Unit 1 - Cellular function Flashcards
what is the role of the peroxisome?
break down of lipids by beta oxidation producing hydrogen peroxide which is neutralised by catalase to water and oxygen
what is the role of the golgi body?
- modifies/ packages proteins for secretion
- transport vesicles from endoplasmic reticulum to golgi to fuse with the cis face
what chemical changes occur to proteins by the golgi body?
post-translational modification:
- glycosylation (addition of oligosaccharides)
- phosphorylation
- sulphation (addition of sulphates)
where and how are vesicles budded off from the cisternae of golgi?
from trans face
- exocytosis
what model describes the cell membrane?
- fluid mosaic model
- fluid - phospholipids can move relative to one another
- mosaic: embedding of proteins different size/shapes
what type of proteins are found in the membrane?
- intrinsic/ integral: carrier proteins/ channels
- extrinsic/ peripheral: surface - receptors, recognition sites
what else is found on extracellular surface in cell membranes?
carbohydrates - form glycocalyx (cell coat) and also involved in cell recognition
what is the role of the cholesterol in the cell membrane?
interfere with hydrophobic interactions between tails so decreases the fluidity - sometimes causing crystallisation
what is the cytoskeleton?
- name four functions
flexible lattice of fibrous proteins - filaments
functions: mechanical structure/ support, intracellular transport, suspension of organelles, adhesion
what are the types of filament found in the cytoskeleton?
- microfilaments: actin - dynamic structure
- intermediate filaments - stronger/ more stable - keratin
- microtubules - formed of alpha/beta tubulin provide strength, form spindle fibres, components of cilia and flagella, moves vesicles around cell by motor proteins that walk them along the tubules (dynein= towards centrosome/ kinesins=away)
what is another term for centrosome?
MTOC - microtubule organzing centre
What is the outer surface of cilia called and what is it composed of?
- axoneme
- nine doublet microtubules arranged around a pair of microtubules with protein links at regular intervals which provide attachment to the cytoskeleton by basal body
how does the rapid motion of cilia/flagella occur?
motor protein = ciliary dynein linked by polypeptide chain to one side of doublet microtubule and other free head interacts with neighbouring microtubule
- ATP hydrolysis occurs so able to bind to next protein subunit
- in this way it bends the cilium so bent region progresses along producing a rhythmic wave-like motion so material is swept across
what defect causes cystic fibrosis?
defect in chloride channel (CFTR) in apical membrane of epithelial cells so no chlorine transport
- no osmotic gradient is formed - no water
- mucus undiluted - difficulty breathing - leads to pneumonia - fertile environment for bacteria
what is lysosomal disease?
lack of lyzozymes so there is an accumulation of fats/sugars in lysosome which disrupts normal cell function leading to lsd
