If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

To log in and use all the features of Khan Academy, please enable JavaScript in your browser.

Unit 1: Chemistry of life

About this unit, structure of water and hydrogen bonding.

  • Hydrogen bonding in water (Opens a modal)
  • Hydrogen bonds in water (Opens a modal)
  • Capillary action and why we see a meniscus (Opens a modal)
  • Surface tension (Opens a modal)
  • Cohesion and adhesion of water (Opens a modal)
  • Water as a solvent (Opens a modal)
  • Specific heat, heat of vaporization, and density of water (Opens a modal)
  • Importance of water for life (Opens a modal)
  • Lesson summary: Water and life (Opens a modal)
  • Structure of water and hydrogen bonding Get 3 of 4 questions to level up!

Elements of life

  • Elements and atoms (Opens a modal)
  • Matter, elements, and atoms (Opens a modal)
  • Carbon as a building block of life (Opens a modal)
  • Carbon and hydrocarbons (Opens a modal)
  • Functional groups (Opens a modal)
  • Elemental building blocks of biological molecules (Opens a modal)
  • Elements of life Get 3 of 4 questions to level up!

Introduction to biological macromolecules

  • Ionic bonds (Opens a modal)
  • Covalent bonds (Opens a modal)
  • Chemical bonds (Opens a modal)
  • Introduction to macromolecules (Opens a modal)
  • Dehydration synthesis or a condensation reaction (Opens a modal)
  • Hydrolysis (Opens a modal)
  • Introduction to biological macromolecules Get 3 of 4 questions to level up!

Properties, structure, and function of biological macromolecules

  • Molecular structure of DNA (Opens a modal)
  • Antiparallel structure of DNA strands (Opens a modal)
  • Molecular structure of RNA (Opens a modal)
  • Introduction to amino acids (Opens a modal)
  • Overview of protein structure (Opens a modal)
  • Introduction to carbohydrates (Opens a modal)
  • Carbohydrates (Opens a modal)
  • Molecular structure of triglycerides (fats) (Opens a modal)
  • Saturated fats, unsaturated fats, and trans fats (Opens a modal)
  • Biological macromolecules review (Opens a modal)
  • Properties, structure, and function of biological macromolecules Get 3 of 4 questions to level up!

Nucleic acids

  • DNA (Opens a modal)
  • Nucleic acids (Opens a modal)
  • Nucleic acids Get 3 of 4 questions to level up!

Logo for BCcampus Open Publishing

Want to create or adapt books like this? Learn more about how Pressbooks supports open publishing practices.

Chapter 2: Introduction to the Chemistry of Life

Photo shows a variety of cheeses, fruits, and breads served on a tray.

The elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus are the key building blocks of the chemicals found in living things. They form the carbohydrates, nucleic acids, proteins, and lipids (all of which will be defined later in this chapter) that are the fundamental molecular components of all organisms. In this chapter, we will discuss these important building blocks and learn how the unique properties of the atoms of different elements affect their interactions with other atoms to form the molecules of life. These interactions determine what atoms combine and the ultimate shape of the molecules and macromolecules, that shape will determine their function.

Food provides an organism with nutrients—the matter it needs to survive. Many of these critical nutrients come in the form of biological macromolecules, or large molecules necessary for life. These macromolecules are built from different combinations of smaller organic molecules. What specific types of biological macromolecules do living things require? How are these molecules formed? What functions do they serve? In this chapter, we will explore these questions.

Search for Key Points in Chapter 2

Media attribution.

  • Figure 2.1 by Bengt Nyman © CC BY (Attribution)

Concepts of Biology - 1st Canadian Edition by Charles Molnar and Jane Gair is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

Share This Book

assignment term 2 chemistry of life

Module 2: The Chemistry of Life

The chemistry of life.

All life exists within the context of its environment. Each environment is characterized by its biological, physical, and chemical properties. Since organisms are adapted to a specific environment, radical changes in these conditions often result in injury to the individual or possibly extinction of the species. Recent reports of declining frog populations, for example, have been correlated with increased ultraviolet radiation from the sun (specifically UVB). Chemical reactions that take place inside of an organism are dependent upon both internal and external chemical and physical properties. We will explore some of these properties in today’s lab.

Part 1: pH Chemistry

Although water is generally regarded as a stable compound, individual water molecules are constantly gaining, losing, and swapping hydrogen atoms. This process is represented by the following chemical reaction:

H 2 O ↔ OH + H

Pure water with a pH of 7 has equal numbers of hydrogen and hydroxide ions at any given moment. Water is considered to be a neutral substance. The pH of any solution can be determined by calculating the total concentration of hydrogen ions in the solution.

What is a MOLE?

A mole is a term used to describe the quantity of something. If you have a mole of paperclips, that means you have paperclips. This is similar to the way we use the word “dozen.” We know that if you have a dozen paperclips, it means you have 12 of them.

1 dozen = 12

1 mole = 6.02×10 23

Scientists measure acidity using the pH scale. The pH scale ranges from 0 to 14, and the numbers represent the concentration of hydrogen ions –1  in the substance. For example, battery acid, with a pH of 1, has 1×10 moles of hydrogen ions per liter of solution. Ammonia, which is a very basic substance with a pH of 12, has 1×10 –12 moles of hydrogen ions per liter of solution. The more acidic the solution, the more hydrogen ions it contains.

Excessive changes in pH can cause metabolic and ecological problems. For example, the pH of your blood is carefully kept between 7.35 and 7.45. Any deviation above or below this range will result in alkalosis or acidosis, and both conditions can be deadly. Acid rain, on the other hand, can dissolve toxic metals from the soil particles into the soil solution and impair plant growth. As we will soon see, plant health is a factor that quickly affects most other life forms on the planet.

Screen Shot 2015-07-09 at 10.04.56 AM

  • pH paper (1–14)
  • Plastic tray with wells

Following the instructions given by your teacher, measure the pH of each solution using pH paper.  Record the pH of these items below.

  • Distilled water
  • Lemon juice

Part 2: Buffers

Buffers are molecules that resist changes in pH. They can take up and release excess hydrogen ions in a solution and therefore prevent drastic changes in pH, regardless of whether acid or base is added to the solution. The net result is that the pH of the solution remains relatively stable (until the buffer is overwhelmed). Buffers are commonly found in dissolved minerals, soils, and in living organisms.

For example, buffers can play a protective role in lake ecosystems. In a lowland lake, acid rain causes very little fluctuation in pH because these lakes are typically high in organic molecules that act as buffers. A lake with little buffering capacity, such as a high alpine lake low in organic molecules, will experience a much greater change in overall pH as a result of acid precipitation.

  • Tap water (H 2 O)
  • 2 beakers (250 mL)
  • 1g NaHCO 3 (baking soda)
  • 0.001 M HCl (hydrochloric acid)
  • Fill two beakers with 50 ml of tap water. Label one beaker “buffered” and label the other beaker “unbuffered.”
  • Add 1 gram of baking soda to the “buffered” beaker. Swirl to dissolve.
  • Using the pH strips, measure the pH of both beakers. Record all measurements in Table 1.
  • Add 10 ml of 0.001 M HCl (hydrochloric acid) to each beaker and swirl.
  • Measure the pH of the two beakers and record.
  • Repeat steps 3–5 until you have added a total of 50 ml of 0.001 M HCl to each beaker.

Record the pH of your buffered and unbuffered solutions after each addition of 10 mL of hydrochloric acid to each beaker.

Data Analysis

Illustrate the buffering capacity of each solution by graphing your results below. Place the volume of  HCl on the x-axis and the pH value on the y-axis. Don’t forget to give your graph a title.

Screen Shot 2015-07-09 at 9.23.59 AM

You can download this  graph paper template  to complete this portion.

Part 3: Buffers in the Blood

Bicarbonate ions act as a powerful buffer in your blood. They are created when carbon dioxide (CO 2 ), produced during cellular respiration, reacts with water:

CO 2  + H 2 O ↔ H 2 CO 3 ↔ HCO 3– + H+

Notice that hydrogen ions are also generated, which increases the acidity of blood and decreases the pH. In your body, the hydrogen ions are absorbed by hemoglobin molecules on your red blood cells. Meanwhile, the bicarbonate ions circulate in the blood plasma, preventing rapid pH changes. As your blood circulates past the metabolizing cells, more and more CO 2 enters your bloodstream and turns to bicarbonate ions. By the time the blood reaches the lungs, it is full of bicarbonate and hydrogen ions. The bicarbonate and hydrogen ions now combine and the reaction goes from right to left, releasing the CO 2 , which is now breathed out. In this exercise, you will bubble CO 2 into tap water and demonstrate the change in pH as carbonic acid is formed. You will use the pH indicator phenol red, which turns yellow in acidic conditions and magenta (red- purple) in basic conditions.

  • Drinking straw
  • Ehrlenmeyer flask (250 mL)
  • Obtain a small flask and a straw, and fill the flask approximately ¼ full with tap water.
  • Measure the pH of the water using the pH paper.
  • Add 6–7 drops of phenol red to the flask.
  • Do not swirl the flask (this may introduce CO 2 into the solution!), but agitate gently to mix the solution.
  • Record the initial color of the water.
  • Using a straw, blow air bubbles into the solution and observe any color changes.
  • Record the final pH of the solution.

Lab Questions

  • What happens when carbon dioxide combines with water?
  • Why did the phenol red solution turn color after you blew air bubbles into it?
  • If a person holds her breath, CO 2 builds up in the bloodstream. What effect does this have on blood pH?
  • If a person hyperventilates, too much CO 2 is removed from the bloodstream. What effect does this have on blood pH?
  • Why is “breathing into a bag” a good treatment for a hyperventilating patient?
  • Why is pH homeostasis so critical in living organisms?

Part 4: Polar and Nonpolar Compounds

Screen Shot 2015-07-09 at 9.28.03 AM

  • 2 test tubes
  • Obtain two test tubes and add 5 ml of water and 5 ml of oil into each tube. Allow the tubes to stand for one minute. Record the appearance of the tubes and label the ingredients in the tube.
  • Add ≈6 drops of beet juice extract to tube #1 and ≈6 drops of chili oil to tube #2. Allow diffusion to take place for 1–2 minutes. Record the appearance of the tubes.
  • Shake each tube gently and let stand for several minutes. Record the appearance of the tubes.
  • Next add a few drops of detergent to each tube; shake gently and observe. Record the appearance the tube.

Download this page to record the appearance of the tubes at every step .

  • What happens when lipids and water are combined? Why?
  • How do beet juice extract and chili oil differ in their chemical properties? How do you know?
  • Explain what happened when the tubes were shaken. What happened after the detergent was added? How can you explain these results?
  • How is the phospholipid bilayer that makes up a cell membrane both hydrophilic and hydrophobic?
  • What is a surfactant? How does it work?
  • Biology Labs. Authored by : Wendy Riggs. Provided by : College of the Redwoods. Located at : http://www.redwoods.edu/ . License : CC BY: Attribution

Library homepage

  • school Campus Bookshelves
  • menu_book Bookshelves
  • perm_media Learning Objects
  • login Login
  • how_to_reg Request Instructor Account
  • hub Instructor Commons
  • Download Page (PDF)
  • Download Full Book (PDF)
  • Periodic Table
  • Physics Constants
  • Scientific Calculator
  • Reference & Cite
  • Tools expand_more
  • Readability

selected template will load here

This action is not available.

Biology LibreTexts

4: Module 2- Chemistry of Life

  • Last updated
  • Save as PDF
  • Page ID 43516
  • 4.1: Why It Matters- The Chemistry of Life
  • 4.2: Introduction to Atoms and Elements
  • 4.4: The Periodic Table of Elements
  • 4.5: Electrons
  • 4.6: Introduction to Atomic Bonds
  • 4.7: Ionic Bonds
  • 4.8: Covalent Bonds
  • 4.9: Hydrogen Bonds
  • 4.10: Introduction to Functional Groups
  • 4.11: Functional Groups
  • 4.12: Introduction to The pH Scale
  • 4.13: Acids and Bases
  • 4.14: Buffers
  • 4.15: Introduction to Chemical Reactions
  • 4.16: Chemical Reactions and Molecules
  • 4.17: Anabolic and Catabolic Pathways
  • 4.18: Enzymes
  • 4.19: Introduction to Thermodynamics
  • 4.20: Open and Closed Systems
  • 4.21: The First Law of Thermodynamics
  • 4.22: The Second Law of Thermodynamics
  • 4.23: Putting It Together- Chemistry of Life
  • 4.24: Assignment- Biological Astronaut
  • 4.25: Assignment- Interacting with Attributes of Molecules

IMAGES

  1. Chapter 2 Chemistry of Life Study Guide

    assignment term 2 chemistry of life

  2. Unit 2- The Chemistry of Life Notes

    assignment term 2 chemistry of life

  3. 2 chemistry of life

    assignment term 2 chemistry of life

  4. PPT

    assignment term 2 chemistry of life

  5. Chapter 2 Chemistry of Life

    assignment term 2 chemistry of life

  6. Chapter 2 Chemistry of Life

    assignment term 2 chemistry of life

VIDEO

  1. Plus 1 chemistry focus area based class chapter 14 Environmental chemistry

  2. Investigatory Project work|CBSE|Class 12|ozone layer deplition|Preventive measures|Effects

  3. कक्षा 12वी chemistry असाइंमेंट अगस्त

  4. +1 CHEMISTRY

  5. Notes on chapter one chemistry part one

  6. Chemistry: chapter 1

COMMENTS

  1. Assignment 2: Chemistry of Life

    Assignment 2: Chemistry of Life Julianna bermudez. Define and give an example of the following terms: matter: anything that has mass and volume (occupies space), a human being is matter because it occupies space. element: the pure substance of one type of atom, carbon is an element. compound: a material composed of two or more components, water

  2. Chapter 2

    1 / 51 Flashcards Learn Test Match Q-Chat Created by HHS_Biology From Miller & Levine Biology Core Edition Inside: 2.1 - The Nature of Matter 2.2 - Properties of Water 2.3 - Carbon Compounds 2.4 - Chemical Reactions and Enzymes Students also viewed Chapter 2: Chemistry of Life 69 terms juliefields Preview

  3. Chapter 2 Chemistry of Life SmartBook Assignment LS

    anything that takes up space and has mass. As a result of interactions between electrons, atoms combine with other atoms by forming links called chemical_______. bonds. A pure chemical substance that consists of one type of atom with specific chemical properties is called a (n) element. Atoms that become electrically charged through the loss or ...

  4. Activity 2 Chemistry of Life

    BIOL 1105 Classwork. Fall 2021 Lesson 2: Chemistry of Life (10 pts) This graded assignment is subject to the Virginia Tech Honor Code. Sharing or posting any content from this assignment, or using such shared or posted assignment content to answer assignment questions, is a violation of the Virginia Tech Honor Code.

  5. Biology: Unit 2-The Chemistry of Life Flashcards

    The basic unit of all matter that consits of three subatomic particles-neutrons, protons, and electrons. Nucleus. The center of an atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities. Electron. Negatively charged particle that is located outside the ...

  6. Chemistry of life

    Unit 1 Intro to biology Unit 2 Chemistry of life Unit 3 Water, acids, and bases Unit 4 Properties of carbon Unit 5 Macromolecules Unit 6 Elements of life Unit 7 Energy and enzymes Unit 8 Structure of a cell Unit 9 More about cells Unit 10 Membranes and transport Unit 11 More about membranes Unit 12 Cellular respiration Unit 13 Photosynthesis

  7. 2.8: Assignment- Chemistry in Biology

    Just post the videos in the appropriate module in the LMS. The idea is to have students generate content that other students can learn from in this assignment. 2.8: Assignment- Chemistry in Biology is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

  8. Chemistry of life

    Familiar Attempted Not started Quiz Unit test About this unit In this unit, we'll explore the foundations of life itself, learning about macromolecules from proteins to nucleic acids. By the end, you'll have a better understanding of the chemical properties that make life possible. Structure of water and hydrogen bonding

  9. 2: Chemistry of Life

    The LibreTexts libraries are Powered by NICE CXone Expert and are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739.

  10. Chapter 2 Chemistry of Life

    Chapter 2 notes based on PowerPoint from a professor! chapter chemistry of life atoms and elements: (lesson matter: anything that has mass and occupies space

  11. 2: Chemistry of Life

    2.1: Why It Matters- The Chemistry of Life; 2.2: Atoms and Elements; 2.3: Atomic Bonds; 2.4: The pH Scale; 2.5: Putting It Together- Chemistry of Life; 2.6: Assignment- Biological Astronaut; 2: Chemistry of Life is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

  12. 2.1: The Chemistry of Life

    Obtain a small flask and a straw, and fill the flask approximately ¼ full with tap water. Measure the pH of the water using the pH paper. Add 6-7 drops of phenol red to the flask. Do not swirl the flask (this may introduce CO 2 into the solution!), but agitate gently to mix the solution.

  13. Chapter 2 Assessment The Chemistry of Life Flashcards

    24. Describe the parts of a nucleotide. The parts are a 5 carbon sugar, a phosphate group, and the base. 26. Infer Explain what the name "carbohydrate" might indicate about the chemical composition of sugars. Carbo means carbon and hydr means hydrogen which make up a carbohydrate. 27.

  14. Chapter 2 Reading Guide

    Chapter 2: The Chemistry of Life. Guided Reading Activity. Module 2 All life is made of molecules, which are made of atoms. Answer the following questions as you read the module: The scientific study of matter is Chemistry. Fill in the table regarding the states of matter by providing an example of each that is not in your book.

  15. Chapter 2: Introduction to the Chemistry of Life

    Chapter 2: Introduction to the Chemistry of Life. Figure 2.1 Foods such as bread, fruit, and cheese are rich sources of biological macromolecules. The elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus are the key building blocks of the chemicals found in living things.

  16. Assignment 2 Chemistry of Life.docx

    Assignment 2: Chemistry of Life 1. Define and give an example of the following terms: Matter: anything that takes up space and has mass Element: a substance that cannot be broken down to other substances by chemical reactions Compound: a substance consisting of two or more elements in a fixed ratio 2.

  17. 2.20 Unit Test

    Answer: Because cellulose molecules join perfectly and become hard like a cell wall, their structure and function. are related. They primarily support cells structurally, thus this is advantageous. (Score for Question 2: ___ of 3 points) 2. Explain how a change in the sequence of nucleotides in a strand of DNA might cause a protein to.

  18. The Chemistry of Life

    Part 1: pH Chemistry. Although water is generally regarded as a stable compound, individual water molecules are constantly gaining, losing, and swapping hydrogen atoms. This process is represented by the following chemical reaction: H 2 O ↔ OH + H. Pure water with a pH of 7 has equal numbers of hydrogen and hydroxide ions at any given moment.

  19. Chapter 2 Test: The Chemistry of Life Flashcards

    Chapter 2 Test: The Chemistry of Life. 4.9 (19 reviews) Get a hint. The three particles that make up an atom are. a) protons, neutrons, and isotopes. b) neutrons, isotopes and electrons. c) positive, negatives, and electrons. d) protons, neutrons, and electrons. Click the card to flip 👆.

  20. 2: Chemistry of Life

    There are four major classes of biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids), and each is an important component of the cell and performs a wide array of functions. Combined, these molecules make up the majority of a cell's mass.

  21. Assignment 2 Chemistry of Life 2 .docx

    View Assignment 2_ Chemistry of Life (2).docx from BIOL 1500 at Nova Southeastern University. Elizabeth Lopez BIO1500 Define and give an example of the following terms: matter: Anything that takes up ... Here are some more terms that you should firmly grasp. Define each term. neutron: Subatomic particle that is electrically neutral.

  22. PDF Chapter 1 The Chemistry of Life

    Chapter 1: The Chemistry of Life 9 Answer these practice questions about atoms and elements: 1. The four key elements that make up most living matter are a. Carbon, hydrogen, nitrogen, and phosphorus b. Oxygen, carbon, sulfur, and nitrogen c. Hydrogen, nitrogen, oxygen, and carbon d. Nitrogen, potassium, carbon, and oxygen 2.

  23. 4: Module 2- Chemistry of Life

    4.24: Assignment- Biological Astronaut. 4.25: Assignment- Interacting with Attributes of Molecules. 4: Module 2- Chemistry of Life is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. 3.16: Putting It Together- Introduction to Biology. 4.1: Why It Matters- The Chemistry of Life.