Cell Ultrastructure

Question 1

Mitochondria:
1)Outer membrane

2) Inner membrane
3) Matrix
4) Intramembranous space

Answer 1

1) Lipid synthesis & fatty acid metabolism
2) Respiratory chain for ATP production
3) Tricarboxylic acid cycle (Krebs)
4) Nucleotide phosphorylation (ADP to ATP)

Question 2

Rough Endoplasmic Reticulum:
1)Purpose

2)Structure

Answer 2

1) The site of protein synthesis

2) Rough due to the abundance of ribosomes and consists of highly folded membrane sheets.

Question 3

Smooth Endoplasmic Reticulum:

1) Purpose
2) Structure

Answer 3

1) Site of membrane lipid synthesis and processes and stores synthesised proteins
2) Highly folded flattened membrane sheets

Question 4

Golgi Apparatus/Body:
1)Purpose

2) The purpose of the first golgi
3) Medial golgi
4) Trans golgi network

What type of cell can the golgi apparatus be seen?

Answer 4

1) Processes and modifies macromolecules synthesised in the endoplasmic reticulum
2) Receives the SER vesicles and protein phosphorylation occurs here.
3) Modifies the products by adding sugars and forms complex oligonucleotides by adding sugars to lipids and peptides.
4) Proteolysis (breakdown of proteins), into active forms. It also sorts the molecules into vesicles which bud from the surface.

Plasma cells

Question 5

What are vesicles?

Give examples

Answer 5

Small, membrane bound organelles that transport and store material and exchange cell membrane between compartments.

Pinocytotic and phagocytotic vesicles are cell-surface derived.
Peroxisomes and lysosomes.

Question 6

What is the purpose of lysosomes?

Where are lysosomes derived from?

What pH do the enzymes work best at?

Therefore?

How is this maintained?

Answer 6

1) Contains digestive enzymes and therefore acts as a waste disposal system and is the site of breakdown for most molecules. They also break down debris from dead cells and bacteria, and damaged cell organelles.
2) The Golgi body
3) pH 5
4) Therefore, they are known as acid hydrolase.

The lysosome must maintain a constant pH of 5 by allowing the uptake of H+ ions though hydrogen ion pumps.

Question 7

Where can you find a lot of lysosomes?

Answer 7

In phagocytes to release lysozymes that digest phagosomes.

Question 8

What is the function of peroxisomes?

What are some examples of enzymes found in them?

Why is Beta oxidation essential?

Answer 8

1) It aids BETA OXIDATION as it contains enzymes that oxidase long FATTY ACID CHAINS.
2) Catalase, Urate oxidase and FAD-amino oxidase.
3) Allows the formation of two-carbon fragments which cells can use as a source for generating ATP

Question 9

What is the cytoskeleton and its purpose?

Answer 9

Filamentous proteins that brace the internal structure of the cell. This helps maintain the shape fo the cell and its internal organisation.

Question 10

What does the cytoskeleton contain?

Answer 10

• Microtubules
• Microfilaments (actin)
• Intermediate filaments

Question 11

Microfilaments:
What is the average size?

What is the purpose of it?

Answer 11

1) 5nm
2) Found in the cytoskeleton of cells and is mainly composed of actin. This forms a cell cortex on the inner surface of the membrane

Question 12

Intermediate filaments:
What is the average size?

What are the six different types of protein and where are they all individually found?

Answer 12

1)10nm

2)There are 6 types of proteins:
Cytokeratins: epithelial cells
Desmin: myocytes
Glial fibrillary acidic protein: astrocytic glial cells 
Neurofilament protein: neurons
Nuclear lamin: nuclei of all cells
Vimentin: mesodermal cells

Question 13

Microtubules:
What is the average size?

What is it made of?

How is this arranged?

How are microtubules derived?

What type of cells are microtubules found in?

Answer 13

1) 25nm
2) Tubulin
3) Alpha and beta tubulin proteins that are arranged in groups of 13, forming hollow tubes.
4) They are derived from 2 centrioles and can attach to the centrosome of chromosomes during mitosis.
5) All cells apart from erythrocytes because they have no nuclei thus no cell division occurs so microtubules are not needed.

Question 14

Name all the different cell storage products and inclusions

Answer 14

Lipofuscin
Lipids
Glycogen

Question 15

What is lipofuscin?

What does it contain?

Where is this mostly found?

Answer 15

1) A membrane-bound orange/brown pigment
2) It contains lipid-containing residue from lysosome digestion, peroxidation of lipids.
3) Mostly in older cells, heart and liver cells, and mostly in older people, as a ‘wear-and-tear’ pigment and thus, sign of ageing

Question 16

How are lipids viewed histologically?

Where are lipids mostly stored?

Answer 16

They are viewed as empty space because it is dissolved during processing.

In adipoctyes and the liver

Question 17

What is glycogen?

Where is it found?

How can glycogen normally be seen?

Answer 17

A polymer of CHO atoms that stores energy.

It is found in the cytoplasm of some cells and may be found in some disease.

Through an electron microscope.