Chapter 7 CELLS. History of Cells It all begins with CORK in 1665

Chapter 7Chapter 7

CELLSCELLS

History of CellsHistory of Cells

It all begins with CORK in 1665.

10 years later, 10 years later, Anton van Anton van Leeuwenhoek Leeuwenhoek viewed pond water viewed pond water under a microscope under a microscope and discovered and discovered many tiny, living many tiny, living creatures which he creatures which he called called “animalcules.”“animalcules.”


Today, we know Today, we know that they were not that they were not animals, but animals, but single-single-celled organismscelled organisms..


The Cell TheoryThe Cell Theory

Three scientists, Schleiden, Schwann, Three scientists, Schleiden, Schwann, and Virchow put together what we and Virchow put together what we know today as the cell theory.know today as the cell theory.

Cells, Cells, CellsCells, Cells, Cells

1.1. All living things are All living things are made of one or made of one or more cells.more cells.

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

3.3. All cells All cells arise from existing cellsarise from existing cells..

2 Major Categories of Cells2 Major Categories of Cells

PROKARYOTESPROKARYOTES– The The smallest and simplestsmallest and simplest cells cells

are prokaryotes. are prokaryotes. – They are They are single-celled single-celled

organismsorganisms that that lack a nucleuslack a nucleus and other internal and other internal compartments.compartments.

2 Major Categories of Cells2 Major Categories of Cells

EUKARYOTESEUKARYOTES

– The first cells The first cells with internal with internal compartmentscompartments..

– Evolved about 2.5 billion years ago. Evolved about 2.5 billion years ago. – Eukaryotes include Eukaryotes include plants and plants and

animalsanimals and and have a nucleus and have a nucleus and other membrane bound organellesother membrane bound organelles..

PROKARYOTESPROKARYOTES

Without separate compartments Without separate compartments (organelles), prokaryotes cannot (organelles), prokaryotes cannot carry out many specialized carry out many specialized functions.functions.


They are very They are very simple and very simple and very smallsmall..


The familiar prokaryotes that The familiar prokaryotes that cause infection and food to spoil cause infection and food to spoil belong to a class commonly belong to a class commonly called called bacteriabacteria..


They can They can live in a live in a range of range of environmentsenvironments: : some do not even some do not even need oxygen to need oxygen to survive, some survive, some make their own make their own food, some live in food, some live in extreme hot or extreme hot or extreme cold.extreme cold.


They can They can grow grow and divide very and divide very rapidlyrapidly..


There are no There are no internal internal organelles, so organelles, so the cell’s the cell’s enzymes and enzymes and ribosomes are ribosomes are free to move free to move around in the around in the cytoplasm.cytoplasm.

Prokaryote StructuresProkaryote Structures Genetic materialGenetic material

(DNA or RNA) is a (DNA or RNA) is a single circular single circular molecule. This molecule. This loop is located loop is located near the center of near the center of the cell.the cell.

Prokaryote StructuresProkaryote Structures Cell Membrane Cell Membrane

(Cytoplasmic (Cytoplasmic Membrane) that Membrane) that allows certain allows certain materials in/out of materials in/out of the cell.the cell.

Prokaryote StructuresProkaryote Structures There is a There is a cell cell

wallwall that that surrounds the cell surrounds the cell membrane, membrane, providing providing structure and structure and support. support.

Prokaryote StructuresProkaryote Structures

They They lack the lack the internal internal supporting supporting skeletonskeleton, so , so they depend on they depend on a strong cell a strong cell wall to give the wall to give the cell shape. cell shape.


Some have Some have flagellaflagella, long , long threadlike threadlike structures structures that protrude that protrude from the from the cell’s surface cell’s surface and and enable enable movementmovement..


Some may Some may have have cilia for cilia for movementmovement..


RibosomesRibosomes to to make make proteins.proteins.

Prokaryotes things to rememberProkaryotes things to remember

Prokaryotes are Prokaryotes are BACTERIA.BACTERIA. Prokaryotes have NO nucleus. Prokaryotes have NO nucleus. PRO PRO

rhymes with NOrhymes with NO….NO NUCLEUS!….NO NUCLEUS! Prokaryotes have Prokaryotes have CELL WALLS.CELL WALLS.


EUKARYOTE – an organism whose EUKARYOTE – an organism whose cells cells have a nucleus and membrane have a nucleus and membrane bound organellesbound organelles..


Eukaryotes include Eukaryotes include Plants and Plants and AnimalsAnimals..


EU rhymes with DoEU rhymes with Do….Eukaryotes DO ….Eukaryotes DO HAVE A NUCLEUS!HAVE A NUCLEUS!

Eukaryote OrganellesEukaryote Organelles

Cell wallCell wall – only in – only in plants. Composed plants. Composed of proteins and of proteins and carbohydrates, carbohydrates, including including cellulose, it helps cellulose, it helps support and support and maintain the maintain the shape of the cellshape of the cell, , protects it from protects it from damage, and damage, and connects it with connects it with adjacent cells.adjacent cells.


Chloroplast Chloroplast – – only in plants. only in plants. Organelles Organelles that that use light use light energy to energy to make make carbohydratecarbohydratess from CO from CO22 and Hand H2O.O.


Central VacuoleCentral Vacuole – – only in plants. only in plants. Stores waterStores water. . When the central When the central vacuole is full, it vacuole is full, it makes the cell makes the cell rigid, which rigid, which enables the plant enables the plant to stand upright.to stand upright.


CytoplasmCytoplasm – – includes includes everything everything inside the cell inside the cell membrane, but membrane, but outside the outside the nucleus.nucleus.


Flagella and CiliaFlagella and Cilia – – only in some only in some animal cells. Both animal cells. Both are are used for used for movementmovement. . Flagella is like a Flagella is like a long tail. Cilia are long tail. Cilia are short, hair like short, hair like structures.structures.


CytoskeletonCytoskeleton – – provides the provides the interior interior framework of framework of an animal cellan animal cell, , much like a much like a human human skeleton.skeleton.


Cell MembraneCell Membrane – it – it is fluid, like a soap is fluid, like a soap bubble. It bubble. It separates the separates the inside from the inside from the outside of the cell. outside of the cell. This barrier This barrier allows allows only certain only certain substances into the substances into the cell and out of the cell and out of the cell.cell.


NucleusNucleus – – houses DNAhouses DNA. . It is like the It is like the brain of the brain of the cell and cell and regulates the regulates the cells cells functions.functions.


NucleolusNucleolus – – small dense small dense region in the region in the center of center of the nucleus the nucleus that puts that puts together together ribosomes.ribosomes.


RibosomesRibosomes – – make make proteinsproteins..


Endoplasmic Endoplasmic ReticulumReticulum – the – the highways system of highways system of the cellthe cell that that transports proteins. transports proteins. If it has ribosomes If it has ribosomes stuck to it, its stuck to it, its known as known as rough rough E.RE.R. If it does not . If it does not have ribosomes have ribosomes stuck to it, it is stuck to it, it is known as known as smooth smooth E.RE.R. .


Golgi Golgi ApparatusApparatus – – packaging and packaging and distribution distribution centercenter of the of the cell. cell.


LysosomesLysosomes – – digestiondigestion center of the center of the cell.cell.


Mitochondria – Mitochondria – The The powerhouse powerhouse of the cell. of the cell. By By breaking down breaking down big molecules, big molecules, the mitochondria the mitochondria makes ATPmakes ATP for for the cell. ATP is the cell. ATP is energy!energy!

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Chapter 7 CELLS. History of Cells It all begins with CORK in 1665