Module 2
Module 2
- Identify the chemical components of life
- Describe metabolic processes as these relate to homeostasis
- Apply scientific inquiry to predict outcomes
- Classify and compare major groups of organisms
Learning Objectives Chapter 5
How does the food you eat and the air you breathe enter your cells?
- Identify major structural components of the cell membrane
- Identify three types of passive transport
- Identify the characteristics of active transport
Chapter 5 Summary
The plasma membrane is composed of primarily phospholipids studded with proteins, some which span the membrane. Carbohydrates are attached to some of the proteins and lipids on the membrane’s outward-facing surface, forming complexes that function to identify the cell to other cells. Plasma membranes enclose and define the cells’ borders. Not static, these membranes are dynamic and constantly in flux. Transport moves molecules across membrane, as substances diffuse from areas of high concentration to areas of low concentration (down the concentration gradient). Moving substances up the gradient requires ATP energy. Active transport requires integral proteins in the cell membrane to move the materials. In a bulk transport process call phagocytosis, other cells can engulf large particles, such as macromolecules, cell parts, or whole cells.
Learning Objectives Chapter 6
How do cells manage energy?
- Recognize the characteristics of metabolism
- Apply the first and second laws of thermodynamics to biological processes
- Examine the role of ATP in metabolism
- Describe the role of enzymes in metabolism
Metabolism refers to the chemical reactions that take place within the cell. Metabolic reactions involve both catabolic reactions (breaking down complex chemicals to release energy) and anabolic reactions (building complex molecules out of simpler ones that require energy). Energy comes in many different forms. Objects in motion do physical work, and kinetic energy is the energy of objects in motion. Objects that are not in motion may have the potential to do work and have potential energy. Molecules can also have potential energy because breaking molecular bonds has the potential to release energy. The laws of thermodynamics are a series of laws that describe the properties and processes of energy transfer. ATP is the primary energy-supplying molecule for living cells. Enzymes are chemical catalysts that lower activation energy. Enzymes are usually proteins consisting of an active site providing a unique chemical environment perfectly suited to convert particular chemical reactants for that enzyme.
Learning Objectives Chapter 7
How does your body convert carbohydrates to energy?
- Describe reactions vital to cellular respiration
- Identify cellular location, requirements and products for the three processes of cellular respiration in eukaryotes
- Describe types of fermentation
Chapter 7 Summary
ATP functions as the energy currency for cells. Energy derived from glucose catabolism is used to convert ADP into ATP. Glycolysis is the first pathway within the cytoplasm used in the breakdown of glucose to extract energy. The six-carbon glucose is converted to two three-carbon pyruvate. It was probably one of the earliest metabolic pathways to evolve and is used by nearly all of the organisms on Earth. Two ATP molecules are invested in the first half and four ATP molecules are produced for a net gain of two ATP. In eukaryotic mitochondria with oxygen present, pyruvate is transformed in to acetyl-CoA. Most often, this molecule enters the Krebs or Citric Acid Cycle (CAC). CAC is a series of redox reactions that move high-energy electrons within the matrix of the mitochondria. Two ATP molecules are produced. The electron transport chain is composed of protein complexes embedded in the inner mitochondrial membrane with electron carriers shuttling electrons. Their action builds up a high concentration of hydrogen ions between the inner and outer membranes of the mitochondria to power ATP synthase (≅32 ATP). In total, aerobic cellular respiration will yield approximately 36 ATP per molecule of glucose. Most organisms will use some form of fermentation (lactic acid and alcohol) to ensure the continuation of glycolysis, when oxygen is not plentiful. The net yield of ATP is much less, but the process is much faster.
Learning Objectives Chapter 8
Where do glucose molecules come from?
- Describe reactions vital to photosynthesis
- Identify cellular location, reactants and products for the two stages of photosynthesis
- Describe the energy cycle
Chapter 8 Summary
By harnessing energy from the sun, photosynthesis provides living things access to enormous amounts of energy. Chlorophyll containing organisms can perform photosynthesis, using carbon dioxide and water to assemble carbohydrate molecules and release oxygen as a byproduct. Plants and algae, have organelles called chloroplasts that contain chlorophyll. The light-dependent reactions, absorb energy from sunlight. A photon strikes chlorophyll to initiate photosynthesis. The thylakoid membrane contains its own electron transport chain, which pumps hydrogen ions into the thylakoid interior. This action builds up a high concentration of hydrogen ions. The hydrogen ions flow through ATP synthase to form molecules of ATP contributed to the Calvin cycle, where CO2 from the atmosphere is converted in a series of enzyme reactions to a carbohydrate molecule. Photosynthesis forms an energy cycle with the process of cellular respiration, as the products of photosynthesis are the reactants for aerobic cellular respiration. The opposite is also true. Because plants contain both chloroplasts and mitochondria, they rely upon both photosynthesis and respiration for their ability to function in both the light and dark.
Learning Objectives Chapter 9
Can cells communicate with each other?
- Recognize characteristics of four types of cell signals
- Identify mechanisms of nerve cell signals
The four categories of signaling in multicellular organisms are autocrine signaling, direct signaling across gap junctions, paracrine signals and endocrine signals. Autocrine signals involve a cell targeting itself. Gap-junction signals are designed for cells to signal adjoining cells. Paracrine signals involve generating signals that travel a short distance. One example is the nerve cell. Nerve cell signals must be degraded by enzymes to terminate the signal. Endocrine signals are capable of signaling distant cells.
When you are ready to review Module 2, you might find this study guide helpful.
