Chemistry Foundations
What is an atom?
The smallest unit of an element.
What are the six classes of nutrients?
Carbohydrates, lipids, proteins, vitamins, minerals, and water.
Every cell in your body is made of atoms. What must happen to atoms for them to become part of the larger molecules found in cells?
Atoms chemically bond together to form molecules.
Name the four major classes of organic compounds found in cells.
Carbohydrates, lipids, proteins, and nucleic acids.
Ribosomes build which major class of organic compounds?
Proteins
Write the chemical names of the elements C, N, O, P, S, and H
Carbon, Nitrogen, Oxygen, Phosphorus, Sulfur, Hydrogen
Which class of nutrients builds and repairs body structures?
Proteins.
A cell needs energy to carry out its functions. Explain how the food you eat can provide that energy at the cellular level.
Food contains nutrients, including carbohydrates. Cells break down molecules such as glucose and release usable energy through chemical reactions.
A cell needs a molecule that stores genetic information. Which major class of organic compounds does DNA belong to?
Nucleic acids.
A cell makes proteins on ribosomes attached to the rough ER. Which organelle modifies, sorts, and packages many of these proteins before they are sent to their destinations?
The Golgi apparatus (Golgi body).
Two scientists each take tiny samples from different parts of the same material. What would they need to find out about those samples to determine whether the material is a substance or a mixture?
They would need to determine whether the samples have the same, definite chemical composition. A substance has a definite, uniform chemical composition; a mixture can contain different proportions of its component substances.
Which two classes of nutrients are associated with energy, one providing a primary energy source and the other storing energy?
Carbohydrates provide a primary energy source; lipids store energy.
A cell is making a protein. Which smaller molecules does it need to build that protein, and which of the four major classes of organic compounds will the finished molecule belong to?
Amino acids; proteins.
Starch and glucose are both carbohydrates. What is one important difference between them?
Glucose is a simple sugar, while starch is a complex carbohydrate made of many sugar units linked together.
A cell needs to produce a large amount of ATP, the molecule it uses to transfer usable energy. Which organelle carries out most of the cell's ATP production through cellular respiration, using energy released from food molecules?
The mitochondria.
A compound contains 2 carbon atoms, 6 hydrogen atoms, and 1 oxygen atom per molecule. Write its chemical formula. How many different elements does it contain, and how many atoms are in one molecule?
C₂H₆O. It contains 3 different elements and 9 atoms per molecule.
A student argues that vitamins and minerals must be the same nutrient class because neither is a major source of energy. Why is this reasoning insufficient?
Nutrients are not classified only by whether they provide energy. Vitamins and minerals are distinct nutrient classes with different roles in the body. Vitamins are organic compounds needed in small amounts; minerals are inorganic substances needed for essential functions.
A cell's membrane is damaged. Which major class of organic compounds is especially important for rebuilding the membrane?
Lipids.
A cell uses a molecule to speed up a chemical reaction without using the molecule up in the process. What is this molecule called, and which major class of organic compounds does it usually belong to?
An enzyme; most enzymes are proteins.
Lysosomes contain enzymes that break down worn-out cell parts and large molecules into smaller components that the cell can reuse. What major class of organic compounds do the enzymes belong to, and does this process contribute to homeostasis, metabolism, or both? Be prepared to explain how when I call on you (don't have to write this part)
Enzymes are proteins. Metabolism includes all the chemical reactions that occur in a cell; breaking down and recycling materials is part of metabolism. This process helps maintain homeostasis by removing damaged materials and keeping the cell functioning properly.
Oxygen gas has the formula O₂. Explain why it is a molecule but not a compound.
It contains two chemically bonded oxygen atoms, making it a molecule. However, it contains only one type of atom, so it is not a compound.
A person eats plenty of carbohydrates, lipids, and proteins but consumes too little water. Why is it still inaccurate to say that the person is getting everything the body needs?
Water is an essential nutrient needed for life. It helps with chemical reactions, transporting substances, and regulating body temperature. Getting the other nutrient classes does not eliminate the need for water.
A cell contains DNA, proteins, lipids, and carbohydrates. These molecules are made of atoms, but the molecules have different structures and functions. Explain how the same basic building blocks of matter can give rise to such different roles inside a cell.
Atoms of different elements can bond in different combinations and arrangements, forming different molecules. Those molecules have different structures and chemical properties, allowing them to perform different functions in cells.
Four samples contain different biological molecules. Sample A is made of amino acids linked together. Sample B consists of many sugar units linked together. Sample C is a fat-like molecule important in cell membranes. Sample D carries genetic information. Identify the major class of organic compound in each sample.
Proteins. B: Carbohydrates. C: Lipids. D: Nucleic acids.
A student claims that DNA makes proteins because DNA contains the instructions for building them. Correct the student's explanation. Include the organelle that stores DNA and the organelle that actually assembles proteins.
DNA is a nucleic acid that stores genetic instructions in the nucleus. Those instructions are copied into messenger RNA, which carries them to ribosomes. Ribosomes assemble amino acids into proteins.