Lecture 6: CSF Flashcards
Cell theory
All organisms 1 or more cells
Cell = basic unit of structure and organisation
All cells arise only from pre-existing cells
Universal similarities between cells (I)
ATP as energy source
DNA = heritable material, RNA messanger, Proteins = workers
Universal similarities between cells (II)
Major cellular organelles - functions and arrangements within the cell
The central dogma
DNA –> RNA –> Protein
Prokaryote cell vs eukaryote cell (similarities)
Both have: plasma membrane, cytosol, DNA, RNA, protein and ribosomes
eukaryote cell
have membrane-bound & organelles are much larger
Prokaryote cell
lack a membrane-bound nucleus
Cytoplasm
everything inside the plasma membrane (organelles).
NOT including the NUCLEUS
Fluid portion of cytoplasm
Cytosol - water + dissolved & suspended substances (ions, ATP, proteins, lipids)
Major organelles include
Mitochondria
ribosomes
Major organelles include
endomembrane system:
nucleus
endoplasmic reiculum (smooth and rough)
golgi apparatus
lysosomes
endomembrane system
along with the plasma membrane, they work together to package, label and ship molecules
Cell diagram
Plasma membrane
is a selectively permable barrier controlling (spbc)the passage of substances in and out of the cell
Plasma membrane structure
Double later of phospholipids with embedded proteins
Physical barrier separating the inside/outside of cell
Plasma membrane function
Much of our body = hydrophilic (water loving)
Fats = hydophobic
Fats in cell membrane provide a barrier to water
Plasma membrane diagram
Phospholipid
Hydrophilic polar heads (phosphate)
Hydrophobic lipid tails (fatty acids)
arranged as a double layer around cytoplasm, tail to tail
Phospholipid Diagram
Plasma membrane proteins
mediate movement of hydrophilic substances
allow cell-cell identification and facilitate intercullular communication
Plasma membrane proteins
are often amphipathic, meaning they have both hydrophilic and hydrophobic regions
Plasma membrane proteins
Integral Proteins
peripheral membrane proteins
Integral Proteins
embedded (partially/fully) into the membrane
eg; transmembrane proteins are integral membrane proteins that fully span the entire membrame, contacting both extracellular and cytoplasmic areas
peripheral membrane proteins
associated with the membrane. but not actually embedded in it
What do protein membranes do (I)
Transport
Enzymatic activity
signal transduction
What do protein membranes do (II)
Cell-cell recognition
intercellular joining
attatchment to cytoskeleton and ECM
Transport
channels, transporters, may be general/selective, gated/or not
Enzymatic activity
carry out chemical reaction, may/may not be a part of a team of enzymes
Signal transduction
External signaling molecule causing communication of information to the inside of the cell
Cell-cell recognition
glycoproteins (carbohydrate + water) as molecular signatures of the extracellular side of the cell
Intercellular joining
Gap junctions/tight junctions
Attatchment to the cytoskeleton & ECM
fibronectin mediates contact between cell surface integrins and ECM (eg; collagen)
can move
Membranes
are not static
Membrane (I)
is a mosaic of molecules bobbing a fluid bilayer of phospolipids
Membrane (II)
cell specific and dynamic repertoire of membrane bound proteins present as required
Nucleus (I)
The largest distinct structure inside the cell
entry and exit through nuclear pores
Nucleus (II)
Enclosed by double lipid bilayer called nuclear envelope, continuous with rough ER
Nucleolus
rRNA production, assembly of small & large subunits of ribosomes
Nucleus functions (I)
house/protect DNA
make RNA and assemble ribosomes
Nucleus functions (II)
Pores regulate movement of substances (eg; protein & mRNA) in and out
molecule segregation to allow temporal and spatial control of cell function
Deoxyribonucleuic acid (DNA)
wrapped 2x around group of 8 histones –> form nucleosomes - collectively known as chromatin
As the cells prepare for cell division
chromatin condenses –> form chromatin fibres, condenses further into loops –> stacks as chromosomes
Most of the time
DNA is present as chromatin and chromatin fibres
Chromosomes
many genes
gene
DNA segment that contributes to phenotype/function
Ribosomes
2 subunits
small and large made of ribosomal RNA (rRNA) in complex with many proteins
rRNA made in
nucleolus
Subunits assemble in the
nucleolus leave through nuclear pores
Ribosomes function (I)
protein production (translation), found in 2 places in cell
Ribosomes function (II)
free in the cytoplasm - making proteins to be used in cytosol (non-endomembrane destinations)
Ribosomes function (III)
attatched to the RER - making non-cytosolic proteins/endomembrane
Endoplasmic reticulum
The ER is an extensive network of tubes & tubles, stretching out from the nuclear membrane
Endoplasmic reticulum types
Rough ER
Smooth ER
Rough ER Major function is Production of:
secreted proteins
membrane proteins
organelle proteins
(smo)
Rough ER (continuous, dotted)
continuous with nuclear envelope
dotted with attached ribosomes
Rough ER (proteins, surrounds)
Proteins enter lumen within the rough ER for folding
surrounds the protein to form transport vesicles destined for the golgi
Smooth ER functions
vary greatly from cell to cell - very cell/tissue-type specific
smooth ER examples
liver & muscles
smooth ER (extends, lacks)
extends from the rough ER
lacks ribosomes: doesnt make proteins
Smooth ER (major, synthesizes)
major function is as a housing unit for proteins and enzymes
synthesizes as lipids, including steriods and phospholipids
Smooth ER (storage)
storage of cell-specific proteins, not all cells make all proteins
Golgi apparatus
receiving and modifying, the “warehouse”
Golgi apparatus (3-20)
3-20 falttened memranous sacs = cisternae, stacked on top of one another (pita bread)
Golgi apparatus (functions)
modify, sort, package & transport proteins received from the rough ER using enzymes in each cisternae.
Golgi apparatus (formation of)
Secratory vesicles (proteins for exocytosis)
membrane vesicles (PM molecules)
transport vesicles (molecules to lysosome)
Golgi Apparatus: to destination (each, proteins)
Each sac or cisternae contains enzymes of different functions
proteins move cis to trans from sac to sac
tus
Golgi Apparatus: to destination (mature, travel)
mature at the exit cisternae
travel to destination
Golgi Apparatus: to destination (modifications)
modifications occur within each sac
(formation of glycoproteins, glycolipids and lipoproteins)
Golgi Apparatus: to destination (endomembrane)
endomembrane system can be a well travelled phospholipid
Lysosomes
Contain powerful digestive enzymes
Lysosomes (vesicles, rest)
vesicles formed from golgi membrane
rest of cell protected by membrane
Lysosomes (membrane)
membrane proteins punp H+ in to maintain acidic pH
Lysosomes (function, I)
function is digestive of:
subtances that enter a cell
important in destruction of pathogens
Lysosomes (function, II)
cell components e.g. organelles - autophagy
entire cells - autolysis
Lysosome (once)
once digested, al building blocks (amino acids, lipids, etc) recycled
Mitochondria Main function
generation of ATP through cellular resipiration
carry a separate small (37 genes) genome encoding mitochondrial specific products
Mitochondria is made up from (outer, inner)
Outer mitochondrial membrane
Inner mitochondrial membrane, with folds called cristae
Mitochondria is made up from (fluid)
fluid filled interior cavity, called the mitochondrial matrix
Mitochondria (the more, NOT)
the more energy a cell requires, the more ATP it must make, and the greater the # of mitochondria present)
NOT in endomembrane system
Cytoskeleton
Strucutral support system of the cell
Cytoskeleton (fibres)
fibres or filaments that help maintain size, shape and inegrity of the cell.
Cytoskeleton (act, involved)
act as a scaffoldung across the cell
involved in intracellular transportation and cell movement
3 types of fibres (smallest –> largest)
microfilaments, intermediate filaments, microtubules
Cytoskeleton microfilaments (made, found)
made = actin, 2 long chains, twisted
found in periphery and lining the interior cell
Cytoskeleton filaments (function; bear)
Bear tension & weight by anchoring cytoskeleton to plasma membrane, and promote amoeboid motility if required (eg; macrophage)
Cytoskeleton filaments (function; assembled)
Assembled and disassembled as required - they are dynamic
Cytoskeleton: intermediate filaments (made, found)
made of different materials; keratin
found in cytoplasm of the cell
Cytoskeleton: intermediate filaments (function; bear, act)
Bear tension and weight throughout cell; eg, during cell anchoring
act as scaffold for cellular organelles; eg, nucleus
Cytoskeleton: intermediate filaments (usually)
most permanent of cytoskeletal strucutres - less dynamic
Cytoskeleton: microtubules (made, coiled, extends)
made from tubulin dimers (alphas and beta)
coiled, to form a tube
extends from centriole into cytoplasm/nucleus
Cytoskeleton: microtubules (functions; supp, guide)
support cell shape and size
guide for movement of organelles
Cytoskeleton: microtubules (functions; chromosome, supp and)
chromosome organization - cell division
supp and movement of cilia/flagella
Cytoskeleton: microtubules (functions;
assembled and desembled as required; are dynamic
