Transcript Cell Organelle packet - Hicksville Public Schools / Homepage

 Light
Microscope
 Electron Microscope



Focuses a beam of electrons through the
speciman.
Two types
TEM and SEM (transmission and scanning)


TEM: through a thin section of the speciman, used to
view ultrastructure of cell.
SEM: Detailed surface, 3D image
 To
take cells apart
 WHY?
 To study the individual organelles
 Ultracentrifuge: separates cells according to
densities.
 Homogenization: disruption of cells, two
parts are created



Pellet: larger structures at the bottom
Supernatant: smaller parts of the cell suspended
in the liquid above the pellet.
Repeated decantation collects smaller and
smaller components.
 Prokaryotic:
 -no
true nucleus, nucleoid(concentration of
DNA), no membrane
 -ex. Bacteria
 Eukaryotic:
 -true membrane organelles
 -has endomembrane system: membranes in
the cell that are related through direct
physical continuity or by transferring
segments in vesicles. These include nuclear
envelope, endoplasmic reticulum, Golgi body,
lysosomes, vacuoles and Plasma membrane.
 Bound
by nuclear envelope(phospholipid
bilayer), porous
 Contains DNA(hereditary information)




Normally spread out in threadlike matrix called
chromatin.
Condenses to form Chromosomes prior to cell
division.
Chromosomes=DNA + Proteins called Histones
Histones organize DNA, coiling it into bundles
called nucleosomes.
 Nucleus
also contains
nucleoliconcentrations of
DNA in the process of
manufacturing
components of
ribosome.
 Serves as the site for
the separation of
chromosomes during
cell division.
 Subunits
are manufactured in the nucleus
and consist of RNA molecules and proteins.
 Subunits- 60S and 40S move across the
nuclear envelope and into the cytoplasm
where they are assembled into a single 80S
ribosome.
 “S” stands for Svedbergs…which is the
sedimentation coefficient…which is the
velocity of sedimentation(think centrifuge!)
 Assist in the assembly of amino acids into
proteins.
Flattened stacks involved in the production of
materials.
 Cisternal Space-look like maze-like channels,
closely associated with the nucleus.
 Rough ER
 -has bound ribosomes attached
 Many specialized cells secrete proteins
(ex.insulin)
 -creates glycoprotein (secretory pro) by
attaching polysaccharide groups to polypeptides
as they are assembled by the ribosomes.
 Leave by secretory vesicles

 Smooth
ER
 -no ribosomes
 Carries out various activities including the
synthesis of lipids and hormones (sex
hormones) and metabolism of carbs (Liver:
glycogen into glucose and release into
bloodstream.)
 Especially in cells that produce these
substances for export from the cell.
 In liver cells, smooth ER is involved in the
breakdown of toxins, drugs, and toxic by
products from cell reactions.
 Increasing
drugs, causes an increase in the
production of smooth er.
 Individual can now intake more toxins and
break them down.
 This causes an increased tolerance!
 Group
of flattened sacs arranged like a stack
of bowls
 Modify and package proteins and lipids into
vesicles-small, spherically shaped sacs that
bud from the golgi apparatus.
 (Center of manufacturing, gets deliveries
from ER)
 Vesicles will merge with plasma membrane
and release their contents to the outside of
the cell.
 Vesicles
form the Golgi apparatus that
contain digestive hydrolytic enzymes.
 Break down food, cell debris, and foreign
invaders such as bacteria
 Not present in plant cells
 Apoptosis: programmed cell death! Ex. Rid of
webbing between fingers and toes.
 Break
down various substances
 During the process, oxygen combines with
hydrogen to form toxic hydrogen perioxide!
 The hydrogen perioxide is converted into
water!
 Common in liver and kidney cells(break down
toxic substances) and in plant cells that are
carrying out photosynthesis.
 Carry
out aerobic respiration
 Two membranes, inner makes up the
infolding called cristae. Matrix is the space
within the cristae.
 Folds increase surface area for respiration.
 -made
of three protein fibers of increasing
diameter. (respectively)
 -involved in establishing the shape of or in
coordinating movements of the
cytoskeleton(the internal structure of the
cytoplasm).
 Made
of the protein tubulin
 Provides support and motility for cell
activities.
 Found in the spindle apparatus (guide the
movement of chromosomes during cell
division)
 Found in the cilia and flagella (project from
plasma membrane to provide motility for the
cell).
 Provide
support for maintaining the shape of
the cell.
 Made
of actin
 Involved in cell motility
 Found in muscle cells and phagocytes
 Protrude
from the cell membrane
 Make wavelike movements
 Flagella-long and few
 Cilia-short and many
 Ex. 1 flagella propels sperm, many cilia line
the respiratory tract and sweep away debris.
 Structure –Both consist of microtubules
arranged in a “9 + 2” array- nine pairs of
microtubules arranged in a circle surrounding
a pair of microtubules.
Microtubule organizing centers
 Centrioles –a pair, enclosed in a centrosome,
located outside of the nuclear envelope, gives
rise to the microtubules that make up the
spindle apparatus used during cell division.
 Basal Bodies-found at the base of each flagellum
and cilium and organize their development.
 Centrioles and Basal bodies: both made of 9
triplets sets arranged in a circle.
 Plant Cells lack centrioles…only lower plants
(mosses and ferns) with motile sperm have
flagella and basal bodies.

 Found
in plants, fungi, protists, and bacteria
 Develop outside of plasma membrane
 Provide support of the cell
 Plants: cell wall made of cellulose(beta
glucose polysaccharide)
 Fungi: cell wall made of cellulose or chitin (a
modified polysaccharide that is different
from cellulose in that one of the hydroxyl
groups is replaced by a group containing
nitrogen. )
Fluid filled, membrane bound organelles
 Transport Vesicles:
 -move materials between organelles or between
organelles and the plasma membrane.
 Food Vesicles:
 -Temporary nutrient receptacles
 -merge with lysosomes, whose digestive enzymes
break down the food.
 Storage Vesicles:
 -in plants they store starch, pigments, and toxic
substances(nicotine)

 Central
Vacuole:
 -large bodies that occupy most of the
interior of some plant cells.
 -When filled, they exert turgor pressure on
the cell walls, which maintains the cells
rigidity.
 -store nutrients and carry out functions
otherwise assumed by lysosomes in animal
cells.
 Contractile Vacuoles:
 -single-celled organisms collect and pump
excess water out of cells.
 Anchor
cells to
one another and
provide a
pathway for
cellular
exchange.
 Protein
attachments between animal cells
inside the plasma membrane
 Have a disc-shaped structure from which
protein fibers extend into the cytoplasm.
 Hold together tissues that undergo a
considerable stress
 Ex. Skin or heart
 Tightly
stitched steams between
animal cells.
 Completely encircles each cell,
preventing the movement of
materials between cells
 Characteristic of cells lining the
digestive tract where materials are
required to pass through cells
(rather than intercellular spaces)
to penetrate the bloodstream.
 Narrow
tunnels between animal cells that
consist of proteins called connexons.
 Connexons prevent the cytoplasm of each cell
from mixing but allow the passage of ions and
small molecules.
 Allow cell communication through the exchange
of materials or through the transmission of
electrical impulses.
 Narrow
channels between plant cells
 A narrow tube of ER(desmotubile, surrounded
by cytoplasm and the plasma membrane,
passes through the channel.
 Material exchange through plasmodesmata
occurs through the cytoplasm surrounding
the desmotubule.
 This
theory states that eukaryotic cells
originated from a symbiotic partnership of
prokaryotic cells.
http://www.sumanasinc.com/webcontent/ani
mations/content/organelles.html
 This
is a theory of how Eukaryotic organisms
evolved from Prokaryotic cells.
 Reminder:

Prokaryotic differences:







Lacks a true nucleus; nucleoid
Simpler in structure, has few organelles
Has many ribosomes
Rigid cell wall with an outer capsule
Can have flagella, pili(for attachment)
Due to simplicity, limits metabolic activities
Smaller…so limits the amount of genetic material
possible in the prokaryote!
 How
did the endomembrane structures form
that were not there… theory that the plasma
membrane infolded.
 NEXT…ENDOSYMBIOTIC THEORY
 This theory believes that the mitochondria
and chloroplasts were once formally small
prokaryotes living inside a larger prokaryotic
cell that served as the host.
 The theory hypothesizes that mitochondria
evolved from aerobic heterotrophic
prokaryotes. Chloroplasts evolved from
photosynthetic prokaryotes. They became
endosymbionts(living inside another cell)
 They
gained entry to the host cell as
undigested prey or parasite.
 It became mutually beneficial!
 If you were a heterotrophic prokaryote, a
“chloroplast” would provide food!
 If you were an anerobic prokaryote, a
“mitochondria” would provide more ATP.
 As they became more interdependent, the
endosymbionts and the host would become
inseparable.
 This is a merger of lineages!! Very different
from traditional evolutionary divergence.
(cladogenesis)
 1)they
are the same size as Eubacteria
 2) The inner membranes of mitochondria and
chloroplasts have several enzymes and
transport systems similar to prokaryotes.
 3) they also reproduce through binary
fission(same as Pro)
 4)if their ribosomes are sliced open and
studied, they resemble prokaryotes more
than a eukaryotes.
 5) Mitochondria and chloroplasts contain
circular DNA like prokaryotes.