Cells

Cell TheoryRobert Hooke—1665 The first person to see cells Used light microscope to look at

cork and noticed little boxes• Called tiny chambers “cells”

Cell Theory• Leeuwenhoek –1673

• first to view pond water organisms

• First to see living things in pond water• he called these "animalcules"

Cell Theory• Theodore Schwann - zoologist who

observed that the tissues of animals had cells (1839)

• Mattias Schleiden - botanist, observed that the tissues of plants contained cells ( 1845)

• Rudolf Virchow - also reported that every living thing is made of up vital units, known as cells. He also predicted that cells come from other cells. (1850 )

Cell Theory

1. All living things are composed of cells

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

3. New cells are produced from existing cells

Cells• Cells that work together to perform a

specific function form a tissue.• Just as cells that work together form

a tissue, tissues that work together form an organ.

• Organs that work together to perform a function form a system. Example: circulatory system.

Cells Each kind of cell has a

particular function. Size and Shape depend upon its function. Red blood cells are small and disc-shaped

to fit through the smallest blood vessel. Muscle cells are long and thin. When they

contract they produce movement. Nerve cells which carry signals to the

brain are very long.

Cell Function

C ell F u n c tion

R e leas in g en erg y from food .

M ak in g n ew ce lls fo r g row th an d rep a ir.

G e ttin g rid o f b od y w as tes .

C e ll w ork tog e th er to p erfo rm b as ic life p rocesses th a t keep o rg an ism s a live .

Prokaryote Cells• Simple cells• Found in Bacteria• These cells do NOT

have a nucleus• their DNA is circular and • floats in the cytoplasm

Eukaryote CellsContain nuclei Contains organelles that perform specialized functions

Uni-or multicellular • Cells found in plants, animals,

protists, and fungi

Cell membrane provides barrier between internal and external environments

is selectively permeable (some things can go in, some cannot; some things can exit, some never can)

made up of phospholipid bilayer with proteins embedded that allow for needed passage of large molecules

Major job of cell membrane is to maintain the cell’s environment – establish homeostasis

CytoplasmEntire region between the nucleus

and the cell membraneThe semifluid substance that fills

this area is called cytosol, and this is what the organelles are suspended in

Nucleus Largest organelle Enclosed by a double membrane with is called a

nuclear envelope Nuclear membrane has pores in it to let

ribosomes and RNA in and out Contains inactive DNA When gets ready to divide, chromatin

condenses into chromosomes Directs protein synthesis by synthesizing RNA

and sending to ribosomes in the cytoplasm(in the nucleolus)

Endoplasmic Reticulum“highway system”Job is to transport materials

quickly from one place to another in cell

2 types: Rough ERSmooth ER

Ribosomes“protein factories”Sites of protein synthesismade of rRNA and proteinCells with high rates of protein synthesis

have MANY ribosomes (human pancreas cell has MILLIONS of ribosomes)

Ribosomes that are attached to endoplasmic reticulum (bound) are making proteins for packaging and export OUTSIDE OF CELL

Golgi Bodies“UPS system”Processes, packages, and ships what the cell makes out of the cell

Vacuoles“Trash cans”Sites of storage in cells

good things stored – water, minerals, food etc.

bad things stored – broken down cell parts, waste

Lysosomes“Recycling facility”Contain digestive enzymes Different lysosomes break down each of the major classes of macromolecules – proteins, polysaccharides, fats, nucleic acids

Mitochondria carry on cellular respirationsites of energy production in cell

(glucose broken down to produce ATP)

The “powerhouse” of the cell

ONLY IN PLANT CELLS!!!!

Chloroplasts Cell Wall

Cell WallFound ONLY in plant cells Protects the cellGives support to cell Is very porous and allows molecules to

pass through, but is NOT SELECTIVELY PERMEABLE

Chloroplastscarry on photosynthesis sites where sunlight, CO2 and water

are converted into glucoseONLY in plant cells!!

Protein Production in Cells The cell is like a factory. It’s product is protein which go to the body to serve

different functions.1.DNA has the instructions to build the protein2.These instructions are sent to the ribosomes3.The ribosomes build the protein and send it

through the endoplasmic reticulum4.The proteins are delivered to the golgi apparatus

where they are completed and “tagged” for export outside the cell