Chapter 4 Notes THE CELL

Name __________________________________ Test Date___Oct 1st , 2nd , 3rd

CELL STRUCTURE AND FUNCTION

I. DISCOVERY OF CELLS

A. History of Microscopes

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

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

in all living things

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

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

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

slices of cork and then described what he saw and called them _cells__. He chose the name cells because the chambers he saw reminded him of the rooms in a monastery which were called cells.

B. Cell Theory

Nearly a century after Hookes findings, several other scientists discoveries led

to the formation of the _cell theory_.

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

together they reached the conclusion that ____all____

living things were composed of cells_.

2. Rudolf Virchow elaborated on Schleiden & Schwanns proposal and

added omnia cellula e cellula : all cells come from cells_

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

cell theory, a fundamental concept 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:

a. Transmission Electron Microscope or _TEM______________- electrons are

Transmitted _through_____the specimen; used to study _internal___ cell structures.

b. 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 the cell by separating and protecting the cell from its

environment. It also regulates exchange with the environment. The cell

membrane is also called the __plasma membrane_. It is _selectively

permeable_ which means that it allows some substances to 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

corresponding structures, 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 cells 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

8

Cell wall - 6

Cell membrane - 4

DNA - 3

Cytosol - 8

Ribosomes - 5

Capsule - 7

Pili 2

Flagella - 1

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