week 1 Flashcards
what structure pattern did hooke see under the microscope
the plant (cork) cells were in a honeycomb pattern
principles of cell theory
1) all orgs are comprised of 1 or more cells
2) cel is the structural unit of life
3) cells can only arise from division from a pre-existing cell
4) cells have genetic info in the form of DNA where info is passes from parent to daughter cell
who proposed the first 2 cell principles
schwann in 1839
who proposed the third cell principle
virchow in 1855
when was the fourth cell princple added and why
during the discovery of DNA
cell properties
- complex and organized
- contain genetic info
- acquire and use energy
-preform many chem rxn - involved in mechanical activities
-respond to stimuli - self regulate
-evolve
-reproduce by division
how do cells commonly carry out rxn
through the use of enzymes so the rxn is complete at a rate that supports the biological system
what are cell mechanical actives
-transportations
- movement of the whole cell
- membrane input/ output
energy source for life
almost all is derivied by the sun
how do cells respond to stim
via the receptors on their extracellular membrane
allows fro binding and signalling pathways
what is meant by cells evolve
all orgs can be traced back to a single common ansestor where all current (unique) cells came from the single ansestor cell type.
what are features unique to eukaryotes
1) division of cell into nuc and cytoplasm (separated via membrane)
2) chromosomes
3) membrane bound organells
4) phagocytosis
5) diploidy (parent via daughter)
6) sexual requirement for meiosis
7) cytiskeletal system and motor proteins
covalent bond
e- pairs are shared btwn moles
polar moles
-hydrophilic
-uneven distribution of charge due to electronegativity and organization of atoms
non polar moles
-hydrophobic
- symetric uniform distribution of charge due to similar electronegativities between atoms
non covalent bond
weak chem bond based on attractive force between opp charged regions
- ionic
-hydrogen
-van
ionic bond
electrostatic int between groups of opposite charged (ions)
hydrogen bond
electrostatic int between H-X and another electroneg atom of another compound
van der waals int
week int force due to the transient asymmetries of charge within adjacent atoms or moles
hydrophobic effect
the tendancey for non polar momles to aggregate to minimize their collective int with polar water moles
what isa the basis of the lipid bilayer mem?
the hydrophobic effect
- polar heads face out while non polar tails face in
3 membrane principles
1) composed of lipids
2) bilayer (via RBC)
3) contain proteins (selective permeability)
what makes phospholipids amphipathic
the phosphate group in the head and the non polar tail
what does the lipid bi layer prevent
random movement of substances in and out of the cell
what are fatty acids
the tail component
- 14-20 Carbons
- sat or unstat (cis double bonds intro a bend)
3 types of membrane lipids
phosphoglycerides
sphingolipids
cholesterol
phosphoglycerides
-all are phospholipids
-built on a glycerol backbone
- 2 fatty acid chains (1 sat and 1 unsat), phosphate, and additional groups
phosphoglyceride back bone strucutre
H2C—-O—R
|
HC—-O—–R
|
H2C—-O—PO2–O– A
what are the 5 additional groups and their polarity
H (-)
Choline (0)
Serine (-)
Ethanol-amine (0)
Inositol (-)
sphingolipids
-build on sphingosine
(sphing+ fatty acids with an additional group to character the type of lipid)
-not all are phospholipids
- amphipathic
- longer and more sat fatty acids
what is the most basic sphingolipid
ceramide (sphingosine w/ a fatty acid)
where do sphingolipids participate the most?
-signal transduction
-membrane structure -sensing ?
addiontal groups
phosphate link= phospholipid
carbohydrate link= glycolipid
2 main types of glycolipids
- cerebroside (simple (single( sugar addition))
- ganglioside (cluster of suagrs are added)
cholesterol
-rigid, muti ring structures
- small OH polar group
- embedded (20-30%) to impact mem fluidity
4 composnents of a phosphoglyceride
phos group
glycerol backbone
fatty acid tails (2)
add group
the the membrane symetric?
no. the edno and xo plasmic membrnae ahev very different chemical make up and sometime differnt proteins attached.
- carb are only found on the extra celluar
what does asymmetry impact
permeability
surface charge
mem shape
stability
glycolipid: glycoprotein
10%=carb to lipid
90%= carb to protien
on the extracell only membrane
importance of carbs for cells
act as receptors, sorting membrane proteins, and recognition of other moles (like antigens)
what is the myeline sheath
multiple layers of plasma membrane with little protein
- high lipid concentration= signal propogation
what does the lipid composition of a cell determine
-physical state of mem
-facilitae prot int
- signal transduction
membrane functions (7)
1)compartmentalization
2) scaffold for biochem activities
3) selective permeable barrier
4) solute trans
5) response to external stim
6) cell-cell comm
7) energy transduction
compartmentalization
grouping of specialized cells via membranes, allowing for their activities to proceed without impaction other cell reactions
scaffold for biochem rxn
membranes promete the correct loaction and oder for biochemical rxn to occur
selectively permeable mem
membranes and filter specific substances into or out of the cell
solute transport
controls the entering or leaving of substances
response to external stim
specifically done by the plasma mem
ex hormes and ligands
cell to cell comm
doen by the plasma mem and allows for int
energy transduction
membranes related to the ECT and promote the differences in ion concentrations to produce an electrical charge.
what influences membrane fluidity
temp! \
fluidity determines the physical state of the mem
what is the transition temp
the temp to which a crystalline gel ‘melts’ into the liquid crystalline phase
what impacts the transistion temp
fatty acid saturation
cholesterol content
chain length
fatty acid saturation on fluidity
- sat= inc rigid
-unsat= dec rigid via bend
cholesterol content on fluidity
- ring impart movement and eliminates the sharpe transition temp
chain length on fluidity
- short chains= fewer van int and less E to brake apart (inc fluid)
why is fluid/ rigid balance important
maintain structural or and mechanical support
enable int
membrane assembly or cell growth and division
cell movement
ways orgs maintain fluid membranes
for colder temps:
- inc # unstat fatty acid tails via unstaturase
- reshuffle fatty chains to create phospholips with 2 unsat tails
- change the types of phospholipids that org produces (will make more unsat and shoter tails)
membrane proteins
-have a set orientation relative to the cytoplasmic or extra cellular side
- distributed asymmetrically between the bilayer
3 types of proteins
integral
peripheral
lipid anchored
integral prot
permanently anchored
monotopic (span 1 layer
transmembrane
- biotopic (span 2 layers)
- ploytopic (span both layers multiple times)
transmembrane proteins
pass though both phospholipid layers and contain one or more transmembrane domains (amphipathic)
- phobic: form van int w/ the fatty tails
philic: connectors near surface or channels (ion import)
transmembrne domain
~20 non polar amino acids
