cells and cell theory. cell scientists robert hooke-1665, observed small cavities in cork which he...

CELLS AND CELL

THEORY

CELL SCIENTISTS

Robert Hooke-1665, observedsmall cavities in cork which he called cells.

Anton van Leeuwenhoek-late 1600’s, refined the microscope; saw single-celledorganisms which he called“animalcules”

Rene Dutrochet-1824, discovered osmosis; concludedthat plants and animals areboth made of cells.

Robert Brown-1831, Firstto see and name the nucleus

Felix Dujardin-1835, first tonotice cytoplasm

Matthias Schleiden-1839, wrote a paper stating all plants are made of cells

Theodor Schwann-1839,wrote a paper stating all animals are made of cells.

Rudolf Virchow-1855, firstto see cell division

CELL THEORY:•All living things are madeof cells•Cells are structurally andfunctionally similar•Cells come from other cells

WHAT IS A CELL?

The smallest unit thatcan perform all life

processes.

What is an Organelle?

•one of several specialized structures, suspended in the cytoplasm of a eukaryotic cell.

Prokaryotic Cells:1. No nucleus2. No membrane-bound organelles3. Very small4. DNA in one loop5. Only bacteria

Eukaryotic Cells:1. DNA in long strands(chromatin) in nucleus2. Large in comparison to bacteria (prokaryotes)3. Many membrane-boundorganelles4. All other organisms, exceptbacteria

EUKARYOTICCELL STRUCTURE:

CELL MEMBRANE-Encloses all parts of the cell;Controls what goes in and out

Cell Membrane Structure:

•Phospholipid bilayer•Embedded with proteins:(Marker, Channel, Receptor)•Glycolipids•Glycoproteins•Fluid Mosaic Model

Cell Wall:

•Found in plants•Made of cellulose•Surrounds cell membrane•Provides rigidity for plant

CELLWALL

Cytoplasm:

•Jelly-like substance in a cell•Surrounds other cell parts•Composed of water, salt, & other organic molecules

cytoplasm

Nucleus:•Directs & stores instructions for cell functions•Encloses DNA (chromatin)

Nuclear Membrane• Double membrane that isolates the

interior of the nucleus from the cytoplasm

• Has pores to allow things to be transported into and out of the nucleus.

• 4 phospholipid layers

Nucleolus:•Inside of nucleus•Assembles ribosomes•May be 1 or more than 1

nucleolus

Chromatin:•Long strands of a DNA-protein complex found innucleus

chromatin

Nucleoplasm:•A viscous fluid in the

nucleus in which the chromatin & nucleolus are suspended.

Ribosomes:•Protein factories of cell•Line up amino acids in correct order ribosomes

Mitochondria:•“Powerhouses” of cell•Make ATP•Complete breaking down of glucose molecules

Golgi Apparatus:•Packages & distributes organic molecules that leave the cell•Surround molecules withmembrane

Lysosomes:

Bags of enzymes that:•Digest macromolecules•Digest worn out cell parts•Destroy invading bacteria

Endoplasmic Reticulum (ER):

•Membrane system of folded sacs & tunnels•Helps maintain homeostasis

•Endoplasmic Reticulum (ER):•Rough ER has ribosomes & transports proteins•Smooth ER has no ribosomes & transports lipid & carbs.•Attached to nucleus

Centrioles & Centrosomes:•Organizing centers for celldivision•Found only in animal cells

centrosomecentrioles

PLASTIDS:

A class of organelles foundonly in plants and in someprotists.

Chloroplasts:•Site where glucose is made•Contain chlorophyll

Leucoplasts:•Change glucose to starch•Look like grains of rice•Starch is stored here

leucoplast

•Manufacture & store plantpigments•Red, orange, purple, yellow•Found in fruit, flowers &colorful leaves

Vacuoles:•Fluid filled sacs•Store enzymes, water, andwaste products•Large, central vacuole in plants•Many small vacuoles inother cells (or none at all)

CYTOSKELETON:

•Helps cell hold its shape•Made of microtubules and microfilaments•Animal cell rely on this for maintaining cell structure

Microtubules:

•Hollow rods of protein•Some extend from the cytoplasm to make up ciliaand flagella

Microfilaments:•Threadlike fibers found below the cell membrane•Produce flowing motion in cytoplasm•Help circulate organelles; improve cell efficiency

Comparison of Plant Cells toAnimal Cells:

PLANT ANIMALCell Wall No Cell WallPlastids No PlastidsLarge Vacuole Small vacuoles

or noneRely on cell wall Rely on

for structure cytoskeletonNo centrioles Centrioles