Cells Organelle Biology

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					Cells & Organelles

Robert Hooke
Demonstrator for Royal Society. During mid 1600’s lenses were a fad.

Lecture 12

The Discovery of Cells
Wanted to know why corks float. Looked at cork (plant) cells. Saw cells in 1665. Looked like monk’s “cells”

Robert Hooke
“If I had seen further, it is by standing on the shoulders of giants” From letter written by Sir Isaac Newton to Robert Hooke who was a dwarf.

The Discovery of Cells
Many men contributed to discovery: Antony van Leeuwenhoek: In 1678, discovered microscopic organisms. First to see bacteria and various protists. Animalcules. Animalcules

Cell Theory
Living organism made up of one or more cells. Basic functional unit. Arise from another or preexisting cells.

Lecture 19

Contributors to Cell Theory: Theodore Schwann & Mathias Schleiden - 1839. All organisms composed of cells, the basic unit of life.

The Cell Theory

The Cell Theory
Contributors to Cell Theory:
Rudolph Virchow: Virchow Best known for his law - 1855: Omnis cellula e cellula, "every cell every originates from a pre-existing cell”. precell

Eukaryotic Cell Components
Cell membrane Cytoplasm Genetic material in nucleus
Cell membrane: Cell boundary, keeps cell distinct from other cells. Cytoplasm: Content of cell inside : membrane excluding genetic material. Genetic material: Inside nucleus.

Prokaryotic Cell Components
Cell membrane Cytoplasm Genetic material in cytoplasm Genetic material: In cytoplasm, not enclosed in nucleus. Other differences.

Prokaryotic Cells
Nucleus absent. Plantae Fungi Animalia Some are Protista anaerobes. Monera Smaller cell size. Unicellular to filamentous. Organelles absent. absent Genetic material consists of one strand of DNA in a circle.

Nucleus present. Aerobes. Cells larger than prokaryotic cell.

Eukaryotic Cells
Plantae Fungi Animalia Protista Monera

Unicellular to multicellular. Organelles present. present Genetic material consists of chromosomes in a nucleus.

Lecture 19

Two Types of Cells
Cells are unifying theme for both types. Focus on eukaryotic cells. Monera: Prokaryotic kingdom. Protista, Plants, Animals and Fungi: Eukaryotic Kingdoms.
Plantae Fungi Animalia

Unifying Theme of Cells
All cells are similar: Specialization occurs, but based on modification of existing structures. Cells are small, i.e., you need a microscope to see them. Small cells have increased membrane surface area.

eukaryotic organisms prokaryotic organisms

Protista Monera

Cell Theory Expanded

Volume to Surface Area

1950: electron microscope

Total surface area 9 times greater. Different Identical Volumes Diffusion distances shorter in small cells.

Process of Diffusion
Diffusion: Spontaneous movement of matter or heat. Movement is from area of high density to lower density.

The 27 smaller cells > surface area than 1 giant cell. Molecules must move in and out of cells!

So What?

Examples: Perfume in air, sugar in coffee.

Much easier to diffuse in and out of smaller cell.

Lecture 19

Significance of Small Cell Size
Short diffusion distance is reason why cells are small and not large. Cells also similar in size. Some exceptions: Inside of egg is one cell. Other generalization: Plant cells larger than animals. Prokaryotic cells smaller than eukaryotic cells.

Structural Similarities of Cells
Surrounded by semisemipermeable membrane: membrane Acts like a sieve, selects what can get in and out of cell. Protein synthesized with same physical structures (=same organelles). Information for protein synthesis stored in DNA.

Functional Similarities of Cells
Energy source ATP. Mechanism of material transport through membrane. Conversion of information into protein. Cell division, i.e., one cell division divides to form another cell.

Examples of Specialized Cells
Epithelial cells (skin). Adipose cells (fat). Muscle cells (3 types). Nerve cells. Eggs & Sperm (unusual)

Epithelial Cells

Adipose Cells

Lecture 19

Muscle and Nerve Cells

Sperms Competing to Fertilize Egg

Three Functional Systems
Manufacturing proteins. proteins Metabolism: Converting Metabolism sugar to useful energy. Photosynthesis: Photosynthesis Capturing light energy.

Manufacturing proteins
Animal Cell

Animal Cell

cell membrane nucleus

Organelles: Sub-Cellular Structures
Protein production. Functions like a factory. Specialized “equipment”.


(ribosomes) endoplasmic reticulum (ER)

Most surrounded by membrane.

Protein Manufacturing Components

Lecture 19

Engineers and Plans

The Factory

Engineering: Copy plans, send to factory.

Factory assembles parts.

Nucleus: Where Plans Are
Nucleus and ER. Nucleus contains the master plans of the cell in the form of DNA.

Nucleus: Where Plans Are
When protein is needed Copy (=RNA) of part of DNA with RNA being info for assembled protein. DNA

Factory: ER and Ribosomes
RNA copy of plans for protein leaves nucleus. Plans go to factory = ribosome and ER.
(ribosomes) endoplasmic reticulum (ER)

Factory: ER and Ribosomes

Protein is assembled in factory like an assembly line.

Lecture 19

Factory: ER and Ribosomes
Protein being assembled Amino acid

Factory: ER and Ribosomes

RNA copy of “plan”

Ribsome= worker


Ribosome moves RNA copy along assembly line conveyor belt so plan can be read.

Finished proteins deposited inside ER.

Finished Products

Where to Now?
Proteins sent into cytoplasm in form of secretory vesicles to the golgi.

Packaged and “sent off” where needed.

Golgi Apparatus

Where to Now?
Proteins sent into cytoplasm in form of vesicles to the golgi. Protein modification.

From ER

secretory vesicles

Packaged in secretory vesicle.

Lecture 19

Where to Now?

Membrane bound structures with little or no structure. Plants: Fills with water and some organic compounds. Pressure from water expands cells.

Plant Vacuoles
Water entering cell


Secretory vesicles now incorporated into cell.

Allows cells to grow.

Dehydrated and Hydrated Plants

Storage Support



Water regulation

Dehydrated Plant Addition of water, filling cell’s vacuoles

vacuole chloroplasts mitochondria

Lecture 19