Cellular respiration does not use glucose alone. Carbohydrates, proteins, and lipids from food can be broken down and their components routed into glycolysis or the citric acid cycle. Understanding these connections explains how a meal can contribute to ATP production and why metabolic pathways are interconnected rather than isolated.
Glycogen is a polymer of glucose used for energy storage in animals. When glucose is abundant and ATP needs are met, liver and muscle cells can store excess glucose as glycogen. When blood sugar falls or muscles need energy during exercise, glycogen is broken down.
All flashcards
How does glycogen enter glycolysis?
Glycogen is broken down into glucose-1-phosphate, which is converted into glucose-6-phosphate and then enters glycolysis.
What is the fate of excess amino-acid nitrogen in mammals?
Amino groups are converted into ammonia. The liver uses ammonia-derived nitrogen and carbon dioxide to make urea, which is excreted in urine.
What is beta-oxidation?
Beta-oxidation is the breakdown of fatty-acid chains in the mitochondrial matrix into two-carbon units that are attached to CoA to form acetyl-CoA.
How can glycerol from a triglyceride enter energy metabolism?
Glycerol can be phosphorylated to glycerol-3-phosphate, which can continue through glycolysis.
What is anoxygenic photosynthesis?
A form of photosynthesis that captures light energy without releasing free oxygen. Some forms use hydrogen sulfide rather than water and can produce sulfur.
Quiz questions
Which type of photosynthesis uses water and releases free oxygen?Answer: Oxygenic photosynthesis.
What geological evidence indicates that oxygen production began before the atmosphere became oxygen-rich?Answer: Oxidized metal deposits formed in marine sediments.
What environmental change allowed aerobic respiration to evolve?Answer: A gradual increase in the availability of oxygen.
Which pair of roles does cholesterol have in animal cells?Answer: It contributes to membrane flexibility and serves as a steroid-hormone precursor.
According to a hypothesis about early nutrient-rich environments, what could favor organisms that used resources efficiently?Answer: Growing populations depleted available nutrients, favoring organisms that used remaining resources effectively.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.