RNA?
rRNA, mRNA, tRNA
What is mRNA?
mRNA is printed as a long linear transcript. It is then processed to the mature form (near the nuclear membrane). It has a 5 prime CAP and a 3 prime Poly A tail.
What is rRNA?
Ribosomes are abundant in eukaryotic cytoplasm, and four main types of rRNA combine with proteins to form 80S ribosomes
What is tRNA?
tRNA are very small molecules that carry an amino acid to ribosomes and check they are in the right position to match the anticodon
What enzymes are involved in DNA replication?
Polymerases, helicase, topoisomerase, ligase, primase
What do polymerases do in DNA replication?
They read the RNA from 3’ to 5’ but prints 5’ to 3’. The substrates are triphosphates and deoxyribonucleotides. The enzyme stays on the strand, at the same time it extends and proof reads.
What does helicase do in DNA replication?
It opens the strands
What does ligase do in DNA replication?
It joins the DNA strands back together
What does topoisomerase do in DNA replication?
It unwinds the separated DNA strands
What does primase do in DNA replication?
The building on the RNA primer is synthesised by primase
What does the unit kDa mean?
It is a kilodalton. 1000 atomic mass units. One dalton is the mass of a hydrogen atom
What does the unit S stand for?
It is a Svedburg unit. It refers to the mass and shape of cellular organelles. A high S means a high mass
What are the four stages of the cell cycle?
G1, S, G2, M
What happens in G1 during the cell cycle?
There is growth and metabolism in the cell. It is diploid and takes 12 hours
What happens during the S phase during the cell cycle?
DNA replication. It goes from 2n to 4n. It takes 8 hours
What happens during G2 in the cell cycle?
There is preparation for cell division. It is 4n. It takes 4 hours.
How long does mitosis take?
1 hour
What are the useful properties of DNA?
- Heat denaturation - Alkali dissociation - Hybridisation
What are the uses of enzymes?
- it can speed up the reaction - disease markers - drugs target
What is an isoenzyme?
Two enzymes that have different structure and sequence but catalyse the same reaction
What are the functions of DNA?
- Acts as a template and regulator for transcription and protein synthesis - It is the genetic material, structural basis of heredity and genetic diseases
What is a porphyrin ring in haemoglobin?
At the core of a haemoglobin molecule is a porphyrin ring, which holds an iron atom. When an iron atom is present in the ring it is termed a heme. The iron atom is the site of oxygen binding. Haemoglobin is when heme and globin are together
What is a beta sheet ?
It is formed by hydrogen bonds between linear regions of polypeptide chains. Chains can be parallel or anti-parallel, pleated or not. If the chain is folding back, the structure is usually a 4 aa turn, called hairpin looper beta-turn
What are the forces in protein chains?
Van der Waals forces, hydrogen bonds, hydrophobic forces, ionic bonds, disulphide bonds
What is the alpha helix?
Hydrogen bonds between each carbonyl group and the H attached to the N which is 4 amino acids along the chain. The side chains look outwards. Proline breaks the helix
What are the sugar derivatives?
Aminosugars; alcohol-sugars; phosphorylated; sulfated
What are hydrophobic forces?
Uncharged and non-polar side chains are poorly soluble in water and are effectively ‘repelled’ by water. These hydrophobic side chains tend to form tightly packed cores in the interior of proteins, excluding water molecules. This attraction is the hydrophobic force.
What are disaccharides?
They contain 2 monosaccharides joined by an O-glycosidic bond
What are oligosaccharides?
They contain 3-12 monosaccharides. They are products of digestion of polysaccharides or part of complex protein/lipids
What are examples of protein structure-function relationships?
- Immunoglobulins - Fibrous proteins: collagen - Enzymes in general - Channel and carrier proteins, receptors and neurotransmitters
What are Van der Waals forces?
Weak attractive interactions between atoms due to fluctuating electrical charges. They are only important when two macromolecular surfaces fit closely in shape. They can also be repulsive at a short distance.
What is a monosaccharide?
A chain of carbons, hydroxyl groups and one carbonyl group. An aldose has an aldehyde (C1). A ketose has a ketone (C2)
What is the formula for a carbohydrate?
Cn(H2O)n
What is lipofuscin?
It is a membrane-bound Orange-brown pigment common in the heart and liver. It is involved in peroxidation of lipids in old cells
What is a lipid?
It is in non-membrane-bound vacuoles in adipocytes and the liver. It appears as empty space as it dissolves in processing
What is glycogen?
It is a CHO polymer in cytoplasm and is normally only seen on electron microscopy
What are intermediate filaments?
They are anchored to transmembrane proteins to spread tensile forces through tissues. Their specific functions are generally not known but they are useful in immunohistochemistry to tell one cell type from another
What are microtubules?
25nm in diameter and consists of tubulin proteins. They are present in all cells except erythrocytes. It is made of alpha and beta tubulin, which are arranged in groups of 13 to form hollow tubes. They arise from centromeres.
What is a microfilament?
It is 5cm in diameter and is made of actin. Globular G-actin polymerises into filamentous F-actin, which forms a bracing mesh (cell cortex) on the inner surface of the cell membrane. This drives many cellular processes including cell motility and muscle contraction.
What is a cytoskeleton?
Filamentous proteins, which brace the internal structure of the cell. It is made of microfilaments, intermediate filaments and microtubules
What are peroxisomes?
They are small membrane-bound organelles containing enzymes which oxidise long-chain fatty acids. They contain D-amino acid oxidase catalase and ureate oxidase
What are lysosomes?
They are derived from the Golgi apparatus. The H+ ATPase on the membrane creates a low pH (pH 5) and it contains acids hydrolases.
How do lysosomes work?
Initial hydrolase vesicles fuse with endosomes with the correct membrane proteins to produce endolysosomes
What are vesicles?
They are very small, spherical, membrane-bound organelles derived from several compartments. There are cell-surface derived pinocytotic and phagocytotic vesicles, golgi-derived transport vesicles, ER-derived transport vesicles, lysosomes and peroxisomes
What are the functions of vesicles?
They can transport materials, store materials, exchange cell membrane between cell compartments
What is the Golgi apparatus?
It is a parallel stack of membrane that processes macromolecules synthesised in the ER. It does this by modifying macromolecules by adding sugars and proteolysis of peptides into active forms and sorts macromolecules
What are the parts of the Golgi apparatus?
The cis face is nuclear facing and receives transport vesicles from the smooth ER and phosphorylates some proteins. The medial golgi is the central part and forms complex oligosaccharides by adding sugars to lipids and peptides. The trans golgi performs proteolysis and sorts macromolecules into vesicles which bud from the surface membrane
What is the rough endoplasmic reticulum?
It is the site of protein synthesis and is made of highly folded flattened membrane sheets
What is the smooth endoplasmic reticulum?
It is the site of membrane lipid synthesis and it processes synthesised proteins. It is also made of highly folded flattened membrane sheets
What does the inner membrane of the mitochondria do?
It is used in the respiratory chain and in ATP production
What is the mitochondrial matrix used for?
It is used in the Krebs cycle and the intermembranous space is used in nucleotide phosphorylation
What are the forms of DNA in the nucleus?
There are two forms: euchromatin and heterochromatin. Euchromatin is dispersed and not readily stainable, it is prevalent in transcriptionally active cells. Heterochromatin is small and dark staining and is prevalent in less active cells.
What does the nucleus do?
It is the brain of the cell. It is enclosed by a double membrane and houses DNA in both euchromatin and heterochromatin forms. It contains the nucleolus, which is the site of ribosomal RNA formation
What is mitochondrial inheritance?
All mitochondrial DNA is from the mother so if free mother is affected all her children will have it but if the father is affected none of the children will have it