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Protein transport

protein transport okay we're gonna do a

little little podcast on how proteins

are produced modified and released out

of a cell or how they might remain

inside the cell first off we have the

nucleolus which you can see right up on

the top left-hand part of the screen

here and this is responsible for making

ribosomes and these will migrate and

position themselves on the rough

endoplasmic reticulum which you can see

here and this is the site of where

proteins are made the DNA is a very very

large molecule and can't leave the

nucleus so it sends out messenger RNA so

it is transcribed and this

single-stranded poly nucleotide will

leave by these pause and find these

ribosomes where translation actually

occurs and this is where you get

transfer RNAs bringing in amino acids

which had joined together by peptide

bonds making a polypeptide this

polypeptide will leave the rough

endoplasmic reticulum in visa khals so

this is often the marking point in exams

and these migrate to the Golgi complex

or the Golgi apparatus where they fuse

and release their contents so these

proteins are meandering through this

Golgi apparatus which isn't a fixed

structure and as they go through from

the sis to the trans face they are

modified and examiner's love to for you

to write down examples of modification

these could include glycolipids

glycoproteins like oscillations are

lovely keyword to use there even

concentration of proteins occur inside

the Golgi proteins will then leave the

golgi in vesicles and migrate towards

the plasma membrane where they fuse

often the marking points and release

their contents into the extracellular

environment these little protein

products here could be hormones or

enzymes part of the endocrine system

where they can float around in the

bloodstream around the body and act on

target cells

alternatively these visa calls over here

shown on the right could remain inside

the cell and help to form

lysosomes and you'll find many of these

in white blood cells which contain

hydrolytic enzymes that can digest

engulfed pathogens also if we think of

specialized cells such as a sperm cell

this contains a modified lysosome known

as the acrosome in the head so sometimes

examiner's may ask how proteins get in

to the acrosome and it's essentially

this whole process ending up in here on

my next page you can see that I've

written out the sequence of events again

which I've just discussed so you need

genes to be switched on which is

transcription mrna will leave the

nucleus go to ribosomes where you have

translation polypeptides physicals golgi

modification with examples visa calls

fusing exocytosis to dwell worth pausing

this page here and making a revision

crib sheet on this information as

examiner's often ask questions as

there's lots of lovely detail here to

write down good luck