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biology exam 2 lecture
Terms in this set (103)
-the ability to do work
-all cells capture and use energy
energy of motion
Networks of chemical reactions sustain life
-metabolism: Sum of all reactions in your body
-endergonic reactions: requires energy, building something
-exergonic reactions: releases energy, breaking something down
-Oxidation reactions: the molecules that accepts the electron now has more energy; OIL RIG- Oxidation is losing electrons, Reduction is gaining electrons
-Electron transport chain- membrane, proteins (act as electron carriers), electron donor at the beginning, electron acceptor at the end, energy is lost as electrons are transporting down the chain
ATP is cellular energy currency
ATP structure: 3 phosphate groups, adenosine, adenine
-water molecule is being used to break bond and when that happens energy is released
-we now have ADP instead of ATP
Function of ATP in the cell
-cellular energy currency
-links endergonic and exergonic reactions
protein that acts as a catalyst
Enzymes speed up biochemical reactions
Enzymes work by lowering the activation energy required for the reactions to proceed
Active site and substrate
-Substrate molecules bind to the enzyme's active site, where the chemical reaction occurs. The substrate is what the enzyme acts on.
-each enzyme fits the shape of a substrate
Enzymes alter substrates to form products
-Once the chemical reaction occurs, product molecules are released. -The enzyme retains its original form
-Products are what the reaction produces.
Factors causing enzyme denaturation
-denatures is when enzymes lose their shape and this alters their function to make them useless
-different enzymes have different pH requirements and optimum temperatures; ex: saliva enzymes vs stomach enzymes
Regulation of metabolic pathways
-metabolic pathway: several different reactions in a row and each of these reactions are catalyzed by an enzyme
-the product made at the end acts as an inhibitor
-Negative feedback- once the product becomes enough, enzymes begin binding and shutting down the pathway, stops the pathways through inhibition of the enzyme (two kinds):
-noncompetitive- the inhibitor molecule binds somewhere other than the active site but when it binds it changes the shape of the active site so the substrate cannot bind
-competitive-when the molecule binds straight the substrate so the substrate can't bind inhibition
-Feedback that tends to magnify a process or increase its output.
-less common in the body
membrane transport may release energy or cost energy
-A property of biological membranes that allows some substances to cross more easily than others.
-difference in the concentration of a substance from one location to another
-Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient
-down concentration gradient
-Diffusion of water through a selectively permeable membrane
-solute concentration is the same on both sides of the membrane
-Having a lower concentration of solute than another solution
-Having a higher concentration of solute than another solution.
-substance moves across membrane with assistance from transport proteins
-moving from an area of high to low concentration
-no energy required
-need a transport molecule to help get it through
-Energy-requiring process that moves material across a cell membrane against a concentration difference
-requires transport protein and energy
transport in vesicles
-vesicle carry large particles into and out of the cell
process by which a cell takes material INTO the cell by infolding of the cell membrane
Process by which a cell RELEASES large amounts of material
Life depends on photosynthesis
photosynthesis is an endergonic reaction; the energy comes from the sun
An organism that makes its own food
organism that obtains energy from the foods it consumes; also called a consumer
-6CO2 + 6H2O --> light energy --> C6H12O6 + 6O2
-inputs: carbon dioxide, water, light energy
-outputs: sugars and oxygen
Sunlight is the energy source for photosynthesis
Photosynthesis is the process of converting light (kinetic) energy into chemical (stored) energy
packets of light energy
The distance between two corresponding parts of a wave
the main pigment for photosynthesis in chloroplasts
energy absorbing plant pigments other than chlorophyll
Small openings on the underside of a leaf through which oxygen and carbon dioxide can move (pores for gas exchange)
-Spongy tissue in the interior of the leaf where most chloroplasts are found.
-photosynthesis occurs in lead mesophyll cells
organelle where photosynthesis takes place
Outer & Inner membrane- intermembrane space
3rd membrane- forms thylakoids & contains pigment molecules
-A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.
-pigment molecules in the thylakoid capture sunlight
space inside thylakoid
-clusters of proteins and pigments that act as a light harvesting unit
-with the photosystem is the reaction center chlorophyll which kickstarts the light reactions
funnel light energy to reaction centers
-Complex of proteins associated with two special chlorophyll a molecules and a primary electron acceptor.
-Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis.
-Excited by light energy, one of the chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain.
Photosynthesis occurs in two stages
light reactions (light reaction comes first) and calvin (Carbon) cycle
-light energy is captured and converted to chemical energy
-requires water and light
inputs: water and light energy
outputs: Water, ATP, and NADPH (which are reactions used in the calvin (carbon) cycle
-purpose for what is produced: Oxygen (waste), ATP (to be used by calvin cycle), NADPH (to be used by calvin cycle)
role of water in photosynthesis
-Water is split, producing electrons that are used to replace the electrons lost in photosystem II.
-water gets oxidized Oxygen is produced as a waste product
role of light energy in photosynthesis
supply the energy to excite electrons
role of NADP+ in photosynthesis
It is reduced and then carries electrons to the Calvin cycle.
role of ADP in photosynthesis
The lower energy ADP is re-energized during photosynthesis as the phosphate group is re-attached, thus completing the cycle of ATP to ADP
Role of Photosystem II in photosynthesis
takes the electron from water and starts the electron down the chain
electron is reenergized from additional light energy
photosystems can take hydrogen ions from the stroma and pump them into the thylakoid spaces
role of hydrogen ions in photosynthesis
The hydrogen ions are allowed to pass through the thylakoid membrane through an embedded protein complex called ATP synthase. This same protein generated ATP from ADP in the mitochondrion.
role of electron transport chain in photosynthesis
-makes ATP and NADPH for the Calvin cycle
Role of ATP Synthase
-through the spinning due to the traveling H+ ions, it binds ATP and a phosphate group to make ATP
-convert ADP into ATP
role of chemiosmotic phosphorylation
Calvin (Carbon) reactions
-energy is used to produce sugar
-location: stroma of chloroplasts
-uses ATP and NADPH from light reactions as sources of energy
inputs: carbon dioxide (C02), ATP, and NADPH
Three stages of Calvin Cycle
1. carbon fixation
-Rubisco enzyme adds CO_2 onto a molecule of RuBP
-An unstable 6-carbon organic molecule is produced
-make the sugar
-create PGAL- small 3, carbon carbohydrate, can hook 2 together to make glucose
-RuBP is regenerated by rearranging the remaining molecules
-keeps the cycle going
The role of CO2 in the Calvin cycle
CO2 from air is fixed. That is the power of calvin cycle. Power of synthesizing molecules.
role of rubisco in the calvin cycle
The enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP).
Role of ATP and NADPH in Calvin Cycle
The Calvin cycle uses ATP and NADPH to convert CO2 to sugar
The carbon reactions produce carbohydrates
-PGAL (combine to build sugars)
-RuBP (regenerated to keep calvin cycle going)
-Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen
cellular respiration equation
-inputs: carbohydrate or sugar and oxygen
-outputs: water, carbon dioxide, and energy
-cells use energy in food to make ATP
-cellular respiration as an exergonic reaction
cellular respiration includes three main processes
-electron transport chain
-the breakdown of glucose by enzymes, releasing energy and pyruvic acid.
-series of reactions in which pyruvate is oxidized to acetyl CoA and CO2
-pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions
-location: mitochondrial matrix
Electron transport chain
-a series of proteins in which the high-energy electrons from the Krebs cycle are used to convert ADP into ATP
-location: across inner mitochondrial membrane
In eukaryotic cells, mitochondria produce most ATP
structure of mitochondria
- outer membrane
-cristae- inner membrane that is folded
- inner membrane divides into: outer compartment and the matrix
-breaks down glucose to pyruvate
-no O2 required
-Inputs: glucose, NAD+, ADP
-Outputs: 2 pyruvate (goes to transition step), NADH (goes to electron transport chain), ATP (used for metabolism)
Aerobic respiration yields abundant ATP
-input: 2 pyruvate, NAD+
-output: 2 Acetyl Co-A (goes to kerb's cycle), NADH (goes to electron transport chain), 2 CO2 (Waste
-input: 2 Acetyl Co-A, ADP, NAD+, FAD
output: 4 CO2 (waste), ATP (used for metabolism), NADH (goes to electron transport chain), FADH2 (goes to electron transport chain
Electron transport chain cellular respiration
-Donor of electron is NADPG and NAD
-Electron acceptor is oxygen
-makes more ATP than anything else
The ETC creates a H+ gradient
As electrons travel through the transport chain, carrier molecules use the potential energy of the electrons to transport hydrogen ions into the intermembrane compartment.
ATP synthase forms ATP
The hydrogen ions move down their concentration gradient from the intermembrane compartment into the matrix and pass through an enzyme called ATP synthase.
ATP synthase produces ATP via chemiosmotic phosphorylation
ETC requires oxygen
-At the end of the transport chain, electrons are donated to an oxygen atom, which combines with hydrogens to form water.
-Oxygen is the final electron acceptor. Without it, the chain shuts down.
electron transport chain
inputs: NADH, FADH2, Oxygen
outputs: ATP (much larger amounts than previous steps, Water (waste)
Other food molecules enter the energy-extracting pathways
other types of food can also be broken down to create ATP:
-polysaccharides (starch and glycogen
some pathways do not require oxygen
Respiration in the absence of oxygen. This produces lactic acid.
Respiration that requires oxygen
fermentation (anaerobic respiration)
-Process by which cells release energy in the absence of oxygen
-ATP from glycolysis only
-lactic acid ex: muscle cells when exercising
anaerobic, aerobic, fermination
all do glycolysis
ATP is coupled with chemical reactions
-ATP breakdown is coupled with endergonic reactions.
-Energy released from ATP breakdown is used to power endergonic reactions.
ATP hydrolysis is coupled with endergonic reactions
ATP is converted to ADP & phosphate energized myosin heads (removal of phosphate) need energy
large protein that uses energy from H+ ions to bind ADP and a phosphate group together to make ATP
Autotrophs (producers) carry out photosynthesis
-Cyanobacteria carry out photosynthesis, mainly in the water.
-Eukaryotes such as algae and plants carry out photosynthesis in the water and on land.
-No Archaea are known to carry out photosynthesis at all.
Plants use different carbon fixation pathways
C3 plants, C4 plants, and CAM plants each do photosynthesis, using different pathways for fixing carbon.
Carbon fixation pathways are plant adaptations
-C3 plants do well in cool, moist weather
-C4 and CAM plants are adapted to hot, dry weather
C3 plants do it all at once
-All reactions take place in mesophyll cells.
-In hot, dry weather the stomata close to conserve water.
-Photorespiration occurs due to oxygen buildup inside the leaf, decreasing photosynthesis.
C4 plants divide the labor between cells
-Light reactions occur in mesophyll cells.
-Carbon reactions catalyzed by Rubisco occur in bundle sheath cells (away from air).
-Photorespiration does not reduce the efficiency of photosynthesis.
CAM plants divide the labor temporally
-About 1% of plants are CAM plants, like this cactus, that live in desert conditions.
-All reactions for photosynthesis occur in mesophyll cells.
-Carbon reactions occur only at night, in the cooler, moister air.
-Photorespiration does not reduce the efficiency of photosynthesis.
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