Cell Ultrastructure Flashcards
(32 cards)
State 3 details about the nucleus.
- Brain of the cell.
- Double nuclear membrane.
- Houses DNA (in the form of chromatin) within the nucleolus (site of ribosomal RNA formation i.e. DNA transcription).
What is the mitochondria responsible for?
The site of oxidative phosphorylation.
What does the mitochondria consist of?
Matrix and double membrane where the inner membrane is highly folded (and there is an intramembranous space).
What occurs in the matrix of the mitochondria?
Tricarboxylic acid (Kreb’s) Cycle.
What occurs in the outer membrane of the mitochondria?
Lipid synthesis and fatty acid metabolism.
What occurs in the inner membrane of the mitochondria?
Respiratory chain/electron transport ATP production.
What occurs in the intramembranous space of the mitochondria?
Nucleotide phosphorylation from ADP to ATP.
Why is the rough endoplasmic reticulum rough?
Due to the numerous ribosomes on the surface.
What is the rough endoplasmic reticulum?
Highly folded flattened membrane sheets and the site of protein synthesis.
What is the smooth endoplasmic reticulum?
Highly folded flattened membrane sheets- the site of lipid synthesis and processes and stores synthesised proteins (check notes- is it meant to be lipids).
What is the golgi apparatus?
Parallel stacks of membrane- processes and modifies macromolecules synthesised in the ER.
- Located close to the cell nucleus.
- N.B. In most cells the golgi apparatus cannot be seen, however, it can be seen clearly in plasma cells.
What is the cis (first) golgi?
Nuclear facing, receives the (smooth) ER vesicles and protein phosphorylation occurs here.
What is the medial golgi?
The middle/central part, modifies (lipid and protein) products by adding sugars to form complex oligosaccharides.
What is the trans golgi?
The last part (this transfers)- the proteolysis of peptides into active forms and the sorting of molecules into vesicles (which bud from the surface).
What are vesicles?
Very small, spherical membrane-bound organelles.
What is the purpose of vesicles?
Transport & store material and exchange cell membrane between compartments
Name 5 types of vesicles.
- Cell-surface derived (pinocytotic and phagocytotic vesicles).
- Golgi- derived transport vesicles.
- ER - derived transport vesicles.
- Lysosomes.
- Peroxisomes.
What are lysosomes responsible for?
- Waste disposal system and is the site of breakdown for most molecules, derived from golgi.
- They also breakdown debris from dead cells & bacteria and damaged cell organelles.
How do lysosomes function?
- Contains digestive enzymes.
- H+ - ATPase on the membrane pumps H+ ions into the cell, creating a low pH (pH5) to enable acid hydrolases to function.
What are peroxisomes responsible for?
- Small, membrane-bound organelles containing enzymes which oxidase long-chain fatty acids (long chain FAD-amino oxidase, catalase and urate oxidase - INVOLVED IN THE PROCESS BY WHICH FATTY ACIDS ARE BROKEN DOWN INTO TWO-CARBON FRAGMENTS WHICH THE CELL CAN USE AS A SOURCE FOR GENERATING ATP) - BETA OXIDATION.
- They also produce hydrogen peroxide (by-product of the breakdown of fatty acids) which can be used to destroy pathogens etc.
N.B. Hydrogen peroxide is toxic to cells, but peroxisomes can destroy hydrogen peroxide thereby preventing its toxic effects and protecting the body etc.
What is the cytoskeleton?
- Filamentous proteins which brace the internal structure of the cell.
- Not visible in light microscopy.
What is the purpose of the cytoskeleton?
- Helps cells maintain their shape and internal organisation.
What are microfilaments?
- (5nm).
- ACTIN forms a bracing mesh (cell cortex) on the inner surface of the cell membrane.
What are intermediate filaments?
- (10nm + 6 types of protein).
- Anchored transmembrane proteins which can spread tensile force through tissues.
