107 module 2 Flashcards
cell theory
- all organisms are composed of one or more cells
- the cell is the basic unit of structure and organisation
- all cells arise only from pre-exisiting cells
cell theory - universal similarities between cells
- DNA as the heritable material, RNA as a messenger and proteins as workers
- major cellular organelles - functions and arrangements within the cell
- ATP as energy source
the central dogma
DNA -> RNA -> PROTEIN
the endomembrane system
nucleus, ER, golgi apparatus, lysosomes along with plasma membrane (work together to package, label and ship molecules)
prokaryote vs eukaryote
both have plasma membrane, cytosol, DNA, RNA, protein and ribosomes. Eukaryote cells have membrane bound organelles and are much larger, prokaryotes cells lack a membrane bound nucleus
cytoplasm
everything inside plasma membrane including organelles but not including nucleus, fluid portion is called cytosol
what is cytosol
water plus dissolved and suspended substances (ions, ATP, proteins, lipids)
plasma membrane
selectively permeable barrier controlling the passage of substances in and out cell. Double layer of phospholipids with embedded proteins, physical barrier separating inside/outside of cell..
peripheral membrane proteins
associated with membrane but not actually embedded in it
integral proteins
embedded either partially or fully into membrane -> eg. transmembrane proteins are integral membrane as they fully span entire membrane contracting both extracellular and cytoplasmic areas.
plasma membrane function
allow cell to cell identification and facilitate intercellular communication
Plasma membrane proteins function list
- transport
- enzymatic activity
- signal transduction
- cell-cell recog
5) intercellular joining
f) attachment to the cytoskeleton and extracellular matrix
transport - plasma membrane
channels, transporters, may be general or selective, gated or not
enzymatic activity - plasma membrane
enzymes on plasma membrane that carry out chem reaction, may or may not be part of a team of enzymes
signal transduction - plasma membrane
external signaling molecule causing communication of information to the inside of cell
cell-cell recognition plasma membrane
gap junctions and tight junctions, function of plasma membrane
attachment to cytoskeleton and ECM - plasma membrane
plasma membrane function, eg, fibronectin mediates contact between cell surface integrins and ECM (collagen) -> can facilitate movement.
is the plasma membrane static
the membrane is a mosaic of molecules bobbing in a fluid bilayer of phospholipids, cell specific and dynamic repertoire of membrane bound proteins present as required.
nucleus
enclosed by double lipid bilayer called nuclear envelope. continuous with rough ER. entry and exit through nuclear pores.
nucelolus
rRNA production. assembly of small and large subunits of ribosomes
nucleus functions
house/protect DNA
make RNA and assemble ribosomes
pores regulate movement of substances (eg protein and mRNA) in and out
molecule segregation to allow temporal and spatial control of cell function
DNA in nucleus
wrapped 2x around a group of 8 histones, to form nucleosomes, as the cell prepares for cell division chromatin condenses to form chromatin fibers then condenses further into loops -> stacks of chromosomes
nucleosomes
DNA wrapped 2x around a group of 8 histones
DNA IN NUCLEUS CELL DIVISION PREP
DNA wrapped 2x around 8 histones -> nucleosomes (chromatin) -> chromatin fibers -> loops and stacks -> chromosomes
ribosomes
RER
continuous with nuclear envelope dotted with attached ribosomes, proteins enter lumen for folding. Major function is production of secreted, membrane and organelle proteins
smooth er
extends from rough ER. Functions of SER vary greatly from cell to cell -> very cell/tissue type specific. no ribosomes doesnt make proteins. Major function is a housing unit for proteins and enzymes
- synthesises lipids (steroids and phospholipids)
- storage of cell-specific proteins not all cells make proteins
golgi
made up of 3-20 flattened membranous sacs called cristinae
- modify sort package and transport proteins received from rough er using enzymes in each cristinae
formation of
- secretory vesicles (proteins for exocytosis)
- membrane vesicles (PM molecules)
- transport vesicles (molecules to lysosome)
golgi apparatus: to destination
each sac/cristinae contains enzymes of diff functions
- proteins move cis -> trans from sac to sac
mature at exit cristernae
travel to destination
modifications at each sac (formation of glycoproteins, glycolipids and lipoproteins).
lysosomes
vesicles formed from golgi membrane
membrane proteins pump H+ to maintain acidic pH
rest of cell protected by membrane
lysosomes main function
digestion of substances that enter a cell
cell components eg. organelles in autophagy
entire cells = autolysis
once digested all building blocks (aa, lipids) are recycled.
mitochondriballz
outer memb, inner memb with cristae, fluid filled interior = mito matrix
more energy needed = more atp = greater no. of mitochondria
mitochondria carry a separate small (37 genes) genome encoding mitochondrial specific products.
cytoskeleton
fibres or filaments that help maintain size, shape and integrity of cell
- act as scaffolding across the cell
- involved in intracellular transportation and cell movement
three types of fibers
microfilaments -> intermediate filaments -> microtubules
cytoskeleton microfilaments
diameter ~7nm, comprised of actin molecules assembled in two long chains twisted around each other. found around periphery and lining interior of cell
cytoskeleton filaments function
bear tension and weight by anchoring cytoskeleton to plasma membrane proteins and promote amoeboid motility if required (macrophage)
What does it mean by cytoskeleton microfilaments being dynamic
assembled and disassembled as required -> dynamic
cytoskeleton intermediate filaments
8-12nm diameter
comprised of diverse range of different materials eg. keratin. FOund in cytoplasm of cell.
function of intermediate filaments of cytoskeleton
bear tension and weight throughout cell. Eg. during cell anchoring
act as scaffold of cellular organelles such as the nucleus
are the intermediate filaments of the cytoskeleton dynamic?
usually most permanent of cytoskeletal structures, less dynamic.
cytoskeleton microtubules
diameter: tubular structure 25nm with central lumen of 15 nm diameter.
comprised of tubulin dimers (alpha and beta) coiled to form a tube.
extends from centriole into cytoplasm/nucleus
cytoskeleton microtubules function
support cell shape and size, guide for movement of organelles (eg vesicles from golgi to membrane)
chromosome organisation - cell division
support and movement of cilia/flagella
are microtubules in the cytoskeleton dynamic
assembled and disassembled as required- are dynamic
paracrine comms intercellular comms,
through extracellular fluid, paracrine factors, primary limited to local area where paracrine factor concentrations are relatively high, target cells must have appropriate receptors
endocrine communication intercellular comms,
through blood stream via hormones, target cells are primarily in other tissues and organs and must have appropriate receptors
intercellular comms: synaptic comms
across synaptic clefts, neurotransmitters, limited to very specific area, target cells must have appropriate receptors.
smallest to largest fibers in cytoskeleton
microfilaments -> intermediate filaments -> microtubules
