Cell Processes Life Science- Chapter 3 Review Mrs. Nell Life Science- Chapter 3 Review Mrs. Nell

Matter is anything that has mass and takes up space. Matter is made up of small units called atoms. At the center of an atom is the nucleus, which contains protons and neutrons. Protons have a positive charge. Neutrons are neutral- they have no charge. Electrons are smaller and orbit the nucleus. They are negatively charged. Atoms

Elements When something is made up of only one kind of atom, it is called an element. An element can’t be broken down into simpler form. If a substance is an element, then it is on the Periodic Table of Elements. The Periodic Table of Elements

How Atoms Combine Atoms of elements combine chemically to form new substances called compounds. When elements form a compound the properties of the individual elements change. One way atoms combine is by sharing electrons. The combined atoms form a molecule. Atoms of elements combine chemically to form new substances called compounds. When elements form a compound the properties of the individual elements change. One way atoms combine is by sharing electrons. The combined atoms form a molecule. Sodium metal + chlorine gas = table salt

Ions Atoms can also combine because they’ve become positively or negatively charged. When an atom loses electrons it becomes positively charged. If it gains electrons it is negatively charged. Electrically charged atoms are called ions. Ions are attracted to each other when they have opposite charges. Sodium has one electron to donate to become stable. Chlorine will accept one electron to become stable.

Mixtures Sometimes two substances can be mixed together without combining chemically. A mixture is a combination of substances in which individual substances retain their own properties. Sometimes two substances can be mixed together without combining chemically. A mixture is a combination of substances in which individual substances retain their own properties.

Solutions A solution is a mixture in which one or more substances mix evenly with other substances. Salt mixed with water forms a salt solution.

Suspension A suspension is a mixture in which substances are evenly spread through a liquid or gas. Unlike solutions, the particles in a suspension settle out over time. Blood is an example of a suspension. Many medicines need to be shaken as they will settle upon standing.

Organic Compounds Most compounds containing carbon are organic compounds. The organic compounds that make up life are carbohydrates, lipids, proteins, and nucleic acids. Most compounds containing carbon are organic compounds. The organic compounds that make up life are carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates Carbohydrates are organic compounds that are located in cell membranes and supply energy to power cell processes. Sugars, starch, and cellulose are examples of carbohydrates. Cellulose is a long chain of linked sugar molecules that gives wood its remarkable strength. It is the main component of plant cell walls, and the basic building block for many textiles and for paper. Cotton is the purest natural form of cellulose.

Lipids Lipids (fats, oils, and waxes) are organic compounds that store and release even larger amounts of energy than carbohydrates. Cell membranes are made up of two layers of lipids. Lipids are found primarily in meats and dairy foods, but most foods contain some fat. Nuts and seeds, soybeans, olives, peanuts, and avocados contain the needed or essential fatty acids. Fats are an important component of our diet, and at least a minimum intake is essential. However, many problems are associated with excessive intake of dietary fat, including obesity, cardiovascular disease, and some forms of cancer.

Proteins Proteins are the building blocks of many structural components of organisms. They are scattered throughout cell membranes and are made up of smaller molecules called amino acids. Certain proteins called enzymes speed up chemical reactions in cells. Many foods contain protein, but the best sources are beef, poultry, fish, eggs, dairy products, nuts, seeds, and legumes like black beans. Protein builds up, maintains, and replaces the tissues in your body.

Nucleic Acids Nucleic acids are large organic molecules that store important information in cells in the form of a code. DNA is found in the nucleus in chromosomes, in mitochondria, and in chloroplasts. It carries information that directs each cell’s activities. RNA carries information for making proteins and enzymes in cytoplasm where these substances are built.

Inorganic Compounds Inorganic compounds are made from elements other than carbon. Water is an example of an inorganic compound.

Cell Membrane Cell membranes allow some materials to pass through while keeping others out. The membrane is selectively permeable.

Diffusion Movement of molecules from an area where there are many to an area where there are few is called diffusion. When the molecules of a substance are spread evenly throughout a space, a state of equilibrium occurs. Water and lipids pass through the cell membrane by diffusion.

Osmosis Osmosis is the diffusion of water through a cell membrane. In plants, wilting occurs when more water leaves the cells than enters them. Animation of water molecules moving across a selectively permeable membrane.

Passive Transport The movement of particles across the cell membrane by diffusion is called passive transport because the cell uses no energy to move the materials.

Facilitated Diffusion Some substances, like glucose molecules, are large and can only enter the cell with the help of transport protein molecules. This is known as facilitated diffusion.

Active Transport In active transport substances are moved from where there are small amounts to where there are large amounts. This requires energy and the aid of transport protein molecules.

Endocytosis Some substances are too large to pass through the cell membrane by passive or active transport. These items are enclosed in a part of the cell membrane. A vacuole, with its contents, goes into the cytoplasm in a process called endocytosis.

Exocytosis Wastes in vacuoles or proteins packaged by Golgi bodies exit by fusing to the cell membrane and releasing from the cell in a process called exocytosis.

Energy in Cells Cells take chemical energy stored in food and change it into energy that can be used in metabolism. Metabolism is the total of all chemical activities of an organism that enable it to stay alive, grow, and reproduce.

Photosynthesis Producers change light energy into chemical energy in a process called photosynthesis. Producers use chlorophyll in chloroplasts to capture light energy.

Consumers Consumers eat producers or other consumers in order to get energy.

Cellular Respiration Both producers and consumers break down food molecules to release energy in a process called cellular respiration. Cellular respiration takes place in mitochondria.

Fermentation If muscle cells run low on oxygen during strenuous exercise, muscle cells convert energy from glucose by fermentation. This produces lesser amounts of energy. Lactic acid is formed and causes muscles to burn and to be sore and stiff. Fermentation takes place in the cytoplasm of cells.

Alcohol Fermentation Yeast (and some bacteria) use alcohol fermentation to gain energy by breaking down the glucose in bread dough to produce CO 2 and alcohol. The bubbles of CO 2 that are released cause the dough to rise while the alcohol is released into the air.

Useful Biomass Organic material from plants or animals that is used for energy is called biomass. Firewood, charcoal, animal dung, and peat supplies can be used as biomass fuel.

Liquid Fuels Sugar in sugar cane, corn, and grain can be changed to ethanol in the process of alcohol fermentation. Ethanol can be burned in automobile engines. A mixture of gasoline and ethanol is gasohol. Methanol (wood alcohol) can also be used as a fuel for cars. Sugar in sugar cane, corn, and grain can be changed to ethanol in the process of alcohol fermentation. Ethanol can be burned in automobile engines. A mixture of gasoline and ethanol is gasohol. Methanol (wood alcohol) can also be used as a fuel for cars.

Other Sources of Energy Animal wastes can be changed into biogas. Biogas produces fewer pollutants than either coal or biomass.

Advantages of Biomass  Reduces dependence on fossil fuels  Makes use of wastes; reduces need for waste disposal areas  Doesn’t pollute atmosphere with CO 2  Reduces dependence on fossil fuels  Makes use of wastes; reduces need for waste disposal areas  Doesn’t pollute atmosphere with CO 2

Disadvantages of Biomass  Plant production requires land and water  Competes with growing of food crops; reduces soil nutrients  Improper use of croplands and forests could lead to soil erosion, flooding, etc.  Plant production requires land and water  Competes with growing of food crops; reduces soil nutrients  Improper use of croplands and forests could lead to soil erosion, flooding, etc.