Unit 5 Cellular Energy

I. Enzymes (159) Speed up Are CATALYSTS: __________ chemical reactions that would otherwise happen too ______ to support life. Catalysts _________ make reactions happen that couldn’t happen by themselves. Are PROTEINS. Their amino acid sequences determines their ______, which are important for their functions. Are _____________ during the reaction— the same enzyme can be used repeatedly slowly DO NOT shapes Not consumed

Because of the importance of its shape, a protein also… Is specific to the __________ it catalyzes. The reactants (called substrates) fit perfectly into a place on the enzyme called the active site. The _________ of the enzyme active site makes it substrate-specific. The enzyme may slightly _____________ (gives substrates a squeeze in a process called induced fit) that allows the reaction to happen. Finally, the products are ___________ from the active site, and the enzyme can be reused over and over again for more reactions. the reaction shape change shape released

Because of the importance of its shape, a protein also… Only functions in _________ pH and temperature ranges, where it has the proper shape. changing the temperature or pH (_______) may change an enzyme’s shape It may no longer ________ its substrates, and therefore not function. An enzyme that has lost its proper shape and does ____________ is said to be denatured. narrow acidity fit not function

How do enzymes work? Favorable chemical reactions involve reactants going through an __________, awkward transition state. Unfavorable states are considered “____ energy” and favorable states are considered “_____ energy.” The amount of energy required to overcome the transition state is called the _________________ unfavorable high low Activation energy

In other words, an enzyme ________ the activation energy of a reaction Enzymes work when the ____________, or squeeze provided by the enzyme, makes the transition state more favorable In other words, an enzyme ________ the activation energy of a reaction induced fit lowers

Chemical Energy and Life ENERGY is the _________________. Cells require energy for __________ reactions, ________ transport, ____ _________ and maintaining _________. We obtain energy from ______, but energy ultimately comes from the sun. Glucose is the preferred energy source, but we can obtain it from _________, _______ and even __________ ability to do work metabolic active cell division homeostasis food other carbs lipids protein

Chemical Energy and Life CHEMICAL ENERGY in food is stored in _______________ as _____________ energy. When bonds are broken, energy of __________ is released. Some is lost as _______, but some portion of it can be converted into a usable form in the bonds of ________ We use ATP energy to “pay for” ___________ reactions chemical bonds potential electrons heat ATP unfavorable

Without ATP and enzyme With ATP and enzyme

Chemical Energy and Life ATP is a better form of energy because it contains __________ packets of energy than glucose If we released the energy from food molecules (like glucose) all at once, it would be ___________ and ___________ smaller wasteful destructive

ATP ___________________is a __________ that is composed of: ___________ - nitrogen base ___________ - 5 carbon sugar __________________ groups Adenosine TriPhosphate nucleotide adenine ribose 3 phosphate

ATP Potential energy is stored in the __________-__________________ ATP is like a rechargeable ________ ATP = “charged” (3 phosphates), ____ PE ADP = “uncharged” (2 phosphates, _______________________), _____ PE phosphate phosphate bonds battery high adenosine disphosphate low

Metabolic pathways (218-221) Metabolism: the sum of all __________ ____________ in a cell Metabolic pathways- series of chemical reactions in which the __________of one reaction is the ___________for the next reactions. chemical reactions product reactant

2 major metabolic pathways in life: CELLULAR RESPIRATION _________ molecules (like glucose) broken down to release _________ for cell use PHOTOSYNTHESIS ____________ from sun is converted to _____________ in the form of glucose organic energy Light energy chemical energy

2 major metabolic pathways in life: The relationship between these two pathways results in the ___________ _______________ within an organism as well as within an ecosystem. Plants and other organisms that can make their own food are known as ______________ Humans and other organisms that have to obtain food are known as ______________ continual flow of energy autotrophs heterotrophs

Aerobic Cellular Respiration- ___________ (requires O2) Energy Production (pp. 228-232) glucose breakdown of __________ in the presence of __________ to “make” ________ The oxygen required for cellular respiration is _________ into the ______, _________ into the _______, and is delivered to the _____________ of the body cells by ________________. The glucose needed is obtained through __________ The glucose is transported in the blood and enter the body cells via __________ ___________ by __________________. oxygen ATP inhaled lungs diffuses blood mitochondria red blood cells digestion facilitated diffusion channel proteins

Do plants use cellular respiration? Do they need oxygen?

Overall Equation C6H12O6 + 6O2  6CO2 + 6H2O Two major parts: Glycolysis Oxidative Respiration, further divided into… Krebs Cycle Electron Transport Chain

Key Players Glucose, the starting molecule of cellular respiration Pyruvic acid, a three-carbon molecule that is the product of the breakdown of glucose during glycolysis NADH and FADH2, which carry high energy electrons. They are forms of chemical potential energy. ATP, a form of chemical potential energy used by cells for energy-consuming processes. CO2, the final breakdown product of glucose, generated in the Krebs Cycle. Oxygen and water. O2 is the final electron acceptor of the electron transport chain. When it receives electrons it takes hydrogen to make water.

Respiration Step 1: Glycolysis Glycolysis – Means _______________. Occurs in the __________ of the cell. does not require ___________. The splitting of glucose, or glycolysis, occurs very quickly in a 10-step process with the aid of _____________, producing two 3-C molecules known as ___________. “sugar-splitting” cytosol oxygen enzymes pyruvic acid

Respiration Step 1: Glycolysis In addition, when the bonds of glucose are broken, the high energy electrons that are released are caught by __________, a molecule that acts as an ________________. This electron energy will be converted to ATP later in the process. Glycolysis requires ___ ATP to occur, but results in the formation of ___ ATP, for a net ______ of ___ ATP. NADH electron carrier 2 4 gain 2

Respiration Step 1: Glycolysis REACTION: glucose + 2ATP  2 pyruvic acid + 4ATP + 2NADH

Respiration Step 1I… Glycolysis releases less than ¼ of the chemical energy stored in glucose. Most of its potential energy remains bound in the __________ formed from glycolysis. pyruvic acid

Respiration Step 1I: Oxidative Respiration In aerobic conditions, meaning ___ is available, the pyruvic acid formed from the breakdown of ___________ during ___________ enters the ______________ of the cell where the _________ of oxidative respiration complete the breakdown of glucose to produce _____, _______, and ______. O2 glucose glycolysis mitochondria enzymes CO2 H2O ATP

Respiration Step 1Ia: Krebs Cycle Series of reactions that occur in the _______________, in which the energy stored in _____________ is released in the form of high-energy ___________ when bonds are broken and pyruvic acid is completely broken down to _______. mitochondria pyruvic acid electrons CO2

Respiration Step 1Ia: Krebs Cycle There are only _____ additional ATP produced in the Krebs Cycle; most of the energy released is captured in the form of electron energy, producing additional _________. In addition, a second type of electron carrier is utilized, producing 2 “filled” ________. 2 NADH FADH2

Respiration Step 1Ia: Krebs Cycle Net Energy Gain = 2ATP + 8 NADH + 2 FADH2 Waste Generated: CO2 (all of glucose is gone, except for its high energy electrons and Hydrogen in the electron carriers)

Respiration Step 1Ib: Electron Transport Chain (ETC) the electron carriers, ________ and _______ “dump” their electrons. These electrons are passed along a series of molecules embedded in the inner membrane of the ______________ of ______________ cells. This same process occurs in the ________________ of ________________ cells. NADH FADH2 mitochondria eukaryotic cell membrane prokaryotic cells

Respiration Step 1Ib: Electron Transport Chain (ETC) As the electrons “fall” down the ETC, the energy they release is used to power an enzyme known as ____________________, which attaches phosphate groups to ________ to produce _______. ATP synthase ADP ATP

Respiration Step 1Ib: Electron Transport Chain (ETC) This process is known as _______________ phosphorylation because oxygen must be present. It is the ___________________ of oxygen that “pulls” the electrons down the ETC. As the electrons are collected by oxygen, __________ is produced from oxygen. Net Energy Gain = oxidative electronegativity H2O ~ 32 ATP

2 N - Y 2 CO2 30+ Y H2O # ATP (not directly) KREBS CYCLE ETC Needs O2? STAGE WHERE # ATP Needs O2? Wastes GLYCOYSIS CYTOPLASM KREBS CYCLE OUTER MITOCHONDRIA ETC INNER 2 N - Y (not directly) 2 CO2 30+ Y H2O

Alternative pathway: Anaerobic Fermentation The Krebs Cycle and ETC depend on ______________ (they are aerobic) to take electrons from the electron carriers. If no oxygen is present, ________ and _________ all fill up with high energy _______________ and have no where to put them, and cellular respiration comes to a halt. oxygen NADH FADH2 electrons

Alternative pathway: Anaerobic Fermentation A ____________ pathway exists called _____________ fermentation. In anaerobic conditions, the cell still uses ___________ and generates 2 ____ and 2 _____________, along with 2 full _______ The cell can empty the electron carriers by converting the 2 pyruvic acids into other chemicals. backup anaerobic glycolysis ATP NADH pyruvic acid

Lactic Acid Fermentation In human muscle cells, pyruvic acid is converted to __________ Lactic acid buildup contributes to the muscle ___________ experienced during intense exercise Some bacteria and fungi do this and are important in producing the lactic acid in ______________ and ____________ lactic acid soreness cheeses yogurt

Alcholic Fermentation In ___________ and some bacteria, the pyruvic acid are converted to alcohol. This is important in commercial brewing and baking. Overall, much ________ energy (only 2 ATP compared to 32) is produced by fermentation yeast less

Photosynthesis

Photosynthesis Photosynthesis is the metabolic pathway that provides energy for ____________________ Occurs in the chloroplasts of plants and other photosynthetic eukaryotes like ______ Occurs in _______________— photosynthetic bacteria most ecosystems algae cyanobacteria

Overall Equation: (light energy) 6CO2 + 6H2O C6H12O6 + 6O2

Chloroplasts Abundant in the_____ _____ of most plants Structure: leaf cells Abundant in the_____ _____ of most plants Structure: Thylakoids-flattened ________ __________ arranged in stacks, where the light-dependent reactions occur sac-like membranes

…Structure continued Grana—stacks of ___________ Stroma—_________________ that is outside the ________, where light- independent reactions take place. thylakoids fluid-filled space grana

Pigments light-___________ colored molecules act like ________ for absorbing energy Different pigments absorb different __________ of light absorbing antennas wavelengths

ENERGY & ELECTRONS http://www.mhhe.com/biosci/pae/botany/uno/graphics/uno01pob/vrl/images/0160.gif http://www.wjcc.k12.va.us/ROBB/Atom%20Animation%20Resources_files/image003.gif

Chlorophyll- most abundant pigments Chlorophyll- most abundant pigments. Absorb ________ and __________ the strongest, and ________ __________. red violet reflect green

Accessory pigments- allows plant to _______ different __________ of light energy ______________- _________in _______________region &________, __________________________ Ex. β – carotene In fall production of ____________________slows down or stops, thus bringing out the colors of the accessory pigments. absorb wavelengths Carotenoids absorb Blue & green reflect Yellow, orange & red chlorophyll

ENERGY & ELECTRONS http://www.mhhe.com/biosci/pae/botany/uno/graphics/uno01pob/vrl/images/0160.gif http://www.wjcc.k12.va.us/ROBB/Atom%20Animation%20Resources_files/image003.gif

PHOTOSYNTHESIS OVERVIEW Pearson Education Inc; Publishing as Prentice Hall

PHOTOSYNTHESIS HAPPENS IN CHLOROPLASTS Proteins that are part of the thylakoid membrane organize ________________________________ into clusters called _____________________ Light absorbing PIGMENTS PHOTOSYSTEMS http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0076.JPG

LIVING THINGS NEED ENERGY CARRIERS Molecule that carries = _______ Molecule that carries HIGH ENERGY ELECTRONS = ___________ ATP NADP+ Images by Riedell

NADP ____________ is one of the carriers that cells use to transport Frying pan image from: BIOLOGY by Miller and Levine; Prentice Hall Publishing©2006 NADP ____________ is one of the carriers that cells use to transport high energy electrons. NADP+ ________ + _____ + _____ → ____________ 2 e- H+

LIGHT-DEPENDENT REACTIONS Requires ______________ Molecules are part of ________________ LIGHT THYLAKOID membranes

Starts at photosystem II: Chlorophyll in thylakoid membrane absorbs ________ _________ and uses it to excite, and strip away electrons from _________ Water broken apart, forming _______ gas (___) light energy H2O oxygen O2

Light-Dependent Reactions

Next to an electron transport chain: High energy electrons are passed to the electron transport chain from one carrier to the next, losing energy that is used to drive the synthesis of _______. The enzyme responsible for ATP synthesis is _______________. ATP ATP synthase

Light-Dependent Reactions

Ends at photosystem I: The now low-energy electron is re-energized by another chlorophyll pigment and _____ in photosystem I The energized electron is passed to ___________, a high energy electron _________. light NADP+ carrier

Light-Dependent Reactions

PHOTOSYNTHESIS OVERVIEW Pearson Education Inc; Publishing as Prentice Hall

Calvin Cycle CO2 Enters the Cycle Energy Input 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced See Calvin cycle animation Sugars and other compounds

Calvin Cycle (Light-independent rxns)—does not require _______, in the stroma _______ gas is used as a source of __________ and __________ atoms to make glucose. NADPH used as a source of high energy ___________ and _____________ _______ is used as a source of ________ light CO2 carbon oxygen electrons hydrogen ATP energy

Factors Affecting Photosynthesis Light—more light, more photosynthetic activity Water—needed to supply electrons. Not enough water, slow or no photosynthesis Temperature—photosynthesis functions best at 0-32 C