Cells Ultrastructure (not a lecture) Flashcards
What features does a nucleus have:
State functions.
Nuclear DNA: euchromatin is actively transcribing chromatin,
heterochromatin in less active cell
Nucleolus - forms rRNA
Nuclear membrane - double membrane, perforated with pores
What features does a mitochondria have:
State functions.
Site of oxidative phosphorylation
Double membrane: Outer is smooth for lipid synthesis + fatty acid metabolism, Inner is folded and has cristae for respiratory chain, ATP production
Matrix - Site of Krebs cycle
Intramembranous space - Nucleotide phosphorylation APD to ATP
What features does a RER have:
State functions.
Site of protein synthesis.
Highly folded flattened membrane sheets
What features does a SER have:
State functions.
Site of lipid synthesis
Processes and stores synthesised proteins
Highly folded flattened membrane sheets
What features does a Golgi apparatus have:
State functions.
Processing and modification of proteins
Parallel stacks of membrane - processes and modifies macromolecules
Cis face - receives vesicles from SER, for protein phosphorylation
Medial face - form complex oligosaccharides by adding sugars to lipids and peptides
Trans face - proteolysis of peptides into active forms
Close to the nucleus of the cell
Can’t be seen in most cells but in a plasma cell, perinuclear hoff
What features does a vesicles have:
State functions.
Very small, spherical membrane-bound organelles - transport & store material + exchange cell membrane between compartments
Types: Cell-surface derived pinocytotic and phagocytotic vesicles
Golgi- derived transport vesicles + ER - derived transport vesicles
Lysosomes
Peroxisomes
Explain the function of lysosomes:
Contains digestive enzymes, site of breakdown for most molecules.
They also breakdown debris from dead cells & bacteria and damaged cell organelles.
Explain function of peroxisomes:
Small, membrane-bound organelles containing enzymes which oxidase long-chain fatty acids - beta oxidation ?
Also produce hydrogen peroxide that can destroy pathogens.
What is the cytoskeleton?
Filamentous proteins which brace the internal structure of the cell
Helps cells maintain their shape and internal organisation
What are the three parts of the cytoskeleton? In size order from smallest to biggest
Microfilaments, Intermediate filaments, microtubules
What are microfilaments?
Smallest 5nm.
Actin protein forms a bracing mesh on the inner surface of cell membrane
What are intermediate filaments?
10nm.
Anchored transmembrane proteins which can spread tensile force through tissues.
6 types:
- Cytokeratins - epithelial cells
- Desmin - myocytes
- Glial fibrillary acidic protein - astrocytic glial cells
- Neurofilament protein - neurons
- Nuclear laminin - nuclei of all cells
- Vimentin - mesodermal cells
What are microtubules?
25nm. Tubulin protein
In all cells except erythrocytes due to lack on nucleus
What storage products and inclusion found in cells?
- Lipofuscin - Membrane-bound orange-brown pigment, degradation of lipids common in heart and liver
- Lipid - Non-membrane-bound vacuoles, appears as empty space in histology since dissolved in processing, stored in adipocytes and liver
- Glycogen - CHO polymer in cytoplasm, normally seen on electron microscopy