Exam 2 Flashcards
Fluid-mosaic model
lipids are free to move in 2D plane
proteins exist as discrete particles
proteins can move laterally in the plane of the membrane
transition temperature
temperature at which the membrane undergoes fluid-to-solid phase change
increased C=C means lower transition temperature
integral membrane proteins
penetrate the hydrophobic core of the membrane
can be removed only by solubilizing the membrane
many are transmembrane (can pass all the way through)
amphipathic
cholesterol interaction with membrane
has a polar region, so it interacts with hydrophobic tails and alters interactions between adjacent fatty acid chains
reduces membrane fluidity at moderate temperatures, hinders solidification at low temperatures
fluidity buffer
anchored membrane proteins
covalently attached to lipids that insert into membrane
no exposed hydrophobic regions
peripheral membrane proteins
loosely bind to integral proteins or to lipids
removed without destroying the membrane
function on only one side of membrane
membrane carbohydrates
short chains of monosaccharides added to protein or lipid
attachment occurs in rough ER and glogi apparatus
functions of membrane carbohydrates
defense
protection
cell sorting
functions of membrane proteins
transport
enzymatic activity
signal transduction
cell-cell recognition
intercellular joining
attachment to the cytoskeleton and extracellular matric
Selective Permeability
unlimited passage of some substances, limited to others
diffusion
movement from a region of higher concentration to a region of lower concentration
when does transport stop
equilibrium
Channels
transport proteins
allows passive diffusion of molecules at all times
hydrophilic pores, no specific binding to one molecule
rapid movement of ions and water
Carriers
transport proteins
specific binding of solute
requires a conformation change
slower than channels
Passive Transport
no energy added
higher concentration to lower concentration
what drives passive transport
direction fo the electrochemical gradient
Active transport
energy added
low concentration to high concentration
only carriers never channels
Osmosis
passive movement of water across a membrane to where there are more solutes
Aquaporins
special channels used by water
Types of passive water movement
Isotonic
Hypotonic
Hypertonic
Isotonic
solution around cell has the same solute concentration as inside the cell
Hypotonic
solution around cell has a lower solute concentration than inside the cell
Hypertonic
solution around cell has a higher solute concentration than inside the cell
Facilitated Diffusion
passive transport aided by proteins
channels and carriers
Ligand Gated Channels
specific molecule needs to bind in order to open up the channel
allows passive diffusion of molecules when signal molecule is around
Cotransport
some transport proteins can move more than 1 substance at a time
Primary Active Transport
energy usually from ATP hydrolysis, is used to pump something across a membrane to a region of higher concentration
uses ATP to transport amolecule against its concentration gradient
Active Cotransport
uses energy to transport two different things across a membrane
can move in the same direction (symport) or opposite directions (antiport)
Primary Active Cotransport
ATP hydrolysis can provide the energy to actively move two substances in two different directions
Secondary Active Cotransport
energy supplied by ATP hydrolysis to transport one ion can be stored in an ion gradient
uses stored potential energy of electrochemical gradient of one molecule to transport another
Bulk Transport
large molecules, proteins and polysaccarides
Exocytosis
bulk transport and active
cells remove materials/molecules from inside the cell
Endocytosis
bulk transport and active
material is brought into the cell
Phagocytosis, Pinocytosis, Receptor-mediated endocytosis
Phagocytosis
cellular eating
cell engulfs a particle into a vesicle
Pinocytosis
cellular drinking
gulp of fluid taken into vesicle
nonspecific uptake of solubilized material
Receptor-mediated endocytosis
used to bring in specific molecules
ligands bind to specific receptors
Cell signaling
communication between cells in a multicellular organism
Juxtacrine signaling
adjacent/next to each other cells
Paracrine Signaling
nearby cells
Synaptic signaling
electrical signal triggers release of neurotransmitter, which diffuses across synapse, and hits receptor of next nerve cells
Endocrine Signaling
between distant cells
uses circulatory and endocrine system
What does responding to cell signaling mean
changing some cellular activity: gene expression, enzymatic activity, cell division
reception (cell signaling)
interaction between a receptor and its signal (ligand) is analogous to a substrate binding to an enzyme or a solute binding to a carrier
Lipid-Soluble Chemical Signals
hydrophobic
pass through the plasma membrane and bind a specific receptor in the cytoplasm or in the nucleus
Water-Soluble Chemical Signals
Hydrophilic
cannot pass through membrane
bind to specific plasma membrane receptors
Membrane-bound receptors
hydrophilic, cant pass through membrane
needs transmembrane protein
G protein coupled receptor
activates a G protein causing affect in a protein leading to cascade of signaling
enzyme linked receptor
receptor is an enzyme that can catalyze reaction
Signal transduction pathway
the pathway of change where the reception of a signal triggers a biochemical response
Protein kinase
an enzyme that helps catalyze the addition of a phosphate group from ATP to a protein
Protein phosphatase
returns the protein to its original conformation
reverses action of kinase
allows for protein to be reused
Second messengers
activated by the initial messenger and carry instructions through the cell
Cyclic AMP (cAMP)
a second messenger
produced by cells in response to several different hormones
generated from ATP
response in Nucleus
changes in gene expression
response in cytoplasm
changes in enzyme activity, motor activity, or skeletal structure
amplification
a small signal leads to a large response
Specificity and Coordination
different cells can respond to the same signal in difference ways
one signal is tied to a different signaling pathway in a different cell
Metabolism
collection of all the biochemical reactions that occur in a cell
oxidation-reduction reactions
when covalent bonds are broken or rearranged, electrons can be transferred between reactants
reduction
electron is gained
reduces overall charge of molecule
Oxidation
electron is lost
Cellular respiration
Glycolysis –> Pyruvate Oxidation –> Citric Acid Cycle –> Electron transport/Oxidative Phosphorylation
Glycolysis
one 6 carbon sugar (glucose) is oxidized to two, three carbon molecules
ATP is generated by the transfer of a phosphate group from a phosphorylated substrate to ADP to make ATP
produces pyruvate, NADH, H+, ATP
substrate-level phosphorylation
in glycolysis
ATP is generated by the transfer of a phosphate group from a phosphorylated substrate to ADP to make ATP
glycolysis reactants
Glucose, NAD+, ADP, Pi (inorganic phosphate)
glycolysis products
pyruvate, NADH and H+, ATP
Fermentation
oxidizes NADH to regenerate NAD+ so that glycolysis can continue in the absence of oxygen
Lactate Fermentation
Pyruvate + NADH + H+ –> Lactate + NAD+
Alcoholic Fermentation
pyruvate is converted into acetaldehyde and carbon dioxide
Acetaldehyde + NADH + H+ –> Ethanol + NAD+
Aerobic Respiration
another solution for regenerating NAD+ in the presence of oxygen
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
catabolic and exergonic
electrons and H+ are removed from carbohydrates –> carbons oxidized to CO2 and electrons and H+ are added to oxygen, which is reduced to O2
Citric Acid Cycle
Acetyl CoA + Oxaloacetate –> Citrate + CoA
then 2 decarboxylations, 4 oxidations (+ 4 reductions), and 1 substrate-level phosphorylation (ATP)
regenerates starting material, oxaloacetate
twice per glucose because glycolysis produces 2 pyruvates for each glucose molecule
Electron transport
high energy electrons are removed from the reduced coenzymes and their energy is extracted through a stepwise series of exergonic oxidation and reduction steps
Respiratory complexes
4 large multi-protein complexes embedded in the inner mitochondrial membrane comprise the Electron Transport Chain
Electron transfer
each one represents a redox reaction
each one is exergonic
electrons lose energy as they move away from NADH or FADH2
Coenzyme Q/CoQ
accepts electrons from Complex I and Complex II and delivers them to Complex III
ATP Synthase Complex
synthesizes ATP from ADP in the mitochondrial matrix using the energy provided by the proton electrochemical gradient
which complexes transport H+
I, III, IV
Chemiosmosis
passive movement of ions across a membrane
ATP synthesis driven by the movement of H+ across a membrane
Oxidative Phosphorylation
harnesses the reduction of oxygen to generate high-energy phosphate bonds in the form of ATP
How much ATP does cellular respiration produce
32
Photosynthesis
Energy + 6CO2 + 6H2O—>C6H12O6 + 6O2
anabolic and endergonic
Calvin Cycle
uses ATP and NADPH to convert inorganic carbon into sugar
product is G3P
carbon fixation –> reduction –> regeneration of CO2 acceptor
Carbon Fixation
covalent attachment of inorganic carbon to an organic acceptor molecule
RuBP + CO2 –> 2 3PG *3
C3 plants
plants that use carbon fixation initially
Reduction of Carbon
the addition of electrons and protons and energy to make a carbohydrate
phosphorylate and reduce the products of carbon fixation
remove 1 G3P
Regeneration of CO2 acceptor
reorganization and rearrangement of remaining products to regenerate the initial reactant
convert five 3C G3P into three 5C RuBP
uses of G3P
starch synthesis (energy storage)
sucrose synthesis (energy transport)
oxidation of G3P in cytosol and mitochondria to generate ATP for cellular needs
photosynthetic pigments
localized within the thylakoid membranes
green chlorophylls
absorption spectra
the wavelengths that are absorbed by different pigments
action spectrium
the wavelengths of light for which there is biological activity
photoexcitation
excited state
absorption of photon by molecule
increasing energy moving from ground state to excited state
Light Dependent Reactions
absorbed light energy is converted and stored transiently in two chemical forms (ATP and NADPH)
Photosystem I
P700 pigment
electron from photosystem II
passes excited electron to an electron transport chain, where it is used to reduce NADP+, forming NADPH
Photosystem II
P680 pigment
gets electron from H2O
passes excited electron to a second electron transport chain, where it is eventually used to reduce chlorophyll a in photosystem I
Photophosphorylation
electron transport drives H+ from stroma to thylakoid space…resulting H+ gradient stores energy
H+ returning to the stroma through ATP synthase provides the free energy to drive phosphorylation of ADP
C4 Plants
separate carbon fixation from where Rubsico is
carbon fixation happens twice
avoids toxic products when rubisco is exposed to O2
CAM Plants
fix carbon only at night
don’t have to open stomata in daytime
cant clear out O2, so it doesn’t come in contact with rubisco
Mendel’s experiments with peas
traits are inherited independently
Morgan’s experiments with fruit flies
genes are located on chromosomes
Griffith’s experiments with R and S bacteria cells
Transforming principles can be passed from dead to living bacteria cells
Avery, McCarty, and MacLeod’s experiments with treating S cells
the transforming principle is DNA
Hershey and Chase’s experiments with bacteriophage viruses
genes are composed of DNA
Chargaff’s rules
an organism has equal ratios of A:T nucleotides and G:C nucleotides in all of its cells
What did Rosalind Franklin’s image of DNA reveal
DNA is a helix with two strands
where does glycolysis occur
mitochondrial matrix…cytosol
which process is responsible for the largest amount of ATP production during cellular respiration
oxidative phosphorylation
Where does fermentation occur
cytosol
where does porin occur
outer membrane of mitochondria
Where does H+ Pyruvate cotransporter occur
inner membrane of mitochondria
Where does pyruvate decarboxylation occur
mitochondrial matrix
How is energy used to generate ATP in oxidative phosphorylation
indirectly from redox reactions in the electron transport chain creating an electrochemical gradient of H+ ions that drives ATP synthase
