IMMS

Question 1

What is a nucleosome?

Answer 1

DNA wrapped around 8 histone proteins

Question 2

What is chromatin?

Answer 2

Repeating units of nucleosomes

Question 3

Describe the nucleus

Answer 3

• Largest membrane bound organelle (Double membrane
• Stores and transfers genetic information

Question 4

Describe the nucleolus

Answer 4

• Site of transcription
• Forms rRNA

Question 5

Describe the mitochondria

Answer 5

• The site of krebs cycle (matrix)
• The site of oxidative phosphorylation (Intermembrane space)

Question 6

Describe the golgi and its different parts

Answer 6

Modifies and processes rER products

• Cis-golgi: faces the nucleus, accepts vesicles from rER
• Medial golgi: modifies proteins
• Trans-golgi: faces away from the nucleus, forms secretory vesicles

Question 7

Describe the rough endoplasmic reticulum

Answer 7

• Rough due to ribosomes
• Site of protein synthesis

Question 8

Describe the smooth endoplasmic reticulum

Answer 8

The site of lipid synthesis

Question 9

Describe ribosomes

Answer 9

• They have 2 subunits
• They read mRNA and create a polypeptide chain

Question 10

Describe the cytoplasm

Answer 10

The site of glycolysis

Question 11

Describe vesicles

Answer 11

Small membrane bound organelles which transport material and exchange cell membrane between compartments

Question 12

Describe the cell membrane structure

Answer 12

Phospholipid bilayer
- 2 Layers of phospholipids
- Hydrophilic head and hydrophobic tail
- Contains proteins
- Contains cholesterol

Question 13

What are the functions of the cell membrane?

Answer 13

• Acts as a physical barrier
• Selective permeability
• Endo/ exocytosis
• Cell signalling

Question 14

What are the functions of cytoskeleton filaments?

Answer 14

• Support cell shape
• Form cell junctions

Question 15

What are the 3 different types of cytoskeleton filaments?

Answer 15

• Microtubules
• Intermediate filaments
• Microfilaments

Question 16

What is the diameter of microtubules?

Answer 16

25nm

Question 17

What is the diameter of Intermediate filaments?

Answer 17

10nm

Question 18

What is the diameter of microfilaments?

Answer 18

5nm

Question 19

Where are microtubules found?

Answer 19

They arise from the centromere and are found in all cells except RBCs

Question 20

Where are intermediate filaments found?

Answer 20

They are transmembrane proteins that can spread through tissues

Question 21

Where are microfilaments found?

Answer 21

They form a mesh on the inner surface of the cell membrane

Question 22

What are the different types of cell junctions?

Answer 22

• Tight junctions
• Adherens
• Desmosomes
• Gap junctions
• Hemi-desmosomes

Question 23

Describe tight junctions

Answer 23

• They are found in epithelial tissues
• They form a continuous barrier between adjacent cells, preventing the passage of molecules between them
• They play a role in maintaining cell polarity and preventing leakage across cell layers

Question 24

Describe adherens junctions

Answer 24

• Found in epithelial tissues and other tissues
• Involve the interaction of actin filaments between adjacent cells

Question 25

Describe desmosomes

Answer 25

- Common in tissues subjected to mechanical stress, such as skin and cardiac muscle - Involve the interaction of cadherins and other proteins, connecting intermediate filaments of adjacent cells - Provide strong adhesion, preventing cells from being pulled apart

Question 26

Describe gap junctions

Answer 26

- Found in many cell types, especially in tissues that require coordinated activity, like cardiac and smooth muscle - Consist of connexin proteins forming channels between adjacent cells, allowing direct communication and exchange of ions and small molecules - Facilitate synchronised activities, such as muscle contraction

Question 27

Describe hemidesmosomes

Answer 27

* Found in epithelial tissues. * Anchor cells to the extracellular matrix by connecting integrins to intermediate filaments inside the cell. * Provide stability and support to the epithelial layer.

Question 28

What are the different types of membrane proteins and what do they transport?

Answer 28

- Uniport- 1 substance - Symport- 2 or more substances in the same direction - Antiport- 2 or more substances in opposite directions