cell structure and function 2012
TRANSCRIPT
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Structure and
Function of the Cell
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Blood Cells
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Sperm Cells
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How did we find out about
cells?
Robert Hooke in 1665
Described little boxes thatlooked like the CELLS thatmonks lived in
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8 Years later...
Dutch microscope maker Anton vanLeeuwenhoek was the first toobserve living cells in 1673
Also observed some
microorganisms
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Observations recorded in over 200 letters
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Who Discovered the Cell
Theory?Schwann, Schleiden, and Virchow
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Matthias Schleiden 1838
German Botanist
Concluded thatall plants weremade of cells
Observed crosssections ofstems
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Theodore Schwann 1839
Germancytologist and
physiologist
Concluded thatall animalswere made upof cells
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Rudolf Virchow 1855
All cells comefrom previously
existing cells
Described the“
human body as acell state in whicheach cell is acitizen”
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The Cell Theory
1. All living things are made ofcells
2. A cell is the smallest unit of life3. All cells come from pre-existing
cells
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Cell Size
Some are tiny (bacteria)and some are long (nervecells)
All are microscopicLargest cells by volume
are eggs
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Cell Shapes
Different shapes for different functions!Nerve Cells are long to transmit information
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Red Blood Cells are shaped like a Frisbee toslip through small openings while still having
lots of membrane surface
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•Muscle Cells are tightly packed to work together
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Life Begins with the Cell
BiosphereEcosystemsCommunitiesPopulationsOrganismsOrgan Systems
TissuesCells Molecules
Atoms
Life
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Internal Organization
All cells haveA cell membraneDNA
CytoplasmRibosomes
Only some cells have a nucleusProkaryotic -noEukaryotic -yes “ you are a eukaryote”
Only some cells have organelles, cellcomponents that performs specific
functions
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Classification of Life is Based
on Cell Structure
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Prokaryotic Cells
“Pro-no” – no nucleus or membranesaround organelles
These are bacterial orarchaebacterial cells
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Bacterial cells have strong protective
capsules and compact shapes
Streptococcus, Bacillus subtilis, Borrelia burgdorferi (Lyme Disease)
CocciBacilli
Spirochaete
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Structure of Prokaryotes
Cell wall (also sometimes a capsule)
Protection from outside
environmentSupport/stiffness
Some have pilli for attachment
Cell membraneRegulate what enters/leaves cell
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Structure of Prokaryotes
A single DNA strand (geneticmaterial)
Ribosomes in cytoplasm makeproteins
Some have flagella for
movement
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A
ProkaryoticCell
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Bacterial cells on the
head of a pin
http://www.cellsalive.com/howbig.htm animation
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Ribosomes
Make proteins
May be 100’s to
1,000’s per cellFound in all cells
Made only of rRNAand proteinsShaped roughly like a
donut
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Cytoplasm
A jelly-like material that fills the cell
Mostly water
Contains molecules, nutrients,organelles
Allows particles to meet and mix
Sometimes called Cytosol (cellsolution)
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Eukaryotic Cells
Eukaryotes
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Eukaryotes
Eukaryotic cells have a nucleus
More complex structure with “rooms”
Start at 1,000 times larger thanprokaryotes
All multicellular organisms areeukaryotesKingdoms Animalia, Plantae, fungi, and
Protista are all eukaryotes
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Eukaryotic Cells
NucleusOrganelles with their own
membranesCytoskeletonComplex fluid mosaic
membraneMuch larger size
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Parts of the Eukaryotic Cell
Chapter 4 Section 2
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Cell Membrane
Isolate the cytoplasm from theenvironmentRegulates what enters and leaves
the cellNutrients in and wastes out
Selectively permeable – only lets
certain things in and outFlexible and changeable fluid
mosaic
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Phospholipid Bilayer
Membrane has embedded proteinsPeripheral- located on the
interior/exterior surface of membrane
Integral- are embedded in themembrane
Proteins play a vital
role in transportingmaterials across a
membrane!
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Membrane StructurePhospholipids have both hydrophilic and
hydrophobic regionsNonpolar tails (hydrophobic) are directed
inward, polar heads (hydrophilic) are
directed outward to face bothextracellular and intracellular fluid
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Nucleus
Contains instructions for makingeverything the cell needsThis is chromatin, DNA wrapped around
proteins
The red circles
are histones
(proteins), the
DNA wraps
around the
histones. The
histone DNA
combo wraps
around itself toeventually form
chromosomes!
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Nucleus
Is an inner chamber surrounded byits own membrane
Pores allow mRNA, signal moleculesto enter and leaveNucleolus is a ball of RNA that makes
ribosomes
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Nucleus
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Mitochondria
“Powerhouse” of the cell
Breaks apart glucose to load ATPmolecules with energyCellular Respiration
Some cells have thousands ofthem
A membrane-bound organelle
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Mitochondrion
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Endoplasmic Reticulum
(ER)A system of bubbles and chambers
that form and change constantly
Act like moveable rooms inside thecellContain and transport molecules
Stays near the nucleusRough ER-ribosomesSmooth ER
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Endoplasmic Reticulum
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Golgi Apparatus
Also called Golgi complex or Golgibody
Made of layers of smoothmembranesA cell that does a lot of exporting
has many golgiThink of a golgi as the UPS station
of the cell
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Golgi Apparatus
Stays near the outer cell membrane
Packages and processes proteins
Accepts the polypeptide from RERPackages/folds it into a final shape
Labels it with destination marker
Processes it through the cell andreleases it as a protein
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Golgi Body
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Lysosomes
Bubbles of membranematerial
Have enzymes tobreak down unwantedmaterials like wastes
and toxinsThese are like little
cell “stomachs”
Th E d b S
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The Endomembrane System
NOTE: Endo= internal
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Cell animation
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Cytoskeleton
Maintains shape andsize of cell
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Cytoskeleton
Made from stiffmolecules which worktogether for internaland external cellmovementMicrofilaments made
of actin proteinMicrotubules made
of tubulin protein
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Cytoskeleton
Only animal cells have an extensive cytoskeleton.
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Cilia and Flagella
Hair-like structures on theoutside of a cell
Function is movement
Cilia are like many small oars
Flagella are like whips, one or fewBoth are extensions of the
cytoskeleton
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Cilia and Flagella
cilia
flagellum
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Centrioles
Consist of 2 shortcylinders ofmicrotubules at right
angles to each otherand are situated in thecytoplasm near thennuclear env.
Found in animal cells;organize microtubulesof the cytoskeletonduring cell division
l ll
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Prokaryotic
CellsCell membrane
Cell wall/capsule
CytoplasmDNA in a loop
Ribosomes
Very small
Animal CellsComplex cell membrane
with proteinsNo cell wallCytoplasmDNA as chromatin,
inside nucleusRibosomesMembrane-bound
organelles like ER,Golgi, mitochondriaCytoskeleton1,000s times larger
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You
will
needto
know
all
theseparts!
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How Plants Cells Differ from
Animal CellsThey also havea cell wall
large vacuoleplastids (chloroplasts, chromoplasts,
leucoplasts)
Plant cells lack Cilia, FlagellaFully developed cytoskeleton
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Plant Cell Walls
Made from cellulose
Outside of the cell membrane
Acts as support
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Vacuoles
Large sac that takes
up the majority of aplant cell
Stores water
May store poisonsand wastes as well
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Turgor Pressure
Pressure of a full vacuole againstcell wall
Holds plant up
Wilting is loss of turgor pressure
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Plastids
Double membrane organelles that canstore starch or fatMost common plastid is the
chloroplastOrganelle that conducts
photosynthesis
Numerous in some cells and absentin others
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Chloroplasts
Use light energy to make carbs from CO2
and water
Contains a system of flattened memb. Sacs(thylakoids)
Thylakoids contain green pigment(chlorophyll) which absorbs light and
captures light energy for the cellGranum – stack of thylakoids
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Chloroplast
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Lysosome
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Animal vs Plant Cells
Organelle Function Animal PlantCytoskeleton Support,
movementYes Yes,
but
Cilia/flagella Movement Yes NoCell wall Support No Yes
Plastids Photosynth
esis;storage
No Yes
Centralvacuole
Storage,support
No Yes
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Multicellular Organization
Chapter 4 Sect 3
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C l i l O i ti
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Colonial Organization
Unicellular organisms mayhave begun to live intemporary groups orcolonies
Some cells in the colonieshave specialized inperforming certainfunctions
Colonial organisms are acollection of geneticallyidentical cells that live in a
One volvox can contain
500-60,000 cells, each
which maintain their own
existence!