Cell Structure & Function

Did You Know?

The average human is composed of over 100 Trillion individual cells!!!

It would take up to 50 cells to cover the dot in the letter i

Definition of Cell

A cell is the smallest unit that is capable of performing life functions.

Recall from your studies in characteristics of life the

organization of living organisms

Cells Tissues Organs Organ Systems Organism

Cell Theory

• All living things are made up of cells. • Cells are the smallest working units of all living

things. • All cells come from preexisting cells through

cell division.

Cell Specialization and Organization

Cells are the basic unit of structure and function in living things

Serve a specific function within the organism

Examples: blood cells, nerve cells, bone cells, skin cells, etc…

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Level 2—Tissues

Made up of cells that are similar in structure and function that work together to perform a specific

activity

Examples: blood, nervous, bone, etc. In humans, we have 4 types of tissue: connective,

epithelial, muscle, and nerve

Level 3--Organs

Made up of tissues that work together to perform a specific

function

Examples: heart, brain, kidney, skin

Level 4—Organ Systems

Groups of two or more organs that work together to perform a specific function for the

organism

Examples—Circulatory System, Nervous System, Digestive System

Level 5--Organism

Entire living things that can carry out all basic life processes. They can take in materials, release energy from food, release

waste, grow, respond to the environment, etc…remember the 6 characteristics of living organisms???

Organisms are usually made up of organ systems, but an organism may only be made up of one cell as is the case

with bacteria

Examples—human, bacterium, amoeba, euglena, mushroom, sunflower

Discovery of Cells

Scientists who were instrumental in the discovery of cells and the development of the Cell Theory:

Robert Hooke

Anton van Leuwenhoek

Matthias Schleiden & Theodore Schwann

Louis Pasteur & Francisco Redi

Robert Hooke

• Discovered Cells while viewing a cork under a microscope

Anton van Leuwenhoek

• Observed single-celled organisms in pond water

• Observed blood cells

Matthias Schleiden & Theodore Schwann

Said that plant parts and animal tissues were made of cells

Louis Pasteur & Francisco Redi

Disproved the Theory of Spontaneous Generation

Two Types of Cells

•Prokaryotic•Eukaryotic

Prokaryotic

• Do not have structures surrounded by membranes

• Few internal structures

• One-celled organisms, Bacteria

Eukaryotic• Contain organelles surrounded by membranes• Most living organisms

Plant Animal

“Typical” Animal Cell

“Typical” Plant Cell

Cell Parts

Organelles

Surrounding the Cell

Cell Membrane

• Outer membrane of cell that controls movement in and out of the cell

• Double layer

Cell Wall

• Most commonly found in plant cells & bacteria

• Supports & protects cells

Inside the Cell

Nucleus

• Directs cell activities• Separated from cytoplasm by nuclear

membrane• Contains genetic material - DNA

Cytoplasm

• Gel-like mixture• Surrounded by cell membrane• Contains hereditary material

Chloroplast

• Usually found in plant cells

• Contains green chlorophyll

• Where photosynthesis takes place