Cell Energy Notes Photosynthesis and Cellular Respiration

QOD 11/13/11  What is ATP?  Energy molecule of the cell

Energy  Energy = the ability to do work  Energy is usually released when bonds are broken and needed to put bonds together  All living organisms must be able to produce, store, and use energy.  Our food energy must always be converted to ATP energy to be useful to our cells

Energy  2 types of organisms  Autotrophs- use energy from sun or inorganic compounds to make organic compounds (like sugar). They use:  Photosynthesis  Chemosynthesis  Heterotroph- organisms that get energy from food

Energy  The main source of cell energy is called ATP (adenosine tri phosphate)  ATP is made of an adenosine molecule with three (tri =3) phosphate groups attached.  The energy is stored in the bonds of the molecule as “potential energy” (energy available for potential, or future, use)

Energy  The energy of ATP is released when the covalent bond between the 2 nd and 3 rd P (phosphate group) is broken.  Energy is released and the resulting molecule is ADP or adenosine di phosphate; di=2

Energy  ADP and P can form ATP again when energy is added back in and the P bonds to the ADP  Cells can make more when needed  ATP is a short term energy storage molecule- once it is made, it is used pretty quickly (the bonds are unstable)

How do cells use the Energy stored in ATP?  When ATP is broken down and the energy is released, cells must have a way to capture the energy and use it efficiently or it will be wasted  Cell proteins have specific sites where ATP can bind, then the phosphate bond is broken and energy is released  The cell can use the energy for activities such as making a protein or transporting molecules through the plasma membrane (active transport)

How do cells use the Energy stored in ATP?  Nerve cells transmit signals by using ATP to power the active transport of certain ions  Making enzymes that help carry out chemical reaction  Build membranes and cell organelles  Kidneys use energy to move molecules and ions in order to eliminate wastes while keeping needed substances in the blood stream  Cells use energy to maintain homeostasis

QOD 11/8/11  Do Enzymes speed up or slow down reactions?

Enzymes  All of the chemical reactions that occur in your body are called your metabolism.  Most of these reactions require energy  Enzymes lower the amount of energy needed for a reaction to occur  This means more reactions can happen in a shorter amount of time because they need less energy  Without enzymes, our metabolism would be too slow for us to live!!

Key terms Substrate = substance enzyme acts on Active site = region where enzyme binds “Lock and Key” Model = one specific enzyme for one reaction Enzymes

 Enzymes…  Are proteins that act as catalysts  Speed up reactions without being changed (so one enzyme can catalyze many reactions)  Ex: break down toxins in liver, digest your food in your stomach  Enzyme reactions happen at an average rate of 1000 reactions per second!  Only work with ONE TYPE of reaction Enzymes

What can affect the functioning of Enzymes?  Heat  Higher temps increase the collisions of substrates and enzymes, which makes the reactions happen faster  So, lower temps DECREASE reaction rates  BUT, if temp is too high, enzymes can be denatured (change shape) and not work  Our enzymes work best at O C (body temp is normally 37 O C)

 pH  Large changes in pH also denature enzymes  Some enzymes, like the ones in our stomachs, work best in acidic conditions  Best pH for our enzymes is 6-8  So, heat and pH can denature (change the shape of) enzymes, which makes them no longer able to function  Other factors :  Radiation, Electricity, Chemicals Catalase What can affect the functioning of Enzymes?

QOD 11/14/12  What is process where plants create organic molecules from sunlight called?  PHOTOSYNTHESIS

Photosynthesis

 Cell Equipment:  Stomata  Chloroplasts  Electron carriers  2 Parts  Light Reactions  Calvin Cycle (also called Dark or light indepepndent Reactions)

Equipment for Photosynthesis  Stomata are like pores, plants use them to take in CO 2 and release O 2  Water is also be released when they are open

Stomata

Electron Carriers  Used in many places throughout photosynthesis- there job is to carry electrons from one place to another

Light Reactions  Require light to happen  Also called light dependent reactions  Light is absorbed by the chloroplasts

Light Reactions  There are pigments in the thylakoid membrane of the chloroplasts that absorb light  The color you SEE is NOT the color absorbed, all other colors are absorbed  When you see a green leaf, it is because the leaf absorbs all other colors and REFLECTS green (so that green hits your eyes).

Light Reactions  There are several pigments found in the membrane of the thylakoids, the most prominent is chlorophyll a and b which absorb most colors except green.  Chlorophyll a is directly involved in photosynthesis, and other pigments assist it in absorbing other colors of light.  More colors absorbed means more energy!

Light Reactions  Pigments that assist chlorophyll are called accessory pigments

Light Reactions  So, what happens in the fall?  Normally, the green color of chlorophyll masks all other colors  In the fall, many plants lose their chlorophyll  So you are able to see the colors of the carotenoids instead (yellow, brown, and orange)

Light Reactions  Turns light energy into chemical energy (ATP)  Involves an enzyme called ATP synthase  Takes place in the thylakoid membranes  H 2 O molecules and light energy make ATP, an e - carrier, and O 2  The oxygen leaves the cell, the ATP and e- carriers move to the Calvin Cycle

Calvin Cycle  Powered by ATP & e - carriers made by light reactions.  Needs CO 2  Happens in stroma of a chloroplast  Sugars are mainly built in this cycle, but lipids, proteins, and nucleic acids can also be made

Other paths  When stomata are open, water is lost  This is BAD for desert plants which need to conserve water  C4 plants keep there stomata half closed during the hottest part of the day  They are able use the small amount of CO 2 that enters  CAM plants keep there stomata closed during the day.  They hold on to the CO 2 that they get at night and use it during the day

Photosynthesis- Summary  Photosynthesis has 2 main parts 1. Light reactions - where light energy is absorbed and converted into ATP and e- carriers 2. Calvin Cycle – where organic compounds are formed using the chemical energy in ATP and e- carriers 6CO 2 + 6H 2 O + light  C 6 H 12 O 6 + 6O 2

Reactants (what is needed?) Products (what is produced?) Light Reactions 1.Light 2.Water 1.O 2 2.e- carrier 3.ATP Calvin Cycle1.CO 2 2.e- carrier 3.ATP 1.Organic compounds 2.e- carrier 3.ADP + P Photosynthesis- Summary

QOD 11/15/12  What organic compounds can be made by photosynthesis?  Lipids, proteins, nucleic acids, and sugars (carbs)

Cellular Respiration

 The energy stored in the chemical bonds of organic molecules (carbs, lipids, etc) must be released and turned in to ATP to be useful to your cells  The process by which this is done is called cellular respiration

Cell Respiration  Cell Equipment:  Cytoplasm  Mitochondria  Electron carriers (NADP/NADPH)  3 Parts  Glycolysis  Krebs Cycle  ETC

Equipment for Cellular Respiration

 Electron Carriers- Cell respiration has them too, they are just different kinds of molecules

Anaerobic Respiration-Glycolysis  Anaerobic means WITHOUT oxygen  Takes place in the cytoplasm  Uses 2 ATP & glucose, to make a total of 4 ATP (net gain of 2 ATP), 2 pyruvate, & e- carriers.  Since few ATP are produced, only VERY SMALL organisms can live by glycolysis alone

Anaerobic Respiration- Fermentation  When oxygen is not present, fermentation occurs after glycolysis  It occurs in the cytoplasm  Fermentation allows glycolysis to continue  So, SMALL amounts of ATP can continue to be produced without oxygen

Anaerobic Respiration- Lactic Acid Fermentation  This type of respiration is used by many kinds of bacteria and is responsible for cheese, buttermilk, sour cream, and yogurt  During strenuous activity, lactic acid fermentation is used by our muscle cells.  Produces lactic acid and CO 2  The build up of lactic acid in our muscle cells is what causes pain, fatigue, and cramps after strenuous activities

Anaerobic Respiration- Alcoholic Fermentation  Creates ethyl alcohol and CO 2  This type of fermentation is used in plants and some microorganisms, such as yeast.  This type of fermentation is used in the beer and wine industry  It is also used in the bread industry, because yeast give off CO 2 when they ferment (this creates fluffy bread)

Aerobic Respiration  Happens after glycolysis IF OXYGEN IS PRESENT  2 major stages  Krebs Cycle  ETC  Pyruvic acid created in Glycolysis diffuses into the mitochondrial matrix

Aerobic Respiration- Krebs Cycle  Occurs within the mitochondrial matrix  Starts with pyruvate molecules from glycolysis  Produces ATP, e- carriers, & some CO 2 molecules (CO 2 is released from the cell).

ETC (Electron Transport Chain)  The ETC is in the inner membrane of the mitochondrion in the folds called cristae  It uses the e - carriers made by Krebs Cycle and O 2 to make H 2 O and 32 ATP.  Lots of energy! 32 ATP just from 1 glucose using these ETC reactions.  Produces way more ATP than any of the other reactions.

Cellular Respiration- Summary C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP  In the anaerobic process of glycolysis, organic compounds are converted into pyruvic acid, producing a small amount of ATP and e carriers in the process  In aerobic respiration pyruvic acid is broken down using oxygen into CO 2 and water, which produces a large amount of ATP  This process is 39% efficient (means 39% of the stored energy in your food is used)

Respiartion- Summary ReactantsProducts Glycolysis 1.2 ATP 2.Glucose 1.4 ATP 2.e- carrier 3.Pyruvate Krebs Cycle 1.Pyruvate 2.e- carrier 3.ADP 1.CO ATP 3.e- carriers ETC1.e- carriers 2.Oxygen 3.ADP 1.Water 2.32 ATP

Cellular Respiration- Summary  But remember that 2 ATP were used in Glycolysis, so cellular respiration produces 36 NET ATP

H2OH2O Energy Cycle Photosynthesis Cellular Respiration sun glucose O2O2 CO 2 plants animals, plants ATP CO 2 H2OH2O C 6 H 12 O 6 O2O2 light energy  +++CO 2 H2OH2O C 6 H 12 O 6 O2O2 ATP energy  +++