Chapter One : Cell Structure and Function

1. Chapter One: Cell Structure and Function Section Three: Chemical Compounds in Cells

2. First objective:What are elements and compounds? An element is any substance that cannot be broken down into simpler substances. When two or more elements chemically combine, they form a compound.

3. its smallest unit is called a molecule (H2). A subscript shows the number of atoms present in a compound. A chemical formula shows which elements are involved in the compound and the ratio of atoms. Elementscompounds its smallest unit is an atom. some of the elements that can be found in organisms include carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. A chemical symbolis a capital letter that represents an element (C- carbon).

4. Chemical formula for water Coefficient:a number written Chemical symbol: in front of a chemical formula a capital letter that that tells you how many molecules represents an element are in a reaction 2H2O Subscript:a small number written slightly below the chemical symbol that tells you how many atoms of the element are in the compound

5. Chemical symbols of common elements carbon - C oxygen - O hydrogen - H nitrogen - N phosphorus - P gold- Au sulfur - S sodium - Na potassium - K calcium - Ca chlorine- Cl iron- Fe

6. Second objective:What are the main kinds of organic molecules in organisms? Compounds that do not contain carbon are known as inorganic compounds (except for CO2). Compounds that contain carbon are known as organic compounds. Carbon is usually found attached to other elements. There are four groups of organic compounds: carbohydrates, lipids, proteins, and nucleic acids.

7. 1. Carbohydrates: energy-rich organic compounds made of C, H, and O. examples are sugar and starch (large molecules of sugar). important component (part) of cell walls and cell membranes. broken down into a simple sugar called glucose, which is used by the body for energy.

8. 2. lipids: energy-rich organic compound made of C, H, and O. examples are fats (solid at r.t.), oils (liquid at r.t.), and waxes. contain more energy than carbohydrates. cell membrane is primarily composed of lipids.

9. 3. proteins: large organic compounds composed of C, H, O, N, and sometimes S. made up of smaller molecules called amino acids. There are 20 different amino acids that can form thousands of different proteins depending on their order. make up many organelles and are also found as part of the cell membrane. hemoglobin in the blood carry O2 throughout the body; antibodies fight germs that invade the body. proteins known as enzymes act as catalysts, which affect the rates of chemical reactions but is not itself changed by the reaction (ex: digestion). sources of protein include eggs, meat, fish, beans, nuts, poultry.

10. 4. Nucleic acids: long organic compounds made of C, H, O, N, and P. contain the instructions that cells need to carry out life functions. there are two kinds: DNA- deoxyribonucleic acid- the genetic material passed from parent to offspring. DNA stores the information needed to build proteins correctly. It is double-stranded. RNA- ribonucleic acid- involved in protein synthesis and found in the cytoplasm and nucleus. It is single-stranded.

11. Lipids Contains the elements C, H, O. Has a lot more of H than O. Has many more atoms than carbohydrates. How to tell the difference between the chemical formulas of carbohydrates, lipids, proteins, and nucleic Acids Nucleic Acids Contains the elements C, H, O like carbohydrates and lipids, but it also has N and P. Proteins Contains the elements C, H, O like carbohydrates and lipids, but it also has N and sometimes S. Carbohydrates Contains the elements C, H, O. Has twice the amount of H than C.

12. Third objective:How is water important to the function of cells? Water is important because: Most chemical reactions within cells occur in water. It helps cells keep their size and shape. It maintains cell temperature. It is the universal solvent (can dissolve many substances).

13. Chapter One: Cell Structure and Function Section Four: The Cell in its Environment

14. First objective:How do most small molecules cross the cell membrane? One important characteristic of the cell membrane is that it is selectively permeable, which means that chooses what can enter and exit the cell. Substances like oxygen, food, and waste need to pass through the membrane and they do so by two different methods: passive transport and active transport.

15. 1. Passive transport: Osmosis the diffusion of water through the cell membrane. the cells cannot function properly without the right amount of water which is why many cellular processes depend on osmosis. a type of passive transport since no energy is required. Diffusion the main method by which small molecules move across the membrane from an area of high concentration to an area of low concentration. caused by molecules moving, colliding and spreading out. after diffusion, the concentrations inside and outside the cell are equal. a type of passive transport since no energy is required.

16. 2. Active transport: Cell energy is used to move substances against their concentration/gradient (low to high). One example of transport are the proteins found in the cell membrane. They are responsible for bringing in Na, K, Ca into the cell by active transport, since they are being moved from an area of low concentration to an area of high concentration. Another example of active transport is endocytosis - when a cell engulfs (surrounds) a substance and forms a vacuole within the cell.

17. Images of cellular transport Endocytosis

18. Second objective:why are cells so small? When a molecule enters a cell, it is carried to its destination by the moving cytoplasm. If the cell is large, the cytoplasm must move farther to bring molecules to all parts of the cell, which takes more energy.