Lecture 6 - Cell Organelles

Question 1

What does the cytoplasm contain and what is it composed of ?

Answer 1

• Contains all cellular components between the membrane and nucleus
• Composed of cytosol which is 75-90% water with dissolved ions and organelles

Question 2

What is the cytoskeleton and what are the three main types ?

Answer 2

• network of protein filaments extending through the cytoplasm, maintains cell shape and internal organisation
• microfilaments
• intermediate filaments
• microtubules

Question 3

Describe the role of microfilaments

Answer 3

Surround the edge of the cell - actin and myosin and act as mechanical support forming microfilaments

Question 4

Describe the role of intermediate filaments

Answer 4

Very strong and stabilise the organelles

And are placed at weaker points within the cell to act as shock absorbers

Question 5

Describe the roll of microtubules

Answer 5

Long unbranched tubules made from tubulin
Form in the centrosome and help with movement of organelles during cell division
Help to make cilia and flagella

Question 6

What is a centrosome, it’s function and the two main types ?

Answer 6

The main microtubule, the centre and regulator of the cell cycle and regulation of growth of mytotic spindle
Consists of cylindrical - 9 clusters of micro tubule triplets at 90 degrees
And pericentriolar - surrounds centrioles and consists of tubulin rings

Question 7

Describe a villi and it’s function

Answer 7

Made from microtubules, numerous short projections each one anchored to a nasal body and microtubule core. 9 pairs encircling a central pair a closed in a membrane . Used to transport fluid along the cell surface

Question 8

Describe flagella and the function

Answer 8

Longer than cilia and found on a cell outer, used for swimming and movement

Question 9

Describe the role of the endoplasmic reticulum (rough and smooth )

Answer 9

A network of flattened sacks and tubules extending from the nuclear envelope
Rough ER- proteins made by ribosomes on the surface are sorted and processed
Smooth ER - large range of enzymes synthesises fatty acids and steroids, helps the liver release glucose and detoxify lipid soluble drugs
Also stores Ca2+ for muscles

Question 10

Describe the golgi

Answer 10

3-20 membranous cisternae (sack like structures)
Cis - recurved proteins removed from RER
Trans - used for shipping and forms vesicles
Anterograde - transport inside of cell from centre to periphery

Question 11

Describe lysosomes and it’s function

Answer 11

Digests substances entering the cell: worm out organelles and entire cells
The isolating membrane elongates and engulfs forming an autophagosome to be destroyed by lysosomes containing lysosome hydrolyses

Question 12

What is autophagy?

Answer 12

Destruction of organelles / proteins in the cell

Question 13

What is auto lysis ?

Answer 13

Destruction of the whole cell

Question 14

What is Tay-Sachs disease ?

Answer 14

Mutation of the lysosomal enzyme Hex A which destroys nerve cells due to glycolipid build up

Question 15

What is a peroxisome and it’s function ?

Answer 15

Similar to lysosomes but smaller
They contain oxidises and they are involved in amino acid and fatty acid metabolism
Contain catalyse enzymes to protect against toxic effects of hydrogen peroxide

Question 16

What are Proteasome’s function?

Answer 16

They degrade free cytosolic proteins and are important in the negative feedback system - also contain protease enzymes

Question 17

What is the function of mitochondria ?

Answer 17

Site or aerobic respiration, signalling cell differentiation and cell death
Cristae provide a large surface area for respiration.

Any mitochondrial abnormality can affect multiple organs

Question 18

Describe the nucleus and function

Answer 18

Double membrane to maintain integrity

Has many nuclear pores

Question 19

Describe the nucleoli

Answer 19

Clusters of protein DNA and RNA responsible for producing ribosomes