17647638
Descripción
Fichas por Mairi Edwards, actualizado hace más de 1 año
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Creado por Mairi Edwards
hace más de 5 años
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| Pregunta | Respuesta |
| What important molecule is distributed evenly in a lipid bi-layer and what is its purpose | Cholesterol It decreases the permeability of the membrane and gives it added strength |
| which lipids are found in the intracellular surface of a phospholipid bi-layer? | PI, PE, PS think of pies |
| which lipids are found in the Extracellular surface of a phospholipid bi-layer? | PC, Glycolipids |
| What method is used to test the fluidity proteins in a phospholipid membrane and what are the steps? | FRAP (Fluorescence Recovery After Photo-bleaching) 1. The fluorescence molecule, GFP is bound to the target proteins. 2. A seleceted chunk of the membrane is bleached by laser beam. 3. If the proteins are mobile, this bleached area will quickly be filled in by moving un-bleached proteins - recovery |
| Which molecules CANNOT travel across membranes without assistance from transport proteins? | Glucose (and other large molecules) & ions |
| What are the 4 types of membrane-bound proteins | 1. Channels and transporters 2. Anchors 3. Chemical receptors 4. Enzymes |
| What is the role of anchor proteins? | To not move within the membrane and to hold the cell in place in relation to its surroundings (inside and outside) |
| What is the role of transporter proteins? | To allow ions/ molecules to pass under particular circumstances |
| how is glucose absorbed into the intestines? | to get in - active co-transport into intestinal epithelium against a conc. gradient to get out - easy passive transport out of glucose sodium potassium pump- active |
| What is a symport | essentially a co-transport protein moving 2 (or more) molecules across the membrane at the same time |
| What are snares and what are the two types? |
Snares hold a vesicle close to the membrane to allow it to bind with the target membrane as membranes dont fuse the moment they touch, they need a moment to fuse.
V-snares on transport Vesicles
T-snares on Target membrane
Image:
Snares (binary/octet-stream)
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| how does botox work? what is botulin? | Botox interferes with t-SNARES preventing this connection and the muscle isn't activated Botulin is a bacterial poison as it stops cell transport and body movement which stops your organs and kills you |
| What are the initial steps in the formation of protein that ALL proteins undergo | mRNA leaves the nucleus and binds to a ribosome molecule and translation is initiated by the chain of amino acids from tRNA beginning to be delivered |
| How are proteins delivered into the nucleus | whilst still in the process of translation, the chain is folded up and moved through a tiny nuclear pore. Once through, they unfold slightly and translation is finished |
| How are proteins delivered out of the cell | Any protein that will be moved out of the cell will begin translation in the cytoplasm of the original cell. the half completed protein is fed into the ER where translation is finished. the copies produced in the ER move to the golgi, and finally into transport vesicles which are able to leave the cell by exocytosis |
| How is translation of a protein stopped mid-way in preparation to move out of the cell | The thing that determines that the mRNA chain will go to the ER is the binding of the SRP molecule onto the signal sequence. once that binds, translation stops. the only way the translation can continue is if the SRP binds to an SRP receptor, only found on ER membrane. |
| What are the three main types of vesicles | 1. Lysosomes - contain digestive enzymes to clear up debris in the cell 2. secretory vesicles - to leave the cell by exocytosis 3. membrane renewal vesicles - yeah |
| What is Familial Isolated Hypoparathyroidism (FIH) | Low calcium and high phosphorous levels in the blood serum, caused by low quantities of parathyroid hormone (PTH) |
| How is parathyroid hormone formed | preproparathyroid hormone has its signal peptide removed, forming proparathyroid hormone. After further processing, it becomes parathyroid hormone, which can then be released into the blood and act as a calcium regulator |
| How is FIH caused | Caused by mutations in the signal peptides found on preproparathyroid hormone |
| What are the main components of the cytoskeleton | 1. microfilaments (actin filaments) 2. microtubules 3. intermediate filaments |
| What are the distribution patterns of the main components of the cytoskeleton | Intermediate - spread across the cell Microtubules - spread in branches from the middle-outwards (from MTOCs) microfilaments - line outside edge of cell and into any microvilli |
| What is in place to prevent myosin from binding to actin | Strands of tropomyosin, on the Actin filament, block the binding sites of the actin |
| Where is troponin found and what is it's role | Troponin is found along strands of actin filaments. In the prescence of calcium, it alters its shape which drags tropomyosin strands out of the way - allowing myosin and actin to bind, therefore causing muscle contraction |
| What is tropomodulin | Tropomodulin caps the growth of actin, to keep all strands universally at the same length |
| What is a z-disc | The Z discs are the attachment sites for the thin filaments. Therefore, from each Z disc, thin filaments extend to two neighbouring sarcomeres. |
| What is a sarcomere | A structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band. |
| What is the role of intermediate filaments and why are they called that | They line the outsides of cells and determine the maximum stretch of a cell to avoid damage It's literally called 'intermediate' because they're intermediate in size between thick and thin |
| What causes blisters | when the epidermis tears away (dissociates) from the basal lamine, leaving a gap which can then be filled with fluid |
| What is a MTOC and what does it do | Microtubule Organising Centres In most animal cells, this is the centriole. These control the number, position, and orientation of microtubules in the cytoplasm |
| What do microtubules do in the cell, depending on the cell type | In non-dividing cells - used to transport materials within the cell In dividing cells - allows the cell organisation into two new cells In ciliated cells - forms the basal body in the cilia |
| What are the two cargo delivery vehicles that travel along microtubules | kinesins - towards the plus-end (to the outside of the cell) Dyenins - towards the minus-end (to the centre of the cell) |
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