Name ______Test Date___Oct1st , 2nd , 3rd

CELL STRUCTURE AND FUNCTION

I. DISCOVERY OF CELLS

A. History of Microscopes

The invention and development of the microscope in the 1600’s enabled

scientists to discover andstudy cells - basic unit of structure and function in

in allliving things

  1. Anton von Leeuwenhoek – was the first to try stacking several

lenses_ together toview tiny objects. He looked at pond water_ through his lenses and became known asthe first scientist to describe living cells as seen through a microscope.

  1. Robert Hooke- In 1665, he used a _microscope_ to examine thin

slices of corkandthen described what he saw and called them _cells__. He chose the name “cells” becausethe chambers he saw reminded him of the rooms in a monastery which were called cells.

B. Cell Theory

Nearly a century after Hooke’s findings, several other scientists discoveries led

to the formation of the_cell theory_.

  1. Matthias Schleiden (botanist) & Theodor Schwann (zoologist) –

together they reached theconclusion that ____all____

living thingswerecomposed ofcells_.

  1. Rudolf Virchow – elaborated on Schleiden & Schwann’s proposal and

added “omniacellula ecellula” : all cells come fromcells_

These discoveries, confirmed by other biologists, are summarized in the

cell theory, a fundamentalconcept in Biology…..

The cell theory states that:

a. All organisms are ____composed of cells______

b. Cells are the smallest working units of life.

c. All cells come from ____pre-existing cells________

II. TYPES OF CELLS

Living organisms are made of either _prokaryotic__ or _eukaryotic_cells –

the two major kinds of cells which can be distinguished by _structural

organization__

PROKARYOTIC / EUKARYOTIC
_Bacteria_____; Divided into two kingdoms, _Archaebacteria____ and _Eubacteria______/ All organisms other than _bacteria______; Found in kingdoms _Protista____, _Fungi__, _Plantae___, and _Animalia______
_No_ true nucleus; Lack nuclear envelope / _True____ nucleus surrounded membrane known as nuclear envelope
Genetic material present in_nucleoid______region / Genetic material contained within_nucleus______
__Lack_ membrane-bound organelles / _Contain____ membrane-bound organelles

A. Prokaryotic Cells – All Unicellular

1. Eubacteria– “True” Bacteria; Ex. include E.coli,Streptococcus.

2. Archaebacteria – “Ancient” bacteria; live in extreme environments (salty,

hot, acidic); Ex. methanogens

B. Eukaryotic Cells – Found in Unicellular and Multicellular organisms

1. Protista– ex. Amoeba, Euglena, Paramecium

2. Fungi- ex. Penicillium, yeasts, molds, mushrooms.

3. Plants– ex. Mosses, ferns, flowering plants.

4. Animals – ex. Sponges, worms, snails, insects, mammals.

III.

C. Microscopes - There are several types of modern microscopes:

1. Compound light microscope – More than one _lens (ocular & objective)______

uses light bent through lenses to magnify objects.

2. Electron Microscope – Uses _beams of electrons______. This enhances the

resolution and magnification to allow researchers to study _cell structures____.

There are two types of electron microscopes:

  1. Transmission Electron Microscope or _TEM______- electrons are

Transmitted_through_____the specimen; used to study _internal___ cell structures.

  1. Scanning Electron Microscope or _SEM_____ - uses electrons to trace the

_surface_____ of the specimen; provides _depth___ of field or 3-D view.

III. CELL BOUNDARIES

A. Cell Wall

Cell Walls are the outer most boundary in _bacteria_, _plants_, and

_fungi_. They are not found in __animal cells_____. The primary function

of the cell wall is to_provide support and structure__.

  • Plants have cell walls made of _cellulose___
  • Fungi have cell walls made of _chitin____.
  • Eubacteria have cell walls made of _peptidoglycan_____.
  • The cell walls of _Archaebacteria___ are composed of other _polysaccharides_____.

B. Cell Membrane

Every cell is surrounded by the cell membrane. Its function is to maintain

homeostasis__ in thecell by separating and protecting the cell fromits

environment. It also regulates exchange with theenvironment. The cell

membrane is also called the __plasmamembrane_. It is _selectively

permeable_ which means that it allows some substancesto pass through;


acts a barrier to others.

IV. INSIDE A EUKARYOTIC CELL

Within the cell membrane, the cell is composed of the nucleus with its

correspondingstructures, the _nucleolus_ and _nuclear envelope__.

The cytoplasm includes all the rest of the material inside the cell membrane.

The cytoplasm includes two components:

Cytosol – a semi-gelatinous substance that contains dissolved nutrients and

wastes

Organelles – means “little organs”. Each has a specific role in the overall

function of the cell.

Illustration / Structure / Type of Cell / Characteristics & Function
/ Nucleus / Euk / _Control center____ of the cell. Contains most of cell’s DNA; stored as _chromatin___ (_DNA______wrapped in _protein_____)
Nucleolus / Euk / Small, dense region in the nucleus. Involved in the synthesis of _ribosomes_____ which are required for _protein______synthesis.
Nuclear Envelope / Euk / Double membrane, each consisting of a _phospholipid bilayer__. Perforated by nuclear _pores______which allow _RNA______to leave the nucleus
/ Ribosomes / Pro + Euk / Tiny, non-membrane bound organelles located on _endoplasmic reticulum_____ (bound) or suspended in _cytosol______(free). Free ribosomes help manufacture _proteins_____ that will stay in the cell; bound ribosomes help make proteins that will transported out of cell
/ Rough Endoplasmic Reticulum / Euk / Extensive network continuous with _nuclear envelope______. Called “rough” due to presence of _ribosomes____ all along the membrane. Function of the rough ER is to _modify____ and transport _proteins_____. Most of these proteins are packaged into _vesicles_____ (bubbles or sacs made from membrane) and shuttled to the _Golgi apparatus______
/ Smooth Endoplasmic Reticulum / Euk / Similar to rough ER in structure, except that it lacks _ribosomes______. Smooth ER functions in the synthesis of _lipids_____, metabolizes _glycogen___, detoxifies _poisons_____ and _toxins___. Also stores _calcium__needed for muscle contractions.
/ Golgi apparatus / Euk / Flattened, round sacs that look like a sack of _pancakes______. Receives, modifies, and ships products by way of _vesicles______into the _cytosol______
/ Lysosome / Euk – Animal Cells / Found in _animal___ cells only?? Membrane-bound sacs containing _hydrolytic enzymes___ that break down _biomolecules______and _recycle____ used cell components. Also used as defense against _bacteria______and _viruses______
/ Vacuole / Euk / Sacs that may be used as _storage_____ for water, ions, wastes. Plants have a large central vacuole.
/ Mitochondria / Euk / Double-membrane organelle with inner folds called _cristae_____. Uses _glucose______to manufacture energy in the form of _ATP_____. Mitochondria have their own _DNA____.
/ Chloroplast / Euk – Plant Cells / Found in _plant____ cells. Contain green pigment called _chlorophyll______and their own _DNA______. Chloroplasts harvest energy from the _sun____ to produce _glucose____ through _photosynthesis______.
/ Centrioles / Euk – Animal Cells / Found only in _animal__ cells. Bundles of _microtubules______that play a role in _cell division_____.
/ Cytoskeleton / Euk / Network of _protein____ fibers known as _microtubules______and _microfilaments______. Anchor _organelles______and provide _support______. Also provide motility for some cells in the form of _cilia______or _flagella______. More extensive cytoskeleton found in _animal____ cells.

VI. THE PROKARYOTIC CELL

VII. THE EUKARYOTIC CELL

EUKARYOTIC CELLS KEY

A. nucleus

B. nuclear envelope

C. chromatin

D. nucleolus

E. mitochondria

F. Golgi apparatus

G. rough endoplasmic reticulum

H. ribosome

I. vacuole

J. cytosol

K. cytoskeleton

L. cell membrane

M. smooth endoplasmic reticulum

N. centrioles

O. lysosome

P. cell wall

Q. chloroplast