Cell Ultrastructure Flashcards
Nucleus function
Largest membrane bound organelle
Storage and transmission of genetic information
Information coded in the DNA synthesises the protein determining the structure and function of the cell
Nucleus structure
Double membrane (nuclear envelope) with gaps called nuclear pores
RNA moves out via pores
DNA and proteins form chromatin- a mass of genetic material
At cell division chromatin becomes chromosomes and condenses
Nucleolus
Nucleolus
No membrane
Site of DNA transcription
Forms ribosomal RNA (rRNA)
Mitochondria function
Site of oxidative -phosphorylation
Mitochondria structure
Outer membrane- lipid synthesis and fatty acid metabolism
Inner membrane- respiratory chain (electron transport)
Matrix- Krebs cycle
Intramembranous space- nucleotide synthesis (ADP-ATP)
Vesicles structure
Very small spherical membrane bound organelles which transport and store material and exchange cell membrane between compartments
Vesicles types
Cell-surface derived pinocytotic and phagocytotic vesicles, Golgi- derived, ER-derived, lysosomes, peroxisomes
• Lysosomes - derived from Golgi, site at which proteins are degraded. H+-ATPase on endosome membrane creates low internal pH5, contain acid hydrolases that degrade proteins, formed by fusion of hydrolase vesicles and endosomes. Contain digestive enzymes
• Peroxisomes - small membrane-bound organelles containing enzymes which oxidise long-chain fatty acids. Involved in process by which fatty acids are broken down to generate ATP. Toxic hydrogen peroxide broken down by peroxisomes
Endosome- membrane bound vesicular tubular structures that live between Golgi and membrane
Vacuole function
Hold various solutions or material- can have been created, stored or excreted and that have been phagocytosed or engulfed
Vacuole structure
Chamber surrounded by a membrane- semi-permeable that only lets certain molecules through
Golgi apparatus structure
Parallel stacks of membrane
Located close to the nucleus
In most cells cannot be seen- very clear in plasma cells (perinuclear hoff)
3 parts: cis-Golgi, medial and trans-Golgi
Golgi apparatus function
Processes and modifies macromolecules synthesised in the endoplasmic reticulum
Cis-Golgi
Nuclear facing- receives from rER
protein phosphorylation occurs here
Medial Golgi
Modifies producers by adding sugars
Forms complex oligosaccharides by adding sugars to lipids and peptides
Trans-Golgi
Proteolysis of peptides into active forms and sorting of molecules into vesicles which bud from the surface
Rough endoplasmic reticulum structure
Rough due to ribosomes on surface
Highly folded flat membrane sheet
Rough endoplasmic reticulum function
Site of protein synthesis
Smooth endoplasmic reticulum structure
Highly folded, flattened membrane sheets
Smooth endoplasmic reticulum function
Site of lipid synthesis
Proteases and store synthesised proteins
Ribosome structure
2 subunits attached to the rER
Ribosome function
Acts as a large catalyst
Translate genetic code into chains of amino acids
Deposits protein into the rER to undergo further modification
3-5 amino acids per second in protein production
Cytoplasm function
Site of glycolysis
Cytoplasm structure
Fluid that fills the cell, includes the cytosol and filaments, proteins, ions and macromolecular structures as well as organelles. NA the nucleus
3 components of cytoplasms:
- Cytoskeleton with associated motor proteins
- Organelles and other multi proteins complexes
- Cytoplasmic inclusions and dissolved solute
Plasma membrane function
Controls passage of various molecules
Physical barrier
Selective permeability
Endo-/exocytosis
Cell signalling