lecture 5 - endomembrane system Flashcards

1
Q

How is the endomembrane system interconnected?

A

By vesicles which move between the organelles

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2
Q

What are the key organelles of the endomembrane system?

A

Nuclear envelope, endoplasmic reticulum (smooth and rough), golgi apparatus, vesicles, lysosome, vacuoles, plasma membrane

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3
Q

What is the structure of the endoplasmic reticulum (ER)

A

A series of flattened sacs, connected by tubules, and divided into two regions (smooth and rough).

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4
Q

What are the spaces within the ER?

A

lumen

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5
Q

What are the key functions of the smooth ER?

A

Metabolises carbohydrates, synthesise lipids for membranes, detoxificate toxins, store calcium ions.

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6
Q

Is the amount of sER in a cell fixed?

A

No - it can change to fit cell function requirements.

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7
Q

Does the sER contain ribosomes?

A

No

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8
Q

Why does the rER have a rough appearance?

A

It has ribosomes.

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9
Q

What is the function of ribosomes?

A

They synthesise proteins in the rER

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10
Q

Where are proteins processed in the rER?

A

In the lumen

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11
Q

Where does synthesis of cytoplasmic proteins occur?

A

The free ribosomes

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12
Q

How do proteins leave the ER?

A

In vesicles that ‘bud off’ the surface of the ER.

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13
Q

What is the main function of the golgi?

A

Receive, sort and distribute proteins from the rER.

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14
Q

What are the two faces of the golgi?

A

Cis and trans face

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15
Q

What part of the golgi do vesicles arrive at?

A

The cis face

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16
Q

Where do processed vesicles leave the golgi?

A

The trans face

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17
Q

What is glycosylation, and where does it occur?

A

Addition of carbohydrates to, or modification of, proteins, in the golgi

18
Q

What do golgi produce?

A

Polysaccharides

19
Q

How does the golgi sort proteins?

A

By adding markers to the proteins that direct them to the appropriate vesicles for transport.

20
Q

How does the golgi direct leaving vesicles?

A

Vesicles leaving the trans face are tagged with short proteins that direct them to the targets, and act as ‘docking sites’ when they get there.

21
Q

What is bulk transport?

A

A process that allows lots of substance to pass through the cell membrane, in one place, at the same time

22
Q

What is exocytosis?

A

The process of transporting glycoproteins out of the cell into the extracellular matrix via vesicles.

23
Q

What is constituitive exocystosis?

A

A continuous default process, where proteins are transported to the extracellular matrix.

24
Q

What is regulated exocytosis?

A

The release of hormones and neurotransmitters from the cell, only when the required signal is received.

25
Q

What is endocytosis?

A

The transport (in bulk) of molecules and particles into the cell from the extracellular matrix.

26
Q

What is phagocytosis?

A

The process in which food vacuoles absorb and break down food or bacteria particles with the aid of lysosomes.

27
Q

Where does phagocytosis occur commonly in humans?

A

In macrophages, a type of white blood cell, which attacks bacteria.

28
Q

How do macrophages kill bacteria?

A

They engulf detected bacteria (which release proteins that attract macrophages), trap them in the phagosome, and break them down using enzymes from lysosomes.

29
Q

What is pinocytosis?

A

The process in which vesicles ‘drink up’ extracellular fluid, and take with it various solutes into the cell.

30
Q

What is the function of the coat protein in pinocytosis?

A

Aids in the formation of the up-take vesicle

31
Q

Why is pinocytosis non-selective?

A

Any solutes dissolved in the extracellular fluid captured will be brought into the cell.

32
Q

What is receptor-mediated endocytosis?

A

A specialised form of pinocytosis, in which receptors in vasicles bind to and capture specific solutes from the extracellular fluid and bring them into the cell.

33
Q

Where are lysosomes made?

A

The rER. (rough endoplasmic reticulum) and golgi body. rER makes proteins that create the lysosome enzymes. These enzymes are then enclosed by vesicles from the golgi complex

34
Q

How do lysosomes aid food vacuoles?

A

They fuse with the vacuoles, passing on their digestive enzymes.

35
Q

What feature of the lysosome keeps the enzymes active?

A

Acidic interior

36
Q

What is autophagy?

A

When lysosomes digest and recycle unwanted cellular material.

37
Q

How is programmed cell death facilitiated?

A

Through lysosomal digestion of organelles.

38
Q

Where are vacuoles derived from?

A

the rER and golgi. ( in plants, the vacuole is formed when vesicles from the rER and golgi merge together)

39
Q

What is the function of the central vacuole in plant cells?

A

The perform lysosome-like fucntion and are able to absorb water to allow the cell to grow without the need for a large increase in the amount of cytoplasm.

40
Q

What is the size of a ribosome?

A

25-30nm

41
Q

What are the enzymes used by lysosomes?

A

Hydrolytic enzymes

42
Q

How are phospholipids delivered to the cell membrane?

A

Via exocytosis