Fundamental Chemistry of Life
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Questions and Answers

What sugar is found in RNA?

  • Glucose
  • Deoxyribose
  • Fructose
  • Ribose (correct)

Which nitrogenous base is found in RNA but not in DNA?

  • Adenine
  • Cytosine
  • Uracil (correct)
  • Thymine

What is the primary role of enzymes in chemical reactions?

  • To increase the activation energy
  • To accelerate the reaction by lowering activation energy (correct)
  • To be consumed in the reaction
  • To act as reactants

How are nucleotides linked together in DNA and RNA?

<p>By phosphodiester bonds (D)</p> Signup and view all the answers

What characterizes passive transport mechanisms?

<p>Movement without the use of chemical energy (C)</p> Signup and view all the answers

Which of the following pairs correctly indicates the number of hydrogen bonds between DNA base pairs?

<p>A-T (2), C-G (3) (A)</p> Signup and view all the answers

What structural feature of DNA is necessary for its replication?

<p>Antiparallel orientation of strands (B)</p> Signup and view all the answers

Which factor does NOT influence the rate of diffusion?

<p>Color of the molecules (D)</p> Signup and view all the answers

Which of the following best describes activation energy?

<p>Energy required to break initial bonds in reactants (C)</p> Signup and view all the answers

Which of the following statements about the sodium-potassium pump is true?

<p>It requires ATP for energy (B)</p> Signup and view all the answers

What is dynamic equilibrium in the context of diffusion?

<p>A balanced condition with continuous molecular movement (A)</p> Signup and view all the answers

What could be a result of mutations in nucleic acids?

<p>Changes in protein structure and function (B)</p> Signup and view all the answers

How does temperature affect diffusion?

<p>Higher temperatures increase molecular movement and enhance diffusion (A)</p> Signup and view all the answers

Which type of molecules diffuse more easily across membranes?

<p>Smaller and non-polar molecules (D)</p> Signup and view all the answers

What role do transport proteins play in passive transport?

<p>They facilitate the diffusion of larger or polar molecules (D)</p> Signup and view all the answers

What distinguishes active transport from passive transport?

<p>Active transport moves substances against their concentration gradient (C)</p> Signup and view all the answers

What plays a critical role in determining the specificity of immune responses?

<p>The diversity of membrane proteins (B)</p> Signup and view all the answers

Which type of transport mechanism does not require energy?

<p>Facilitated diffusion (B)</p> Signup and view all the answers

What is the primary effect of enzymes on activation energy during chemical reactions?

<p>Enzymes lower the activation energy barrier. (D)</p> Signup and view all the answers

What is a primary example of active transport?

<p>Sodium-potassium pump (B)</p> Signup and view all the answers

How does the interaction between membrane proteins and pathogens affect the immune system?

<p>It triggers signaling cascades for immune cell activation. (D)</p> Signup and view all the answers

Which mechanism is NOT one of the ways enzymes lower activation energy?

<p>Increasing temperature drastically (B)</p> Signup and view all the answers

What is the significance of passive transport in cellular function?

<p>It enables nutrient intake and waste expulsion without energy consumption. (C)</p> Signup and view all the answers

What does the induced-fit model explain about enzyme-substrate interactions?

<p>Enzymes can change shape to better fit the substrate. (D)</p> Signup and view all the answers

How do enzymes affect the overall change in free energy (ΔG) of a reaction?

<p>Enzymes have no effect on the ΔG of the reaction. (D)</p> Signup and view all the answers

Why is selective permeability of the plasma membrane important for cells?

<p>It maintains homeostasis by controlling what enters and exits the cell. (C)</p> Signup and view all the answers

What role does thermal energy play in biological systems concerning enzyme activity?

<p>It can serve as activation energy but too much can cause denaturation. (C)</p> Signup and view all the answers

What consequence can uncontrolled transport across cell membranes lead to?

<p>Cellular dysfunction or disease (D)</p> Signup and view all the answers

What characterizes a polar covalent bond?

<p>Atoms with differing electronegativities share electrons unequally. (C)</p> Signup and view all the answers

How has the discovery of transport mechanisms advanced our understanding of cellular physiology?

<p>It has improved knowledge of how cells maintain homeostasis and respond to changes. (C)</p> Signup and view all the answers

What is a potential consequence of excessive heat on enzymes in biological systems?

<p>Denaturation of the enzymes leading to loss of function. (B)</p> Signup and view all the answers

Which electronegativity difference typically indicates the formation of ionic bonds?

<p>Exceeds 1.7 (D)</p> Signup and view all the answers

Which statement best describes Maud Menten's contribution to enzymology?

<p>She developed equations to measure enzyme reaction rates. (A)</p> Signup and view all the answers

Why are polar molecules significant in biological systems?

<p>They attract other polar molecules, which is crucial for biological reactions. (A)</p> Signup and view all the answers

Which process highlights the importance of enzymes in accelerating chemical reactions?

<p>Maintaining energy balance without changing free energy. (D)</p> Signup and view all the answers

What is the main function of hydrolysis reactions in biological processes?

<p>To break down larger molecules into smaller subunits. (D)</p> Signup and view all the answers

What is a characteristic of dehydration reactions?

<p>They result in the formation of larger molecules. (C)</p> Signup and view all the answers

How do non-polar molecules interact with polar solvents?

<p>They tend to be excluded by polar solvents. (C)</p> Signup and view all the answers

What is the role of water as a polar molecule in biological systems?

<p>To regulate temperature and transport nutrients. (A)</p> Signup and view all the answers

Which of the following is an example of a dehydration reaction?

<p>The formation of methyl acetate from methanol and acetic acid. (C)</p> Signup and view all the answers

What role does the sodium-potassium pump play in maintaining cellular homeostasis?

<p>It maintains high sodium concentration outside the cell and high potassium concentration inside. (D)</p> Signup and view all the answers

How are electrochemical gradients relevant to action potential generation in neurons?

<p>They help in the rapid change of membrane potential during signaling processes. (D)</p> Signup and view all the answers

What is exocytosis primarily responsible for?

<p>Exporting secretory proteins and waste products from the cell. (C)</p> Signup and view all the answers

Which condition exemplifies the clinical significance of electrochemical gradients?

<p>Cystic fibrosis and cardiac arrhythmias. (B)</p> Signup and view all the answers

What cellular process does endocytosis primarily facilitate?

<p>Importing proteins and larger aggregates into the cell. (C)</p> Signup and view all the answers

What implications does understanding exocytosis have in modern science?

<p>It informs drug delivery systems and vaccine development. (B)</p> Signup and view all the answers

What is a primary function of an electrochemical gradient in cellular processes?

<p>Storing potential energy for various cellular functions. (B)</p> Signup and view all the answers

Which of the following accurately describes the process of exocytosis?

<p>Secretory vesicles fuse with the plasma membrane to release contents outside. (C)</p> Signup and view all the answers

Flashcards

Polar Covalent Bond

A type of bond formed when atoms with differing electronegativities share electrons unequally, resulting in partial charges within the molecule.

Ionic Bond

A type of bond formed when atoms completely transfer electrons due to a large electronegativity difference, resulting in ions with opposite charges.

Non-polar Covalent Bond

A type of bond formed when atoms with similar electronegativities share electrons equally, resulting in no partial charges.

Polar Molecules

Molecules with uneven distribution of charge, possessing partial positive and negative poles.

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Hydrolysis

The process of breaking down large molecules into smaller subunits using water.

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Dehydration Reaction

The process of joining subunits together to form larger molecules, releasing water in the process.

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Redox Reaction

A type of chemical reaction involving the transfer of electrons between reactants.

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Neutralization Reaction

A reaction that involves the combination of an acid and a base, resulting in the formation of salt and water.

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Cell Membrane Permeability

The selective permeability of the cell membrane allows cells to control the movement of substances in and out, maintaining a stable internal environment.

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Passive Transport

Passive transport relies on the natural movement of substances from areas of high concentration to low concentration, without requiring energy. Examples include simple diffusion and facilitated diffusion.

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Active Transport

Active transport utilizes energy, usually from ATP, to move substances against their concentration gradients. This is essential for maintaining specific concentrations of ions and molecules inside the cell.

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Sodium-Potassium Pump

The sodium-potassium pump is a prime example of active transport that uses energy to move sodium ions out of the cell and potassium ions into the cell. This is vital for maintaining membrane potential and regulating cellular processes.

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Membrane Protein Role in Immunity

The diversity of membrane proteins enables specific recognition of pathogens, triggering immune responses. The interaction between these proteins and invaders activates immune cells to fight off infections.

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Importance of Membrane Transport

Membrane transport is crucial for cell survival. It allows cells to take in nutrients, remove waste products, and communicate with their environment. Dysregulation of transport can lead to cellular dysfunction and diseases.

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Significance of Transport Mechanisms

The study of membrane transport mechanisms is essential for understanding basic cellular processes and developing treatments for various diseases. It has revolutionized our understanding of how cells function and interact with their environment.

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What is the structure of DNA?

DNA consists of a double helix structure made up of deoxyribose sugar, phosphate groups, and four nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

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What is the structure of RNA?

RNA is typically single-stranded and contains ribose sugar, phosphate groups, and nitrogenous bases adenine (A), guanine (G), cytosine (C), and uracil (U).

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What are nucleotides?

Nucleotides are the building blocks of nucleic acids and are composed of a sugar, a nitrogenous base, and one to three phosphate groups.

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How are nucleotides linked in DNA and RNA?

DNA and RNA are formed by linking nucleotides together through phosphodiester bonds, which connect the 5' carbon of one sugar to the 3' carbon of the next.

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What holds the DNA strands together?

The double helix structure of DNA is stabilized by hydrogen bonds between complementary base pairs. Adenine (A) forms two hydrogen bonds with thymine (T), and guanine (G) forms three hydrogen bonds with cytosine (C).

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What is the orientation of DNA strands?

The two strands of DNA run in opposite directions, one from 5' to 3' and the other from 3' to 5'. This antiparallel orientation is essential for DNA replication and other functions.

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What is the function of nucleic acids?

Nucleic acids play a crucial role in storing and expressing genetic information. They guide protein synthesis through transcription and translation processes.

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What are enzymes?

Enzymes are biological catalysts that accelerate chemical reactions by lowering the activation energy required for the reaction to proceed.

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Activation Energy

The minimum amount of energy required for a chemical reaction to occur. Think of it as the 'energy hill' that reactants need to climb to become products.

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Enzymes and Activation Energy

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required. They don't change the overall energy of the reaction, just the pathway.

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Enzyme Mechanism: Proximity Effect

Enzymes bring substrates together, creating a favorable environment for them to interact. This increases the likelihood of successful collisions needed for the reaction to proceed.

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Enzyme Mechanism: Charge Environment

Enzymes can affect the charge distribution around the active site, promoting catalysis by attracting or repelling substrate components. This can stress bonds in the substrate, making them easier to break.

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Induced-Fit Model

Enzymes can change shape when they bind to a substrate, creating a snug fit that weakens chemical bonds and lowers the activation energy needed to break them.

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Enzymes and Reaction Rates

The rate of a reaction is directly proportional to the number of reactant molecules that can overcome the activation energy barrier. Enzymes increase the rate by lowering this hurdle.

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Thermal Energy and Enzyme Function

Thermal energy, usually from the environment, provides the activation energy for reactions within the body. However, excessive heat can denature enzymes, disrupting their function.

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Maud Menten and Enzyme Kinetics

Maud Menten was a pioneering scientist who developed mathematical equations to measure the rate of enzyme reactions. These are crucial for understanding how enzymes work.

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Diffusion

Net movement of molecules from an area of higher concentration to an area of lower concentration, seeking a balanced distribution.

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Dynamic Equilibrium

The state where continuous movement of molecules results in balanced conditions within the cell, with no net movement of molecules.

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Primary active transport

The movement of substances across a membrane using energy derived directly from ATP hydrolysis.

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Concentration Gradient and Diffusion Rate

A larger concentration gradient results in a faster rate of diffusion.

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Size and Charge of Molecules

Smaller and non-polar molecules diffuse more easily across membranes than larger or charged molecules.

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Selective Permeability

The ability of a membrane to allow some molecules to pass through while blocking others, crucial for cellular function.

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Electrochemical Gradient

The difference in charged particles (ions) and electrical potential across a cell membrane.

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Exocytosis

The process of releasing materials from a cell using membrane-bound vesicles.

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Endocytosis

The process of taking materials into a cell by engulfing them in membrane-bound vesicles.

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Vesicle Fusion

The fusion of secretory vesicles with the plasma membrane, releasing their contents outside the cell.

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Phagocytosis

The process of cells engulfing large particles or bacteria into membrane-bound vesicles.

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Pinocytosis

The process of cells taking in fluids and dissolved solutes into membrane-bound vesicles.

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Study Notes

Fundamental Chemistry of Life and Biological Molecules

  • Matter is anything that occupies space and has mass, including living organisms.
  • Elements are pure substances that cannot be broken down into simpler substances; atoms are the fundamental units of elements.
  • Atoms bond in specific ratios to form molecules and compounds, essential for biological function.
  • Four elements (carbon, hydrogen, oxygen, and nitrogen) account for 96% of living organism mass.
  • Essential elements like calcium, phosphorus, potassium, sulfur, sodium, chlorine, and magnesium are crucial for biological functions.

Organic Compounds in Living Organisms

  • Organic compounds primarily consist of carbon, hydrogen, oxygen, and sometimes nitrogen.
  • These four elements are crucial for life.
  • Organic molecules are essential for various biological functions.

Polar & Nonpolar Molecules

  • Electronegativity is an atom's tendency to attract electrons, influenced by atomic number and distance from the nucleus.
  • Polar covalent bonds form when atoms with differing electronegativities share electrons unequally.
  • Ionic bonds form when the electronegativity difference exceeds 1.7, leading to complete electron transfer.
  • Nonpolar covalent bonds form when the electronegativity difference is less than 0.4, indicating equal sharing.
  • Polar molecules attract other polar molecules, increasing solubility in polar solvents like water.

Chemical Reactions in Biological Processes

  • Dehydration reactions involve removing water to join subunits, forming larger molecules (essential for macromolecule synthesis).
  • Hydrolysis reactions use water to break down larger molecules into smaller subunits (crucial for digestion and metabolism).
  • Neutralization reactions involve reacting an acid and a base to produce salt and water.

Major Classes of Biological Molecules

  • Living organisms primarily use complex molecules containing carbon, hydrogen, and other elements, rather than simple hydrocarbons.
  • Major classes include carbohydrates (energy and structure), lipids (energy storage and membrane formation), proteins (various functions), and nucleic acids (genetic information storage).

Functional Groups in Organic Chemistry

  • Functional groups are small reactive groups of atoms that significantly impact molecule properties and reactivity.
  • Examples include hydroxyl (-OH), carboxyl (-COOH), and amino (-NH2) groups.

Reactions Involving Functional Groups

  • Dehydration and hydrolysis reactions are fundamental processes in macromolecule synthesis and breakdown.
  • These reactions are important examples of how functional groups influence chemical reactions within organisms. Using Ethanol and Ethane as examples.

Proteins and Nucleic Acids

  • Proteins are large molecules composed of amino acid subunits linked by peptide bonds, forming specific 3D shapes for their function.
  • Nucleic acids (DNA and RNA) store and transmit genetic information, with DNA primarily responsible for long-term storage and RNA playing a role in protein synthesis.
  • DNA structure is a double helix with nitrogenous bases (A-T, C-G) paired via hydrogen bonds
  • RNA structure is typically single-stranded with bases A-U,C-G.

Cell Structures and Organelles Overview

  • Organelles are specialized internal structures in cells with distinct functions.
  • The plasma membrane maintains homeostasis by regulating substance entry and exit.
  • The nucleus houses most of the cell's DNA.

The Nucleus, Nucleolus, Ribosomes, and Endomembrane System

  • The nucleus is enclosed by a double membrane, facilitating transport.
  • The nucleolus is responsible for rRNA synthesis and ribosomal subunit assembly.
  • Ribosomes are responsible for protein synthesis within the cell.
  • The endomembrane system, including the ER, vesicles, Golgi apparatus, and plasma membrane, is involved in protein and lipid synthesis, transport, modification, and packaging.

Mitochondria and Energy Production

  • Mitochondria are the 'powerhouses' of cells, producing ATP through aerobic respiration, crucial for energy metabolism.
  • The inner membrane is highly folded into cristae, increasing surface area for ATP production and electron transport.

The Cytoskeleton and Cell Surface Structures

  • The cytoskeleton provides structural support and facilitates cell movement, division, and intracellular transport.
  • The cell wall (in plants) provides structural support and rigidity.
  • The extracellular matrix (ECM) supports and anchors cells, contributing to tissue formation.

Membrane Structure and Function

  • The plasma membrane is a selectively permeable barrier, regulating substance entry and exit.
  • The fluid mosaic model describes the plasma membrane as a dynamic structure composed of a phospholipid bilayer.

Cell Recognition and Immune Response

  • Membrane proteins are crucial for cell recognition and the immune system's response to pathogens.
  • Antigens (e.g., major histocompatibility complex) contribute to immune recognition.

Transport Mechanisms

  • Passive transport does not require energy, including simple and facilitated diffusion.
  • Active transport requires energy and moves substances against their concentration gradient. The sodium-potassium pump illustrates active transport.
  • Bulk transport, including exocytosis and endocytosis (pinocytosis, receptor-mediated, phagocytosis), handles large molecules or particles.

Enzymes and Activation Energy

  • Enzymes are biological catalysts, lowering the activation energy needed for chemical reactions.
  • Enzymes accelerate reactions, increasing reaction rates without altering the change in overall free energy (ΔG).

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