10/27/2015 CHAPTER 6 BIOCHEMICAL PATHWAYS. 10/27/2015 BIOCHEMICAL REACTIONS Organisms obtain energy...
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Transcript of 10/27/2015 CHAPTER 6 BIOCHEMICAL PATHWAYS. 10/27/2015 BIOCHEMICAL REACTIONS Organisms obtain energy...
CHAPTER 6
BIOCHEMICAL PATHWAYS
BIOCHEMICAL REACTIONSBIOCHEMICAL REACTIONS
Organisms obtain energy through enzyme-Organisms obtain energy through enzyme-controlled biochemical reactionscontrolled biochemical reactions
Release energy stored in chemical bondsRelease energy stored in chemical bonds The ultimate source of all energy is the sun The ultimate source of all energy is the sun
Converted to chemical energy through Converted to chemical energy through photosynthesisphotosynthesis
Organisms convert this chemical energy (food) Organisms convert this chemical energy (food) into usable energy through cellular respirationinto usable energy through cellular respiration
Controlled releaseControlled release Large organic molecules are broken downLarge organic molecules are broken down
Photosynthetic organisms produce food for Photosynthetic organisms produce food for their own use and for otherstheir own use and for others
BIOCHEMICAL REACTIONSBIOCHEMICAL REACTIONS
All organisms carry out cellular All organisms carry out cellular respiration which may be:respiration which may be:
Aerobic – uses oxygenAerobic – uses oxygen Anaerobic – does not use oxygenAnaerobic – does not use oxygen
Organisms can be classified based on how Organisms can be classified based on how they obtain nutrients:they obtain nutrients:
Autotrophs – make their own food (green plants, Autotrophs – make their own food (green plants, algae)algae)
Heterotrophs – obtain food from their Heterotrophs – obtain food from their surroundings (all animals, fungi)surroundings (all animals, fungi)
BIOCHEMICAL REACTIONSBIOCHEMICAL REACTIONS
Some bacterial cells can produce food Some bacterial cells can produce food through chemosynthesis (chemical through chemosynthesis (chemical reactions)reactions)
Occur within the cytoplasmOccur within the cytoplasm In eukaryotic cells, these reactions are In eukaryotic cells, these reactions are
carried out in specific organellescarried out in specific organelles Photosynthesis – chloroplastsPhotosynthesis – chloroplasts Cellular respiration – mitochondriaCellular respiration – mitochondria
BIOCHEMICAL PATHWAYSBIOCHEMICAL PATHWAYS Can be classified two ways:Can be classified two ways:
Catabolic reactionsCatabolic reactions - breakdown of organic - breakdown of organic molecules; releases energymolecules; releases energy
Anabolic reactionsAnabolic reactions - synthesis of new - synthesis of new organic molecules; requires energyorganic molecules; requires energy
Energy for these reactions is supplied Energy for these reactions is supplied by adenosine triphosphate (ATP)by adenosine triphosphate (ATP)
Energy is released when ATP is broken Energy is released when ATP is broken down into ADPdown into ADP
Reformed when a phosphate group is Reformed when a phosphate group is added to ADP (phosphorylation reaction)added to ADP (phosphorylation reaction)
““Like charging a Like charging a battery”battery”
The “actual” processThe “actual” process
AMPAMP
ADPADP
ATPATP
AEROBIC CELLULAR AEROBIC CELLULAR RESPIRATIONRESPIRATION
The breakdown of glucose molecules in The breakdown of glucose molecules in the presence of oxygenthe presence of oxygen
Carbon dioxide and water are producedCarbon dioxide and water are produced
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy (ATP + heat) (ATP + heat)
glucose + oxygen glucose + oxygen →→ carbon dioxide + water + carbon dioxide + water + energyenergy
AEROBIC CELLULAR AEROBIC CELLULAR RESPIRATIONRESPIRATION
Begins in the cytoplasm and is Begins in the cytoplasm and is completed in the mitochondria.completed in the mitochondria.
Series of enzyme-controlled reactions Series of enzyme-controlled reactions that are divided into three pathways:that are divided into three pathways:
Glycolysis Glycolysis Krebs cycle (citric acid Krebs cycle (citric acid cycle)cycle)
Electron transport systemElectron transport system
GLYCOLYSIS GLYCOLYSIS GlycolysisGlycolysis – the breakdown of glucose; – the breakdown of glucose;
occurs in the cytoplasmoccurs in the cytoplasm Glucose (6-carbon atoms) is broken into Glucose (6-carbon atoms) is broken into
two 3-carbon molecules called two 3-carbon molecules called pyruvatepyruvate (pyruvic acid). (pyruvic acid).
2 ATP molecules are produced 2 ATP molecules are produced Electrons released from these reactions Electrons released from these reactions
are transferred to the electron transport are transferred to the electron transport chain.chain.
Will be attached to oxygen atomsWill be attached to oxygen atoms
GLYCOLYSISGLYCOLYSIS
KREBS CYCLEKREBS CYCLE The pyruvate produced in the cytoplasm The pyruvate produced in the cytoplasm
moves into the mitochondria, releasingmoves into the mitochondria, releasing Carbon dioxide (remnants of pyruvate)Carbon dioxide (remnants of pyruvate) Electrons Electrons 2 ATP molecules2 ATP molecules
The electrons are transferred to NADH The electrons are transferred to NADH and FADH2 (electron carriers), which and FADH2 (electron carriers), which take them to the electron transport take them to the electron transport system.system.
KREBS CYCLEKREBS CYCLE
ELECTRON TRANSPORT ELECTRON TRANSPORT CHAINCHAIN
When electrons receive additional energy When electrons receive additional energy they move to a higher energy level. they move to a higher energy level.
When the electrons fall back to their When the electrons fall back to their original position they give up that energy. original position they give up that energy.
Special molecules (NADH, NADPH, FADH2) Special molecules (NADH, NADPH, FADH2) capture these excited electrons and capture these excited electrons and transfer them to other chemical reactionstransfer them to other chemical reactions
Tied to the formation of ATPTied to the formation of ATP Oxidation-reduction reactionsOxidation-reduction reactions
Electrons usually come from hydrogen Electrons usually come from hydrogen creating H+ (hydrogen nucleus)creating H+ (hydrogen nucleus)
ELECTRON TRANSPORT ELECTRON TRANSPORT SYSTEMSYSTEM
Electrons are transferred through a Electrons are transferred through a series of reactions until they are series of reactions until they are accepted by oxygenaccepted by oxygen
Oxygen combines with hydrogen ions Oxygen combines with hydrogen ions to make water.to make water.
This process generates large This process generates large amounts of ATPamounts of ATP
32 ATP total 32 ATP total
Electron Transport Electron Transport SystemSystem
FERMENTATIONFERMENTATION(Anaerobic Respiration)(Anaerobic Respiration)
Two main types of fermentation:Two main types of fermentation: Alcoholic fermentationAlcoholic fermentation Lactic acid fermentationLactic acid fermentation
Alcoholic fermentation – used by Alcoholic fermentation – used by yeast cells in the absence of oxygenyeast cells in the absence of oxygen
Pyruvate from glycolysis is converted to Pyruvate from glycolysis is converted to ethanol and carbon dioxide ethanol and carbon dioxide
The yeast cells gain 2 ATPThe yeast cells gain 2 ATP
FERMENTATIONFERMENTATION
Lactic acid fermentation – pyruvate from Lactic acid fermentation – pyruvate from glycolysis is converted to lactic acidglycolysis is converted to lactic acid
2 ATP molecules are produced2 ATP molecules are produced In bacteria, the build up of lactic acid In bacteria, the build up of lactic acid
interferes with metabolic functions and they interferes with metabolic functions and they die.die.
Humans use lactic acid waste products from Humans use lactic acid waste products from these types of bacteria to make yogurt, these types of bacteria to make yogurt, cultured sour cream, cheeses, and other cultured sour cream, cheeses, and other fermented dairy products.fermented dairy products.
ANAEROBIC ANAEROBIC RESPIRATIONRESPIRATION
In humans, red blood cells produce energy In humans, red blood cells produce energy through lactic acid fermentationthrough lactic acid fermentation
They don’t have mitochondriaThey don’t have mitochondria
Muscle cells can use aerobic and anaerobic Muscle cells can use aerobic and anaerobic respiration. respiration.
For anaerobic respiration, lactic acid For anaerobic respiration, lactic acid accumulates resulting in fatigue, cramping, accumulates resulting in fatigue, cramping, and pain.and pain.
Must stop the activity or muscles will dieMust stop the activity or muscles will die When enough oxygen is available, lactic acid When enough oxygen is available, lactic acid
is converted to pyruvic acid Krebs cycle will is converted to pyruvic acid Krebs cycle will proceed.proceed.
ANAEROBIC RESPIRATIONANAEROBIC RESPIRATION
RESPIRATIONRESPIRATION
FAT RESPIRATIONFAT RESPIRATION Fats and proteins can also be used as a Fats and proteins can also be used as a
source of energy.source of energy. Fats are digested to fatty acids and glycerolFats are digested to fatty acids and glycerol Proteins are digested to amino acidsProteins are digested to amino acids
Requires several more complex steps. Requires several more complex steps. In fats, fatty acids and glycerol are broken In fats, fatty acids and glycerol are broken
down through the Krebs cycle in the down through the Krebs cycle in the mitochondria.mitochondria.
Can produce more ATP than carbohydratesCan produce more ATP than carbohydrates Serve as long term energy storageServe as long term energy storage Twice as much energy per gram of fat than gram Twice as much energy per gram of fat than gram
of carbohydrateof carbohydrate
PROTEIN RESPIRATIONPROTEIN RESPIRATION
After proteins are broken down to amino After proteins are broken down to amino acids, the amino group is removed. acids, the amino group is removed.
The carbon skeleton enters the respiratory The carbon skeleton enters the respiratory cycle as acetyl, pyruvic acid, or other cycle as acetyl, pyruvic acid, or other molecules found in the Krebs cycle.molecules found in the Krebs cycle.
The removed amino group is converted to The removed amino group is converted to ammonia.ammonia.
Excreted as ammonia, uric acid, or urea (very Excreted as ammonia, uric acid, or urea (very toxic; must be eliminated)toxic; must be eliminated)
Proteins cannot be stored, so they are Proteins cannot be stored, so they are converted to fat or carbohydrates.converted to fat or carbohydrates.
PHOTOSYNTHESISPHOTOSYNTHESIS
Process in which energy from sunlight is Process in which energy from sunlight is converted to chemical energy.converted to chemical energy.
Anabolic processAnabolic process Used by plants, algae, and some bacteriaUsed by plants, algae, and some bacteria
The green pigment chlorophyll absorbs The green pigment chlorophyll absorbs sunlight.sunlight.
Takes place in chloroplasts, which have Takes place in chloroplasts, which have 2 regions:2 regions:
Granum – stacks of membranous sacs Granum – stacks of membranous sacs (thylakoids) that contain chlorophyll(thylakoids) that contain chlorophyll
Stroma - the space between the membranes Stroma - the space between the membranes
PHOTOSYNTHESISPHOTOSYNTHESIS Can be summarized by the following Can be summarized by the following
equation:equation:
Light energy + 6 CO2 + 6 H2O → C6H12O6 Light energy + 6 CO2 + 6 H2O → C6H12O6 + 6 O2+ 6 O2
carbon dioxide + watercarbon dioxide + water→→ glucose + glucose + oxygenoxygen
Opposite of cellular respiration!Opposite of cellular respiration!
PHOTOSYNTHESIS
PHOTOSYNTHESISPHOTOSYNTHESIS Three separate events:Three separate events:
Light-capturing eventsLight-capturing events Light-dependent reactionsLight-dependent reactions Light-independent reactionsLight-independent reactions
Visible light is a combination of Visible light is a combination of different wavelengths of light seen different wavelengths of light seen as different colors.as different colors.
Chlorophyll absorbs red and blue light, Chlorophyll absorbs red and blue light, reflects greenreflects green
Pigments called carotenoids (yellow, Pigments called carotenoids (yellow, orange, red) also capture light, produce orange, red) also capture light, produce excited electrons – visible in the fallexcited electrons – visible in the fall
PHOTOSYNTHESISPHOTOSYNTHESIS Light-capturing eventsLight-capturing events
Pigments capture light energy which causes Pigments capture light energy which causes some electrons to become “excited” some electrons to become “excited”
Pigments are arranged into clusters called Pigments are arranged into clusters called photosystems – helps concentrate energyphotosystems – helps concentrate energy
Light-dependent reactionsLight-dependent reactions Take place in the thylakoid membranes of the Take place in the thylakoid membranes of the
granagrana Excited electrons are passed through an electron Excited electrons are passed through an electron
transport system, producing ATP and NADPH transport system, producing ATP and NADPH (electron carrier)(electron carrier)
Some electrons split water producing oxygen Some electrons split water producing oxygen gas, hydrogen ions, and additional electronsgas, hydrogen ions, and additional electrons
PHOTOSYNTHESISPHOTOSYNTHESIS
Light-independent reactionsLight-independent reactions Occur in the stroma Occur in the stroma Energy from excited electrons is used to Energy from excited electrons is used to
make glucose, lipids, phospholipids, make glucose, lipids, phospholipids, steroids, and other organic molecules steroids, and other organic molecules from carbon dioxidefrom carbon dioxide
Some of these molecules may also be Some of these molecules may also be used to produce DNA, RNA, or ATPused to produce DNA, RNA, or ATP
OTHER ASPECTS OF OTHER ASPECTS OF PLANT METABOLISMPLANT METABOLISM
Plants produce carbohydrates, fats, Plants produce carbohydrates, fats, proteins, and nucleic acids from the proteins, and nucleic acids from the products of photosynthesisproducts of photosynthesis
Can produce some toxins and organic Can produce some toxins and organic molecules that are used as medicinesmolecules that are used as medicines
May also produce vitamins for themselves May also produce vitamins for themselves and other organismsand other organisms
Produce oxygen in photosynthesis which is Produce oxygen in photosynthesis which is used for cellular respiration by all living used for cellular respiration by all living thingsthings
AUTOTROPHS AND AUTOTROPHS AND HETEROTROPHSHETEROTROPHS
All living things need oxygen for cellular All living things need oxygen for cellular respirationrespiration
Green plants produce oxygen in Green plants produce oxygen in photosynthesis, but they also use it in photosynthesis, but they also use it in cellular respirationcellular respiration
Produce more than enough and release the restProduce more than enough and release the rest Animals are dependent on plants not only Animals are dependent on plants not only
for oxygen, but also for essential nutrients for oxygen, but also for essential nutrients to maintain metabolism and construct to maintain metabolism and construct tissuestissues
Animals supply materials needed by plants Animals supply materials needed by plants and vice versa.and vice versa.
Essential to life on EarthEssential to life on Earth
Need to KnowNeed to Know
What is cellular respiration?What is cellular respiration? What are the 3 steps?What are the 3 steps? How much ATP is formed at each step?How much ATP is formed at each step? Where in the cell do these occur?Where in the cell do these occur? What is ATP?What is ATP? What is photosynthesis?What is photosynthesis? What are the 3 steps?What are the 3 steps? Where do these processes occur in a Where do these processes occur in a
cell?cell?
CHAPTER 6
BIOCHEMICAL PATHWAYS
AMPAMP
ADPADP
ATPATP
PHOTOSYNTHESIS
CHAPTER 6
BIOCHEMICAL PATHWAYS
AMPAMP
ADPADP
ATPATP
PHOTOSYNTHESIS