Exploring Life's Characteristics: Cells, Metabolism, and More

1. Topic 1 Characteristics of Life & Cells

2. Characteristics of Life • Cells are the basic unit of life. All living things are made of one or more cells. • Metabolism is the sum of all chemical reactions in an organism. Since all living things use energy they undergo metabolism.

3. 3. Homeostasis is the maintenance of a relatively stable internal environment. • Reproduction is the passing on of genetic information. • Biotic = living • Abiotic = nonliving

4. Similarities Among Living Things • Obtaining nutrients from the environment • Transportation of materials throughout the organism • Breaking nutrients into smaller units to release chemical energy • Synthesis – building large units out of small ones • Growth – increasing the # or size of cells • Excretion – removal of waste products • Responding to internal and external stimuli • Reproduction of the species

5. Organic Chemistry • The 4 main elements that all living organisms are made of include: Carbon, Hydrogen, Oxygen and Nitrogen • Organic – describes molecules that contain both carbon and hydrogen • Inorganic – Does not contain both Carbon and Hydrogen

6. Major Organic Compounds in the Body • Carbohydrates (ex. starches, glucose…) • Lipids (ex. fats, cell membrane…..) • Proteins (muscle, enzymes…..) • Nucleic Acids (the building blocks of genes)

7. Major Inorganic Substance in the Body • Water • Oxygen • Carbon Dioxide • Salts (many minerals are classified as salts)

8. Levels of Organization in Living Organisms • Larger - Organism - Organ System - Organ - Tissue - Cell • Smaller -Organelle

9. Cell Theory • Cells are the basic unit of living things. All living things are made up of cells. • Given #1, all life functions that are carried out by a living organism are carried out by a cell. • Cells arise from other cells – not non-living matter.

10. Exceptions to Cell Theory • Viruses are not made up of cells, yet they can act like living things and do contain genetic information. • The first cell could not have come from another cell.

11. Question • What are 4 differences between a plant and animal cell?

12. Differences Between Plant and Animal Cells • Plants have a cell wall, animals do not. • Plants have chloroplasts, animals do not. • Plants have large vacuoles and animals have small vacuoles. • Animals have many more mitochondria than plants. • Animal cells are more oval shaped and plant cells are more box shaped.

13. Organelles • Cytoplasm – the jellylike substance inside of a cell that: surrounds organelles, transports materials in and out of the cell and is the site of many chem. reactions. • Nucleus – stores genetic info and controls metabolism • Vacuoles – storage sacs for food, water and waste. (vacuoles in plants tend to be much larger than those in animals) • Ribosomes – important to the protein making process

14. Organelles • The Cell Membrane: is selectively permeable, controls what moves in and out of the cell and plays a major role in maintaining homeostasis in the cell • It is make of a double layered structure called a lipid bi-layer, proteins and carbohydrates. • Mitochondria – contain enzymes used to extract energy from nutrients

15. Organelles • Chloroplasts – only in plants and some single celled organisms, they contain a green pigment called chlorophyll which capture light energy and converts it to chemical compound used for food • Cell Wall – provides the cell with structure and protection. Only in Plants!

16. Types of Transport in the Cell Passive Transport: Requires no Energy (ex. sled downhill) • Diffusion- direct movement determined by concentration gradient (Areas of high concentration diffuse to areas of low concentration. (Salt on roads destroying plants ex.) • Facilitated Diffusion- Transport proteins in the lipid membrane move molecules along the concentration gradient faster than normal diffusion (the express lane). Ex. Glucose • Osmosis- Diffusion of water

17. Types of Transport Cont. Active Transport = Movement against the concentration gradient, energy is required in the form of ATP (ex. pulling a sled up hill) (desert plants use A.T.P. a lot to pull water up from their roots)

18. Types of Active Transport • Endocytosis- moving materials into the cell • Exocytosis- moving materials out of the cell. • Pinocytosis- cell drinking • Phagocytosis- cell eating

19. Digestion in a Cell • Most proteins and carbohydrates are too large to enter the cell and must be broken down first. • Protein digestion results in smaller molecules of amino acids • Carbohydrate (starch) digestion results in smaller molecules of simple sugars

20. Signal Recognition • Receptor Molecule – certain protein molecules in the cell membrane that can receive chem. messages (ex. nerve cell communication ex. Neurotransmitters=N.T.) • Hormone – chemical produces in the endocrine glands and responsible for communication b/t cells • If nerve cell or hormone communication is interrupted than homeostasis may be affected.