[FMS] CBS - cells + organelles Flashcards
What is a solution to the limitation of size?
use of the cytoskeleton to actively move things around cells [CBS cytoskeleton].
creation of “giant” cells with multiple nuclei so that gene expression can occur in more than one place (e.g. skeletal muscle cells).
gap junctions between cells so there is efficient movement of metabolites between cells.
What is a prokaryote?
Single-celled organism in which the chromosome is a circular strand lying free in the cell (i.e. no nucleus) and has no membranous organelles e.g. Bacteria
What is a Eukaryote?
One or more cells in which chromosomes are enclosed in a nucleus; typically have cytoplasmic, membrane-bound organelles, DNA divided into a series of linear chromosomes, and considerable differences occur between cells within the same organism.
What is a Virus?
Assemblage of nucleic acid (DNA or RNA) and proteins (and often other molecules) which is parasitic on prokaryotes/eukaryotes.
Viruses invade cells, subvert their protein synthesis machinery to make more viruses instead of normal cell proteins, then escape to infect other cells.
Viruses are not cells or organisms in the strict sense (lack a plasma membrane and only operate chemically within host cells).
What can a light microscope see? What conditions must cells be in for Electron Microscopy?
Light microscope has limited ability to visualise components of cells (only nucleus and plasma membrane can be resolved).
EM sample preparation is highly artificial: cells are dead, fixed and dehydrated.
Plasma membrane definition and function?
Definition = phospholipid bilayer.
Function = defines the boundary of cell, regulates entry and exit of chemicals
Cytosol definition?
Definition = consists of three types of protein polymers: actin filaments, microtubules (tubulin) and intermediate fibres.
Function = Mechanical strength of cell, control of shape, facilitation of movement, guide movement within cells, interaction with other cells [CBS Cytoskeleton]
Nucleus definition and function?
Definition = surrounded by nuclear membrane.
Function = storage of chromosomes; site of DNA replication [MCG Replication and Mutagenesis]; site of gene expression
[MCG Molecular Basis of Gene Transcription]
Nucleolus definition and function?
Definition = region of nucleus.
Function = site of rRNA synthesis and ribosome biogenesis
Nuclear membrane definition and function?
Definition = Double phospholipid bilayer.
Function = Regulates the entrance and exit of mRNA and proteins; maintains the integrity of the nucleus
Mitochondria definition and function?
Definition = Surrounded by membrane; also second inner membrane that is folded into cristae that increases its surface area.
Function = Aerobic oxidation of glucose to generate ATP (Krebs cycle); components of Electron Transport Chain are located in the inner membrane [NAM Aerobic Metabolism]; involved in oxidation of fatty acids; involved in gluconeogenesis [NAM The Liver and Gluconeogenesis]; involved in regulated intrinsic apoptotic pathway [CBS Cell death]
RER definition and function ?
Definition = Membrane bilayer surrounded endosomes.
Function = Coated with ribosomes; mRNA translation and synthesis of proteins for secretion or insertion into cell membrane; proteins are folded; Cys-Cys bridges form [CBS Protein Structure]; vesicles are budded from RER and transported to the Golgi body [CBS Protein targeting]
SER definition and function?
Definition = Membrane bilayer surrounded endosomes; continuation of RER.
Function = Biosynthesis of membrane lipids and steroids; start of N-linked glycosylation [CBS Protein structure]
Ribosome definition and function ?
Definition = Protein – rRNA complex.
Function = Assembly responsible for the translation of mRNA and the synthesis of proteins
Golgi definition and function ?
Definition = Consists of 4-8 closely stacked, membrane-bound channels (cisterna). Protein containing vesicles delivered from the RER.
Function = Directs new proteins within vesicles to their correct location in cell [CBS Protein targeting].
Transport of membrane lipids around cell.
Creates lysosomes.
Site of glycosylation modifications (modifying N-linked carbohydrates, glycosylation of O-linked carbohydrates and lipids).
Synthesis/packaging materials to be secreted
