click below
click below
Normal Size Small Size show me how
Golgi Secretion
Question | Answer |
---|---|
Outside or inside the cell? Collagen, keratin, nuclear lamina proteins, lamins, N-linked glycosylation, disulfide bridges, isomerases, GPI linked proteins? | Outside, Inside, inside, inside, outside, outside, in ER, outside |
What are free ribosomes? | Proteins generated in the cytoplasm |
What is golgi? | A series of flattened sacs that sit on top of eachother |
What are the common places that proteins can go? | The plasma membrane, outside the cell for secretion or lysosome |
Proteins that are typically synthesized in the cytosol on free ribosomes are destined to what places? | Nucleus, peroxisomes, mitochondira or cytoplasm |
Where do endocrine cells secrete their product? | Into the blood system which is on basal side |
Where do exocrine glands secrete? | Into a ductal system into the lumen. Granules are on apical side |
Name the types of secretion | Merocrine, Apocrine and holocrine |
Describe merocrine secretion | A simple vesicular trafficking and release mechanism. It sits in cytoplasm or goes straight to plasma membrane and dumps its contents outside the cell |
Describe apocrine secretion | The product in cytoplasm is shert with a little bit of the plasma membrane to the extracellular space |
What is apocrine glands? Where does apocrine secretion occur? | Apocrine are specialized sweat glands. It occurs in mammary glands. |
How do mammary glands release lipids? Proteins? | Release lipids through aporcine secretion and protein through merocrine secretion |
Describe holocrine secretion | Entire cell body ruptures and whole cytoplasmic region is released |
What is an example of holocrine secretion | Sebaceous gland which is found in skin |
How do proteins get out of a cell? | Golgi vesicle secretion and microvesicles(small membrane-enclosed sac) |
Describe atypical transport across the plasma membrane | Need the signal sequence or signal peptide to get into vesicles to get into ER to golgi and out |
What happens to proteins withough a signal peptide? | Get across the plasma membrane through another unknown mechanism |
Do axons have tight junctions? | No, they have different components than cell body of dendrites |
What does the signal sequence on ribosomes help? | It will recognize the particle which will link it to the ER |
If a protein is destined for lysosome, cell surface or extracellular matrix where is it synthesized? | ER/Golgi pathway |
What does the K-D-E-L stand for in the KDEL sequence? | K=Lysine, D=Aspartic Acid, E=Glutanic acid, L=Leucine |
Describe Anterograde transportation in Golgi | From cis face to cis cisternae to medial cisternae to trans cisternae |
What happens to proteins at the trans golgi network? | Either packed to go into vesicles for lysosomes or plasma membrane |
If proteins are going to plasma membrane what do they do to get there? | Sit in vesicles that sit in cytoplasm until signal tells it to release its product or constitutively go to plasma membrane |
Can you see golgi under light microscope? | If you have fluorescent imaging |
How is the nucleus in golig? | Perinuclear |
Where do microtubules come out? | Centrosomes |
How are golgi stacks anchored? | By the microtubules so they position around perinuclear where microtubules are radiating from |
What type of tissue do plasma cells sit in? | Loose connective tissue |
How are the nucleus in plasma cells? | Eccentrically place nucleus with some heterochromatin |
What do plasma cells secrete? | A lot of antibodies |
Do plasma cells have vesicles? | No, antibodies are made and just released |
Are plasma cells basophillic? | Yes, a lot of RNA |
Why are things made in the lumen of the ER facing outside of the cell? | Product is facing the lumen of the ER, then comes to a vesicle facing the lumen of the vesicle, the vesicle fuses with cisternae it faces the lumen of the cisternae and is modified in golig cisternae. Fuses with plasma membrane and faces outside. |
What do cis cisternae and trans cisternae almost look like? | Cis cisternae looks like ER and trans cisternae looks like plasma membrane |
Golgi is a polar organelle. If you stain it with osmium for lipids what lights up? | Only cis lights up |
If you stain golgi for NADPase what lights up? | Medial cisternae light up |
What do you need in order to target hydrolases to lysosomes? | Mannose 6-phosphate |
What are some functions of golgi? | Sulfation of proteoglycans and proteolytic events |
What does insulin exist as and what is it synthesized as? | Exist as a alpha and beta chain. It's synthesized as proinsulin where you have a connecting peptide |
After insulin is secreted through ER/golgi what happens when it is packed in secretory vesicles? | There is a proteolysis event where connecting peptide gets clipped off |
Why can you measure the connecting peptide? | Because it is always packaged one to one with insulin |
How does N-linked glycosylation occur? | Sugars are linked to asparigine group which has nitrogen. Mannose is puto onto Asparagine. glycosylation in lumen of ER. modification starts in ER and continues in golgi. |
What precursor in the lumen helps with modification of asparigine with a N-linked sugar group? | dalichol phosphate (contains high mannose sugar group that gets transferred onto asparigines) |
Where are the enzymes for O-linked glycosylation found? | In the golgi and cytoplasm |
How many sugars at a time do the enzymes put on in O-linked glycosylation? | One by one |
Where are N-linked glycoylation found? O-linked glycosylation? | N-linked: Extracellular, Plasma membrane, lysosomes, golgi and ER. O-linked: Everywhere |
Name functions of glycosylation | protection, adhesion, solubility, recognition |
How do mannose 6-phosphate target proteins? | The signal sequence drives the right protein to the ER. If M6P is in lumen of ER or golgi, it will drive protein to lysosomes |
What is on the 6th carbon of M6P and what happens there? | Acetyl-glucosamine is linked to 6th carbon. A enzyme takes out glucosamine and a phosphate group is left. (phosphotransferase is also required) |
What happens if enzymes are not present in certain diseases for M6P? | If a protein is not tagged with M6P it will end up in extracellular |
What does KDEL do? | Drives components back to ER. Proteins captured and bought back contain KDEL sequence. |
What do KDEL receptors contain? | An active binding domain facing the lumen of the vesicle |
What are the affects of the cisternae maturation process? | The cis face can become the medial face and so on. Some proteins can't get into vesicles |
Difference between constituitive and regulated secretory of proteins to plasma membrane | constituitively: go to plasma membrane. Regulated secretion: vesicles wait in cytoplasm for signal |
Describe examples of regulated secretion, Insulin and mast cells | Insulin: When sugar level goes up, it signals insulin to be secreted from pancreatic beta cells. Ex. Mast cell, histamin, heparin sulfate sit there til signal comes and responds with exocytosis |
What portion of the gland is the acinar unit? | The secretory portion |
Descibe the secretory product mucus | Highly glycosylated protein, tend to have nuclei that are flattened to the basal end |
Describe the secretory product serous | Protonaceous, nuclei tend to retain its circular shape. It is watery and non-glycosylated |
What stains paler, mucus or serous? | Mucus stains paler |
What are demilunes? | They are capping portions of secretory units |