cells are the building blocks of all plants and animals
all cells come from the division of preexisting cells
cells are the smallest units that perform all vital physiological functions
each cell maintains homeostasis at the cellular level
Two classes of cells
sex cells (sperm and oocytes)
somatic cells
Functions of plasma membrane (4)
physical isolation
regulation of exchange with the environment
sensitivity to the environment
structural support
the plasma membrane is also called
the phospholipid bilayer
what cannot cross directly through the lipid bilayer?
water
ions
A 1:1 molar ration exists between what two molecules in the membrane?
carbohydrates and phospholipids
Integral proteins
traverses all membranes going from outside to inside
peripheral proteins
remain on one side of cell
5 functional types of proteins
anchoring
recognition
receptor
carrier
channel
Function of integral proteins
provide structural support
unify lipid bilayer with cytoskeleton
outnumber peripheral proteins
peripheral proteins function
connect with integral proteins uniting the protein/phospholipid moity.
provide support and shape to cell
anchoring protein function
attach to cell membrane and stabilize cell position
recognition protein function
identify tissue as self or foreign, normal or abnormal
receptor proteins function
accept ligands that trigger changes int he acticity of a cell
carrier proteins function
bind solute and in the process change shape carrying solute across membrane where it is released. teh carrier protein then returns to its original shape.
May require ATP
channel proteins functions
permit the movement of water, ions and other small water solublue solutes
certain channels are highly selective
Membrane lipids are
choline phospholipd
sphingomyelin
ceramide
aminophospholipids
cholesterol
choline phospholipids (lecithins)
are associated with regulating points of lipid exchange across the membrane and metabolism by the cell
proteoglycans, glycolipds and glycoproteins are comprised of
membrane carbohydrates
function of the glyocalyx
lubrication and protection of membrane
anchoring cell in place and locomotion of specialized cells
specificity in binding-function as receptors
recognition of glycoprotein glycolipids as either normal or abnormal by cells of immune system
Membrane transport processes are categorized by mechanism into 3 categories
diffusion: results from random motion and collision of ions. is a passive process
carrier-mediated transport (CMT): requires presence of specialized integral membrane proteins. can be active or passive. eg: Na+ transport(active); glucose transport (passive)
vesicular transport: involves the movement of material within membranous sacs.
Tonicity refers to
the concentration of the solute in solution
Steps of Receptor Mediated Endocytosis
1. ligands bind to receptors
2. Endocytosis occurs
3. fusion of membranous sac with primary lysosome in order to make secondary lysosome
4. membrane with receptors detaches from seconday lysosome and ligands removed
5. receptors and membrane returned to surface
Transmembrane potential relates to
neurons
transmembrane potential is the
difference in electrical potential between inside and outside of a cell.
donnan/gibbs equilibrium
with a cell are non diffuse
Apoptosis
genetically controlled death of cells
mitosis vs meiosis
nuclear division of somatic cells vs production of sex cells
What occurs during prophase
chromosomes condense
nuclear membrane disappears
centriols migrate to polar regions of cell
aster formation occurs
spindle begins to form
what occurs during metaphase
spindle develops
chromosomes align along equatorial plane of spindle
what occurs during anaphase
division of centromere of centrosomes
What is manufactured during the G1 phase
nucleotides
DNA replication takes place during what phase?
S phase
what is an Okazaki fragment
section of RNA and DNA nucleotide manufactured as part of lagging strand
Laggin strand replication occurs in which direction
C3 to C5
leading strand replication occurs in which direction
5' to 3'
DNA polymerase I has what function
synthesizes DNA in a C5 -> C3 Direction
RNA primase has what funcction
synthesizes start fragment on DNA called an RNA primer
DNA polymerase II has what function
cleans Okazaki fragment by remoivng RNA nucleotides or incorrect DNA nucleotides
Ligase has what function?
ties okazaki fragments together in a direction that follows helicase
Transcription involves the production of
RNA, mRNA and tRNA
Ribosomes function
protein synthesis (translation)
the 3 phases of translation are
initiation
elongation
termination
what is required to begin the process of translation