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.