BL+MCBG Flashcards
What is the rough endoplasmic reticulum?
The Rough Endoplasmic reticulum is a network of membranes in the cell that are covered in ribosomes, and play a role in protein synthesis
Example sentence: The rough endoplasmic reticulum is responsible for synthesizing membrane proteins.
What is the fluid of the cytoplasm called?
The fluid of the cytoplasm is called cytosol and has a pH of 7.2
What are inclusion bodies?
Inclusion bodies are non-metabolically active substances within the cell, such as lipid droplets and metabolites, which do not survive cell division
Main Structure of the plasmalemma?
-Three layers-2 phosoplipid layers-Non-polar (hydrophobic) fatty acid tails of phospholipids go into the middle layer-Polar (hydrophilic) heads located on inner and outer side of the membrane
Function of the peripheral proteins of the plasmalemma?
-Peripheral proteins adsorb so inner and outer si de of the membrane-Involved in cell recognition and interactions
Function of integral proteins of the plasmalemma?
-Integral proteins go through the width of the membrane-regulate passage and materials and active transport
Describe the structure of a mitochondrion?
-Outer, sieve-like membrane and inner folded membrane, separated by intermembranous space-Inner membrane has finger-like folds called cristae-Space deep within the inner membrane is called the matrix-Integral proteins on inner/outer membranes provide passage for small molecules-Matrix has some chromosomes, ribosomes and RNA in order to synthesise a small amount of proteins
What does the number of cristae in a mitochondrion correspond to?
The number of cristae in a mitochondrion corresponds to the energy needs of the cell
Why are mitochondria eosiniophillic?
Mitochondria are stained by eosin due to the high content of mitochondrial DNA
Structure of a ribosome?
-Small, electron dense particles-Made of RNA and 80 different proteins-Exist in three different forms
-polyribomse, isolated cell, RER
Which form of ribosomes synthesises cytosolic (free) proteins?
Polyribsomes synthesise cystosolic proteins
Which form of ribosomes synthesises secretory and endoplasmic reticulum proteins?
Rough Endoplasmic Reticulum (ER with ribosomes adsorbed) synthesises secretory and endoplasmic reticulum proteins
Why are ribosomes called basophillic?
Ribosomes are basophillic because they are stained by most basic dyes
Lyosomes
-membrane bound organelle-for cellular digestion and recycling of cell components-contains (mostly) acid hydrolase enzymes; protease, nuclease, phosphate sets, phospholipases, sulphatases, beta-glucuronidases-theses enzymes are active in cytosol due to 7.2 pH-lysosomes made in golgi
Peroxisomes
-membrane bound organelles -contain enzyme-utilise oxygen without ATP-oxidise organic substrates by removal of H+, which produces H2O2, which is broken down by peroxisomal catalase-peroxisomes are involved in lipid metabolism
Difference between negative and positive feedback loop?
Positive; stops when stimulus ceases i.e regulation of blood clotting
definition of acidosis
Imbalance in which arterial blood pH is below normal (< 7.35)
Control centre for temp regulation pathway
Hypothalamus
How to calculate pH
pH = -log[H+]
stages of a feed back loop
Stimuli, sensor, control centre, effector
Alkalosis
pH above 7.45
Healthy pH ranges
Arterial blood ; 7.45
Venous blood ; 7.35
pH range outside of which death is likely?
6.8-8
Acidosis symptoms
Headache, tired, confusion, tremors, coma
Cause of metabolic acidosis
Build up of metabolic acids either due to increased production or inability to excrete them
cause of respiratory acidosis
Build up of CO2 due to hypoventilation; can occur as a response to metabolic alkalosis
Treatment of acidosis
Bicarbonate infusion
mechanical Ventilation if respiratory
How is the stomach wall protected against the high pH of stomach acid?
Specialised epithelial cells (goblet cells) of the stomach lining secrete mucus
Best treatment for when stomach acid damages oesophagus
anatacids containing weak bases, preferably aluminium hydroxide as this is mild, long lasting and has less side-effects due to being insoluble
What percentage by weight is the human body?
60%
What proportion of body water is intracellular fluid?
2/3
What proportion of body water is extracellular fluid?
1/3
What proportion of extracellular fluid is interstitial fluid?
3/4 of extracellular fluid, 15% body weight
What proportion of extracellular fluid is blood plasma?
Blood plasma makes up 1/4 of extracellular fluid, 5% of body weight
Water in the transmembrane space
-0.5
What percentage by weight is the human body?
60%
60% of body weight is water
What proportion of body water is intracellular fluid?
2/3
2/3 of body water is intracellular fluid
What proportion of body water is extracellular fluid?
1/3
1/3 of body water is extracellular fluid
What proportion of extracellular fluid is interstitial fluid?
3/4 of extracellular fluid, 15% body weight
3/4 of extracellular fluid, equivalent to 15% of body weight, is interstitial fluid
What proportion of extracellular fluid is blood plasma?
Blood plasma makes up 1/4 of extracellular fluid , 5% of body weight
Blood plasma makes up 1/4 of extracellular fluid, which is equivalent to 5% of body weight
Water in the transmembrane space
-0.5 litres (not counted as intra or extracellular fluid)
Water in the transmembrane space is not counted as either intra or extracellular fluid and is approximately -0.5 litres
Standard amount of blood in a 70kg man
5L
A standard amount of blood in a 70kg man is 5 liters
Four types of body tissue and an example of each
epithelial, simple squamous epithelium
Example of epithelial tissue is simple squamous epithelium
connective, adipose tissue
connective, adipose tissue
Example of connective tissue is adipose tissue
Muscle, skeletal muscle
Muscle, skeletal muscle
Example of muscle tissue is skeletal muscle
nervous, neurons
nervous, neurons
Example of nervous tissue is neurons
Limit of resolution
Measurement of how far 2 points must be before the microscope can view them as separate. The smaller D is the better.
Measurement of how far 2 points must be before the microscope can view them as separate. The smaller D is the better.
Limit of resolution is proportional to…
Limit of resultion is proportional to wavelength of viewing light
Limit of resolution is proportional to the wavelength of viewing light
Needle methods for tissue procurement
+Fine needle aspiration suspicious lumps
+venepuncture for a blood sample
+pipelle for (uterus lining)
+trephine for bone marrow
Needle methods for tissue procurement include fine needle aspiration for suspicious lumps, venepuncture for a blood sample, pipelle for uterus lining, and trephine for bone marrow
Explain the value of histology in diagnosis
- Disease Identification: Histological analysis allows for the identification of disease processes at the cellular level. For example, it can distinguish between benign and malignant tumors, helping to confirm diagnoses such as cancer.
- Tissue Characterization: By examining the morphology of cells and their arrangement in tissues, histology can provide insights into the type of disease present. Different diseases often have characteristic histological features that can aid in diagnosis.
- Treatment Planning: Histological findings can inform treatment decisions. For instance, the presence of certain biomarkers in a tumor can indicate the likely effectiveness of targeted therapies.
- Monitoring Disease Progression:
- Research and Development:
Explain why tissues need to be fixed and state which fixatives are commonly used
Tissue samples need to be fixed to preserve their structure and cellular details
Fixation stabilizes the tissues by cross-linking proteins and halting enzymatic degradation, preventing autolysis and putrefaction.
- Collection: Tissue samples are collected as soon as possible to minimize degradation.
-
Choice of Fixative: A suitable fixative is selected based on the intended analysis. Common fixatives include:
- Formalin (usually 10% formalin, which is a buffered solution of formaldehyde) for general histology.
- Glutaraldehyde for electron microscopy, as it preserves ultrastructure well.
- Alcohols for certain cytological preparations.
Describe how tissue processing can lead to shrinkage and other artefacts
Tissue processing is a critical step in preparing samples for microscopic examination, but it can introduce artifacts, including shrinkage, that can affect the interpretation of results. Here’s how these issues can arise:
- Dehydration: During processing, tissues are dehydrated using increasing concentrations of alcohol. This step removes water, causing tissues to shrink. The extent of shrinkage depends on the type of fixative used and the dehydration protocol.
- Embedding Media: The embedding process often involves infiltrating tissues with paraffin or resin. If tissues are not adequately infiltrated or if the embedding medium has a different refractive index, it can result in further shrinkage or distortion.
- Crumpling and Wrinkling: If tissues are not properly fixed or are subjected to mechanical stress during handling, they may become crumpled or wrinkled. This can obscure cellular details.
- Loss of Cytoplasmic Components: Over-fixation or prolonged exposure to fixatives can lead to the loss of important cellular components, resulting in empty spaces or reduced staining intensity.
- Artifactual Spaces: During dehydration and embedding, air can become trapped in the tissue, creating artificial spaces that can be misinterpreted as pathological changes.
- Differential Shrinkage: Different components of the tissue (e.g., fat, muscle, connective tissue) may shrink at different rates, leading to altered morphology that does not reflect the original tissue architecture.
What is immunohistochemistry?
Immunohistochemistry (IHC) is a lab technique used to visualize the presence and localization of specific proteins in tissue sections. It involves the use of antibodies that bind to the target proteins, allowing researchers and pathologists to identify and study cellular structures and functions.
IHC is widely used in clinical diagnostics, particularly in cancer pathology, to help determine the presence of specific markers that can inform treatment decisions.
Tissue procurement methods
Surgical removal
scraping
needle
transvascular
patient collection
Methods of tissue procurement include surgical removal, scraping, needle methods, transvascular collection, and patient collection
Transvascular tissue procurement
Insert wire/catheter into blood vessel then travel to target site to collect sample, tissue needs good vascular supply, used in heart, lung, liver tissue
Transvascular tissue procurement involves inserting a wire or catheter into a blood vessel to travel to the target site for sample collection, suitable for tissues with good vascular supply such as heart, lung, and liver tissue
Stages of preparing tissue for examination
Procurement
fixation
embedding
cutting into slices
staining
microscope exam
Stages of preparing tissue for examination include procurement, fixation, embedding, cutting into slices, staining, and microscope examination
Tissue procurment methods
Surgical removal
scraping
needle
transvascular
patient collection
These are methods used for obtaining tissue samples for clinical diagnostics.
Transvascular tissue procurement
Insert wire/catheter into blood vessel then travel to target site to collect sample, tissue needs good vascular supply, used in heart, lung, liver tissue
This method involves inserting a wire or catheter into a blood vessel to collect tissue samples.
Stages of preparing tissue for examination
Procurement
fixation
embedding
cutting into slices
staining
microscope exam
These are the steps involved in preparing tissue samples for examination.
Haematoxylin
Basic dye
blue/purple
binds to acidic cell structures
Haematoxylin is a basic dye that binds to acidic cell structures.
Eosin
Pink/red
acidic dye
binds to basic cell structures
Eosin is an acidic dye that binds to basic cell structures.
osmolality of blood
285-295 mOsm/kg, (millimoles per kg)
Osmolality is the total number of solute particles per kilogram of blood.
If some NaCl at 40mOsm if added to a solution, how to calculate new osmolality?
Add 40 mOsm for Cl and 40 mOsm for Na!!!
This is the calculation for determining the new osmolality after adding NaCl to a solution.
Oedema
-body fluid becomes dilated
-reduction in [Na] in extracellular fluid
-water moves into cells
-cells/tissues swell
Oedema is characterized by the swelling of cells and tissues due to fluid accumulation.
Best way to measure temp in child under 4 weeks old
Electric thermometer in axilla
This is the recommended method for measuring temperature in infants under 4 weeks old.
Severe hypothermia
28-32 degrees
rigid muslces, no shivering
slow/weak pulse
drowsiness
Severe hypothermia is indicated by low body temperature and symptoms like rigid muscles and drowsiness.
Mild hypothermia
32.1-35
shivering
fatigue
slurred speech
confusion
stiffness
Mild hypothermia is characterized by shivering and symptoms like fatigue and confusion.
Arterial blood gases
A test performed on arterial blood to determine levels of oxygen, carbon dioxide, and pH
Arterial blood gases are used to assess the levels of oxygen, carbon dioxide, and pH in the blood.
Haemtocrit
Percentage by volume of red blood cells in blood
Haemtocrit measures the percentage of red blood cells in the blood.
aquaporin
A membrane protein, specifically a transport protein, that facilitates the passage of water through channel proteins.
Aquaporin is a protein that aids in the movement of water across cell membranes.
Osmotic presure
Tendency of water to move into cell by osmosis
Osmotic pressure refers to the force that drives water into cells through osmosis.
Osmolality
Total no. Of solute particles per kilogram
Osmolality is a measure of the concentration of solute particles in a solution.
Tonicity
The ability of a solution surrounding a cell to cause that cell to gain or lose water.
iso = same amount both sides of membrane
hypotonic = solution surrounding cell is more dilute
hypertonic = solution surrounding cell has higher concentration of solute
Tonicity refers to the effect of a solution on the movement of water into or out of a cell.
Colloid
A mixture containing small, undissolved particles that do not settle out.
Colloids are mixtures with particles that do not dissolve or settle.
Oedema causes
Increased hydrostatic presssure; hypertension, right side heart failure, DVT, pulmonary oedema (left side heart failure)
Decreased oncotic pressure; decreased blood albumin liver dieases malnutrion/ alabsortion renal dieases
Oedema can be caused by factors like increased hydrostatic pressure or decreased oncotic pressure.
epithelial tissue
-lines, organs, vessels and tissues
-polarised; apical surface faces lumen, basal surface avascular
Epithelial tissue forms the lining of organs and vessels, with distinct polarity.
Nervous tissue
neurons and neuroglia, bundled in fibres called fascicles, fascicles bundled into nervers
Nervous tissue consists of neurons and supporting cells bundled into nerves.
Muscle tissue
Sketch, cardiac, smooth movement of skeleton, movement of internal contents also secretes hormones under control of nervous tissue
Muscle tissue is responsible for movement and hormone secretion, under the control of the nervous system.
Connective tissue
Protects, supports, and binds structures and organs, can be loose or dense
Connective tissue provides structural support and protection to organs and tissues.
Fixation of tissue
-sample soaked in formalin
-formaldehyde penetrates tissue and cross-links proteins
Tissue fixation involves preserving samples in formalin to prevent decay.
Embedding tissue
Dehydrate tissue with alcohol, solvent added to help heated paraffin wax infiltrate the tissue sample placed in a mould, more wax added, left to solidify over night
Tissue embedding involves dehydrating samples and infiltrating them with wax for cutting.
Microtome
An instrument that produces very thin slices of body tissues
A microtome is used to cut thin sections of tissues for microscopic examination.
H and E
Hematoxylin and eosin- a dye combination used to stain pathology specimens
H = basic
E = acidic
H and E staining is a common technique in pathology to visualize tissue structures.
frozen section biopsy
-tissue rapidly frozen in cryostat
-sliced in cryotome
-quicker than FFPE but lower quality
-prone to artifacts
-does’t stain as well as FFPE
-can be fixed and stored at -80*
-used intraoperatively
Frozen section biopsy is a rapid method for examining tissue samples during surgery.
Phase contrast microscopy
Allows examination of living organisms and internal cell structures used to enhance image contrast for transparent and colourless samples, no need for stains/fixative
Phase contrast microscopy is a technique for visualizing transparent samples without staining.
Fluorescent microscopy
-high-intensity light source excites a fluorescent molecule (flurophore) which is added to its sample via stain or antibody
-can detect TB, observe process like cell proliferation, differentiation and migration
-can detect any specific component of living/fixed cells
Fluorescent microscopy uses fluorescent dyes to visualize specific components in cells.
confocal microscopy
-special form of fluorescence microscopy
takes multiple images at different depths and compiles them used for eye diseases diagnosis
Confocal microscopy is a technique for imaging samples at different depths to diagnose eye diseases.
Immunohistochemistry
Localizing antigens or proteins in tissues using labeled (colored or fluorescent)
Immunohistochemistry is a method for visualizing specific proteins in tissue samples.
What is the process of using a high-intensity light source to excite a fluorescent molecule in a sample?
Fluorescent microscopy
-high-intensity light source excites a fluorescent molecule (flurophore) which is added to its sample via stain or antibody
What type of microscopy can detect TB, observe cell proliferation, differentiation, and migration?
Fluorescent microscopy
-can detect TB, observe process like cell proliferation, differentiation and migration
What is a special form of fluorescence microscopy that takes multiple images at different depths and compiles them?
Confocal microscopy
What is the purpose of dark field microscopy?
Illuminates unstained sample so they appear bright against a dark background
-useful in examining cell surface structure instead of internal contents
What type of microscopy is used for examining cell surface structure instead of internal contents?
Dark field microscopy
What are artefacts on tissue samples?
Features in tissue samples due to mistakes in processing of the sample
For what tissues would the scraping method of procurement be used?
Skin and uterus
What is the function of centrosomes and centrioles?
Aids in cell division (spindle fibres)
Supports cell structure
What is the function of the Golgi apparatus?
A system of membranes that modifies and packages proteins for export by the cell
Cis face toward the nucleus
What is the function of the smooth endoplasmic reticulum?
An endomembrane system where lipids are synthesized, calcium levels are regulated, and toxic substances are broken down
What is the Henderson-Hasselbalch equation?
pKa = -logKa
What is the secondary structure of a protein?
Local structure of alpha helix or beta pleated sheets; stabilized by peptide-linkage hydrogen bonds (no R-group interactions at this level)
What is the tertiary structure of a protein?
Overall 3D shape of protein
What are the features of a peptide bond?
Planar
Rigid
Trans, carbonyl oxygen on opposite side of peptide bond to amide hydrogen
R-group from each amino acid residue are on opposite sides of the peptide bond
What is the importance of the amino acid cysteine in the tertiary structure of a polypeptide?
Forms disulphide bonds
What is a zygote?
A diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum
How does the oocyte travel down the fallopian tube?
Specialized cilia (under action of progesterone) in the oviduct move zygote to ampulla end of the fallopian tube to the junction with uterus
What is the structure that contains one or more ovules?
Ovary
Structure that contains one or more ovules
What is the tube connecting the ovary to the uterus?
Fallopian tube
Tube connecting the ovary to the uterus
What is the pear-shaped organ in the pelvic cavity in which the embryo develops?
Uterus
Pear-shaped organ in the pelvic cavity in which the embryo develops
What is cell division without growth?
Cleavage
Cell division without growth, occurs whilst zygote travels down fallopian tube
What is the middle layer that develops into muscles, bones, and the circulatory system?
Mesoderm
Middle layer that develops into muscles, bones, cartilage, blood, the circulatory system, and connective tissues. It also forms the kidneys, gonads, and the lining of body cavities
What is the innermost layer that forms the epithelial lining of the gastrointestinal tract?
Endoderm
Innermost layer that forms the epithelial lining of the gastrointestinal tract, respiratory system, and several glands, including the liver and pancreas
What is the outermost layer that forms the skin, nails, and nervous system?
Ectoderm
Outermost layer that forms the skin, hair, nails, and the nervous system (including the brain and spinal cord). It also gives rise to sensory organs and parts of the endocrine system
What is a groove-like structure that appears on the surface of the embryo during gastrulation?
Primitive streak
Groove-like structure that appears on the surface of the embryo during gastrulation. It acts as a ‘gateway’ for cells to migrate inward and form new layers within the embryo. Arises from epiblast cells which migrate
Derivatives
It develops into muscles, bones, cartilage, blood, the circulatory system, and connective tissues. It also forms the kidneys, gonads, and the lining of body cavities.
Define primitive streak
This is a groove-like structure that appears on the surface of the embryo during gastrulation. It usually forms along the midline on the dorsal side (back).It acts as a ‘gateway’ for cells to migrate inward and form new layers within the embryo. It arises from epiblast cells which migrate toward the midline at the posterior end of the bilaminar disk.
Neurolation process
- rod of notochord forms from mesoderm
2.ectoderm gives rise to neural plate, which overlaps the notochord - neural plate is folded into neural tube
Define the pre-embryonic stage
The preembryonic stage of development refers to the initial phase of human embryonic development, which occurs from fertilization until the end of the second week of gestation. This stage includes several key processes:
See text for additional information.
Define the embryonic stage
the period after implantation, during which all of the major organs and structures within the growing mammal are formed
Define the fetal period of prenatal development
follows the embryonic period, beginning of ninth week. time of maturation of existing structures and also proliferation, differentiation and morphogenesis.
What goes wrong in ectopic pregnancy
Conceptus is implanted elsewhere than the uterus, usually the fallopian tube, can cause ruptured fallopian tube
What causes placenta praevia
Conceptus is implanted too low down in the uterus, meaning the placenta is blocking the vagina, can cause haemorrhage
Differentiation of the mesoderm
-Development of the mesoderm creates;
axial rod, notochord, somites and intermediate mesoderm, lateral plate
notochord
long supporting rod that runs through a chordate’s body just below the nerve cord
Somites
-Series of segments either side of the mesoderm
-Gives rise to dermatome (skin section), myotome (muscle section) and sclerotome (hard tissue section)
Intermediate mesoderm
Forms the kidneys
lateral plate mesoderm
somatic and splanchnic layers, with coelom (space) between them
-somatic layer forms diaphragm and limb muscles
-splanchnic layer forms heart and viscera muscles
-coelom becomes the body cavities
Segmentation
Organising mesoderm into somites gives rise to vertebrae, ribs, intercostal muscles, spinal cord segments
Embryonic folding
process by which an embryo develops from a flat disc of cells to a three-dimensional shape resembling a cylinder, puts tissues in the right place
Key stages of early embryonic development
Fertilisation and implantation
Gastrulation
Neurulation
Segmentation
Folding
Notochord
-formed from mesoderm during gastrulation
-solid rod of cells running through midline
directs conversation of ectoderm, to neuroectoderm, to neural plate, to neural tube
Describe the formation of the intra-embryonic coelum
-arises from mesoderm
-small cavities pear as mesodermal cells divide and migrate
-the cavities fuse to form a large continuous cavity
Describe the differentiation of the somites into dermatome, myotome and sclerotic and the fate of these at later development
-somites are segmented blocks of mesoderm
-dermatome is the lateral part of the somite that will form skin
-myotome is the medial part which will form muscle
-sclerotome will develop into bone and cartilage
Explain the use of the terms dermatome and myotome in describing the innervation of skin and muscle in the adult
Dermatome: Refers to the sensory skin area supplied by a single spinal nerve, important for assessing sensation and diagnosing nerve injuries.
Myotome: Refers to the muscle group innervated by a single spinal nerve, crucial for assessing motor function and diagnosing muscle
Dermatome
Refers to the sensory skin area supplied by a single spinal nerve, important for assessing sensation and diagnosing nerve injuries.
Dermatome: Refers to the sensory skin area supplied by a single spinal nerve, important for assessing sensation and diagnosing nerve injuries.
Myotome
Refers to the muscle group innervated by a single spinal nerve, crucial for assessing motor function and diagnosing muscle weakness.
Myotome: Refers to the muscle group innervated by a single spinal nerve, crucial for assessing motor function and diagnosing muscle weakness.
Head Fold
The head fold, arises at the cephalic (head) end of the embryonic disc. It is primarily formed by the growth of the forebrain and the underlying mesoderm. As the forebrain develops, it pushes the ectoderm and endoderm layers ventrally (downward).
Function: The head fold brings the heart and structures of the head and neck into their appropriate positions.
Tail Fold
The tail fold occurs at the opposite end of the embryonic disc. It forms similarly due to the growth of the caudal part of the embryo, including the developing hindbrain and spinal cord.
Function: The tail fold helps position the future structures of the tail and lower body, including the cloacal membrane (which will become the anus).
Lateral Body Folds
The lateral body folds develop from the lateral edges of the embryonic disc. As the mesoderm expands and the ectoderm grows, the lateral edges fold inward toward the midline.
Function: These folds facilitate the enclosure of the intra-embryonic coelom (the future body cavity) and help form the lateral aspects of the trunk and limbs.
Primitive yolk sac
As the hypoblast margins spread around the edges of the blastocyst cavity, this is created
As the hypoblast margins spread around the edges of the blastocyst cavity, this is created
Secondary yolk sac
Formed at 23 days when the primary yolk sac is pinched off by the extraembryonic coelom
Formed at 23 days when the primary yolk sac is pinched off by the extraembryonic coelom
Hydrophobic amino acids
Glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), proline (Pro), phenylalanine (Phe), methionine (Met), and tryptophan (Trp).
Glycine (Gly), alanine (Ala), valine (Val), leucine (Leu), isoleucine (Ile), proline (Pro), phenylalanine (Phe), methionine (Met), and tryptophan (Trp).
How is enzyme/substrate binding stabilised ?
Substrate binding is stabilised by specific interactions amino acid residues in the active site. Substrate interactions are non-covalent and relatively weak
Substrate binding is stabilised by specific interactions amino acid residues in the active site. Substrate interactions are non-covalent and relatively weak
Equilibrium constant
[products]/[reactants]
[products]/[reactants]
Michaelis constant (Km)
Concentration of substrate at which an enzyme works at half its maximum velocity; serves as a measure of enzyme affinity for the substrate (KM is inversely related to affinity)
Concentration of substrate at which an enzyme works at half its maximum velocity; serves as a measure of enzyme affinity for the substrate (KM is inversely related to affinity)
Lineweaver-Burk Plot
Double reciprocal of michaelis menten. x int: is -1/Km, y int: 1/vmax
Double reciprocal of michaelis menten. x int: is -1/Km, y int: 1/vmax
Competitive inhibition
Substance that resembles the normal substrate competes with the substrate for the active site
Substance that resembles the normal substrate competes with the substrate for the active site
Non-competitive inhibitor
Binds somewhere away from the active site, causes conformational change that reduces enzyme activity. Captopril is an ACE inhibitor, reduces production of angiotensin 2, which is a vasoconstrictor, treats hypertension and heart failure
Binds somewhere away from the active site, causes conformational change that reduces enzyme activity. Captopril is an ACE inhibitor, reduces production of angiotensin 2, which is a vasoconstrictor, treats hypertension and heart failure
Isoenzymes
Enzymes that catalyse the same reaction but have different primary structures. May be encoded by different genes or alternative splicing of the same genes
Enzymes that catalyse the same reaction but have different primary structures. May be encoded by different genes or alternative splicing of the same genes
Allosteric regulation
Regulating the activity of a protein by binding the regulatory molecule to a different site to the active/substrate site. Can alter enzymes from T (low activity state) and R (high activity state)
Regulating the activity of a protein by binding the regulatory molecule to a different site to the active/substrate site. Can alter enzymes from T (low activity state) and R (high activity state)
Amino acids with a hydroxyl group
Serine, threonine, tyrosine
Serine, threonine, tyrosine
Action of zymogens
Some enzymes need to be activated quickly. The enzyme is expressed as an inactive precursor molecule, known as a zymogen. Zymogen is activated by cleaving of a region called the prosegment. This is irreversible as a peptide bond is broken
Some enzymes need to be activated quickly. The enzyme is expressed as an inactive precursor molecule, known as a zymogen. Zymogen is activated by cleaving of a region called the prosegment. This is irreversible as a peptide bond is broken
Example of an enzyme regulated by zymogen
The protease enzyme called trypsin are secreted into the pancreatic duct in it’s inactive form, trypsinogen. Trypsin gets activated by a duodenum-associated enzyme called enteropeptidase
The protease enzyme called trypsin are secreted into the pancreatic duct in it’s inactive form, trypsinogen. Trypsin gets activated by a duodenum-associated enzyme called enteropeptidase
Three types of cells that are not organised into tissue
Ova, spermatozoa, corpuscles of the blood
Ova, spermatozoa, corpuscles of the blood
Mesothelium
Epithelium lining enclosed cavities, such as the peritoneal cavity
Epithelium lining enclosed cavities, such as the peritoneal cavity
Endothelium
Specialised form of epithelium that lines the heart, blood vessels and lymphatic vessels
Specialised form of epithelium that lines the heart, blood vessels and lymphatic vessels
Simple squamous epithelium
Functions: Exchange of gases, fluids, nutrients or metabolites. Secreting lubricant. Protective lining
Functions: Exchange of gases, fluids, nutrients or metabolites. Secreting lubricant. Protective lining
Simple cuboidal epithelium
Function: Secretion and absorption
Function: Secretion and absorption
-ova
Epithelium lining enclosed cavities, such as the peritoneal cavity
-
spermatozoa
Epithelium lining enclosed cavities, such as the peritoneal cavity
-
corpuscles of the blood
Epithelium lining enclosed cavities, such as the peritoneal cavity
-
Mesothelium
Epithelium lining enclosed cavities, such as the peritoneal cavity
-
Endothelium
specialised form of epithelium that lines the heart, blood vessels and lympathic vessels
-
simple squamous epithelium
Functions;
-Exchange of gases, fluids, nutrients or metabolites
-Secreting lubricant
-Protective lining
-
simple cuboidal epithelium
Function: secretion and absorption (hormones/enzymes)
Location: Kidney tubules; exocrine ducts and secretory portions of small glands, ovary surface.
simple columnar epithelium
Function: Absorption; secretion of mucus, enzymes, and absorbing nutrients/fluids
Location: nonciliated type lines most of the digestive tract (stomach to anal canal), gallbladder and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.
1 unit of enzyme activity
the amount of enzyme that transforms 1.0 micromole of substrate to product per minute at standard conditions
-
irreversible inhibitors
form covalent bonds with enzymes and irreversibly inactivate them
-
Describe the reversible covalent modification of enzymes and why it is useful
-protein kinases uses ATP to phosphorylation the -OH group of Ser,Thr, Tyr
-large free energy of phosphorylation, adds negative charges and ability to form H-bonds
-
Describe the process of activating a zymogen
.N terminus peptide is cleaved
.New N-terminus rotates toward active site
.Leads to conformational changes that creat functional active ite
-
Major short-term enzyme regulatory mechanisms
-Isoenzynes
-Allosteric regulation (conformational changes)
-Phosphorylation
-Proteolytic activation
-Gene expression (longer term)
-
Allosteric regulation of PFK
Activated by AMP and fructose-2,6-Bisphosphate
Inhibited by citrate, AMP and H+
-
Define tissue
Group of similar cells that are adapted for a specific function
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Define organ
2 or more tissues the combine to form a structural unit with a specific functions
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