7A Biology Notes Chapter 1: Cells Miss Iman Bouarfa What is Biology? *Let’s break down the word: Bio: Life or living -logy: the study of, a branch of *So, biology is the study of life, or the study of the living. What are living organisms? Scientists have made a list of requirements needed for something to be considered “living”: 1. They respire 2. Exhibit irritability and movement 3. Nourish themselves 4. Grow and develop 5. Excrete 6. Reproduce What are living organisms made of? *There are microscopic living structures called cells in every single living organism. *Each cell carries out a specific function required for the living organism to survive. *As a part of cellular function, sometimes cells work together in a network producing tissue. *Tissues also work together in a network with a specific function called an organ. What are cells? *Cells: the smallest structural and functional unit of an organism. *Robert Hooke, who was an English scientist, was among the first scientists to become very curious about the world we live in. *He was so curious that he cut thin slices of cork and placed them under the lens of his microscope to see what he could find. *Robert Hooke saw tiny boxes; he then gave these boxes the name “cells.” And it sort of just stuck, we use the term today. *In 1839, two German scientists named Schleiden and Schwann, decided that all living things must be made up of cells. *This theory went on to be called the cell theory. Onion Cells Cheek Cells Structure of cells: There are generally two types of cells: 1. Animal Cell 2. Plant Cell **Both type, however, have shared structures called organelles. **Animal and Plant cells have cytoplasm, cell membranes, and a nucleus. Animal Cells: Consist of cytoplasm, nucleus, and a cell membrane. Cytoplasm- gel-like region inside the cell where all organelles are located and all cellular processes occur. Cell membrane- extremely thin layer found all around the outside of the cell, controls what goes in and out of the cell. Nucleus- contains the information needed for the cell to function, it basically controls the cell. Mitochondria- powerhouse of the cell, where energy production occurs. Plant Cells: **Also have cytoplasm, cell membrane, and a nucleus. However there are some organelles and structures in plant cells that animal cells do not have. Cell wall- strong and firm structure found all; around the plant cell meant for protection and water regulation. Cellulose- substance found in the cell wall that provides the rigid feature of the cell wall. Chloroplasts- structures that contain a substance called chlorophyll which gives the plants their green color. Important for energy absorption from the sun for photosynthesis. Vacuole- storage of food (sugars) for the plant cell to use for energy, important for cell survival. Specialized cells: What are specialized cells? They are cells that have specific functions. Examples: sperm cells, ovaries, white blood cells, muscle cells, nerve cells, etc. Where do cells come from? **Most cells in living organisms are products of a process called mitosis. **It’s a form of cellular division, where every single cell divides giving you two new cells, and so on.