organelles and compartmentalisation

Outline the functions of rough endoplasmic reticulum and Golgi apparatus (3)

a. ribosomes on RER synthesize/produce polypeptides/proteins ✔

b. proteins from RER for secretion/export/use outside cell/for lysosomes ✔

c. Golgi alters/modifies proteins/example of modification ✔

d. vesicles budded off Golgi transport proteins «to plasma membrane»
OR
exocytosis/secretion of proteins in vesicles from the Golgi ✔

organelles with no membrane (3)

ribosomes

microtubules

centrioles

organelles with a single membrane (4)

vesicles and vacuoles

rough and smooth endoplasmic reticulum

golgi apparatus

lysosomes

state organelles with a double membrane (3)

nuclei

mitochondria

chloroplasts

why are cell walls not considered organelles?

outside the plasma membrane - so they are extracellular structures

why are cytoskeletons not considered organelles?

consist of narrow protein filaments spread throughout the cell, that are not discrete enough to be an organelle

why is the cytoplasm not considered an organelle?

cytoplasm is not a discrete structure as it includes many different structures

and performs many functions.

advantages of the separation of nucleus and cytoplasm

• allows mRNA to be modified after it has been produced by transcription in the nucleus, but before it is translated. The process is called post-transcriptional modification

• safeguards DNA by keeping chromosomes inside the nucleus

advantages of compartmentalisation in the cytoplasm

• enzymes and substrates for a particular process can be concentrated

• substances that could cause damage to the cell can be kept inside the membrane of an organelle

• conditions such as pH can be maintained at an ideal level for a particular process

• organelles with their contents can be moved around within the cell