Cell Structure 2

Question 0

What are the identifying features of the rough endoplasmic reticulum?

Answer 0

stacks of flattened membrane bound compartments; surface is decorated with black dots (ribosomes); continuous with SER

Question 1

What is the only non-membrane bound organelle?

Answer 1

Ribosome.

Question 2

What would you find an abundance of in adrenocortico cells that synthesize hormones?

Answer 2

Smooth endoplasmic reticulum.

Question 3

What is an explanation for why alcoholics have enlarged livers?

Answer 3

Detoxification of lipid soluble drugs, metabolic waste and
ingested toxins by cytochromeP450 system happens in SER. Alcohol ends up in SER/cytochrome p450 system;
oxidative enzymes oxidize drugs (inactivates drug directly) or oxidizes down to a material that can be excreted. Alcoholics have large livers because liver cells have large amounts of SER to break down the alcohol.

Question 4

Where would you find large amounts of Ca+2 stored?

Answer 4

SER, which is involved in calcium homeostasis. Ca pumps can be used to sequester Ca from cytoplasm and store in SER, protein channels can be stimulated to open and release Ca
Skeletal muscle: sarcoplastic reticulum; regulates muscle contraction

Question 5

Where are integral and secreted proteins made?

Answer 5

Rough endoplasmic reticulum.

Question 6

Why is the RER also known as a plasma cell?

Answer 6

RER makes proteins that will be secreted. Plasma cell: makes antibodies, once stimulated, secretes proteins; secretory vesicles are packed with antibody.

Question 7

What is the initial site of posttranslational modification of proteins and lipids?

Answer 7

RER

Question 8

What are polysomes and what do they look like?

Answer 8

Polysomes or polyribosomes are several ribosomes all translating the same mRNA. They assemble in rosettes.

Question 9

Where does translation begin?

Answer 9

In cytoplasm. mRNA released from nucleus; enters cytoplasm
small subunit binds to mRNA; large subunit binds to complex
large subunit begins to translate mRNA into protein
if protein being synthesized is a soluble protein (actin) process will continue out in cytoplasm.

Question 10

What is the process of translation for proteins that are secreted or transmembrane?

Answer 10

if mRNA is a secreted or transmembrane protein; first 20 aa are extremely hydrophobic- called a signal sequence; bound by another protein out in cytoplasm called signal recognition particle; further translation stops
complex of RNA and ribosome floating around;
eventually comes into contact with surface of RER- signal recognition particle receptor, ribsome receptor binds- docks on SRP (ribosome receptor) complex, dissociates from polypeptide chain, pore is formed in membrane, translation reinitiaties into interior of RER

Question 11

What is the function of the golgi?

Answer 11

Further post-translational
modification of proteins
Assembly of multisubunit proteins
Protein sorting and packaging into secretory vesicles

Question 12

What are lysosomes filled with?

Answer 12

Acid hydrolases. These will show up as blue.

Question 13

Where do lysosomes come from?

Answer 13

Derived from trans Golgi network-
Membranes contain
mannose-6-phosphate
receptors that bind lysosomal enzymes

Question 14

What are secondary lysosomes?

Answer 14

Result from fusion of primary lysosome with late endosome. Primary lysosome buds of golgi and fuses with endosome (might have LDL inside); contents of endosome are exposed to lysosome enzymes; begin to break down material
secondary lysosome: materials undergoing various stages of degregation; digesting contents of endosome

Question 15

In what type of cells will you see the most lipofuscin?

Answer 15

sympathetic neurons
pigment is lipofuscin
gradually accumulates
terminally differntiated cells continue to accumulate insoluble material

Question 16

What are the hallmarks of lysosomal storage diseases?

Answer 16

Characterized by build up of substrate material that would normally be broken down by enzymes
For example: Tay Sachs-when gangliosides can’t be broken down, disrupts function of neurons
-early infant onset, by 2 years of age become vegetative, die by age of 3

Question 17

What can you expect to see with Pompe disease?

Answer 17

symptoms are in heart because the heart has large glycogen stores, massive enlarged hearts because of accumulation of glycogen granules; die by 2-3 yrs.

Enzyme deficient:glucosidase
Result: accumulation of glycogen in heart

Question 18

What is affected by Hurler disease?

Answer 18

Dermatan sulfate build up in skeletal system. Sulfate found in cartilage and bone.

Question 19

What substance builds up in Niemman-Pick patients due to deficiency in sphingomyelinase?

Answer 19

Sphingomyelin. Affects CNS.

Question 20

What do peroxisomes metabolise?

Answer 20

Fatty acids.

Break down of long-chain fatty acids to produce Acetyl CoA and hydrogen peroxide

Question 21

what is the main enzyme in peroxisomes?

Answer 21

catalase. catalase breaks down the hydrogen peroxide produced in fatty acid metabolism into oxygen and water

Question 22

Half of alcohol consumed is broken down by what molecule?

Answer 22

Peroxisome.

Question 23

What molecule is self-replicating?

Answer 23

Peroxisome.

Question 24

Where are enzymes of Krebs cycle located?

Answer 24

Mitochondrial matrix.

Question 25

Where is the ATPsynthase protein complex located?

Answer 25

Inner mitochondrial membrane.

Question 26

Why are mitochondrial granules important?

Answer 26

Important in binding Ca+2

Question 27

What is the main function of a mitochondria rich in cardiolipin?

Answer 27

cardiolipin: instead of 2 fatty acid chains; has 4 fatty acid chains
- function is to make membrane extremely impermeable to electrons and protons

Question 28

Where are protons pumped during oxidative phosphorylation?

Answer 28

Into intermembrane space.

Question 29

How do mitochondria replicate?

Answer 29

By fission. Maternal pattern of inheritence.

Question 30

What are inclusions?

Answer 30

non living comoponents of cells
things cells are storing; things cells created that will secrete
things cells are accumulating and can’t get rid of

•Glycogen granules
•Lipid droplets
•Pigment granules
- Lipofuscin, melanin
•Crystalline inclusions

Question 31

What is the outer nuclear membrane continuous with?

Answer 31

RER.

Question 32

What type of chromatin is actively being transcribed?

Answer 32

Euchromatin. Visually, disbursed in nucleus.

Question 33

What type of chromatin is found around the perimeter of the nucleus, in condensed and inactive form?

Answer 33

Heterochromatin.

Question 34

What is the site of RNA synthesis?

Answer 34

Nucleolus.

Question 35

What type of chromatin is organized into histones and is available for transcription?

Answer 35

Euchromatin. Heterochromatin is tightly coiled.

Question 36

If a molecule is 70 kdaltons, can is pass through the nuclear pore?

Answer 36

No. Only things that are 60 kdaltons or less.