introduction to cells...cells are really small but some are still visibleto our eye the smallest...
TRANSCRIPT
Introduction to CellsCell Theory
Cell Basics
Plant v Animal Cells
What is Life? Characteristics of Life
Organization
Ability to develop and grow
Ability to respond to environment
Ability to reproduce
Needs of Life
Energy
Materials
Living Space
Organisms are made of cells Whether one cell or many, every living organism in our
universe is made of cells.
The word “cell” was first used around 300 years ago.
Robert Hooke was looking through a homemade microscope at some cork, when he noticed the cork was made of empty cavities.
He called these cavities “cells”, meaning “little rooms”.
But who actually discovered the first cell? There’s some controversy.
Two Types of Organisms
All organisms are made of one or more cells that contain DNA.
Unicellular Made of a single cell
Usually too small to see directly
Such as bacteria
Multicellular Made of multiple cells
Made of many different types of cells
First appeared nearly 750 million years ago
Such as plants, fungus, animals
Cell Theory1. Every living thing is made of one or more cells.
2. Cells carry out the functions needed to support
life.
3. Cells come only from other living things.
Cell Theory
Cell Size & Shape
Cells are really small
But some are still visible to our eye
The smallest organisms on Earth are single-cell bacteria
Your body is made of 10 trillion (10,000,000,000,000) cells
Prokaryote cells are ~ 2 micrometers
Eukaryote cells are ~ 10 - 30 micrometers
Most are spherical, though some are flexible or column-shaper
Basic Cell Structure
Cell membrane
Encloses and protects the cell
Any material moving into or out of a cell must pass through
Cytoplasm
Inside jelly-like material
Protects internal structures
DNA
genetic material that allow them to reproduce and function
Sometimes located in the cytoplasm and sometimes it’s in a nucleus.
What are cells made of?
All cells are made of the same elements.
An element is a type of atom
Each element (listed on the periodic table) has unique properties.
About 25 elements are essential for life
Only 6 elements account for about 99% of a
human’s body mass
Oxygen, Carbon, Hydrogen, Sulfur, Nitrogen, Phosphorous
About 2/3 of a cell is water
About 70% of a cell is
water
All of the chemical
reactions inside the cell
take place in water
Water is polar, which
means it has a
positively charged end
& a negatively charged
end
Large Molecules Support Cells1. Carbohydrates
Made of small sugars
Used by cells for structure and energy
2. Lipids
Fats, Oils, Waxes (do not dissolve in water)
Used by cells for structure and energy
3. Proteins
Made of amino acids
Used by cells for hundreds of jobs
4. Nucleic Acids
DNA & RNA
Used by cells for making proteins
Two Cell Categories
Prokaryote = Bacteria
No nucleus
DNA is a long circular
molecule in the cytoplasm
Eukaryote = all other cells
Nucleus contains DNA
More complex, ~10 times
larger
Membrane-bound organelles
that carry out specific functions
Plant versus Animal Cells Plant cells have a cell wall
tough outer covering that lies just outside the cell membrane
Supports & protects
Animal cells do NOT
have a cell wall, only
a cell membrane
Plant versus Animal Cells
Plant cells have
chloroplasts
Organelle that use sunlight to make sugar for energy
Photosynthesis
Animal cells do NOT have a
chloroplast
Must obtain energy from food
Plant versus Animal Cells
Plant cells have a central
vacuole
A large sac that holds water, waste, and other materials
Moves stuff into or out of the cell
Animal cells have lysosomes
Holds materials
Contains chemicals that can break down nutrients taken into a cell
Big Ideas
1. What is the cell theory?
2. What is the difference between prokaryotic &
eukaryotic cells?
3. What are cells made of?
4. List three differences between plant cells & animal
cells.