protein production + cytoskeleton (cell structure)

Question 1

where are proteins made

Answer 1

at the ribosomes - the ribosomes on the rough endoplasmic reticulum make proteins that are excreted or attached to the cell membrane, whereas the free ribosmes in the cytoplasm make proteins that stay in the cytoplasm

Question 2

what happens once the proteins are produced at the RER

Answer 2

they are folded + processes in the RER, then theyre transported to the golgi apparatus in vesicles. at the golgi apparatus the proteinsmay undergo further processing. the proteins enter more vesicles to be transported around the cell.

Question 3

describe making extracellular proteins

Answer 3

the protein will be secreted by the cell + function outside the cell.
egs) -insulin in the beta cells of the islets of langerhans in the pancreas.
-antibodies in B lymphocyte plasma cells
-mucus, a glycoprotein made by goblet cells.

will need to be packed by the golgi into a secretory vesicle, motor proteins drag the secretory vesicles along cytoskeleton tracks to plasma membrane, the protein is secreted out of the cell by exocytosis

Question 4

describe making intracellular proteins

Answer 4

the protein will remain and function inside the cell where it was made. egs) -Hb in maturing RBCS before they lose nucleus + ribosomes. - hydrolytic enzymes within a phagocytic cell such as a macrophage.
the protein packs into lysosome by the golgi apparatus.

Question 5

what is a phagocytic cell

Question 6

what is a macrophage

Question 7

explain the steps of protein production

Answer 7

1- mRNA copy of the instructions (gene), for insulin is made in the nucleus
2- mRNA leaves the nucleus through a nuclear pore
3- mRNA attaches to a ribosome, in this case attached to a RER. ribosome reads the instructions to assemble the protein (insulin)
4- insulin molecules are pinched off in vesicles and travel towards golgi apparatus
5- vesicle fuses w golgi apparatus
6- golgi apparatus processes and packages insulin molecules ready for release.
7- packaged insulin molecules are pinched off in vesicles from golgi apparatus and move towards plasma membrane
8- vesicle fuses w plasma membrane
9- plasma membrane opens to releae insulin molecules outside

Question 8

why do u think beta cells of the islets of langerhans in the pancreas contain many mitochondria

Answer 8

they use energy to synthesise + export many molecules of insulin/protein

Question 9

explain how the vesicles containing insulin, that pinch off from the golgi apparatus, arre moved to the plasma membrane of the beta cells

Answer 9

via motor proteins that drag them along the cytoskeleton threads. ATP required

Question 10

what is exocytosis

Answer 10

where the protein gets secreted out of the cell (in stage 8/9)

Question 11

why does mucin need to be produced by the stomach

Answer 11

for protetion (of cells/epithelia) from the acid in stomach

Question 12

what is the cytoskeleton

Answer 12

organelles in cells are surrounded by the cytoplasm. the cytoplasm has a network of protein threads running though it.
these protein threads are called the cytoskeleton. in eukaryotic cells the protein threads are arranged as microfilaments (very thin protein strands) and microtubules (tiny protein cylinders)

Question 13

what are microfilaments

Answer 13

very thin protein strands

Question 14

what are microtubules

Answer 14

tiny protein cylinders

Question 15

what are the 4 main functions of the cytoskeleton

Answer 15

1- the microtubukes + microfilaments support the cells organelles, keeping them in position.
2- they also help to strengthen the cell and maintain its shape
3- theyre responsible for the ttransport of organelles + materials within the cell
4- the proteins of the cytoskeleton can also cause the cell to move