Exam 2- DSA Cell Organelle

Question 1

plasma membrane

Answer 1

outer boundary of cells, bilayer

- protective barrier, has transporters and facilitates signaling

Question 2

nucleus

Answer 2

contains the genome

-principle site for DNA and RNA synthesis

Question 3

Cytoplasm

Answer 3

• consists of cytosol and cytoplasmic organelles

- intermediary metabolism

Question 4

endoplasmic reticulum

Answer 4

• Rough ER: ribosomes attached (make up large percentage of total pancreatic exocrine cell membrane)
• Smooth ED: no ribosomes
• overall site for protein synthesis, lipid synthesis, protein folding, and storage of Ca2+

Question 5

Golgi apparatus

Answer 5

• stacks of disc-like compartments

- post translational changes on proteins and lipids, trafficking

Question 6

mitochondria

Answer 6

• outer and inner membrane and matrix
• make up 20% of cytoplasmic volume
• inner membrane (makes up large portion of liver hepatocyte cell membrane)
• makes ATP, signaling, cell differentiation and cell death

Question 7

lysosomes

Answer 7

• contain digestive enzymes that degrade organelles and biomolecules

Question 8

peroxisomes

Answer 8

• small vesicular compartments that contain enzymes used in oxidation reactions
• contain a number of enzymes that form H2O2
  Functions: syntesize and degrade H2O2, beta oxidation of long-chain fatty acids, bile acid and cholesterol synthesis, detoxify EtOH

Question 9

3 topological compartmentalizations

Answer 9

1) nucleus and cytosol (communicate through nuclear pore complex)
2) organelles in secretory and endocytic pathways (ER, golgi apparatus, endosomes, lysosomes) communicate through vesicles
3) mitochondria

Question 10

rough endoplasmic reticulum

Answer 10

• functions: proteins modified and assembled, protein - segregation, export from the cell
• cells that make secreted proteins have lots of RER
• mechanism by which secreted proteins are directed to the ER is explained by signal sequence
• most proteins exit the RER in vesicles transported to the cis portion of the golgi apparatus

Question 11

smooth endoplasmic reticulum

Answer 11

• unlike RER in that is lacks ribosomes and tubular cisternae
• functions: glycogen metabolism, lipid synthesis, phospholipid synthesis, detoxification, steroidogenesis, calcium regulation
• abundant in cells that make steroids or lipids

Question 12

golgi appartus

Answer 12

• cluster of flattened stacks of sacs called cisternae
• has two distinct faces 1) entry (cis) face [near ER] and 2) exit (trans) face [near PM]
• functions: modification of carbohydrates, synthesis polysaccarides, sorting secretory products, packing and storing secretory products into granules or vesicles

Question 13

types of vesicles

Answer 13

1) clathrin- coated vesicles (transport from golgi to lysosomes) (exocytosis and endocytosis pathyways) (cholesterol)
2) COP- coated vesicles (COP1 transport between stacks in golgi apparatus and COP2 is from the ER to the golgi apparatus)

Question 14

lysosomes

Answer 14

• recycling system of the cell
• contains hydrolytic enzymes that are most active at acidic pH
• remove material from outside the cell as well as obsolete components of the cell

Question 15

primary lysosomes

Answer 15

• storage site of lysosomal hydrolases

- no digestive events, inactive enzymes, homogenous

Question 16

secondary lysosomes

Answer 16

• engaged in catalytic process
• digestive enzymes (low pH of ~5.5)
• active enymes
• heterogeneous

Question 17

3 pathways for intracellular digestion

Answer 17

1) phagocytosis (cell or particle from outside cell)
2) autophagy (damaged organelle)
3) receptor-mediated endocytosis (macromolecules)

Question 18

familia hypercholesterolemia

Answer 18

• mechanism of cholesterol uptake is disrupted
• characterized by elevation of LDL, the predominant cholesterol transport protein in the plasma
• defect is mutation of gene encoding for LDL receptor

Question 19

Zellweger Spectrum disorders

Answer 19

• caused by defects in the assembly of the peroxisome
• Zellweger syndrome is characterized by an absence or reduced number of peroxisomes in the cells
• congenital, usually causes death in the first year of life

Question 20

organelles that originated from bacteria

Answer 20

• mitochondria and chloroplasts

Question 21

evolution of mitochondria

Answer 21

• eukaryotic cell engulfs aerobic prokaryotic cell by endocytosis
• mitochondria evolved to retain their own DNA

Question 22

mitochondria and diseases

Answer 22

• changes in mitochondrial tRNAs have been linked to over 200 disease states
• mitochondrial diseases are sometimes caused by mutations in the mt DNA that affect mitochondrial function