Energy and Living Things

Life Processes• Although living things look different, all living things

possess the same eight characteristics.All living things: • Move• Reproduce (sexual or asexual)• Respond to their environment• Need energy (metabolism)• Are Organized• Grow• Are made of cells• Maintain homeostasis

Capturing the Energy of Life

• All organisms require energy • Some organisms (autotrophs) obtain energy

directly from the sun and store it in organic compounds (glucose) during a process called photosynthesis

Photosynthesis Reaction6CO2 + 6H2O + energy --> 6O2 + C6H12O6

Energy for Life Processes• Energy is the ability to do work. Energy is a

measurement of the amount of work that can be done by a certain force, subject to the laws of physics. Energy cannot be created or destroyed, but it can be converted between different types of energy.

• Work for a cell includes growth & repair, active transport across cell membranes, reproduction, synthesis of cellular products, etc.

• Work is the ability to change or move matter against other forces (W = F x D)

Kinetic Energy• Kinetic energy is the energy of motion.• The kinetic energy of an object is the energy it

possesses because of its motion. • Kinetic energy of an object is relative to other

moving and stationary objects in its immediate environment.

• The greater the mass and velocity of the moving object, the greater the kinetic energy

• Kinetic energy can be transferred from one moving object to another, say, in collisions.

• Examples

Potential Energy

• Potential Energy is the stored energy in an object or system because of its position or configuration.

• Potential energy is not relative to the environment of an object.

• Potential energy cannot be transferred.• Examples

Autotrophs“Producers”

• Plants, algae, and blue-green bacteria, some prokaryotes, are producers or autotrophs

• Only 10% of the Earth’s 40 million species are autotrophs

• Other autotrophs use inorganic compounds instead of sunlight to make food; process known as chemosynthesis

Photosynthesis vs. ChemosynthesisChemosynthesis is the biological conversion of one or

more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the

oxidation of inorganic molecules (e.g. hydrogen gas) or methane as a source of energy, rather than sunlight,

as in photosynthesis

Heterotrophs “Consumers”

• Producers make food for themselves and heterotrophs or consumers cannot make food for themselves

• Heterotrophs include animals, fungi, & some bacteria, & protists

• More than 95% of all organisms are heterotrophic.

Autotrophs vs. Heterotrophs• Autotrophs make their own food, most through

photosynthesis. • Photosynthetic organisms are known as the "primary

producers" of the food chain. They are the foundation on which all other organisms depend. In general, the food chain moves from plants and other autotrophs to herbivores, and then to omnivores and carnivores, which eat the herbivores.

• In contrast to autotrophs, heterotrophs survive through respiration, using oxygen and an energy source (carbohydrates, fats or protein) to produce ATP, which powers cells.

• Heterotrophs depend on other organisms for food and oxygen.

How Does Photosynthesis Benefit Heterotrophs?

• Photosynthesis benefits heterotrophs in several different ways.

– First, photosynthesis consumes carbon dioxide (a waste product of respiration) and produces oxygen (necessary for respiration). – Heterotrophs therefore depend on

photosynthesis as a source of oxygen.

In addition, photosynthesis sustains the organisms that heterotrophs consume in order to stay alive.

Even if a heterotroph is strictly carnivorous and does not eat plants, it must eat animals that eat plants to survive.

Cycle between Autotrophs & Heterotrophs

Photosynthesis Reaction

• In photosynthesis, CO2(carbon dioxide) and H2O (water) are combined to form C6H12O6 (glucose) & O2 (oxygen)

• 6CO2 + 6H2O + energy --> 6O2 + C6H12O6

• Photosynthesis occurs in the chloroplasts

Light Absorption in Chloroplasts

• Chloroplasts in plant & algal cells absorb light energy from the sun during the light dependent reactions

• Photosynthetic cells may have thousands of chloroplasts

• Chloroplasts are double membrane organelles with the an inner membrane folded into disc-shaped sacs called thylakoids

Chloroplast

Factors Determining the Rate of Photosynthesis

• Light intensity - As light intensity increases, the rate of photosynthesis initially increases and then levels off to a plateau

• Temperature - Only the dark, not the light reactions are temperature dependent because of the enzymes they use (25 oC to 37oC)

• Length of day • Increasing the amount of carbon dioxide available

improves the photosynthesis rate • Level of air pollution

Cellular Respiration• Cellular respiration is a process that allows

organisms to use the energy stored in glucose.• In cellular respiration, O2 (oxygen) is used to

burn C6H12O6 (glucose) & release CO2(carbon dioxide), H2O (water), and energy

• Usable energy released in cellular respiration is called adenosine triphosphate or ATP

• Energy in glucose is first used to produce ATP, which the cells use to supply energy needs

Cellular Respiration • Both autotrophs & heterotrophs perform cellular

respiration to release energy to do work

• Occurs in the mitochondria• Produces the most energy

EquationO2 + Glucose—>CO2 + H2O + ATP

• There are 2 types of Cellular Respiration:• Aerobic-requires the use of oxygen• Anaerobic-doesn’t require oxygen

Mitochondria• Mitochondria are the cell's power producers. They convert

energy into forms that are usable by the cell. Located in the cytoplasm, they are the sites of cellular respiration which ultimately generates fuel for the cell's activities.

• Mitochondria are very small organelles. You might find cells with several thousand mitochondria. The number depends on what the cell needs to do. If the purpose of the cell is to transmit nerve impulses, there will be fewer mitochondria than in a muscle cell that needs loads of energy. If the cell feels it is not getting enough energy to survive, more mitochondria can be created. Sometimes they can even grow, move, and combine with other mitochondria, depending on the cell's needs.

How are mitochondria used in cellular respiration?

• The matrix is filled with water (H2O) and proteins (enzymes). Those proteins take food molecules and combine them with oxygen (O2). The mitochondria are the only place in the cell where oxygen can be combined with the food molecules. After the oxygen is added, the material can be digested. They are working organelles that keep the cell full of energy.

Mitochondria

Cellular Respiration

• Photosynthesis (you recall...) is the process by which CO2 and H2O are used to make sugars and starches.

• During Cellular Respiration, sugar is broken down to CO2 and H2O, and in the process, ATP is made that can then be used for cellular work.

• The overall reaction for cellular respiration: does this reaction look familiar? Overall, it is the reverse reaction of photosynthesis, but chemically, the steps involved are very different.

• C6H12O6 + 6O2 ---------------> 6CO2 + 6H2O + ~38 ATP

Pigments

• Light travels as waves & packets called photons

• Wavelength of light is the distance between 2 consecutive peaks or troughs

Visible SpectrumSunlight or white light is made of different wavelengths or colors carrying different amounts of energy A prism separates white light into 7 colors (red, orange, yellow, green, blue, indigo, & violet) ROY G. BIV These colors are called the visible spectrum

Light and Color

• When light strikes an object, it is absorbed, transmitted, or reflected

• When all colors are absorbed, the object appears black

• When all colors are reflected, the object appears white

• If only one color is reflected (green), the object appears that color (e.g. Chlorophyll)