Topic 5A Flashcards
(19 cards)
Photophosphorylation
Photophosphorylation is the process of generating adenosine triphosphate (ATP) using energy from sunlight during photosynthesis. It occurs in the thylakoid membranes of chloroplasts and involves the movement of electrons through an electron transport chain. The energy released pumps protons across the membrane, creating a proton gradient. ATP synthase then uses this gradient to synthesise ATP from ADP and inorganic phosphate.
Adenosine Triphosphate (ATP)
ATP is the primary energy carrier in all living cells. It consists of adenine, ribose (a sugar), and three phosphate groups. Energy is released when the terminal phosphate bond is broken, converting ATP into ADP. This energy powers various cellular processes such as muscle contraction and active transport.
Adenosine Diphosphate (ADP)
ADP is a nucleotide formed when ATP loses one phosphate group. It consists of adenine, ribose, and two phosphate groups. ADP can be converted back into ATP through phosphorylation, using energy from cellular respiration or photosynthesis. This conversion forms part of the energy recycling system in cells.
Photosynthesis
Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy. It occurs in the chloroplasts and uses carbon dioxide and water to produce glucose and oxygen. The overall equation is:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂.
Photosynthesis consists of light-dependent reactions and the Calvin cycle (light-independent reactions).
Nucleotide
A nucleotide is the basic building block of nucleic acids such as DNA and RNA. It is composed of a nitrogenous base, a five-carbon sugar (either ribose or deoxyribose), and one or more phosphate groups. Nucleotides also function as energy carriers (e.g., ATP) and signalling molecules in cells.
Nitrogenous Base
A nitrogenous base is a molecule that contains nitrogen and acts as a base. In nucleotides, it forms part of DNA and RNA structure. The four main nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine. In RNA, uracil replaces thymine.
Hydrolysis Reaction
A hydrolysis reaction involves breaking a chemical bond in a molecule using water. It is the reverse of a condensation reaction. In biology, it is commonly used to break down polymers like proteins, carbohydrates, and nucleic acids into monomers. Enzymes often catalyse hydrolysis reactions in digestion.
Condensation Reaction
A condensation reaction joins two molecules together with the removal of a water molecule. It is how biological polymers like proteins and polysaccharides are formed. For example, amino acids are joined by peptide bonds in protein synthesis through condensation. These reactions require energy and are enzyme-controlled.
Biological Reaction
A biological reaction is a chemical reaction that takes place in living organisms. It is usually catalysed by enzymes to increase the rate of reaction under mild conditions. Examples include respiration, digestion, and DNA replication. These reactions maintain life and cellular function.
Active Transport
Active transport is the movement of substances across a cell membrane against their concentration gradient, from a low to a high concentration. This process requires energy, usually from ATP. Carrier proteins in the membrane are involved in the process. It allows cells to absorb nutrients and remove waste efficiently.
Diffusion
Diffusion is the passive movement of particles from an area of high concentration to an area of low concentration. It continues until equilibrium is reached. Diffusion does not require energy and occurs due to the random motion of particles. It is essential for gas exchange in lungs and cells.
Diffuser
In biology, the term “diffuser” is not standard; however, if referring to a substance that diffuses, it is a molecule that moves passively through a medium or membrane. Diffusers typically include gases like oxygen and carbon dioxide or small solutes. These move by diffusion along a concentration gradient. In physiology, it helps maintain concentration differences across membranes.
Facilitated Diffusion
Facilitated diffusion is the passive transport of molecules across a membrane with the help of transport proteins. It occurs down the concentration gradient and does not require energy. It enables the movement of larger or polar molecules like glucose and ions. Channel or carrier proteins assist in this process.
Exocytosis
Exocytosis is the process by which a cell expels materials in vesicles to the external environment. Vesicles containing waste or secretory products fuse with the plasma membrane. It is an active process requiring ATP. Exocytosis is crucial for releasing hormones and neurotransmitters.
Endocytosis
Endocytosis is the process of a cell engulfing substances from its environment by enclosing them in a vesicle. It involves the plasma membrane folding inward to form a pocket. This active process requires energy from ATP. Types of endocytosis include phagocytosis (for solids) and pinocytosis (for liquids).
Mole of a Substance
A mole is a unit used to measure the amount of a substance. One mole contains 6.022 × 10²³ particles (Avogadro’s number) of that substance—atoms, molecules, or ions. The mass of one mole of a substance is equal to its relative molecular or atomic mass in grams. It allows chemists and biologists to count and compare quantities of substances in reactions.
Inorganic Molecule
An inorganic molecule is a compound that does not contain carbon-hydrogen (C–H) bonds. Examples include water (H₂O), oxygen (O₂), and carbon dioxide (CO₂). These molecules are often involved in simple, non-living chemical processes in organisms. Inorganic molecules are essential for life, particularly in respiration and water balance.
Organic Molecule
An organic molecule contains carbon atoms bonded to hydrogen, and often other elements like oxygen and nitrogen. Examples include carbohydrates, proteins, lipids, and nucleic acids. These molecules form the structure and function of living organisms. They are usually complex and involved in energy storage, information transfer, and cellular processes.
Synthesis
Synthesis refers to the process of building complex molecules from simpler ones. In biology, it often involves enzyme-controlled reactions, such as protein synthesis from amino acids. Synthesis requires energy, typically from ATP. It is essential for growth, repair, and reproduction in living organisms.
