Biology test review

What is metabolism?

Metabolism is the collective term for all chemical reactions within a living organism, encompassing two main categories: anabolic reactions, which build larger molecules from smaller ones, and catabolic reactions, which break down larger molecules to release energy.

Define metabolic pathway.

A metabolic pathway is a series of interconnected biochemical reactions occurring within a cell. Each step in the pathway is typically facilitated by specific enzymes, allowing for precise control and regulation of metabolic processes.

What does induced fit mean in enzymatic action?

Induced fit refers to the phenomenon in enzymatic reactions where an enzyme undergoes a conformational change upon substrate binding, enhancing the enzyme's ability to facilitate either the formation or breakdown of chemical bonds.

What is substrate specificity?

Substrate specificity is a crucial characteristic of enzymes that determines their ability to selectively bind and react with particular substrates, ensuring that each enzyme catalyzes only one or a limited range of reactions.

What is an enzyme inhibitor?

An enzyme inhibitor is a molecule that interferes with the enzyme's activity, hindering its ability to catalyze reactions. Inhibitors can be classified into two main types: competitive inhibitors, which compete with the substrate for the active site, and non-competitive inhibitors, which bind to an alternative site, altering the enzyme's function.

Differentiate between competitive and non-competitive inhibitors.

Competitive inhibitors directly compete with substrates for the active site on the enzyme, thus preventing substrate binding. In contrast, non-competitive inhibitors bind to an allosteric site on the enzyme, leading to changes in its shape that diminish its catalytic activity without directly blocking the active site.

What are statins?

Statins are a class of pharmaceutical drugs that reduce levels of low-density lipoprotein (LDL) cholesterol in the bloodstream. They function by acting as competitive inhibitors against the enzymes involved in the synthesis of cholesterol in the liver.

How does penicillin affect bacteria?

Penicillin functions by irreversibly binding to and inhibiting transpeptidase, an enzyme essential for the synthesis of bacterial cell walls. This action disrupts cell wall formation, ultimately leading to bacterial lysis and death.

What is end-product inhibition?

End-product inhibition is a regulatory mechanism wherein the final product of a metabolic pathway binds to an allosteric site of the initial enzyme, thereby decreasing its activity and, consequently, slowing down the production of the pathway's end product.

Define cellular respiration.

Cellular respiration is a biochemical process in which living organisms break down organic compounds, primarily glucose, in a controlled manner to release energy stored in their chemical bonds, converting it into adenosine triphosphate (ATP) for cellular functions.

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration takes place in the presence of oxygen and produces a significantly higher yield of ATP, whereas anaerobic respiration occurs in the absence of oxygen, leading to lower ATP production along with various byproducts like lactic acid or ethanol.

What are electron carriers?

Electron carriers are specialized molecules that transport electrons during metabolic reactions, playing a pivotal role in linking oxidation and reduction processes crucial for energy production in cells, particularly during cellular respiration.

What happens to pyruvate under low oxygen conditions?

When oxygen levels are low, pyruvate generated from glycolysis is converted into lactic acid through lactic acid fermentation, allowing for the continuation of ATP production despite the lack of oxygen.

What are the four stages of cellular respiration?

The four stages of cellular respiration are: 1) Glycolysis - the breakdown of glucose into pyruvate; 2) Link reaction - conversion of pyruvate into acetyl-CoA; 3) Krebs cycle - series of reactions that generate electron carriers; and 4) Oxidative phosphorylation - the production of ATP via the electron transport chain and chemiosmosis.

What is oxidative phosphorylation?

Oxidative phosphorylation is a vital phase of cellular respiration where most adenosine triphosphate (ATP) is generated. It occurs through the electron transport chain coupled with chemiosmosis, where energy from electron transfer is used to pump protons, creating a gradient that drives ATP synthesis.

What is the role of ATP Synthase?

ATP Synthase is an essential enzyme embedded in the inner mitochondrial membrane that facilitates ATP production. It harnesses the energy from the flow of protons (H+ ions) across the membrane, catalyzing the conversion of adenosine diphosphate (ADP) and inorganic phosphate into ATP.

Where does the Krebs cycle occur?

The Krebs cycle, also known as the citric acid cycle, takes place in the mitochondrial matrix, where it plays a critical role in energy production and metabolic intermediates generation.

What are the functions of the different membranes in mitochondria?

The outer mitochondrial membrane regulates the transport of molecules in and out of the mitochondrion. Beneath it, the inner mitochondrial membrane houses the electron transport chain, while the intermembrane space plays a key role in proton concentration and gradient formation essential for ATP generation.

What are the end products of glycolysis?

The end products of glycolysis include 2 ATP molecules (net gain), 2 NADH + H+ (electron carriers), and 2 molecules of pyruvate, which serve as substrates for further metabolic processes.

What is an anabolic reaction?

An anabolic reaction is a metabolic process that synthesizes larger, complex molecules from simpler ones, generally requiring an input of energy, exemplifying the growth and repair functions of cells.

What is glycolysis?

Glycolysis is the initial metabolic pathway that converts glucose into pyruvate, occurring in the cytoplasm. It generates ATP and NADH, helping to facilitate energy production, especially in anaerobic conditions.

What occurs during the link reaction?

In the link reaction, pyruvate produced from glycolysis is converted into acetyl-CoA, releasing carbon dioxide and generating NADH in the process, linking glycolysis to the Krebs cycle.

What are the main products of the Krebs cycle per acetyl-CoA?

For each acetyl-CoA that enters the Krebs cycle, the main products generated are 3 NADH, 1 FADH2, 1 ATP, and 2 carbon dioxide (CO2) molecules, contributing to overall energy production.

What is chemiosmosis?

Chemiosmosis is the process by which adenosine triphosphate (ATP) is synthesized in cells as protons diffuse down their concentration gradient across a membrane, driving the production of ATP by ATP Synthase.

What is the role of oxygen in aerobic respiration?

In aerobic respiration, oxygen functions as the final electron acceptor in the electron transport chain, enabling the continuation of electron flow, which is crucial for producing a large quantity of ATP.

What happens in lactate fermentation?

Lactate fermentation is an anaerobic metabolic process in which glucose is converted into lactic acid, enabling the production of ATP in low-oxygen environments without relying on oxidative phosphorylation.