Cellular Respiration and Human Nutrition

Flashcards covering key concepts of cellular respiration, human nutrition, ATP, and the four stages of aerobic respiration based on lecture notes.

When does the first topic for Exam 2, Cellular Respiration, begin?

It begins after covering the material for Exam 1, as topics are not cumulative for exams but build on each other.

Why is cellular respiration considered a difficult topic despite being covered at a basic level in this course?

It involves a very complicated concept and process even when scratching the surface.

What are mitochondria commonly referred to as, and why is this concept important?

Mitochondria are the 'powerhouses of the cell' because they are organelles that make energy (ATP), which is essential for life.

What happens to food after it is eaten and passes through the digestive tract?

It undergoes mechanical and chemical digestion in the mouth and stomach, then the majority of absorption occurs in the small intestine.

Where is glucose absorbed after digestion, and how is it transported throughout the body?

Glucose is absorbed into the bloodstream in the small intestine (via microvilli and capillaries) and then delivered to every cell in the body by the blood.

Why do all cells in the body need glucose?

Every cell needs glucose to perform cellular respiration, the process that produces energy for the cell.

Where does cellular respiration primarily occur within an animal cell?

In the mitochondria.

What is the definition of cellular respiration?

It is the process in cells that releases the chemical energy stored in glucose and converts it into ATP (Adenosine Triphosphate).

What is chemical energy?

A form of potential energy stored in the bonds of a chemical structure, such as the C-H bonds in glucose.

Which organisms perform some form of cellular respiration?

Every single living thing (plants, animals, bacteria, fungi, protists, etc.) does some form of cellular respiration as a requirement for life.

Why can't cells directly use light energy from the sun or chemical energy from food to fuel cellular work?

Neither can be used directly; they require conversion into ATP, which is the direct energy currency of the cell.

What is ATP often called in the context of cellular energy?

ATP is like the 'energy currency of the cell' or 'money for the cell'.

What does ATP stand for, and what are its main structural components?

ATP stands for Adenosine Triphosphate. It consists of an adenine group, a ribose sugar (forming adenosine), and three phosphate groups.

How does ATP release energy for cellular activities?

Energy is released when the bond of the third phosphate group is broken, converting ATP into ADP (Adenosine Diphosphate).

Describe the ATP-ADP cycle.

Cells use ATP for energy by converting it to ADP and a free phosphate; cellular respiration then re-attaches the phosphate to ADP, reforming ATP, in a continuous cycle.

What are the two types of cellular respiration mentioned, and what distinguishes them?

Aerobic respiration requires oxygen, while anaerobic respiration occurs without oxygen.

Which type of cellular respiration do humans primarily perform?

Aerobic respiration.

What are the two main inputs for aerobic cellular respiration in humans?

Sugar (glucose) and oxygen.

What are the three main outputs (products) of aerobic cellular respiration?

Carbon dioxide, water (both byproducts), and ATP molecules.

What is the basic chemical formula for cellular respiration?

Sugar + Oxygen yields Carbon Dioxide + Water + ATP.

What are the four stages of aerobic cellular respiration?

Glycolysis, the preparatory reaction (or transition reaction), the citric acid cycle (or Krebs cycle), and the electron transport chain.

Where does glycolysis occur within the cell?

In the cytoplasm.

What is the main event of glycolysis?

Glucose (a 6-carbon molecule) is broken down into two 3-carbon molecules called pyruvate.

What is the net ATP yield from glycolysis?

A net gain of 2 ATP molecules (2 are invested, 4 are made).

Where does the preparatory reaction occur?

In the mitochondrial matrix (middle of the mitochondria).

What happens to pyruvate during the preparatory reaction?

Each 3-carbon pyruvate loses one carbon (released as CO2) to become a 2-carbon acetyl group, which then combines with Coenzyme A to form Acetyl CoA.

How much ATP is directly produced during the preparatory reaction?

No direct ATP is produced.

Where does the citric acid cycle occur?

In the mitochondrial matrix (middle of the mitochondria).

What molecule enters the citric acid cycle?

Acetyl CoA.

What waste product is released during the citric acid cycle as glucose is fully broken down?

Carbon dioxide.

How much ATP is directly produced during the citric acid cycle?

2 ATP molecules.

Where does the electron transport chain occur?

On the inner mitochondrial membrane.

What is the primary function of electron carriers (like NAD+ and FAD) in cellular respiration?

They act like 'taxis' to pick up electrons (in the form of hydrogen) from glycolysis, the preparatory reaction, and the citric acid cycle, and deliver them to the electron transport chain.

What happens to electron carriers (NADH and FADH2) in the electron transport chain?

They drop off their electrons, which are then passed along a chain of proteins to generate a large amount of ATP.

What is the role of oxygen in the electron transport chain?

Oxygen is the 'final electron acceptor'; it removes the last electron from the chain, allowing the process to continue, and forms water (H2O) as a byproduct.

Approximately how many ATP molecules are produced in the electron transport chain, and what is the total maximum ATP yield from one glucose molecule?

About 34 ATP molecules are produced in the electron transport chain, leading to a total of 36-38 ATP per glucose molecule.

What happens to electron carriers after they have delivered their electrons in the electron transport chain?

They are recycled back to their 'empty' form (NAD+ or FAD) to pick up more electrons from earlier stages of cellular respiration.