Comprehensive Notes on Cells, Respiration, and Ecosystems

The Modern Cell Theory

• The cell is the smallest living unit in all organisms.

• All living things are made of cells.

• All cells come from other pre-existing cells.

Cell Types: Prokaryotes vs. Eukaryotes

Prokaryotes

• Examples: Bacteria and archaea.

• Lack a nucleus.

• Lack membrane-bound organelles.

• Possess DNA, cytoplasm, ribosomes, and a cell membrane.

• May have a cell wall.

Eukaryotes

• Examples: Fungi, animals, protists, and plants.

• Contain a nucleus.

• Contain membrane-bound organelles.

Organelles and Their Functions

Cell Wall

• Function: Provides shape maintenance and additional protection to cells and structural support.

Cell Membrane

• Function: Supports, protects, and determines what goes in and out of the cell.

Cytoplasm

• Function: Jelly-like material which holds and protects cell components from damage.

Cytoskeleton

• Function: A collection of fibers that provide support to the cell and its organelles, and play a role in cell movement.

Ribosomes

• Function: Make proteins or amino acids.

Nucleus

• Function: Holds genetic material (DNA) and directs and controls cell activities.

Nucleolus

• Function: Produces ribosomes.

Rough Endoplasmic Reticulum (RER)

• Function: Contains ribosomes and transports proteins.

Smooth Endoplasmic Reticulum (SER)

• Function: Detoxification and production of some types of lipids.

Golgi Apparatus

• Function: Processes and packages proteins and lipids, and moves materials in and out of the cell.

Mitochondria

• Function: Makes ATP by cellular respiration and produces energy from sugar.

Chloroplast

• Function: Produces sugar/glucose by photosynthesis.

Vacuoles

• Function: Can have many functions, including storing materials and facilitating chemical reactions.

Cellular Respiration and Fermentation

Purpose of Eating

• To obtain energy by breaking down food, extracting glucose, and converting that energy into ATP (adenosine triphosphate).

Cellular Respiration Overview

• Releases energy in glucose to make ATP.

• Involves many chemical reactions summarized by the equation:
  $C<em>6H</em>{12}O<em>6 + 6O</em>2 \rightarrow 6CO<em>2 + 6H</em>2O + ATP$

• Occurs in three stages: glycolysis, Krebs cycle (citric acid cycle), and electron transport.

• Glycolysis occurs in the cytoplasm and does not require oxygen.

• The Krebs cycle and electron transport occur in the mitochondria and require oxygen.

• Net ATP harvest: 36-38 ATP.

Stage I: Glycolysis

• Occurs in the cytosol of the cytoplasm.

• Does not require oxygen.

• Universal pathway for making ATP.

• Involves splitting glucose (glucose splitting).

• Enzymes split a molecule of glucose into two molecules of pyruvate (pyruvic acid).

Results of Glycolysis

• Energy is needed to start glycolysis and split the glucose molecule and is provided by two molecules of ATP.

• Energy is released, and the energy is used to make four molecules of ATP.

• Net gain of two ATP molecules.

• High-energy electrons are transferred to molecules of $NAD^+$ to produce two molecules of NADH.

Anaerobic Respiration: Fermentation

• An important way of making ATP without oxygen.

• Louis Pasteur demonstrated the role of microorganisms in fermentation.

• Some organisms use anaerobic respiration when oxygen is in short supply.

• Certain microorganisms can only use anaerobic respiration.

• Used to make yogurt, bread, wine, and biofuels.

• Human muscle cells use fermentation when they cannot get oxygen fast enough for aerobic respiration.

Types of Fermentation

• Lactic acid fermentation

• Alcoholic fermentation

Lactic Acid Fermentation

• Pyruvate from glycolysis changes to lactic acid.

• $NAD^+$ forms from NADH, allowing glycolysis to continue, resulting in additional ATP.

• Carried out by bacteria in yogurt and by muscle cells during intense exercise.

• $2 Pyruvate + 2 NADH \rightarrow 2 NAD^+ + 2 Lactic Acid$

Alcoholic Fermentation

• Pyruvate changes to alcohol and carbon dioxide.

• $NAD^+$ forms from NADH, allowing glycolysis to continue making ATP.

• Carried out by plants, yeasts, and some bacteria.

• Used to make bread, wine, and biofuels.

• $2 Pyruvate + 2 NADH \rightarrow 2 NAD^+ + 2 CO_2 + 2 Ethanol$

Summary of Cellular Respiration and Fermentation

• Cellular respiration transfers the energy stored in glucose to ATP.

• Fermentation makes ATP without oxygen and involves glycolysis only.

• Fermentation recycles $NAD^+$ and produces 2 ATPs.

• Lactic acid fermentation changes pyruvate to lactic acid.

• Alcoholic fermentation changes pyruvate to alcohol and carbon dioxide.

Permafrost and Decomposition

• Energy and matter from plants are typically returned to the atmosphere by decomposers.

• Conditions such as temperature and oxygen levels affect the rate of decomposition.

• Decomposition happens through cellular respiration.

• In the permafrost/peat system, cold temperatures and low oxygen levels slow the rate of decomposition and cellular respiration.

• When rates of decomposition are low, the matter and energy do not flow out of the permafrost/peat system, making a carbon sink.

• Peat retains much of the original energy and matter from the plants because decomposition is incomplete.

• Plant matter breaks down through the action of decomposers that use enzymes to break down complex molecules.

• Low oxygen levels, high temperatures, and the removal of volatile organic compounds during zombie fires inhibit complete decomposition.

• Decomposition and cellular respiration are slower in cold temperatures and faster in warm/hot temperatures.

• Yeast decomposes sugar like decomposers in peat decompose plant matter.

• When glucose and oxygen react, they produce bioproducts like water and carbon dioxide, and (ATP) energy.

• Cold temperatures slow down reaction rate, while hot temperatures increase reaction rate.

• Other factors that might affect the rate of reaction in the zombie fire system include moisture and oxygen availability.

• The larger surface area of peat increases the potential for water absorption and storage.

• Cellular respiration is the mechanism that allows energy/matter flow in decomposition.

• The matter starts as glucose (organic matter).

• Sugar/Glucose turns into $CO<em>2 + H</em>2O$.

• Energy gets converted into ATP.

• Cold temperatures lead to less decomposer activity.

Arctic Ecosystem and Peat Formation

• Increased solar radiation in the Arctic increased the potential for plants to capture and store chemical energy in carbon-based compounds through photosynthesis.

• As solar radiation in the Arctic decreased, many plants died, and peat and permafrost were formed.

• The Arctic used to be green and had plenty of vegetation.

• Rainforests and the tropics have a lot of plant matter because they get a lot of rain and sunlight.

• Features that cause a lot of matter to be stored in plants: photosynthesis, sun, and nutrient-rich soil.

• Temperature affects the speed of reaction.

• They have a lot of photosynthesis and water, and are hot and sunny.

Earth's Tilt and Energy Storage in Plants

• Through photosynthesis, plants convert carbon dioxide and water into sugar and oxygen.

• More solar energy means more carbon dioxide is captured and stored by plants.

• Plants convert excess sugar into larger carbon-based molecules, such as starch.

• Increased solar radiation in the Arctic increased the potential for plants to capture and store chemical energy in carbon-based compounds.

• The flow of energy slowed because of the earth's tilt decreasing over thousands of years.

Photosynthesis and Cellular Respiration

• Direct relationship: As one variable increases, the other increases.

• The relationship between available sunlight and the amount of carbon plants store through photosynthesis: As the amount of sun increases, carbon stored in plants increases.

• Light energy is converted to chemical energy.

• Photosynthesis inputs: Water and CarbonDioxide . Outputs: Glucose and Oxygen

• Cellular respiration inputs: Glucose and Oxygen. outputs: Water ATP(energy) and Carbon Dioxide.

Carbon Sinks in Different Ecosystems

• Many different ecosystems have carbon sinks created from the flow of energy and matter into plants by photosynthesis.

• Fire increases the flow of matter and energy from the biosphere to the atmosphere.

Chemistry of Life Vocabulary and Notes

Matter

• Anything that occupies space and has mass.

Compound

• Atoms of two or more different elements that are joined by chemical bonds in a fixed proportion.

• Elements form compounds because all elements in the periodic table (except the noble gases) have an incomplete valence shell.

Elements

• Made of a single kind of atom and cannot be broken down by chemical means into simpler substances.

• Fewer than 30 elements are relevant to living things.

• Living things are composed of 4 elements: Oxygen, carbon, Hydrogen and nitrogen.

Atoms

• Composed of protons, neutrons, and electrons.

• The simplest particle of an element that retains all properties of elements.

• Properties of atoms determine the structure and properties of matter.

Nucleus

• Central region of an atom. Protons and neutrons make up the mass of the nucleus.

• Electrons move around the nucleus in orbitals.

Orbital

• A three-dimensional region around the nucleus that indicates the probable location of an electron.

Covalent Bond

• Atoms can have a complete (stable) valence shell by either sharing electrons with one another or a complete transfer of electrons.

Ionic Bond

• A type of chemical bond between opposite charged ions due to complete transfer of electrons.\

Molecule

• the simplest part of a substance that retains all of its properties and can exist in a free state.