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is the totality of an organism’s chemical reactions; is an emergent property of life that arises from interactions between molecules within the cell
is energy that matter possesses because of its location or structure
energy and matter can be transferred between the system and its surroundings
The reactant that an enzyme acts on is called the enzyme’s what?
a partial degradation of sugars that occurs without O2
uses phosphorylation instead of an electron transport chain to generate ATP; consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis
The NADH and FADH2 produced by the citric acid cycle relay electrons extracted from food to the ______
the use of energy in a H+ gradient to drive cellular work
in this type of fermentation, pyruvate is converted to ethanol in two steps, with the first releasing CO2
include sugars and the polymers of sugars, serving as fuel and building material
the polymers of sugars, have storage and structural roles
Consists entirely of glucose monomers. Plants store surplus of this as granules within chloroplasts and other plastids
Consists entirely of glucose monomers. Humans and other vertebrates store this mainly in liver and muscle cells
have the maximum number of hydrogen atoms possible and no double bond; what type of fatty acid?
have one or more double bonds; what type of fatty acid?
unsaturated fatty acids
Which lipids in the membrane are more fluid?
two fatty acids and a phosphate group are attached to glycerol
is the head/tail hydrophilic/hydrophobic?
are lipids characterized by a carbon skeleton consisting of four fused rings
Polymers of amino acids
Proteins- biologically functional molecule that consists of one or more polypeptides
The molecules that relay a signal from receptor to response are mostly what?
stores genetic information on chromosomes made of chromatin
produces ribosomes in nucleolus
Site of cellular respiration/ATP production
Have separate genetic material and ribosomes
Site of photosynthesis
Contains own ribosomes and DNA
are specialized metabolic compartments; produce hydrogen peroxide and convert it to water; oxygen is used to break down different types of molecules
Enzymes produce hydrogen peroxide
Break down fatty acids
Detoxify by transferring hydrogens from poisons to oxygen
During prophase, assembly of spindle microtubules begins in the ______, the microtubule organizing center
Regulates protein and lipid processing
Performs metabolic functions
found in many freshwater protists, pump excess water out of cells
found in many mature plant cells, hold organic compounds and water
Stores various compounds
Important for growth
a network of protein fibers extending throughout the cytoplasm; they are not membrane-bound
Microtubules: polymers of tubulin, largest - hollow tubes ex: centrioles, cilia, flagella
Microfilaments: polymers of actin, smallest - solid rods ex: muscle fibers, clvge furrows
Intermediate filaments: keratins, filaments of coiled fibers ex: nuclear lamina
membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
(anchoring junctions) fasten cells together into strong sheets
(communicating junctions) provide cytoplasmic channels between adjacent cells
the plasma membrane exhibits this, allowing some substances to cross it more easily than others
What are the most abundant lipids in the plasma membrane?
phospholipids are these type of molecules; exhibiting it exhibits both a hydrophilic and hydrophobic region
the fluid mosaic model
states that a membrane is a fluid structure with a “mosaic” of various proteins embedded in it
drift laterally; flip-flop
Most of the lipids within the bilayer and some proteins exhibit this movement and rarely exhibit what other movement?
liquid to solid
As temperature cools, the membranes go from what state to what?
This is dependent on the type of lipids in the membrane.
restrains movement of phospholipids
At warm temperatures, what does the steroid cholesterol do to membrane fluidity?
maintains fluidity by prevention of tight packing
At cool temperatures, what does the steroid cholesterol do to membrane fluidity?
hydrophobic (nonpolar molecules) (hydrocarbons); polar molecules (sugars)
What type of molecules pass through the membrane easily? What type do not?
allow passage of hydrophilic substances across the membrane
Some transport proteins, called this , have a hydrophilic channel that certain molecules or ions can use as a tunnel
Channel proteins called this, facilitate the passage of water
transport proteins called this, bind to molecules and change shape to shuttle them across the membrane
undergo a subtle change in shape that translocates the solute-binding site across the membrane
proteins bound to the surface of the membrane
proteins that penetrate the hydrophobic core
transport, enzymatic activity, signal transduction, cell-to-cell recognition, intercellular joining, attachment of the cytoskeleton to the extracellular matrix
What are the 6 major functions of membrane proteins?
concentration gradient- substances diffuse down
the difference in concentration of a substance from one area to another; no work must be done
The diffusion of a substance across a biological membrane is called this,
because it requires no energy from the cell to make it happen
the diffusion of water across a selectively permeable membrane
Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration
Diffusion of water
the ability of a solution to cause a cell to gain or lose water
Solute concentration is the same as that inside the cell; no net water
movement across the plasma membrane
Solute concentration is greater than that inside the cell; cell loses water
Solute concentration is less than that inside the cell; cell gains water
transport proteins speed the passive movement of molecules across the plasma membrane
ion channels (gated channels)
channel proteins that open or close in response to a stimulus
when some transport proteins move solutes against their concentration gradients - consumes energy in the form of ATP; allows cells to maintain concentration gradients that differ from their surroundings
Requires transport proteins
Against concentration gradient
sodium potassium pump
is one type of active transport system
3 sodiums out, 2 potassiums in
What is the flow of sodium and potassium ions in the sodium-potassium pump?
voltage difference across a membrane; Voltage is created by differences in the distribution of positive and negative ions; is key to nutrient uptake into cells and signal transduction over long distances
a transport protein that generates voltage across a membrane
main electrogenic pump of plants, fungi, and bacteria
occurs when active transport of a solute indirectly drives transport of another solute
ccurs when active transport of a solute indirectly drives transport of another solute
electrochemical gradient of hydrogen ions or protons (H+)
two combined forces of sodium and protons collectively drive the diffusion of ions across a membrane and is called this
the ion’s concentration gradient
the effect of the membrane potential on the ion’s movement
the cell takes in macromolecules by forming vesicles from the plasma membrane
is any molecule that binds specifically to a receptor site of another molecule
begins with a specific molecule and ends with a product; each step is catalyzed by a specific enzyme
release energy by breaking down complex molecules into simpler compounds
the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism
ncludes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
consume energy to build complex molecules from simpler ones
-The synthesis of protein from amino acids is an example of this
is the study of how organisms manage their energy resources
are macromolecules that speed up the dehydration process
is kinetic energy associated with random movement of atoms or molecules
is potential energy available for release in a chemical reaction
is the study of energy transformations
Energy can be transferred and transformed, but it cannot be created or destroyed
Every energy transfer or transformation increases the entropy (disorder) of the universe
proceeds with a net release of free energy and is spontaneous
absorbs free energy from its surroundings and is nonspontaneous
Reactions in a _____ system eventually reach equilibrium and then do no work
the use of an exergonic process to drive an endergonic one; mostly mediated in cells by ATP
is the cell’s energy shuttle
ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant. The recipient molecule is now ______.
is a chemical agent that speeds up a reaction without being consumed by the reaction
The initial energy needed to start a chemical reaction; often supplied in the from of heat from the surroundings
The reactant that an enzyme acts on is called the enzyme’s _____________.
is the region on the enzyme where the substrate binds
positions that enhance their ability to catalyze the reaction
Chemicals that specifically influence the enzyme; nonprotein enzyme helpers; may be inorganic (such as a metal in ionic form) or organic
organic cofactor; include vitamins
bind to the active site of an enzyme, competing with the substrate
bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
a regulatory molecule binds to a protein at one site and affects the protein’s function at another site
The binding of an ______ stabilizes the active form of the enzyme
The binding of an _______ stabilizes the inactive form of the enzyme
is a form of allosteric regulation that can amplify enzyme activity; in this, the binding by a substrate to one active site stabilizes favorable conformational changes at all other subunits
the end product of a metabolic pathway shuts down the pathway; prevents a cell from wasting chemical resources by synthesizing more product than is needed
is the most common mechanism for control of cellular respiration
s similar to aerobic respiration but consumes compounds other than O2
uses an electron transport chain with an electron acceptor other than O2, for example sulfate
The transfer of _______ during chemical reactions releases energy stored in
organic molecules; This released energy is ultimately used to synthesize ATP
Chemical reactions that transfer electrons between reactants
a substance loses electrons
The electron donor is called this
Some redox reactions do not transfer electrons but change the electron ______ in covalent bonds
pulls electrons down the chain in an energy-yielding tumble
C6H12O6 + 6 O2 ---> 6 CO2 + 6 H2O + Energy (ATP + heat)
Before the citric acid cycle can begin, pyruvate must be converted to______ which links the cycle to glycolysis
The citric acid cycle oxidizes organic fuel derived from pyruvate, generating what per turn?
combining with oxaloacetate, forming citrate
Following glycolysis and the citric acid cycle, ______ and _______ account for most of the energy extracted from food
free; O2; H2O
The reducing power of a redox pair, or a measure of the affinity of the oxidized form of a redox pair has for electrons. The more negative the value, the lower the affinity; the more positive the value, the higher the affinity
The energy stored in a H+ gradient, referred to as a ________ ____ _____, across a membrane couples the redox reactions of the electron transport chain to ATP synthesis
Electron transfer in the electron transport chain causes proteins to pump H+ from the ________ to the __________
In mitochondria, protons are pumped to the______________ and drive ATP synthesis as they diffuse back into the ____________________.
H+ moves back across the membrane, passing through channels after electron transfer causing proteins to pump H+; uses the exergonic flow of H+ to drive phosphorylation of ATP
glucose -> NADH -> electron transport chain -> proton-motive force -> ATP
In the absence of O2, glycolysis couples with ______ or ____________ to produce ATP
carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
Yeast and many bacteria are ___________ , meaning that they can survive using either fermentation or cellular respiration
In a this, pyruvate is a fork in the metabolic road that leads to two alternative catabolic routes
If ATP concentration begins to drop, respiration _______; when there is plenty of ATP, respiration _______ via feedback inhibition
Control of catabolism is based mainly on regulating what? at strategic points in the catabolic pathway
is the process that converts solar energy into chemical energy
sustain themselves without eating anything derived from other organisms; are the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules
use the energy of sunlight to make organic molecules from H2O and CO2
obtain their organic material from other organisms; are the consumers of the biosphere; almost all depend on photoautotrophs for food and O2
the green pigment within chloroplasts; Light energy absorbed by this drives the synthesis of organic molecules in the chloroplast
is the main photosynthetic pigment; violet-blue and red light absorbed best
CO2 enters and O2 exits the leaf through microscopic pores called ____.
Chloroplasts are found mainly here, the interior tissue of the leaf
connected sacs in the chloroplast; may be stacked in columns called grana; chlorophyll is in its membranes
6 CO2 + 12 H2O + Light energy -> C6H12O6 + 6 O2 + 6 H2O
Photosynthesis is a redox process in which _____ is oxidized and ____ is reduced
are substances that absorb visible light; different ones absorb different wavelengths
When a pigment absorbs light, it goes from a ground state to an excited state, which is unstable. When excited electrons fall back to the ground state, photons are given off, an afterglow called what?
consists of a reaction- center complex (a type of protein complex) surrounded by light- harvesting complexes
pigment molecules bound to proteins) funnel the energy of photons to the reaction center
in the reaction center accepts an excited electron from chlorophyll a
system that functions first in the thylakoid and is best at absorbing a wavelength of 680 nm
The reaction-center chlorophyll a of PS I
the primary pathway, involves both photosystems and produces ATP and NADPH using light energy
in linear electron flow, a photon hits a pigment and its energy is passed among pigment molecules until it excites P680 a process that occurs via _______________ without movement of electrons - therefore no redox reactions)
the electrons of NADPH, one of the products of linear electron flow, are available for the reactions of the ______ _____.
Energy released by the ‘fall” of free energy of electrons during transport drives the creation of a proton gradient across the thylakoid membrane
Diffusion of H+ (protons) across the membrane drives ______.
uses only photosystem I and produces ATP, but not NADPH
From what sources do the mitochondria and chloroplasts get energy to transform it into ATP?
In chloroplasts, protons are pumped into the ____________ and drive ATP synthesis as they diffuse back into the _____
to fix carbon, these open their stomata at night, incorporating CO2 into organic acids; Stomata close during the day, and CO2 is released from organic acids and used in the Calvin cycle
minimize the cost of photorespiration by incorporating CO2 into four-carbon compounds in mesophyll cells
C4 plants require the enzyme _________, which has a higher affinity for CO2 than rubisco does; it can fix CO2 even when CO2 concentrations are low
The four-carbon compounds made by C4 plants are exported to _______, where they release CO2 that is then used in the Calvin cycle
is a series of steps by which a signal on a cell’s surface is converted into a specific cellular response
Cells in a multicellular organism communicate how?
Animal and plant cells have these, that directly connect the cytoplasm of adjacent cells
In local signaling, animal cells may communicate by direct contact, or _______ ____ ____ _____.
In long-distance signaling, plants and animals use chemicals called this
a signal molecule (ligand) binds to a receptor protein, causing it to change shape
G protein-coupled receptors, Receptor tyrosine kinases, Ion channel receptors
is a plasma membrane receptor that works with the help of a G protein
The active G protein binds and activates an enzyme, causing a ______ ______.
Releasing of active G protein from enzyme, when job is done, returns G protein to _____ ____.
are membrane receptors that attach phosphates to tyrosines; can trigger multiple signal transduction pathways at once
acts as a gate when the receptor changes shape; when a signal molecule binds as a ligand to the receptor, the gate allows specific ions, such as Na+ or Ca2+, through a channel in the receptor
Some receptor proteins are intracellular, found in the____ or ____ of target cells
Which types of chemical messengers can readily cross the membrane and activate receptors?
Examples of hydrophobic messengers are ________ (2)
Cascades of molecular interactions relay signals from receptors to target molecules in the cell
In many pathways, the signal is transmitted by a cascade of _____ _________: which act as a molecular switch, turning activities off and on.
transfer phosphates from ATP to protein, a process called phosphorylation
remove the phosphates from proteins, a process called dephosphorylation
The extracellular signal molecule that binds to the receptor is a pathway’s “_____ ______".
are small, nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion
is one of the most widely used second messengers
an enzyme in the plasma membrane, converts ATP to cAMP in response to an extracellular signal
A signal relayed by a signal transduction pathway may trigger an increase in calcium in the ______.
Pathways leading to the release of calcium involve what and what as additional second messengers?
cell signaling leads to regulation of gene transcription or cytoplasmic activities called a what?
The cell’s response to an extracellular signal is sometimes called the "__________ _______"
The response may occur in the ______ or may involve action in the _______.
Many signaling pathways regulate the synthesis of _______ or ______, usually by turning genes on or off in the nucleus
The final activated molecule may function as a _______ factor
proteins that helps starting transcription of a gene
Amplifying the signal (and thus the response) & Contributing to the specificity of the response
are large relay proteins to which other relay proteins are attached; can increase the signal transduction efficiency by grouping together different proteins involved in the same pathway
When signal molecules leave the receptor, the receptor reverts to its _____ ____.
is programmed or controlled cell suicide in which a cell is chopped and packaged into vesicles that are digested by scavenger cells; it prevents enzymes from leaking out of a dying cell and damaging neighboring cells
are the main proteases (enzymes that cut up proteins) that carry out apoptosis
An extracellular death-signaling ligand, DNA damage in the nucleus, Protein misfolding in the endoplasmic reticulum
the life of a cell from formation to its own division
yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cell
All the DNA in a cell constitutes the cell’s what?
DNA molecules in a cell are packaged into what?
In preparation for cell division what happens?
Each duplicated chromosome has two ____ _______, which separate during cell division
is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached
If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state
is an apparatus of microtubules that controls chromosome movement during mitosis
a radial array of short microtubules
During prometaphase, some spindle microtubules attach to the _________ of chromosomes and begin to move the chromosomes
At metaphase, the chromosomes are all lined up at the ______ _______, the midway point between the spindle’s two poles
In animal cells, cytokinesis occurs by a process known as ______, forming a _____ _____
In plant cells, a ____ ____ forms during cytokinesis
Prokaryotes (bacteria and archaea) reproduce by a type of cell division called this
In binary fission, the chromosome replicates (beginning at the where??), and the two daughter chromosomes actively move apart
The sequential events of the cell cycle are directed by a distinct what, which is similar to a clock
where the cell cycle stops until a go-ahead signal is received during the cell cycle
cyclins and cyclin-dependent kinases (Cdks)
MPF (maturation-promoting factor)
is a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the M phase
animal cells may exhibit this, in which they must be attached to a substratum in order to divide
-They may make their own growth factor
-They may convey a growth factor’s signal without the presence of the growth factor
-They may have an abnormal cell cycle control system
masses of abnormal cells within otherwise normal tissue
If abnormal cells remain at the original site, the lump is called a what?
invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form secondary tumors