Membrane Transport and Energy in Cells

A comprehensive set of flashcards covering key concepts related to membrane transportation, energy storage and conversion, enzymatic activity, cell respiration, and photosynthesis.

Why is membrane transportation important?

It regulates the movement of substances in and out of cells, maintaining homeostasis.

What are the permeability rules?

They determine which molecules can pass through the cell membrane based on size, charge, and solubility.

What transport would a low concentration, charged molecule use?

Facilitated diffusion through channel or transporter proteins.

What is passive transport?

Movement of molecules across the cell membrane without energy input.

What are the types of passive transport?

Diffusion, facilitated diffusion, and osmosis.

What are the characteristics of passive transport?

It occurs down the concentration gradient and does not require energy.

What is active transport?

Movement of molecules against their concentration gradient, requiring energy.

What are the types of active transport?

Primary active transport and secondary active transport.

What are the characteristics of active transport?

It requires energy, often in the form of ATP, and it works against the concentration gradient.

What is osmosis?

The movement of water across a semi-permeable membrane from a region of lower solute concentration to higher solute concentration.

What is hypertonic, hypotonic, and isotonic?

Hypertonic: higher solute concentration; hypotonic: lower solute concentration; isotonic: equal solute concentration.

How do channel and transporter proteins work?

Channel proteins form pores in the membrane, while transporter proteins change shape to move molecules.

What is endocytosis and exocytosis?

Endocytosis: process of taking substances into the cell; exocytosis: process of expelling substances from the cell.

What is energy?

The capacity to do work or produce change.

What are the types of energy?

Kinetic energy, potential energy, chemical energy, and thermal energy.

What are phototrophs and autotrophs?

Phototrophs convert light energy into chemical energy; autotrophs produce their own food from inorganic sources.

What are the laws of thermodynamics?

1. Energy cannot be created or destroyed; 2. Energy systems tend toward disorder (entropy).

What is enthalpy?

The total energy of a thermodynamic system, including internal energy and pressure-volume work.

What is entropy?

A measure of disorder or randomness in a system.

What is Gibbs free energy?

G = H - TS, where G is free energy, H is enthalpy, T is temperature, and S is entropy.

What do exergonic and endergonic reactions look like?

Exergonic reactions have a negative delta G and are spontaneous; endergonic reactions have a positive delta G and are non-spontaneous.

What is ATP?

Adenosine triphosphate, the primary energy carrier in cells.

How does ATP supply energy to the cell?

By releasing a phosphate group, converting ATP to ADP and releasing energy that can be used for cellular processes.

What are enzymes?

Biological catalysts that speed up chemical reactions without being consumed.

How do enzymes work?

They lower the activation energy necessary for reactions to occur.

How do enzymes interact with their substrate?

Enzymes bind to specific substrates at the active site, forming an enzyme-substrate complex.

What factors affect enzyme activity?

Temperature, pH, substrate concentration, and presence of inhibitors or activators.

What are cofactors and coenzymes?

Cofactors: non-protein molecules that assist enzymes; coenzymes: organic cofactors that usually derive from vitamins.

What are the types of inhibitors?

Competitive inhibitors: compete with substrate for active site; non-competitive inhibitors: bind to a different site reducing enzyme activity.

What is a redox reaction?

A chemical reaction involving the transfer of electrons between two species.

What are metabolic, catabolic, and anabolic pathways?

Metabolic pathways are chemical reactions in cells; catabolic pathways break down molecules for energy; anabolic pathways build more complex molecules.

What are the steps of cellular respiration?

Glycolysis, Krebs cycle, and oxidative phosphorylation.

What are the inputs and outputs for each step of cellular respiration?

Glycolysis: inputs - glucose, outputs - pyruvate, ATP; Krebs cycle: inputs - acetyl-CoA, outputs - CO2, NADH; oxidative phosphorylation: inputs - electrons from NADH/FADH2, outputs - ATP, water.

What occurs at each step of cellular respiration?

Glycolysis breaks down glucose, Krebs cycle processes acetyl-CoA for electron carriers, oxidative phosphorylation generates ATP using the electron transport chain.

Where do the steps of cellular respiration happen in the cell?

Glycolysis occurs in the cytoplasm, Krebs cycle in the mitochondria matrix, and oxidative phosphorylation across the inner mitochondrial membrane.

What are the two reactions in photosynthesis?

Light-dependent reactions and light-independent reactions (Calvin cycle).

Where do the reactions of photosynthesis happen in the cell?

Light-dependent reactions occur in the thylakoid membranes; light-independent reactions occur in the stroma of chloroplasts.

What occurs in the two reactions of photosynthesis?

Light-dependent reactions convert solar energy to chemical energy; light-independent reactions fix carbon dioxide into glucose.