Enzyme Inhibition and Regulation

An inhibitor directly competes with the substrate for the enzyme's active site, blocking substrate binding.

An inhibitor binds to a site other than the active site (allosteric site), changing the enzyme's shape and reducing its activity.

The product of an enzyme-catalyzed pathway inhibits the earlier steps of the pathway.

The temperature at which an enzyme works most efficiently.

The pH value at which an enzyme is most active.

The process in which high temperatures cause an enzyme to lose its structural integrity, affecting activity.

Enzymes that lose their activity at higher temperatures.

Membranes that control what passes through them, allowing some molecules and ions to cross but not others.

The model describing cell membranes as a fluid bilayer with proteins embedded and floating.

Movement of molecules across a membrane without energy input, driven by concentration gradients.

Molecules moving directly across a membrane from high to low concentration.

Molecules moving across a membrane with the help of transport proteins, still down their concentration gradient.

Diffusion of water across a selectively permeable membrane, from a lower solute to higher solute concentration.

Movement of molecules against their concentration gradient requiring energy (ATP).

Active transport where the transport protein directly uses ATP to move substances.

Active transport that uses energy stored in an electrochemical gradient created by a primary active transporter.

The ability of lipid molecules to move within the cell membrane.

Having both hydrophilic and hydrophobic parts.

Major component of cell membranes, composed of hydrophilic head and hydrophobic tails.

Two layers of lipids arranged with tails facing each other.

A chemical reaction involving the transfer of electrons, where one molecule is oxidized and another is reduced, exemplified by the interconversion of NAD+ and NADH.

A chemical reaction involving the transfer of electrons, where one molecule is oxidized and another is reduced, exemplified by the interconversion of FAD and FADH2.

The process where glucose is broken down to release energy in the form of ATP, using oxygen, producing carbon dioxide and water as byproducts.

The first stage of cellular respiration, breaking down glucose into pyruvate in the cytoplasm.

A series of reactions that oxidizes acetyl groups (derived from pyruvate), producing ATP, NADH, and FADH2.

The final stage of cellular respiration where NADH and FADH2 donate electrons to the electron transport chain, generating ATP.

A metabolic process that produces ATP from glucose without the need for oxygen; produces products like lactic acid or ethanol.

Type of fermentation in animals and bacteria where the NADH produced during glycolysis transfers electrons to pyruvate, forming lactate and regenerating NAD+.

Type of fermentation in plants and fungi where NADH from glycolysis transfers electrons to pyruvate, forming ethanol and regenerating NAD+.

A series of protein complexes in the inner mitochondrial membrane that use electrons from NADH and FADH2 to generate a proton gradient, which is used to produce ATP.

Vesicles fuse with the plasma membrane to secrete substances.

Internalization of external materials via vesicles.

Non-specific uptake of fluids (cell drinking).

Uptake of large particles (cell eating).

Specific uptake via receptor-clathrin interactions.

Signal molecule binds to receptor.

Signal relayed via intracellular cascades.

Cellular activity altered.

Signal turned off after response.

One signal activates multiple downstream molecules.

Add phosphates to molecules.

Remove phosphates from molecules.

Partial or full loss of electrons from a substance.

Partial or full gain of electrons by a substance.

Oxidation and reduction occur simultaneously.

Accepts 2 electrons and 1 proton (becomes NADH).

Accepts 2 electrons and 2 protons (becomes FADH2).

Respiration that does not utilize oxygen as the terminal electron acceptor.

A metabolic pathway used in respiration when oxygen is absent.

One type of fermentation, producing lactate as a byproduct.

Another type of fermentation, producing alcohol as a byproduct.

Harmful oxidizing agents like superoxide and hydrogen peroxide.

The body's protection against reactive oxygen species.

Major photosynthetic pigments in plants and some bacteria.

Pigments that assist chlorophyll in capturing light energy.

Graph showing light absorbed by a pigment at different wavelengths.

Graph showing the efficiency of different wavelengths in driving photosynthesis.

Experiment demonstrating the wavelengths most effective for photosynthesis.

First stage of photosynthesis, capturing light energy.

Second phase of photosynthesis, using energy to create sugars.

Part of photosystem that absorbs light and transfers energy.

Specific chlorophyll molecules where light energy is converted into chemical energy.

Photosystem responsible for extracting electrons from water.

Photosystem involved in reducing NADP+ to NADPH.

Chain that links PSII and PSI, moving electrons.

When photons of light hit an object, they can be reflected, transmitted, or absorbed.

For light to be used as energy, it has to be absorbed. This energy is transferred to an electron in a molecule.

Absorption of light energy causes an electron in a molecule to move from its original level to a higher energy level, an excited state.

Molecules that absorb photons of specific wavelengths. Their structure affects what wavelengths they absorb.

A chain of carbon atoms linked by alternating single and double bonds. This is needed to absorb photons for pigments including chlorophyll.

The color of a pigment is determined by the wavelengths of light it doesn't absorb.

A photosynthetic pigment that is highly efficient at absorbing visible light.

Arrangement of different types of electromagnetic radiation, from high-energy gamma rays to low-energy radio waves, visible light is one form.

The range of wavelengths of light visible to humans, from violet (400 nm) to red (700 nm).

When an electron returns to its ground state, releasing energy as a longer wavelength of light.

Energy transfer between neighboring pigment molecules.

Transfer of excited-state electron to a nearby electron-accepting molecule.

Process using light energy to convert CO2 into organic molecules, releasing oxygen as a byproduct.

Organisms that produce their own food from inorganic sources.

Autotrophs that use light as their energy source for photosynthesis.

Organisms that obtain energy by consuming other organisms.

The first stage of photosynthesis, converting light energy into ATP and NADPH, producing oxygen as a byproduct.

The second stage of photosynthesis, using ATP and NADPH from the light reactions to fix carbon dioxide into sugars.

Organelles in eukaryotic cells where photosynthesis takes place.