KA2: Proteins: The synthesis and transport of proteins Flashcards

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1
Q

What do eukaryotic cells have?

what do they do?

A

*system of internal membranes
*increases the total area of membrane

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2
Q

why do eukaryotes have a relatively small surface area to volume ratio?

so why can plasma membrane of eukaryotic cells not carry out all the vital functions carried out by membranes?

A

due to their size

the plasma membrane is too small an area

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3
Q

Describe the structure of the endoplasmic reticulum

A

forms a network of membrane tubules continuous with the nuclear membrane

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4
Q

Describe the structure of The Golgi Apparatus

A

a series of flattened membrane discs

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5
Q

Describe the structure of lysosomes

A

membrane bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates

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6
Q

Describe the role of vesicles

A

transport materials between membrane compartments

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7
Q

Where are lipids and proteins synthesised?

A

ER

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8
Q

where does the synthesis of all proteins begin?

A

in cytosolic ribosomes

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9
Q

Describe the difference between the rough er (RER) and smooth er (SER)

A

Rough ER=> has ribosomes on its cytosolic face

Smooth ER=> lacks ribosomes

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10
Q

Give the location where lipids are produced

A

the SER and inserted into its membrane

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11
Q

Give the location where cytosolic proteins are produced

A

completed in the SER, and remain in the cytosol

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12
Q

Describe the location of transmembrane protein production

A
  • Transmembrane proteins carry a signal sequence
  • halts translation and directs the ribosome synthesising the protein to dock with the ER
  • forming RER
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13
Q

what is a signal sequence?

what does it determine?

A

a short stretch of amino acids at one end of the polypeptide chain

the eventual location of a protein in a cell

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14
Q

translation continues after __________, and the protein is _________ into the __________ of the ___ .

A

*docking
*inserted
*membrane
*ER

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15
Q

What happens to the proteins when they are in the ER?

A

-transported by vesicles that bud off from the ER

-fuse with the Golgi apparatus

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16
Q

What happens to proteins as they move through the golgi apparatus?

A

they undergo post translational modification

17
Q

explain how molecules move through the golgi discs

A

*in vesicles that bud off from one disc and fuse with the next one in the stack

18
Q

describe the actions of enzymes in the Golgi

what is the major modification?

A

*catalyse the addition of various sugars in multiple steps to form carbohydrates

the addition of carbohydrate groups is the major modification

19
Q

What do the vesicles that leave the golgi apparatus do?

A

take proteins to the plasma membrane and lysosomes

20
Q

What do vesicles move along and what do they do?

A

They move along microtubules to other membranes and fuse with them within the cell

21
Q

Give the location of translation of proteins which are secreted from the cell

A

The RER and enter its lumen

22
Q

Give examples of a secreted protein that require proteolytic cleavage to become active

A

Digestive enzymes and peptide hormones

23
Q

Describe the secretory pathway

A

-proteins move through the gorgi apparatus and are packaged into secretory vesicles

-vesicles move to andf use with the plasma membrane releasing proteins out of the cell

24
Q

what are many secreted proteins synthesised as?

A

inactive precursors and require proteolytic cleavage to produce active proteins

25
Q

what is proteolytic clevage?

give an example of secreted proteins that require proteolytic cleavage to become active

A

another type of post-translational modification

digestive enzymes

26
Q

What does binding cause?

A

conformational change in the protein, which may result in a ltered function and may be reversible