DSA Cellular organelles

Question 1

1. Define the basic structure of the Endoplasmic Reticulum

Answer 1

• Rough ER: Has ribosomes attached to it - Smooth ER: has no ribosomes
• The endoplasmic reticulum system, consisting of cisternae (flat sacs), tubules, and vesicles, divides the cytoplasm into two compartments:
• The luminal or cisternal compartment.
• The cytoplasmic or cytosolic compartment

Question 2

Define the functions of the ER

Answer 2

Functions include: protein synthesis, lipid synthesis, protien folding and sorage of calcium.

Question 3

Describe the structure of the Golgi apparatus and then define its function.

Answer 3

Looks like stacks of disc-like compartments.

• Functions include:
  
  • synthesis of sphingomylein and glycosphinolipids
  • sorting secretory producs
  • packaging and storing secrotory products into secretory granules or vesicles
  • pollysaccharide and oligosaccharide synthesis
  • modification of carbs attached to glycoprotiens and proteoglycans

Question 4

Mitochondrial function and structure:

Answer 4

-structure: it has an outer and inner membrane and consists of a matrix

Question 5

Lysosomes function and structure:

Answer 5

• Membrane-enclosed organelles that contain 50-60 hydrolytic enzymes most active at acidic pH that are capable of breaking down proteins, carbohydrates, lipids and nucleic acids.
• Remove both material from outside the cell as well as obsolete components of the cell itself

Question 6

When digestive enzymes leave the golgi they will have what tag to ensure they are going to the right place?

Answer 6

Mannose 6 Phosphate tag

Question 7

Nucleus strucure and function

Answer 7

Contains the genome and is a principal site for DNA and RNA synthesis.

Question 8

What are ribosomes and what are there function?

Answer 8

Ribosomes are the site of protien synthesis. They are found on the rough ER or flotying in the cytoplasm.

Question 9

What is the cytoplasm?

Answer 9

Consists of the cytosol and cytoplasmic organelles.

Question 10

Describe the plasma membrane and its functions.

Answer 10

It is a bilayer that is the outer boundary of cells. It is a protective barrier for the cells, has transporters and is used for signaling.

Question 11

What are preoxisomes?

Answer 11

They are small vesicular compartments that contain enzymes used in oxidation reactions.

Question 12

The rough ER is ______ of the total cell membrane in a ________.

Answer 12

• 60%
• pancreatic exocrine cell.

Question 13

The mitochondria inner mermbrane is _____ of the total cell membrane of the in ________.

Answer 13

• 32%
• liver hepatocyte

Question 13

The cell is devided into 3 topoloigcal catagories

Answer 13

• nucleus and cytosol
• organelles in secreatory and endocytic pathways (ER, golgi, endosomes and lysosomes)
• mitochondria

Question 14

The mechanism by which secretory proteins are directed to the endoplasmic reticulum is explained by the _______.

Answer 14

Signal Sequence

Question 15

Cells that make ________ have a lot RER.

Answer 15

secreted protiens

Question 16

The vesicular transport mechanism involves two types of coated vesicles:

Answer 16

• Clathrin-coated vesicles
• COP-coated vesicles (coat protein)

Question 17

Clathrin-coated vesicles, transporting products from the ________ to _________. Or products from the _______ to________.

Answer 17

• golgi apparatus to lysosomes
• exterior of the cells to lysosomes (like cholestorl)

Question 18

COP-coated vesicles (coat protein), transporting products between stacks of the ________, and from the _________________.

Answer 18

• Golgi apparatus (COPI-coated vesicles)
• endoplasmic reticulum to the Golgi apparatus (COPII-coated vesicles)

Question 19

Describe primary Llysosomes.

Answer 19

Storage site of lysosomal hydrolases. They have no digestive evevnts, are homogenous and have inactive enzymes.

Question 20

Describe secondary lysosomes.

Answer 20

They are engaged in a catalytic process, have digetive enzymes, are heterogenous and have active enzymes.

Question 21

Describe the lysosomal sorting pathway.

Answer 21

1. First the synthesis of lysosomal enzymes occur in the rough ER which are then exported
2. phosporylation of lyosomal enzymes (Mannose 6 phosphate is added)
3. transported by the inter golgi tranporting vessciles
4. the lyosomal enzymes bind to the MP6 receptor
5. clatharin coated tramporting vesscile
6. the coat is lost and tthe receptor is recycled back to the golgi app and the enzymes are sorted in the primary lysozme.

Question 22

Describe early endosomes

Answer 22

add

Question 23

Endocytosis and Lysosome Formation steps

Answer 23

1. One of the major functions of lysosomes is digestion of material taken up from outside the cell
2. Lysosomes are formed from fusion of transport vesicle with endosome (contain molecules – like cholesterol - taken up by endocytosis)
3. Clathrin components recycled and early endosomes mature into late endosomes which are precursors of secondary lysosomes
4. Important change in endosome maturation is lowering of internal ph to 5.5

Question 24

Decribe the structure and fuction of peroxisomes.

Answer 24

* found in cytoplam of all cells * Contains a number of enzymes that form hydrogen peroxide (can damage cell) which is immediately broken down by catalase. * synthesize and degrade hydrogen peroxide * do beta ox of LCFA * bile and cholestrol synthesis * detox EtOH

Question 27

Describe Dynamin and adaptins

Answer 27

dynamin: surrounds the neck of the invagonated coat pit causing the neck of the vesscile to pinch off of the plasma membrane adaptins: mediate clathring binding to the vesicle