CellsCells

Discovery of the CellDiscovery of the Cell

We could not have We could not have discovered the cell without discovered the cell without the invention of the the invention of the microscope in the 17th microscope in the 17th centurycentury

Robert Hooke (1635-1703)Robert Hooke (1635-1703)

1.1.Used a microscope to Used a microscope to examine cork, trees examine cork, trees carrots, and ferns. carrots, and ferns.

2.2.He saw little boxes that he He saw little boxes that he compared to the rooms compared to the rooms that monks live in: cells.that monks live in: cells.

Anton van LeeuwenhoekAnton van Leeuwenhoekwas the first person to observe live cells.was the first person to observe live cells.

The Cell Theory:The Cell Theory:

All living things are composed of one or more All living things are composed of one or more cellscells

Cells are the basic unit of structure and function Cells are the basic unit of structure and function of all living organismsof all living organisms

Cells come from other cellsCells come from other cells

Cell DiversityCell Diversity

SizeSize

A nerve cell can extend all the ways A nerve cell can extend all the ways down a giraffe’s leg.down a giraffe’s leg.

Most cells are not visible without a Most cells are not visible without a microscopemicroscope

ShapeShape• cells have a cells have a

variety of shapesvariety of shapes• Nerve cells have Nerve cells have

long extensions, long extensions, skin cells are flat, skin cells are flat, and white blood and white blood cells can change cells can change their shapetheir shape

Internal OrganizationInternal Organization– Eukaryotic cells contain organelles that Eukaryotic cells contain organelles that

can be compared to our organs.can be compared to our organs.– All cells have a cell membrane and All cells have a cell membrane and

genetic information called DNA (called genetic information called DNA (called chromosomes when compacted)chromosomes when compacted)

Prokaryotic vs. Eukaryotic Prokaryotic vs. Eukaryotic

– Prokaryotic cells: have a Prokaryotic cells: have a membrane and DNA only. THEY membrane and DNA only. THEY HAVE NO nucleus or HAVE NO nucleus or organelles. EXAMPLE: Bacteriaorganelles. EXAMPLE: Bacteria

– Eukaryotic cells: have a Eukaryotic cells: have a membrane, DNA, and membrane, DNA, and organelles. EXAMPLE: plant, organelles. EXAMPLE: plant, animal, fungi, and protist cellsanimal, fungi, and protist cells

Parts of all cellsParts of all cells

Cell membrane: surrounds and Cell membrane: surrounds and protects the cell and protects the cell and selectivelyselectively allows nutrients in and waste out allows nutrients in and waste out

(present in prokaryotes and (present in prokaryotes and eukaryotes)eukaryotes)

ChromosomesChromosomes

Compact DNA Compact DNA present in prokaryotes and present in prokaryotes and

eukaryotes eukaryotes

OrganellesOrganelles

Found in Found in Eukaryotic Cells Eukaryotic Cells only!only!

NucleusNucleus

Stores hereditary information called DNA. Synthesizes (makes) RNA and ribosomes.

MitochondriaMitochondria

Transfers energy from organic Transfers energy from organic compounds to ATP (energy) compounds to ATP (energy)

Muscle cellTumor cell

RibosomesRibosomes

Organizes the synthesis of proteins Organizes the synthesis of proteins found in cytoplasm and on Rough ER found in cytoplasm and on Rough ER

Endoplasmic ReticulumEndoplasmic Reticulum

prepares proteins for export prepares proteins for export RoughRough-packages proteins -packages proteins

SmoothSmooth-makes steroids -makes steroids

Golgi ApparatusGolgi Apparatus

Processes and packages substances Processes and packages substances made by cell.made by cell.

LysosomeLysosome

digests waste (old molecules, digests waste (old molecules, organelles, and foreign substance) organelles, and foreign substance)

CiliaCilia

short hair-like structures on the short hair-like structures on the outside of the cell present in large outside of the cell present in large numbers that assist in movement. numbers that assist in movement.

Example: in respiratory system to Example: in respiratory system to keep out foreign particles keep out foreign particles

FlagellaFlagella

long hair-like structures that whip long hair-like structures that whip back and forth to propel the cell back and forth to propel the cell forward. forward.

Example: sperm cell Example: sperm cell

PLANT CELLS ONLYPLANT CELLS ONLY

Cell WallCell Wall supports and protects (plant cells supports and protects (plant cells

only) only)

ChloroplastChloroplast

use energy from the sun and convert use energy from the sun and convert it into energy. (plant cells only)it into energy. (plant cells only)