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55 terms

Biology

Test 2
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Catabolic pathways
breaking down complex molecules to simpler compounds "breakdown pathways"
Anabolic pathway
consumes energy to buld complicated molecules from simpler ones "biosynthetic pathways"
Bioenergetics
the study how energy flows through living organisms
Engery
capacity to cause change
Kinetic engery
energy can be associated with the relative motion of objects
Heat/thermal energy
kinetic energy associated with the random movement of atoms or molecules
Potential energy
energy that matter possesses because of its location or structure
Chemical energy
term used by biologists to refer to the potential energy available for release in a chemical reaction
thermodynamics
the study of energy transformation that occur in a collection of matter
first law of thermodynamics
the energy of the universe is constant: energy sn be transferred and transformed, but it cannot be created or destroyed. also known as the principle of conservation of energy
entropy
measure of disorder, or randomness
second law of thermodynamics
every energy transfer or transformation increases the entropy of the universe
spontaneous process
a process that can occur without an input of energy
free energy
the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell
exergonic reaction
"energy outward" proceeds with a net release of free energy. energy released, spontaneous
endergonic reaction
"energy inward" one that absorbs free energy from its surroundings.energy required, non spontaneous
chemical work
the pushing of endergonic reaction that would not occur spontaneously, such as the synthesis of polymers from monomers
transport work
the pumping of substances across membranes against the direction of spontaneous movement
mechanical work
such as the beating of cilia, the contraction of muscle cells, and the movement of chromosomes during cellular reproduction
energy coupling
the use of exergonic process to drive an endergonic one
ATP
responsible for mediating most energy coupling in cells, and in most cases it acts as the immediate source of energy that power cellular work
enzyme
macromolecule that acts as a catalyst
catalyst
a chemical agent that speeds up a reaction without being consumed by the reaction
activation energy
the initial investment of energy for starting a reaction
active site
a pocket or groove on the surface of the enzyme where catalysis occurs
induced fit
chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction
substrate
the reactant an enzyme acts on is referred to as the enzyme's _____
enzyme-substrate complex
the enzyme binds to its substrate
competitive inhibitor
reduce the productivity of enzymes by blocking substrate from entering active sites
noncompetitive inhibitors
do not directly compete with the substrate to bind the enzyme at the active site . Instead they impede enzymatic reactions by binding to another part of the enzyme. this interaction causes the enzyme molecule to change its shape in such a way that the active site becomes less effective at catalyzing the conversion of substrate to product
feedback inhibitor
a metabolic pathway is switched off by the inhibitor binding of its end product to an enzyme that the inhibitory binding of its end product to an enzyme that acts early in the pathway
cell division
unicellular organisms reproduce by this
cell cycle
an order sequence of events in the life of a cell form its origin until it divides into daughter cells
genome
a cell's endowment of DNA, its genetic information
chromosomes
DNA is manageable because the DNA molecules are package into structures called ___
chromatin
the entire complex of DNA and proteins that is the building material of chromosomes
stomatic cell
any body cell except the reproductive cells
gametes
sperm or eggs
sister chromatids
duplicated chromosome, which are joined copies of the original chromosome
centromere
a region containing specific DNA sequences where the chromatid is attached most closely to its sister chromatid
Mitosis
the division of the genetic material in the nucleus
cytokinesis
the division of the cytoplasm
mitotic (M) phase
includes both mitosis and cytokinesis, usually the shortest part of the cell cycle
G1 phase
first gap in cell cycle
S phase
synthese in cell cycle
G2 phase
second gap in cell cycle
cell cycle
In a dividing cell, mitotic (M) phase alternates with interphase, a growth period. the first part of the interphase (G1) is followed by the S phase, when the chromosomes duplicate; G2 is the last part of interphase. In the M phase mitosis distributes the daughter chromosome to daughter nuclei and cytokinesis divides the cytoplasm producing two daughter cells, the relative duration of G1, S, and G2 may vary
Stages in mitosis
prophase, prometaphase, metaphase, anaphase and telophase
mitotic spindle
apparatus of microtubles that controls chromosome movement during mitosis
centrosomes
a subcellular region containing materials that functions throughout the cell cycle to organize the cell's microtubles. spindle microtubules start here
aster
a radial array of short microtubules, extends from each centrosome
kinetochore
a structure of proteins associated with specific sections of chromosomal DNA at each centromere
cleavage
animals carrying out mitosis in cytokinesis
cell plate
plants carrying out mitosis in cytokinesis
binary fission
A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size