the cellchapter 1

history• invention of the microscope

• hans and zacharias janssen - 1590• galileo galilei - 1609

• giovanni faber• robert hooke -1665 - Micrographia• anton van leewenhoek - 1676• schleiden & schwann

cell theory• three basic tenets

• all organisms are composed of cells• cell is the structural unit of life• cells only arise from division of other cells

• cells can be cultured• HeLa cells

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basic properties of cells• complex but organized

• cells from different species share characteristics• each type of cell exhibits structural consistency• cells are structurally conserved

• possess genetic information• can produce proteins

• can copy themselves• acquire and utilize energy

MI W

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r / P

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basic properties of cells• carry out chemical reactions

• metabolism• have mechanical activity

• “motor” proteins• can respond to stimuli• robustness• cells evolve

• all cells evolved from LCA

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right

© J

ohn

Wile

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• prokaryotic • Archaea and Bacteria

• eukaryotic• Eukarya

• Fungi, Animalia, Plantae, Protists

two main types of cells

scale• microns (micrometers, µm)• nanometers (nm)• size constraints

• surface area-to-volume ratio

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prokaryotic• no nucleus

• DNA packaged up in unbound nucleoid region

• single circular DNA • no true membrane-bound

organelles• reproduction by binary

fission• most diverse and numerous

cells

Ribosome

Cell wall

Plasma membrane

DNA of nucleoid

Capsule

Bacterial flagellum

Cytoplasm

Pilus

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eukaryotic• nucleus

• separated by complex nuclear membrane

• complex chromosomes• complex organelles• complex cytoskeletal system• possess ability to phagocytize

particles• cellulose cell wall in plants• divide through mitosis/

cytokinesis• 5 different RNA polymerases

plant cellnuclear

envelope

nucleoplasm

nucleolus

rough endoplasmic reticulum

cell wallplasma

membrane

plasmodesmata

mitochondrion

ribosomes

vesicle

cytosol

chloroplast

smooth endoplasmic

reticulum

peroxisome

golgi complex

tonoplast

microtubules

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right

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ohn

Wile

y &

Son

s, In

c. A

ll rig

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.

nucleus:

animal cell

microtubulemicrofilament

intermediate filament

microvilli

pericentriolar material

microtubule

secretory vesiclelysosome

smooth endoplasmic reticulumperoxisome

mitochondrionmicrotubule

cytoskeleton:

centrosome:

flagellumcilium

proteasome free ribosomeschromatin

nuclear porenuclear envelope

nucleolusglycogen granules

cytosol

rough endoplasmic

reticulum

bound ribosome

golgi complex

microfilament

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cytoplasm• prokaryota

• relatively simple• eukaryota

• cytosol• cytoskeleton• ribosomes

From

O. M

edal

ia, e

t al,

Scie

nce 2

98:1

211,

200

2, F

igur

e 3a

. © 2

002,

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ith

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om A

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organelles• prokayotes

• none• eukaryotes

• membrane bound organelles• nucleus• ER• golgi apparatus• mitochondria• chloroplasts• vacuoles

cellular reproduction• prokaryotes• eukaryotes

• involves mitosis / meiosis• spindle fibers

Cou

rtesy

Cha

rles

C. B

into

n, J

r., a

nd J

udith

Car

naha

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rtesy

Con

ly R

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flagella• prokaryotes

• simple protein filaments that rotate quickly

• eukaryotes• complex

Cou

rtesy

of C

harle

s C

. Brin

ton,

Jr.,

and

Jud

ith C

arna

han

Cou

rtesy

ML

DeP

amph

illis

and

Juliu

s A

dler

From Bernhard R Gerber, et al, J.Mol. Biol.,71:317-323. 1972, with permission from Elsevier

prokaryotic diversity• Archaea

• often extremophiles• Bacteria

• includes mycoplasma• includes cyanobacteria

• general diversity• identified by specific

DNA sequences• species concepts

perhaps not appropriate

prokaryotic diversity• identification

• culture - • only 0.1% identifiable

by traditional means• DNA sequencing

• metagenomes

• endosymbiont theory -- symbiogenesis • mitochondria -

eubacteria• chloroplasts -

cyanobacteria

heterotrophic eukarya

autotrophic eukarya

eukaryotic origins Eukaryotic diversity• eukarya

• fungi, protista, plantae, animalia• unicellularity

• protist groups, algae• multicellularity

• evolved multiple times• specialization of cells

• differentiation

Car

olin

a B

iolo

gica

l Sup

ply

/ Pho

tota

ke

Eukaryotic diversity• sponges

Spongocoel

Osculum

Pore

Epidermis Waterflow

Mesohyl

Choanocyte

Spicules

Amoebocytes

FlagellumCollar

Food particlesin mucus

Choanocyte

AmoebocytePhagocytosis offood particles

Eukaryotic diversity

OTHEREUKARYOTES

Choanoflagellates

Sponges

Other animals

Anim

als

Individualchoanoflagellate

Collar cell(choanocyte)

• reductionism

Escherichia coli (bacterium) Saccharomyces (yeast) Arabidopsis (mustard plant)

Caenorhabditis elegans (nematode) Drosophila (fruit fly) Mus musculus (mouse)

model organisms

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genome size• chromosome number• number of genes

SPECIES haploid number of chromosomes

mosquito 3

house fly 6

frog (Rana pipiens) 13

mouse 20

human 23

cattle 30

dog 39

goldfish 47

carp 52

viruses?• viruses

• virions• structure

• DNA or RNA • surrounded by capsid• some surrounded by lipid

envelope• living?

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viruses?• viruses (cont.)

• lytic• lysogenic

• viroids• potato spindle-tuber disease

• prions

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