Organelles Working Together Flashcards
Explain the steps of protein synthesis where the protein product is secreted
1) As the chromosome is too large to leave the nucleus, the gene which codes for the protein’s amino acid sequence is copied by making mRNA.
2) The mRNA leaves the nucleus through a nuclear pore
3) The mRNA attaches to a ribosome attached to the rough endoplasmic reticulum. The ribosome reads the instructions to assemble the protein.
4) The protein then travels through the cisternae of the RER
5) The protein molecules are “pinched off” in vesicles and travel towards the Golgi apparatus body
6) The vesicles fuses with the Golgi body
7) The Golgi body modifies the protein (e.g adds carbohydrate to make a glycoprotein) then packages it into vesicles
8) The packaged protein product then travels in a vesicle from the Golgi body and moves towards the cell surface membrane
9) The vesicles fuses with the cell surface membrane
10) The cell surface membrane opens to release the protein (secretion by exocytosis)
Explain briefly the steps for making intracellular proteins
1) proteins made by free of cytoplasmic ribosomes
2) protein remains in the cells and may be packed into lysosomes by the Golgi apparatus (e.g hydrolytic enzymes)
What is the cytoskeleton?
Found in the cytoplasm, it’s a network of protein threads, they’re arranged as microfilaments (small solid strands), and microtubules (tiny protein cylinders), that have 4 main functions.
What are the 4 main functions of the cytoskeleton?
1) The microtubules and microfilaments SUPPORT the cells organelles, keeping them in POSITION.
2) They help to STRENGTHEN the cell and MAINTAIN its shape
3) They’re responsible for the MOVEMENT OF MATERIALS within the cell. E.g the movement of chromosomes when they separate during cell division depends on the contraction of microtubules in the spindle
4) The proteins of the cytoskeleton can also cause the CELL TO MOVE. E.g the movement of cilia and flagella is caused by the cytoskeleton protein filaments that run through them. So in single cells that have a flagellum (e.g sperm cells), they cytoskeleton propels the whole cell.
