Chapter 5 Flashcards
The Working Cell
fluid mosaic model
molecules suspended in a fluid phospholipid bilayer
selective permeability
property of plasma membrane; regulates entry / exit of substances
six different functions of proteins in a plasma membrane ?
1) attachment to cytoskeleton
2) signal reception / relay
3) enzymatic activity
4) cell-to-cell recognition
5) intracellular joining
6) transport of substances
diffusion (passive transport)
movement of particles down concentration gradient w/ no cellular energy used
concentration gradient
areas of high and low density of substances in an area
movement of substances in diffusion ?
down concentration gradient; move solutes from high concentration area to low concentration area
net diffusion
overall directional movement of substances
osmosis
free water diffusion across a selectively permeable membrane
what is the point of osmosis ?
balances water in / out of cell; make in / out of cell reach equilibrium
water movement between a 0.5% sucrose solution and a 2% sucrose solution will move into which solution ?
water will move into the 2% sucrose solution to reach equilibrium
tonicity
surrounding ability to make cell gain / lose water; depends on the solutes in / out of cell
isotonic
no net movement; equilibrium
hypotonic
lower concentration solute compared to another solution
what happens to an animal cell in a hypotonic solution ?
water will rush into the animal cell to reach equilibrium; the animal cell will be lysed (bursts)
what happens to a plant cell in a hypotonic solution ?
water will rush into the plant cell to reach equilibrium; due to the cell wall, the plant will be turgid (stiff)
hypertonic
higher concentration solutes compared to another solution
what happens to an animal cell in a hypertonic solution ?
water will move out of the animal cell into the environment to reach equilibrium; the animal cell will shrivel
what happens to a plant cell in a hypertonic solution ?
water will move out of the plant cell into the environment to reach equilibrium; the plant cell will become plasmolyzed (limp)
osmoregulation
homeostatic maintenance of solute concentration and water
facilitated diffused
diffusion using transport / carrier proteins in plasma membrane; for polar / large / charged substances
aquaporin
type of transport protein; facilitates water diffusion
carrier proteins
they open on one side, close all together, then open on the other side ( /\, O, \/)
transport protein
direct open channel for substances ( || )
how do transport proteins contribute to selective permeability ?
they transport only certain particles and affect what is brought in / out of cell
active transport
use cellular energy to transport solute against concentration gradient; high to low concentration
how does active transport work ?
ATP binds to transport proteins to open and allow solutes to pass
cells actively transport Ca2+ out of the cell, is Ca2+ more concentrated in / out of the cell ?
out the cell if it is being actively moved out the cell, against its concentration gradient
exocytosis
vesicles moving out of cell w/ material
where do vesicles to be transported for exocytosis come from ?
the golgi body makes vesicles to be kept in the cell or to be transported out of the cell
endocytosis
cell takes in large molecules / fluid
phagocytosis
cell engulfs particle turning substances into vesicles once inside (food, etc.)
receptor-mediated endocytosis
receptors on plasma membrane pick up specific coinciding particles and make a protein coated vesicle once inside (cholesterol, etc.)
as a cell grows the plasma membrane expands, does that involve exo / endocytosis ?
exocytosis since the vesicles being transported out of the cell fuse / add to the cell membrane
all chemical reactions involve what ?
transformation of energy / matter
energy
capacity to cause change / do work
3 main forms energy ?
1) kinetic
2) thermal
3) potential
kinetic energy
energy of motion / moving
thermal energy
energy of random atom / molecule movement (includes heat energy)
heat energy
transfer of thermal energy from one piece of matter to another
potential energy
energy from matter’s location / structure (includes chemical energy)
chemical energy
potential energy to be released from chemical reactions
thermodynamics
study of energy transformation in a system of matter
system of matter
matter under study
universe of matter
all other external matter not being focused on / studied
1st law of thermodynamicws
energy can only be transformed / transferred; not created / destroyed
2nd law of thermodynamics
- energy conversion reduces order; increases entropy
- ordered form of matter release heat
entropy
measure of disorder / randomness / chaos
cellular respiration
transforming chemical energy into energy (ATP)
cellular respiration includes what steps ?
- glycolysis
- pyruvate oxidation
- citric acid cycle
- oxidative phosphorylation
the percent yield split up of cellular respiration produces what ?
~34% make energy (ATP)
~66% is lost as heat
how does 2nd law of thermodynamics explain solute diffusion
diffusion means that there is more solutes being transferred from one section to another and so an increase in solutes means a more disorder arrangement leading to higher entropy
exergonic reaction
release of energy; has more reactant and less product allowing for some of reactant to be released as energy
endergonic reaction
input of energy; has less reactant and more product requiring for an input of energy to make all of the product
metabolism
organism’s total chemical reactions
metabolic pathway
multiple chemical reactions to breakdown / build a specific molecule
energy coupling
energy gained from exergonic reactions fuel endergonic reactions
ATP
adenosine triphosphate; main energy of all cells
how is energy released in ATP ?
by hydrolyzing a phosphate bond
adenosine + triphosphate (ATP) —hydrolysis—> adenosine + diphosphate + ATP
why is the phosphate release from ATP a good source of energy ?
the phosphate is negatively charged and the mutual repulsion of all three lead to high levels of potential energy
is the hydrolysis of ATP an exo / endergonic reaction ?
exergonic since the hydrolysis causes the ATP to RELEASE energy
phosphorylation
transfer of a phosphate group to a molecule
nearly all work is done by ?
ATP phosphorylizing molecules
the 3 types of work done ?
- chemical; building / breaking molecules
- mechanical; muscle contraction, etc.
- transport; molecule transport, etc.
activation energy
the minimum amount of energy needed to start a chemical reaction
one way of speeding up reactions ?
adding heat
enzymes
a catalyst; usually a protein thats changes the rate of chemical reactions w/o being consumed
how do enzymes work ?
by lowering the minimum activation energy needed
substrate
specific substance that a specific enzyme recognizes
active site
part of enzyme that substrate attaches to
induced fit
active site changes its shape to acommodate for substrate
regular temp for human enzymes ?
35° - 40°C (body temp: 37°C)
regular temp for prokaryote enzymes ?
70°C
optimal pH for enzymes ?
6-8; exceptions for extreme conditions (stomach, etc.)
cofactor
nonprotein ion / molecule required for proper enzyme function
coenzyme
organic molecule acting as a cofactor (majority of vitamins, etc.)
how do enzymes speed up reactions ?
induced fit; enzyme orients substrate to be in most optimal position to break apart, lowering the amount of energy needed to break them apart
competitive inhibitor
binds to enzymes active site; blocks substrate from binding
noncompetitive inhibitor
binds anywhere on the enzyme; changes the active site so the substrate cannot bond
feedback inhibitor
end product of the metabolic pathway acts as an enzyme inhibitor at the very beginning of the pathway
what does an increase in substrate / enzyme concentration lead to ?
increased rates of enzymatic reactions until eventually it levels off until there is no more substrate to act on
how does DNA directly influence what is being worked on by enzymes ?
DNA –makes–> RNA –directs formation–> proteins –make up–> enzymes –helps reactions–> all other molecules
what is the structure of an enzyme ?
enzymes = proteins; follow primary, secondary, tertiary forming; hydrophobic inside, hydrophilic outside
