cell structure Flashcards
what are the advantages of having membranous organelles?
- allows compartmentalisation of specific reactions to provide specific conditions for enzymatic reactions to occur
- regulation of cell’s contents
- increase membrane surface area for embedding enzymes and proteins
- increases efficiency of enzymatic reactions
- maintain characteristic differences for incompatible processes to occur simultaneously
what organelles have double membranes?
nucleus, chloroplast, mitochondrion
what 5 organelles are part of the endomembrane system?
rough endoplasmic reticulum, smooth endoplasmic reticulum, golgi apparatus, lysosomes, vesicles
what is the function of the nucleus?
the nucleus encloses genetic material and protects DNA from the metabolically active cytoplasm
what is the function of the rER?
the rER contains ribosomes which is the site of protein synthesis. polypeptide chains synthesised by ribosomes are folded in the ER lumen
what is the function of the sER?
the sER synthesises lipids, detoxifies drugs and poisons, stores calcium ions and metabolises carbohydrates
what are ER cisternae? (singular: cisterna)
the extensive network of hollow, membranous tubules, sacs or sheets in the ER
the extensive network of cisternae increases membrane surface area for synthesis
what is the function of the golgi apparatus?
the golgi apparatus is the site of modification and packaging ofER products
what are GA cisternae? (singular: cisterna)
flattened, membrane bound sacs
what modifications can the golgi apparatus carry out?
glycosylation (adding sugar groups) and trimming (removing excess monomers)
what is the function of lysosomes?
digestion of materials taken into cells, autophagy of worn-out organelles and autolysis
why is it necessary for lysosomes to be membranous?
lysosome contents are acidic in nature and contain hydrolytic enzymes. segregation is necessary to provide optimal pH for hydrolytic reactions and to protect cellular contents from hydrolysis
what is the difference in structure for vacuoles between in animal cells and that of plant cells?
animal cells: small, mobile vacuoles
plant cells: one large central vacuoles surrounded by a single membrane called the tonoplast
what is the difference in function for vacuoles in animal cells and plant cells
animal cells: house and transport substances
plant cells: store organic compounds, dispose toxic substances, pigmentation, plant protection, cell growth & elongation
what are cristae?
the highly convoluted inner membrane of mitochondria which increases the surface area for attachment of enzyme systems
what is the function of mitochondria?
mitochondria are the site of cellular respiration, generating ATP for cellular activities
what is the name of the compartment enclosed by the inner membrane of the mitochondria?
the mitochondrial matrix
what is the function of chloroplasts?
chloroplasts are the sites of photosynthesis and convert solar energy to chemical energy by absorbing sunlight
what is the name of the double membrane surrounding the chloroplast?
the chloroplast envelope
what is the stroma?
the semi-fluid compartment enclosed by the inner membrane of the chloroplast envelope. the stroma contains circular DNA which enables the synthesis of chloroplast proteins
what are thylakoids?
thylakoids are the 3rd set of membranes within the stroma. thylakoids enclose the thylakoid lumen. the thylakoid lumen and thylakoid form a flattened sac called the thylakoid discs
what is a granum? (singular: grana)
thylakoid discs stack up to form granum
what is the function of ribosomes?
ribosomes are the site of protein synthesis
what are the 4 cellular locations ribosomes can be found in?
eukaryotic cells: attached to the rER and free in the cytosol.
prokaryotic cells: in the mitochondrial matrix and in the chloroplast stroma
what is the cytoskeleton?
an intricate 3D array of interconnected filaments and tubules
what are the functions of the cytoskeleton?
- provide mechanical support
- allow for anchorage + direct movements of organelles and molecules
- provide cell motility
are centrioles found in plant cells?
NO. they are only found in animal cells
describe the shape of centrioles.
centrioles are found in pairs are right angles to each other. each member of the pair consists of 9 triplets of microtubules arranged in a ring
what is the cell wall made up of?
cellulose
what are the functions of the cell wall?
- protect the cell from mechanical injury and invasion
- withstand hydrostatic pressure exerted by uptake of water (because of cellulose high tensile strength)
what is the name of the region between adjacent plant cells?
the middle lamella
how does the golgi apparatus modify and package ER products?
- membranes of transport vesicles fuse with the cis face membrane and deposit their contents into the golgi cisternal space
- at the trans face, membranes bud off to form secretory vesicles, which contain materials to be transported to the extracellular matrix
- membranes can also bud off from the trans face to form lysosomes
- some golgi vesicles also bud off from the trans face to transport substances to other organelles in the cell
- between the golgi sacs, golgi vesicles are responsible for transferring materials between the parts of the golgi
