Both whales and dolphins retain their pelvic (hip) bones. These bones play a role in supporting and distributing the trunk's weight to the hind limbs.
This suggests that the existence of pelvic bones may point to a terrestrial lineage for whales.
Answer:
1.) Mitochondria produce energy via a sequence of chemical reactions where electrons are transferred along a membrane. "Maintaining some genes within mitochondria allows the cell to manage mitochondria independently," explains Johnston, as key proteins are synthesized there.
2.) The transition from DNA to protein happens through mRNA, involving transcription followed by translation, processes collectively referred to as gene expression.
Explanation:
As a phosphorus molecule, I start by being absorbed by plants from the soil through assimilation. Next, I am consumed by animals. When these plants and animals die, they decompose, releasing me back into the soil. Additionally, processes like weathering and erosion cause me to be liberated from rocks. Then, I flow into the ocean carried by water, and eventually, I find my way back to the soil through the water cycle.
Answer:
The steps in order are:
1. The body requires energy for its activities
2. The body secretes epinephrine
3. Epinephrine attaches to fat cells in adipose tissue
4. Triacylglycerols (triglycerides) get hydrolyzed into glycerol and fatty acids
5. Fatty acids are transported to tissues
Explanation:
Fat mobilization is a process of gluconeogenesis (extracting energy from non-carbohydrate sources), in which fat stored in adipose tissue is broken down for energy.
This process initiates when the body is in a state needing energy (hypoglycemic), triggering glucagon release from the pancreas and epinephrine from the brain's adrenal medulla.
These hormones promote gluconeogenesis and glycogenolysis (the breakdown of glycogen) in the liver, activate lipolysis in muscle and liver cells, and also suppress fat synthesis. This occurs as these hormones bind to specific receptors on fat cell surfaces, activating lipases (enzymes that catalyze lipolysis). Lipases catalyze the breakdown of triglycerides (common dietary fats) into glycerol and three free fatty acids. These free fatty acids enter the bloodstream, where they bind to serum albumin – a transport protein for fatty acids to muscle cells where they are utilized for energy and CO₂ production.
