Chapter 3
Chemistry of Life
Courtesy of Eskom
Everything is made of atoms. Atoms are the smallest part of an element. Atoms have a nucleus of protons and neutrons. Protons have a positive charge, and neutrons have no charge. Outside the nucleus are electrons. Electrons have a negative charge.
Something that is made of only one kind of atom is an element. Elements cannot be broken down into simpler forms through ordinary chemical reactions. They are arranged in a table called the periodic table of elements and are given a one or two letter symbol. For example, the element oxygen's symbol is O.
Compounds are made of two or more elements in exact proportions. For example, water always has one oxygen atom for every two hydrogen atoms. Compounds have different properties from the elements they are made of. There are two types of compounds, molecular and ionic.
The smallest part of a molecular compound is a molecule. A molecule is a group of atoms held together by the energy of chemical bonds. Molecular compounds are formed when atoms share their outermost electrons. For example, two atoms of hydrogen and one atom of oxygen share one electron to form a water molecule. Oxygen and hydrogen are usually gases, but when they come together and share their outermost electrons, they create water. Water can be a solid, liquid, or gas.
Atoms can combine because they are positively or negatively charged. Atoms are usually neutral and have the same number of protons and electrons. When an atom loses an electron, it becomes positively charged. When an atom gains and electron, it becomes negatively charged. Electrically charged atoms, positive or negative, are ions.
Oppositely charged ions attract each other. When they bond together, they form an electrically neutral compound called an ionic compound. Ionic compounds have completely different properties from the ions they are made from. In the ionic compound NaCl, the sodium and chlorine are very hazardous by themselves. When they are bonded together, though, they make table salt! Ions are very important in life processes. Messages are sent on your nerves with ions. Ions are used to cause your muscles to contract. They are also involved in transporting oxygen.
A mixture is a combination of substances in which individual substances retain their own properties. Mixtures can be solids, liquids, or gases. There are two types of mixtures, solutions and suspensions. Most chemical reactions in living organisms take place in solutions. A solution contains two or more substances that are mixed evenly. A suspension forms when a liquid or gas has another substance spread evenly throughout it. Suspensions are different from solutions because the substances will eventually sink to the bottom.
Living things are made up of two types of compounds, organic and inorgainc. Organic compounds must contain carbon and hydrogen and are always associated with living things. There are four organic compounds that have different jobs in living things. They are carbohydrates, lipids, proteins, and nucleic acids. Inorganic compounds don't contain both carbon and hydrogen and don't have to be associated with living things. The most important inorganic compound is water.
Living things are made up of over fifty percent water. All chemical reactions of living things take place in water solutions. Water also is used to transport substances through the bodies of living things.
Something that is made of only one kind of atom is an element. Elements cannot be broken down into simpler forms through ordinary chemical reactions. They are arranged in a table called the periodic table of elements and are given a one or two letter symbol. For example, the element oxygen's symbol is O.
Compounds are made of two or more elements in exact proportions. For example, water always has one oxygen atom for every two hydrogen atoms. Compounds have different properties from the elements they are made of. There are two types of compounds, molecular and ionic.
The smallest part of a molecular compound is a molecule. A molecule is a group of atoms held together by the energy of chemical bonds. Molecular compounds are formed when atoms share their outermost electrons. For example, two atoms of hydrogen and one atom of oxygen share one electron to form a water molecule. Oxygen and hydrogen are usually gases, but when they come together and share their outermost electrons, they create water. Water can be a solid, liquid, or gas.
Atoms can combine because they are positively or negatively charged. Atoms are usually neutral and have the same number of protons and electrons. When an atom loses an electron, it becomes positively charged. When an atom gains and electron, it becomes negatively charged. Electrically charged atoms, positive or negative, are ions.
Oppositely charged ions attract each other. When they bond together, they form an electrically neutral compound called an ionic compound. Ionic compounds have completely different properties from the ions they are made from. In the ionic compound NaCl, the sodium and chlorine are very hazardous by themselves. When they are bonded together, though, they make table salt! Ions are very important in life processes. Messages are sent on your nerves with ions. Ions are used to cause your muscles to contract. They are also involved in transporting oxygen.
A mixture is a combination of substances in which individual substances retain their own properties. Mixtures can be solids, liquids, or gases. There are two types of mixtures, solutions and suspensions. Most chemical reactions in living organisms take place in solutions. A solution contains two or more substances that are mixed evenly. A suspension forms when a liquid or gas has another substance spread evenly throughout it. Suspensions are different from solutions because the substances will eventually sink to the bottom.
Living things are made up of two types of compounds, organic and inorgainc. Organic compounds must contain carbon and hydrogen and are always associated with living things. There are four organic compounds that have different jobs in living things. They are carbohydrates, lipids, proteins, and nucleic acids. Inorganic compounds don't contain both carbon and hydrogen and don't have to be associated with living things. The most important inorganic compound is water.
Living things are made up of over fifty percent water. All chemical reactions of living things take place in water solutions. Water also is used to transport substances through the bodies of living things.
Moving Cellular Materials
Substances can move through a cell membrane in a few different ways. One of them is called passive transport. A passive transport is the movement of substances through a cell membrane without the input of energy. The three types of passive transports are diffusion, osmosis, and facilitated diffusion.
Diffusion is the movement of molecules from an area of greater concentration to an area of lesser concentration without the input of energy. Diffusion moves small molecules. The movement of molecules stops when an equilibrium is reached. This means the number of molecules in the two areas is relatively equal.
Osmosis is the diffusion of water through a cell membrane. All of the steps are the same in osmosis and diffusion except that osmosis moves water molecules instead of small molecules.
Facilitated diffusion moves substances from an area of greater concentration to an area of lesser concentration without the input of energy and with the help of transport proteins. The transport proteins are needed to transport large molecules like glucose molecules.
Another way substances can travel through a cell membrane is called active transport. Active transport is the movement of molecules from an area of lesser concentration to an area of greater concentration with the input of energy and with the help of transport proteins. Active transport moves substances against the normal flow. This is why energy and transport proteins are needed in the process. The two types of active transport are endocytosis and exocytosis.
Endocytosis and exocytosis are active transports that transport molecules too large to be transported through active transports. Endocytosis is the process of moving substances into a cell by surrounding it with the cell membrane. Exocytosis is the process in which a vesicle's membrane fuses with the cell's membrane, releasing the vesicle's contents outside the cell. Endocytosis brings substsnces into a cell while exoctosis takes substances out of a cell.
Diffusion is the movement of molecules from an area of greater concentration to an area of lesser concentration without the input of energy. Diffusion moves small molecules. The movement of molecules stops when an equilibrium is reached. This means the number of molecules in the two areas is relatively equal.
Osmosis is the diffusion of water through a cell membrane. All of the steps are the same in osmosis and diffusion except that osmosis moves water molecules instead of small molecules.
Facilitated diffusion moves substances from an area of greater concentration to an area of lesser concentration without the input of energy and with the help of transport proteins. The transport proteins are needed to transport large molecules like glucose molecules.
Another way substances can travel through a cell membrane is called active transport. Active transport is the movement of molecules from an area of lesser concentration to an area of greater concentration with the input of energy and with the help of transport proteins. Active transport moves substances against the normal flow. This is why energy and transport proteins are needed in the process. The two types of active transport are endocytosis and exocytosis.
Endocytosis and exocytosis are active transports that transport molecules too large to be transported through active transports. Endocytosis is the process of moving substances into a cell by surrounding it with the cell membrane. Exocytosis is the process in which a vesicle's membrane fuses with the cell's membrane, releasing the vesicle's contents outside the cell. Endocytosis brings substsnces into a cell while exoctosis takes substances out of a cell.
Courtesy of William's Class
Energy for Life
Courtesy of Water.me.vccs.edu
There are three main processes for trapping and storing energy. They are photosynthesis, respiration, and fermentation.
Photosynthesis is a process used by producers (organisms that make their own food). Before photosynthesis, chlorophyll in the producers captures light energy to be used in photosynthesis. The producers start with carbon dioxide, water, and light energy. Chemical reactions occur, and the producers now have glucose and oxygen. The glucose is sugar which can be used as food. The purpose of photosynthesis is to take light energy and turn it into food.
Respiration is used by producers and consumers (organisms that don't make their own food). During respiration, producers and consumers start with glucose and oxygen. Chemical reactions occur, and the organisms now have carbon dioxide, water, and energy. Respiration starts in the cytoplasm. The carbohydrates are broken down into glucose molecules. The glucose molecules break down into two smaller molecules. Energy is released when the glucose molecules are broken down. The smaller molecules are broken down again but in the mitochondria, releasing even more energy. Whenever you need energy, respiration takes place to make it for you. The purpose of respiration is to take food and make chemical energy.
Fermentation is used by oxygen lacking cells that are not able to carry out respiration. the process of fermentation also starts in the cytoplasm like respiration. Glucose molecules are broken down into smaller molecules, but these molecules don't go to the mitochondria. Chemical reactions take place in the cytoplasm. Some energy is released along with wastes. Different wastes are released based on the type of cell. Possible wastes are lactic acid or carbon dioxide and alcohol.
Photosynthesis is a process used by producers (organisms that make their own food). Before photosynthesis, chlorophyll in the producers captures light energy to be used in photosynthesis. The producers start with carbon dioxide, water, and light energy. Chemical reactions occur, and the producers now have glucose and oxygen. The glucose is sugar which can be used as food. The purpose of photosynthesis is to take light energy and turn it into food.
Respiration is used by producers and consumers (organisms that don't make their own food). During respiration, producers and consumers start with glucose and oxygen. Chemical reactions occur, and the organisms now have carbon dioxide, water, and energy. Respiration starts in the cytoplasm. The carbohydrates are broken down into glucose molecules. The glucose molecules break down into two smaller molecules. Energy is released when the glucose molecules are broken down. The smaller molecules are broken down again but in the mitochondria, releasing even more energy. Whenever you need energy, respiration takes place to make it for you. The purpose of respiration is to take food and make chemical energy.
Fermentation is used by oxygen lacking cells that are not able to carry out respiration. the process of fermentation also starts in the cytoplasm like respiration. Glucose molecules are broken down into smaller molecules, but these molecules don't go to the mitochondria. Chemical reactions take place in the cytoplasm. Some energy is released along with wastes. Different wastes are released based on the type of cell. Possible wastes are lactic acid or carbon dioxide and alcohol.
