Could you please check that I am on the right track with all of this? Thank you!
The Protein Synthesis and Modification Pathway
Task 1: Match the organelle with its definition
The Name of the Organelle
Nucleus
Nucleoli:
Definition of the Organelle
Prominent structure in cells that contains
chromosomes and is surrounded by a double
plasma membrane (envelope)
Located inside the nucleus. Area where
ribosomal RNA is combined with proteins to
make ribosomes.
Golgi Apparatus:
An ordered series of flattened membrane
bound compartments that resemble tubes.
Membranes bud off to form secretary vesicles.
Lysosomes
Vesicles containing powerful digestive enzymes.
Endoplasmic Reticulum
A vast network of interconnecting membranous
tubules, compartments and flattened sacs
which have ribosome’s attached.
Made from protein and rRNA, these organelles
have a large and a small subunit.
Ribosome’s
Smooth ER:
A network of interconnecting membranous
tubules, compartments and sacs
Question: Could you please explain the Smooth ER to me? What exactly is its role in the cell?
The endoplasmic reticulum in eukaryotic cells is an organelle that consists of a complex network of
tubules and sacs called cisternae. Inside all these tubules and sacs which are connected by a single
membrane of the endoplasmic reticulum is found a large, single, internal space called the cisternal
space which is filled up with cytosol (intracellular fluid). The endoplasmic reticulum also has a peri
nuclear space which is the space between the inner and outer nuclear membranes that cover the
nucleus of a cell. The function of smooth endoplasmic reticulum is to transport the protein
molecules manufactured by the rough endoplasmic reticulum around the cell. The smooth
endoplasmic reticulum is a small part of the endoplasmic reticulum but is prominent in cells found
in the liver, adrenal cortex and muscles. Smooth endoplasmic reticulum also has the role of
carbohydrate metabolism, regulation of calcium ions, synthesis of steroids and lipids.
Question: Could you please explain the makeup of ribosome’s to me?
Ribosome’s are the site the of protein synthesis in all cells, ribosome’s are not bound by a
membrane and consist of two ribosomal sub units. Ribosome’s lock onto messenger RNA
molecules and move along the mRNA to translate its code and link amino acids to form a
polypeptide. Ribosome's can be found within the cell either free flowing in the cytosol (free
ribosome's) where protein produced is excreted into the cytoplasm or attached to the
endoplasmic reticulum (bound ribosome's) where the protein produced is usually transported to
the cell membrane. The position of ribosomes within the cell is interchangeable based on the cell’s
protein production needs.
Task 2: Order the steps, give them a number and find an image below that highlights this part of
the process.
Step 1: Protein building instructions move from the nucleus into the cytoplasm using codons of
three bases in mRNA for every amino acid to be added to the protein.
Step 2: Peptide chains of amino acids are manufactured (synthesised) on ribosomes attached to
the E.R.
Side Step: Some proteins to be used within the cell are produced on free ribosomes.
Step 3: Protein chains enter the E.R. for chemical modification (shaping or additions).
Side Step: Sugars are modified into lipids and amino chains into hormones here. This is where
material for new membranes is produced.
Step 4: Vesicles bud off ER and take unfinished proteins to the Golgi.
Step 5: Final modification of proteins / lipids in Golgi.
Side Step: Macromolecules are often broken down and recycled in the cell within these
structures that contain strong concentrations of enzymes.
Step 6: Vesicles budding off Golgi transport final products to the cell membrane where they
leave the cell via exocytosis.