Topic 1 Topic 1

Characteristics of Life Characteristics of Life

& Cells& Cells

Characteristics of LifeCharacteristics of Life

1. Cells are the basic unit of life. All living things are made of one or more cells.

2. Metabolism is the sum of all chemical reactions in an organism. Since all living things use energy they undergo metabolism.

3. Homeostasis is the maintenance of a relatively stable internal environment.

4. Reproduction is the passing on of genetic information.

• Biotic = living

• Abiotic = nonliving

Similarities Among Living ThingsSimilarities 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

Organic ChemistryOrganic 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

Major Organic Compounds in Major Organic Compounds in the Bodythe Body

• Carbohydrates (ex. starches, glucose…)

• Lipids (ex. fats, cell membrane…..)

• Proteins (muscle, enzymes…..)

• Nucleic Acids (the building blocks of genes)

Major Inorganic Substance in Major Inorganic Substance in the Bodythe Body

• Water

• Oxygen

• Carbon Dioxide

• Salts (many minerals are classified as salts)

Levels of Organization in Living Levels of Organization in Living OrganismsOrganisms

• Larger - Organism

- Organ System

- Organ

- Tissue

- Cell

• Smaller -Organelle

Cell TheoryCell Theory

1. Cells are the basic unit of living things. All living things are made up of cells.

2. Given #1, all life functions that are carried out by a living organism are carried out by a cell.

3. Cells arise from other cells – not non-living matter.

Exceptions to Cell TheoryExceptions to Cell Theory

1. Viruses are not made up of cells, yet they can act like living things and do contain genetic information.

2. The first cell could not have come from another cell.

QuestionQuestion

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

Differences Between Plant and Differences Between Plant and Animal CellsAnimal Cells

1. Plants have a cell wall, animals do not.

2. Plants have chloroplasts, animals do not.

3. Plants have large vacuoles and animals have small vacuoles.

4. Animals have many more mitochondria than plants.

5. Animal cells are more oval shaped and plant cells are more box shaped.

OrganellesOrganelles

• 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

OrganellesOrganelles

• 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

OrganellesOrganelles

• 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!

Types of Transport in the CellTypes 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

Types of Transport Cont.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)

Types of Active TransportTypes of Active Transport

• Endocytosis- moving materials into the cell

• Exocytosis- moving materials out of the cell.

• Pinocytosis- cell drinking

• Phagocytosis- cell eating

Digestion in a CellDigestion 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

Signal RecognitionSignal 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.