Anton van Leeuwenhoek (1632-1723) was the first to adapt lenses to the study of living organisms. He discovered microorganisms.
1665 – Robert Hooke
Observed chambers, dead plant cells, in cork.
Coined the term "cells” in 1665.
1833 - Robert Brown
Studied the nucleus. Do all living cells have a nucleus?
Nucleus Human Cheek Cell
1838 - M.J. Schleiden
Botanist…. Discovered plants are made of cells.
Elodea….Typical Plant Cell
1839 - T. Schwann
Zoologist….discovered animals are made of cells.
1855 - Rudolph Virchow
“ Omnis cellula e cellula”
“ All cells are from other
Discovered while researching cancer cells.
The Cell Theory
1. All living organisms are composed of one or more cells.
2. Cells are organisms' basic units of structure and function.
3. Cells come only from pre-existing cells.
How do you measure cells?
Cells are measured using “microns”.
A micron is another casual name for a micrometer.
Note: 1.0 m = one millionth of a meter
What limits the size of a cell?
Cell volume to surface area ratios favor small size... an efficient amount of materials must enter and leave the cell.
Nucleus’ ability to control the cell is limited by the size of the cell.
Types of Cells
Lack a nucleus and other membrane bound organelle.
First appeared 3.5 BYA
Have a nucleus and membrane bound organelle.
First appeared 2.0 BYA
include protists, fungi, plants and animals.
Basic Cell Organization
Cell (Plasma) Membrane
Nucleus (eukaryotes only)
Cytoplasm (an area!!)
Organelles (structures with specialized functions)
The Cell Membrane AKA: Plasma Membrane
Separates the cell from the environment.
Is “semi-permeable”…… regulates the movement of materials in/out of a cell.
ALL cells have a plasma membrane
The Cytoplasm is an Area (not stuff) between the plasma membrane and the nuclear envelope. The cytoplasm contains the cytosol, nucleus (if present) and cell organelles.
Semi-fluid portion of the cytoplasm (the gooey stuff inside the cell)…. Composed mostly of water, nutrients .
Most conspicuous organelle.
usually spherical, but can be lobed or irregular in shape.
Typically found near the center of a eukaryotic cell…..prokaryotes do not have a nucleus.
Control center for the cell.
Contains the genetic instructions.
Nuclear Envelope … the outer boundary of the nucleus which gives the shape to the nucleus.
Dark area in the nucleus.
0 - 4 per nucleus.
Storage area for ribosomes.
DNA and Protein in a “loose” format (stringy form of DNA) Will eventually form the cell’s chromosomes. The DNA holds the cell’s genetic information.
Found in the nucleus of eukaryotes and in the center region of prokaryotes.
The Cell Organelle
Term means "small organ” Formed body in a cell with a specialized function.
Keeps various enzymes separated in space.
(bags of enzymes)
Structure: made up of protein and RNA
Function: site of protein synthesis.
Free in the cytosol…..make proteins for use in cytosol.
Attached to the Endoplasmic Reticulum….. make proteins that are exported from the cell.
Often referred to as ER.
Stacks of flattened stacks involved in the production and transportation of proteins, sugars, fats,…..etc
Endoplasmic reticulum with attached ribosomes. The attached ribosomes create proteins
Endoplasmic Reticulum without Ribosomes….. Responsible for producing lipids and hormones, especially in cells that export these substances from the cell. In liver cells, the smooth ER breaks down toxins and drugs.
Golgi Apparatus AKA Golgi bodies or Golgi Complex
Structure: flattened sacs arranged in a stack. (looks like a stack of Pita bread)
3 to 20 per cell.
The Golgi Apparatus package and modify proteins and lipids into vesicles (small, spherical shaped sacs that bud from the Golgi apparatus). The vesicles often merge with the plasma membrane to release contents to the outside of the cell.
Vesicles from the Golgi apparatus that contain digestive enzymes. They breakdown food, cellular debris and foreign invaders such as bacteria.
Assist with cell death.
Not present in plant cells.
Organelles that breakdown various substances. During digestion 0xygen is produced and combines with H 2 O to form Hydrogen Peroxide…. a toxin. Peroxisomes break down Hydrogen Peroxide.
Function: Site of Cellular Respiration – Cellular Respiration is the release of energy from food to form ATP…. All cells use ATP as their energy source.
“ Powerhouse” of the cell.
Found in the cytosol.
Have their own DNA. Can reproduce themselves.
Function: Site of Photosynthesis - chloroplasts use of light energy to make food, sugars, from carbon dioxide and water.
Contain the green pigment chlorophyll.
Found in the Cytosol
Have their own DNA. Can reproduce themselves.
Enzymes in a crystal
Chromoplasts Function : store plant pigments such as chlorophyll (green) and carotene (orange, red).
Found in plants only.
Classified (named) by color….example:
“ Chloro” means green, therefore a chloroplast is a green plastid that stores chlorophyll
“ Leuco” means white, therefore Leucoplasts (AKA Amyloplasts) are white plastids that store starch.
Network of protein fibers and in the cytoplasm.
Give Cells structure and shape.
Involved in Cell movement.
Cytoskeleton is composed of 2 different types of fibers, which are organized in deceasing diameter….they are:
Microtubule Function Maintenance of cell shape. Hold organelles in place.
Responsible for Muscle contractions.
Cytoplasmic streaming in plants, like Elodea.
Maintenance and changes in a cell’s shape.
Cilia and Flagella Classified by their lengths and numbers
Function - to move cells or to sweep materials past a cell.
Cilia - short, but numerous.
Flagella - long, but few (usually only one).
Usually one pair per cell, located close to the nucleus.
Found in animal cells only.
Help in cell division.
Same structure as a centriole.
Found at the base of the cilia and flagella .
Plant Cell Walls
All plant cells have a Primary Cell Wall.
Some cells will develop a Secondary Cell Wall.
Plant cell walls are made of cellulose
( a polysaccharide made of -glucose).
Fungi cell walls are made of chitin (a polysaccharide)
Function as the cell's exoskeleton for support and protection.
Thin layer rich in pectin (used to make jelly) found between adjacent plant cells.
Glues cells together.
Vacuoles and Vesicles Fluid-filled, membrane-bound bodies
3 Types of Vacuoles and Vesicles
Central water vacuoles
The function of the vacuole depends on the organism.
single-cell organisms …….“Food” vacuoles store newly ingested food until the lysosomes can digest it.