Week 2 Flashcards
What is the process of ATP turning into ADP and how is energy released?
ATP (adenosine triphosphate) stores energy in its high-energy phosphate bonds. When ATP breaks one of these bonds, it releases energy and becomes ADP (adenosine diphosphate), which has two phosphates instead of three. ADP needs to be recharged to become ATP again.
How is ADP recharged back into ATP in the cell?
ADP is recharged in the mitochondria. The mitochondria add a phosphate group to ADP, capturing energy in the bond and recharging it back into ATP.
What is the overall reaction for cellular respiration?
The oxidation of glucose in cellular respiration is represented by the following equation:
C₆H₁₂O₆ + 6O₂ → 6H₂O + 36 ATP + heat
What happens during glycolysis?
Glycolysis is the breakdown of a 6-carbon glucose molecule into two 3-carbon pyruvic acid molecules. This process requires some energy to start but results in a net gain of 2 ATP. Hydrogen is removed and joined with NAD+ to form NADH.
What is the role of the Krebs cycle in cellular respiration?
The Krebs cycle occurs in the mitochondria and starts with Acetyl-CoA. It produces energy carriers NADH and FADH₂, releases CO₂, and generates a small amount of ATP. The energy carriers fuel the electron transport chain for further ATP production.
How does aerobic respiration differ from anaerobic respiration?
Aerobic Respiration: Requires oxygen, occurs in mitochondria, produces around 36-38 ATP per glucose, by-products are CO₂ and H₂O.
Anaerobic Respiration: Does not require oxygen, occurs in the cytoplasm, produces around 2 ATP per glucose, by-products vary (lactic acid in humans, ethanol and CO₂ in yeast).
What role does the plasma membrane play in the transport of molecules?
The plasma membrane separates intracellular fluid (inside cells) from extracellular fluid (outside cells). It is essential for transporting molecules (such as ions, nutrients, and waste) in and out of the cell, maintaining cell function and homeostasis.
What are the functions of body fluids?
Body fluids serve as a medium for metabolic reactions, transport nutrients and waste products, provide lubrication, insulation, and shock absorption, and regulate body temperature. Fluids are eliminated via urine, feces, and sweat.
How does body water content change with age?
Body water content varies by age and body composition:
Infants: 73% or more water
Young men: 60% water
Young women: 50% water
Older adults: About 45% water
How is water distributed in a healthy male’s body?
In a 70 kg male:
60% of body weight is water, which equals about 40 L
Intracellular fluid: 40% of body weight (25 L)
Extracellular fluid: 20% of body weight (15 L)
Interstitial fluid: 12 L (80% of ECF)
Blood plasma: 3 L (20% of ECF)
What substances are found in body fluids?
Body fluids contain solutes like nutrients, waste products, and ions (electrolytes). These substances are dissolved in both intracellular and extracellular fluids.
How do fluids and substances exchange in the body?
Homeostasis is maintained by the movement of electrolytes, oxygen and waste products:
- electrolytes move in and out of cells
- oxygen travels from plasma to interstitial fluid and then to cells
- waste products move from cells to interstitial fluid, then to plasma for elimination. This exchange occurs through the selectively permeable membrane via diffusion, osmosis, active transport and filtration
What is bulk transport and how does it work?
Bulk transport is an active transport mechanism that moves large molecules or particles in and out of the cell via vesicles. It requires energy (ATP) for processes like endocytosis and exocytosis.
What is endocytosis?
Endocytosis is the process where substances are transported into the cell by the membrane folding around particles, forming a vesicle that brings the particles into the cytoplasm.
What is exocytosis?
Exocytosis is the process where substances are transported out of the cell when a vesicle containing waste or cell particles fuses with the cell membrane, releasing its contents outside the cell.
What is the difference between passive and active transport?
Passive transport does not require energy and occurs through diffusion or osmosis, while active transport requires energy (ATP) to move substances against their concentration gradient.
How does simple diffusion work?
In simple diffusion, nonpolar or lipid-soluble substances diffuse directly through the plasma membrane from high to low concentration until equilibrium is reached.
What is facilitated diffusion?
Facilitated diffusion is the passive transport of substances through membrane proteins for molecules that cannot pass through the lipid bilayer, such as ions or large polar molecules.
What is the difference between channel-mediated and carrier-mediated facilitated diffusion?
In channel-mediated diffusion, transmembrane proteins form water-filled channels for ions and water. In carrier-mediated diffusion, carrier proteins transport larger molecules like sugars and amino acids by changing shape to envelop and release the substance.
What is osmosis?
Osmosis is a type of diffusion where water moves across a selectively permeable membrane from an area of low solute concentration (more water) to an area of high solute concentration (less water).
What is tonicity?
Tonicity refers to the ability of a solution to affect the shape or tone of a cell by altering its internal water volume, leading to swelling or shrinking of the cell.
What happens in an isotonic solution?
In an isotonic solution, the osmolarity is the same as inside the cell, and the cell retains its normal shape with no net movement of water. Example: 0.9% saline solution.
