Cells and organelles

Question 1

What are the properties of cells?

Answer 1

1. They are microscopic packages that act as individual cells
2. Originate from pre-existing cells
3. They die
4. Their internal processes allow them to change/adapt/respond to their external environment

Question 2

Describe the plasma membrane that encloses cells?

Answer 2

A semi-permeable membrane, that is composed of a bi-layer of lipid molecules with added protein molecules

Question 3

How is mRNA passed from nucleoplasm to cytoplasm?

Answer 3

Via nuclear pores that are selective aqueous channels for transport

Question 4

What is the function of ribosomes? Talk about the two different types.

Answer 4

Make proteins by decoding/ translating mRNA
Two different types:
1. Free ribosomes: produce cytosolic proteins
proteins made here will be floating in the cytosol or transported to organelles
2. Bound to ER: produce proteins pushed into ER

Question 5

How is the DNA packaged?

Answer 5

via proteins called histones that form chromatin

Question 6

What are the two types of chromatin?

Answer 6

Euchromatin (most active genes) and heterochromatin (densely packaged with proteins)

Question 7

How is the Golgi specifically oriented?

Answer 7

Cis: reception site from the ER
Medial
Trans: exist for vesicles to move to cell surface

Question 8

Describe the two types of secretion

Answer 8

Constitutive: default pathway used to replenish material at the plasma membrane and other membrane-bound organelles

Regulated: terminated in secretory vesicles that store secreted materials until a signal triggers fusion with plasma membrane

Question 9

What are the functions of rough ER?

Answer 9

1. Site of membrane synthesis
2. Modifies proteins (adds sugars)
3. Quality control (monitor correct folding)
4. Signals stress when secretion is blocked or poorly folded proteins

Question 10

How does rough ER monitors correct folding, and where it occurs?

Answer 10

Happens in cystic fibrosis. CFTR

Question 11

Secretory vesicles releases content by?

Answer 11

Exocytosis

Question 12

How do vesicles more toward and away from golgi?

Answer 12

Microtubule tracks

Question 13

What is the centre for organising microtubules?

Answer 13

Centrosome, contains two centrioles that has 9 array of microtubule triplets

Question 14

How does uptake take place? for large proteins and smaller molecules?

Answer 14

Endocytosis - Phagocytosis (specific and enhanced by certain proteins) - Pinocytosis (non-specific and samples the substances)

Question 15

How does degradation occurs?

Answer 15

Cargo internalised are taken to endosomes then passed to lysosomes

Question 16

How is vesicle budding regulated?

Answer 16

It is clathrin coat regulated. Vesicle budding is aided by molecular scaffold support and one of the scaffold coat is clathrin that helps form a vesicle

Question 17

What are the subunits of microfilaments?

Answer 17

Actin and myosin (motility)

Question 18

What are the subunits of microtubule?

Answer 18

Tubulins

Question 19

What are the subunits of intermediate filaments?

Answer 19

Keratins (in cytoplasm) and Lamins (suppport nuclear envelope)

Question 20

Apoptosis can be useful to form digits but it can go wrong resulting in?

Answer 20

Syndactylism: partial or total webbing connecting 2 or more digits

Question 21

How do cells communicate?

Answer 21

1. Endocrine (long signalling)
2. Paracrine (local signalling)
3. Neuronal (rapid secretion of vesicles across synapse)
4. Contact dependent (membrane bound signal molecule)