Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

4BBY1030 > Cell structure and Organelles > Flashcards

Cell structure and Organelles Flashcards

L2 L4

1
Q

Why aren’t viruses organisms?

A

They can’t reproduce independently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the function of the plasma membrane?

A

Maintains composition of external and internal compartments
Used to communicate between cells
Import and export of molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are defining features of prokaryotes?

A

They have no nucleus and are unicellular

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are defining features of eukaryotes?

A

They contain a nucleus and membrane bound organelles with a cytoskeleton. Usually multicellular, by not always (yeast for example is a unicellular eukaryote)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are archaea?

A

Extremophile prokaryotes. Environmental conditions are extreme yet these organisms are specifically adapted to live in them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the nucleus’ features?

A

Double membrane which forms nuclear envelope. There are nuclear pores in the envelope for milecules to enter and exit nucleus.
Nucleus contains nucleolus which is the site of ribosome synthesis.
DNA is packages with histones to form chromosomes in the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of rER and sER?

A

rER function is to package proteins produced by the ribsomes attached to the rER. Proteins produced in rER are secreted by the cell.

sER are the site of lipid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of the Golgi appartus?

A

Package proteins into secretory vesicles and modify them by adding sugars to them. The secretory vesicles are transported to where they need to go by the Golgi.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do lysosome do?

A

Contains enzymes used to degrade unwanted proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are peroxisomes?

A

Contains catalase to oxidise H2O2.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do the mitochondria do?

A

Site of aerobic respiration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the cytosol?

A

The medium within the cell for molecules to travel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a specialised function of the lysosome?

A

The pH of the lysosome is 5. If lysosome bursts open, enzymes would be outside the optimal pH range so would not function so cell components wouldn’t damaged.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What 3 things the cytoskeleton made of?

A

Intermediate filament, microfilament (actin filament) and microtubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the diameter of microfilaments?

A

7nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the diameter of intermediate filaments?

A

10nm

17
Q

What is the diameter of microtubules?

A

25nm

18
Q

What is the structure of microfilaments?

A

Identical globular actin form filaments. Two of these filaments wind into a chain forming the microfilament.

The globular actin all point in the same direction giving the strands polarity.

19
Q

What are the two ends of the actin filaments?

A

-ve is the pointed end and the +ve end is the barbed end.

20
Q

How do microfilaments produce tread-milling?

A

Actin is bound to ATP or ADP

Growth is faster on the barbed end as ATP-actin binds more favourably at the barbed end.
There is a net loss at the pointed end and a net gain at the barbed end leading to tread-milling allowing movement.

21
Q

How does nucleation of actin filament occur?

A

For nucleation to occur, the G-actin trimer must be formed first.
It is energetically unfavourable for the trimer to be formed because of rapid dissociation of actin monomers. Dissociation rate reduces as more monomers are added.
Once the trimer is formed, it becomes favourable for the trimer to bind to the actin filament.

22
Q

What controls actin filament stability and disassembly?

A

When the trimer binds to the barbed end, ATP on the actin is hydrolysed to ADP. Hydrolysis decreases strength of binding between monomers so decreases the stability of the filament.

Phosphate dissociates slowly so only some of the polymerised subunits are converted to ADP bound actin. In this way ATP hydrolysis acts as a timer for filament stability and disassembly. ATP hydrolysis helps the cell to disassemble filaments after they are formed

23
Q

What is actin polymerisation regulated by?

A 
Actin monomer binding proteins
Actin nucleators
Actin filament elongation factors
Actin filament capping proteins
Actin filament severing proteins
Actin filament cross-linking proteins
24
Q

How do actin filaments produce movement of cells?

A

Barbed ends of the actin filaments face the plasma membrane.
Actin filaments are anchored to the surface on which the cell is crawling.
Elongation of these anchored actin filaments pushes the membrane forward.
The retraction at the rear of the cell is mediated by myosin motors pulling on antiparallel bundles of actin filaments.

25
Q

How do actin filaments produce movement of muscles?

A

There are myosin filaments as well as actin filaments in muscle cells.
The myosin head binds to actin and move along the actin filament to produce movement.

26
Q

What is the structure of microbtubules?

A

Tube-like structure composed of dimers of GTP/GDP bound α- and β-tubulin which are all arranged in the same direction as 13 parallel protofilaments.
The microtubules towards the centromere is the -ve end, and away from the centromere is the +ve end

27
Q

Where are microtubules located in the cell?

A

There are found all throughout the cell, all microtubules emitting from the centrosomes.

28
Q

Where are microfilaments located in the cell?

A

They line the edge of the cell.

29
Q

Where are intermediate filaments located in the cell?

A

They are found interspersed throughout the cell, they also go beyond the cell, going through desmosomes to fill the space of adjacent cells and hemidesomosomes to link to connect to extracellular matrix.

30
Q

How do microtubules grow?

A

Microtubules emit from the centrosomes

31
Q

What is the function of the microtubules?

A

Due to dynamic instability, the +ve end of the microtubules can explore the cytoplasm for chromosomes during mitosis or delivery of vesicles to the plasma membrane

32
Q

What is the function of intermediate filaments?

A

IT strengthen cells against mechanical stress

33
Q

What is dynamic instability?

A

Microtubules grow, then rapidly shorten followed by regrowth.
Hydrolysis of GTP bound β-tubulin drives dynamic instability because microtubules with GDP bound β-tubulin are unstable.

34
Q

What are motor proteins?

A

Kinesins and Dyneins move ‘cargo’ to and from the microtubules utilising ATP hydrolysis.
Kinesins move to the +ve end
Dyneins move to the -ve end

35
Q

What is the cis and trans region of the Golgi apparatus?

A

Cis region is the region that faces the rER and the trans region is the region that faces the plasma membrane.

4BBY1030 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions