DAT Bio Flashcards
Gibbs FE Formula
delt G = delt H - t delt S
cell metabolism
the sum of all chemical reactions in a cell
(metabolism= catabolism + anabolism + energy transfer)
Catabolism:
the breakdown of complex molecules into
simpler molecules. Releases energy which can drive
anabolic pathways
Anabolism:
the synthesis of complex molecules from
simpler ones, using energy
3 Laws of thermodynamics:
- Energy cannot be created or destroyed – only
transferred and transformed - Entropy of closed systems tends to increase over
time.
a. Livings organisms are not closed systems, so
they can become more ordered (decreased
entropy) over time by increasing disorder in
their surroundings - Entropy minimizes as a system approaches absolute
0 Kelvin
Substrate:
the molecule that an enzyme acts on
Active site:
the location on the enzyme where the
substrate binds. The shape of the active site
determines the enzyme’s substrate specificity (i.e. what
molecules it can interact with)
Cofactors:
nonprotein structures that assist enzymes in
their function. Can bind permanently or reversibly.
Ribozymes:
RNA molecules with enzymatic function
Vmax:
maximum rate of a reaction
Vmax increases as
the amount of substrate increases.
- Limited by enzyme saturation (increasing enzyme
concentration also increases Vmax)
1/2 vmax
half of the max rate
Km (Michaelis Constant):
the concentration of substrate
at 1⁄2 Vmax. Inversely proportional to substrate binding
affinity (how well the enzyme binds to a substrate)
Small Km:
high binding affinity; less substrate
needed to saturate the enzyme
Large Km:
low binding affinity; more substrate
needed to saturate the enzyme
Competitive Inhibition:
inhibitor reversibly binds to
the active site. Can be overcome by increasing
substrate concentration.
Non-Competitive Inhibition:
the inhibitor binds to the
enzyme at a location other than the active site. Cannot
be overcome by increasing substrate concentration.
- Vmax decreases, Km is unaffected
Allosteric Inhibition:
inhibitor binds to the allosterc site
of enzyme and induces the enzyme’s inactive form.
Allosteric inhibition is a form of non-competitive
inhibition.
Cellular Respiration:
combination of aerobic and anaerobic 1
catabolic pathways that cells use to breakdown organic
compounds (e.g. glucose) into ATP
Aerobic Cellular Respiration of glucose: consists of 3 steps
- Glycolysis (in cytosol of cell)
- Citric Acid/Krebs/Tricarboxylic Acid Cycle (in
mitochondrial matrix) - Oxidative Phosphorylation/Electron Transport Chain
(across inner mitochondrial membrane)
Mitochondria
critical to cellular respiration in eukaryotic
cells as they are the site of aerobic cellular respiration to
synthesize ATP.
Overall Reaction of Cellular Respiration:
C6H12O6 (glucose) + O2 ➞ 6CO2 + 6H2O + Energy
Glycolysis
Glucose + 2 NAD+ + 2 ADP ➞ 2 Pyruvate + 2 ATP + 2
NADH + 2 H2O
Pyruvate decarboxylation:
if oxygen is present, pyruvate is
converted into acetyl CoA in the mitochondrial matrix
CAC summarized:
Acetyl CoA from pyruvate
decarboxylation merges with oxaloacetate to form citrate
➞ citrate undergoes 7 more steps, forming different
intermediates ➞ oxaloacetate is reformed ➞ cycle repeats
Electron Transport Chain (ETC):
a series of proteins which
pass high energy electrons to each other; embedded in the
inner membrane of the mitochondria
Final step of ETC:
electrons are transferred to O2. The O2,
protons, and electrons combine to form water (H2O)
ATP Synthase:
makes ATP from ADP via oxidative
phosphorylation, powered by the proton-motive force.
Embedded in inner mitochondrial membrane.
Proton-Motive force:
gradient of protons (high [H+] in
intermembrane space, low [H+] in mitochondrial matrix)
forming electrochemical gradient
Chemiosmosis:
movement of ions down a
concentration gradient across a semipermeable
membrane
Protons flow down their gradient (from the
intermembrane space into the mitochondrial matrix)
through
ATP synthase
Anaerobic respiration:
cellular respiration (glycolysis ➞
CAC ➞ ETC) that occurs with molecules other than O2 as
the final e-
acceptor (e.g. SO42-, NO3-
, S).
Fermentation:
anaerobic recycling of NADH into NAD+
from pyruvate. Occurs in the cytoplasm of the cell and
does not generate any ATP (only regenerates NAD+)
2 types of fermentation
alcohol and lactic acid
Glycogenesis:
body stores extra glucose as
glycogen by linking glucose molecules
together.
Glycogenolysis:
breakdown of stored glycogen
into glucose for energy. Occurs when glucose
levels are low.
Gluconeogenesis:
synthesis of glucose from
non-carbohydrate molecules (proteins and
lipids). Occurs in the liver and the kidney when
glucose and glycogen levels are low.
Glycolysis:\
breakdown of glucose to make
pyruvate and produce ATP.
Insulin:
endocrine hormone released when
blood glucose is high.
Glucagon:
released when blood glucose is low.
lipolysis,
triglycerides are broken down into glycerol
+ 3 fatty acid chains
Oxidative deamination:
removal of amino group from
amino acids in order to make other metabolic
intermediates. Mostly occurs in the liver.
