The Cell:History and Theory

Chapter 7 Powerpoint #2

Honors Biology

Cell Theory and the Scientists Who Helped

Shape It

Scientists and the Cell Theory

Anton van Leeuwenhoek

• Born: October 24, 1632• Died: August 30, 1723

• He is known as the “Father of Microscopy.”

http://en.wikipedia.org/wiki/Anton_van_Leeuwenhoek

Anton van Leeuwenhoek• Discoveries:

- 1673: He looked at pond scum under the microscope and discovered small organisms he called animalcules or little animals (Protists)- 1676: discovered

bacteriahttp://www.kent.k12.wa.us/staff/TimLynch/sci_class/chap09/lesson_protista/Protista_Lesson.html#Algae

Robert Hooke

• Born: July 18, 1635• Died: March 3, 1703

• Wrote and published “Micrographia”

• Known as the “English Father of Microscopy”

http://www-groups.dcs.st-and.ac.uk/~history/PictDisplay/Hooke.html

Robert Hooke

Contributions:

- He observed pieces of cork from the bark of a cork tree under the microscope.

- His observations led him to coin the word “cell.”

- “Cell”- means little rooms in Latin

- He compared the small boxes to the small rooms that monks lived in.

http://www.learner.org/channel/courses/essential/life/session1/closer1.html

Matthias Schleiden

• Born: April 5, 1804• Died: June 23, 1881

• German botanist

• Discovered that all plants were made of cells

• Contributed to the creation of the cell theory

http://www.britannica.com/eb/article-9066147/Mathias-Jacob-Schleiden

Theodor Schwann

• Born: December 7, 1810• Died: January 11, 1882

• German zoologist

• Concluded that all animals are made of cells.

• Contributed to the creation of the cell theory http://www.nndb.com/people/357/000096069/

Rudolph Virchow• Born: October 13, 1821• Died: September 5, 1902

• German pathologist

• He is known as the

“Father of Pathology.”

• Discovered that all living cells come only from other living cells.

http://en.wikipedia.org/wiki/Image:Rudolf_Virchow.jpg

The Cell Theory

1. All living things are made of cells.

2. Cells are the basic units of structure and function in living things.

3. Living cells come only from other living cells.

Two Main Types of CellsProkaryote• generally smaller and simpler• DO NOT have a nucleus –

DNA is not contained• All prokaryotic organisms are unicellular• example: all bacteria

Two Main Types of CellsEukaryote = “true nucleus”• Contains a nucleus • Contains dozens of specialized cell parts

(organelles)• Some unicellular organisms,

many multicellular• example: all plants, animals, and fungi

Cell Types (Review)

Eukaryotic

1. Contains a nucleus and other membrane bound organelles.

2. Rod shaped chromosomes

3. Found in all kingdoms except the Eubacteria and Archaebacteria

Prokaryotic

1. Does not contain a nucleus or other membrane bound organelles.

2. Circular chromosome

3. Found only in the Eubacteria and Archaebacteria Kingdoms

Two Main Types of Cells

Prokaryote vs. Eukaryote

Both:• Have a cell membrane• Contain DNA• Have cytoplasm with ribosomes

Prokaryotes Eukaryotes

Cell membraneContain DNARibosomesCytoplasm

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

Parts and Functions of Eukaryotic Cells

Organelles

• “mini-organs”• Each part of a cell with a specific job

is called an organelle

Cell-City Analogy• Just as a city is made up of many different components,

each with respective functions that they perform for the city to thrive, a cell is also made of structures (organelles), each with specific roles and duties.

Nucleus• Contains the genetic

material (DNA) & controls the cell’s activities

• Provides protection for nuclear material

• Made of 3 parts: – (1) nuclear envelope– (2) nucleolus– (3) chromatin

Nuclear Envelope• Double –membrane layer that

surrounds the nucleus of a cell

Nucleolus• Small, dense region within most

nuclei that produces rRNA

Ribosome• Site of protein synthesis• May be either free-floating or

attached to E.R.

Endoplasmic Reticulum • Network of transport

Channels• 2 Kinds

– Smooth ER(SER): Synthesis of lipids and steroids

– Rough ER (RER): Synthesis and processing of proteins (ribosomes make it “rough”)

Golgi Apparatus • Packages proteins from the RER for secretion.• Packages lipids & steroids from the SER in to

vesicles to send to other organelles, or out of the cell.

Lysosome• Membrane-enclosed sac of enzymes needed to

break down cellular debris • recycling the cell's organic material• Made by the Golgi apparatus

Mitochondrion • Releases energy from glucose (cellular

respiration)• Makes ATP, the main energy source for almost

all cell processes.

Cytoplasm• Contents of a cell inside the

cell membrane but outside of the nucleus.

• The gel-like substance in the cytoplasm is called cytosol

Cell Membrane• Thin, Flexible barrier around a cell that regulates

what enters and leaves the cell.• More about this later…

Microtubule

• Long, thin filament that functions in the movement and support of the cell

• Hollow tube of protein that maintains cell shape and functions as a “track” along which organelles move through the cell

Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Mitochondrion

CytoskeletonMicrofilament

Animal Cells ONLY !!!

Centriole• One of two small cylindrical structures

near the nuclear envelope of animal cells.• It helps organize microtubules during cell

division• Helps build cilia & flagella

Plant Cells ONLY !!!

Cell Wall• Provides structure and

protection to the cell. Found outside cell membrane in plants, algae, and some bacteria

• Made of:– Cellulose – Plants– Chitin – Fungi– Peptidoglycan - Bacteria

Chloroplast• Converts energy

from the sun into chemical energy, in the form of glucose

Vacuole • Membrane-bound sac, largest structure in

plant cell• Helps maintain water pressure in the cell• Site in the cell where water, salts, proteins,

and carbohydrates are stored

Animal Cells Plant Cells

Centrioles

Cell membraneRibosomes

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

Cell WallChloroplasts