IMMS Flashcards
What is a nucleosome?
DNA wrapped around 8 histone proteins
What is chromatin?
Repeating units of nucleosomes
Describe the nucleus
- Largest membrane bound organelle (Double membrane
- Stores and transfers genetic information
Describe the nucleolus
- Site of transcription
- Forms rRNA
Describe the mitochondria
- The site of krebs cycle (matrix)
- The site of oxidative phosphorylation (Intermembrane space)
Describe the golgi and its different parts
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
Describe the rough endoplasmic reticulum
- Rough due to ribosomes
- Site of protein synthesis
Describe the smooth endoplasmic reticulum
The site of lipid synthesis
Describe ribosomes
- They have 2 subunits
- They read mRNA and create a polypeptide chain
Describe the cytoplasm
The site of glycolysis
Describe vesicles
Small membrane bound organelles which transport material and exchange cell membrane between compartments
Describe the cell membrane structure
Phospholipid bilayer
- 2 Layers of phospholipids
- Hydrophilic head and hydrophobic tail
- Contains proteins
- Contains cholesterol
What are the functions of the cell membrane?
- Acts as a physical barrier
- Selective permeability
- Endo/ exocytosis
- Cell signalling
What are the functions of cytoskeleton filaments?
- Support cell shape
- Form cell junctions
What are the 3 different types of cytoskeleton filaments?
- Microtubules
- Intermediate filaments
- Microfilaments
What is the diameter of microtubules?
25nm
What is the diameter of Intermediate filaments?
10nm
What is the diameter of microfilaments?
5nm
Where are microtubules found?
They arise from the centromere and are found in all cells except RBCs
Where are intermediate filaments found?
They are transmembrane proteins that can spread through tissues
Where are microfilaments found?
They form a mesh on the inner surface of the cell membrane
What are the different types of cell junctions?
- Tight junctions
- Adherens
- Desmosomes
- Gap junctions
- Hemi-desmosomes
Describe tight junctions
- 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
Describe adherens junctions
- Found in epithelial tissues and other tissues
- Involve the interaction of actin filaments between adjacent cells
Describe desmosomes
- 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
Describe gap junctions
- 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
Describe hemidesmosomes
- 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.
What are the different types of membrane proteins and what do they transport?
- Uniport- 1 substance
- Symport- 2 or more substances in the same direction
- Antiport- 2 or more substances in opposite directions
