Transcript Chapter 7 A tour of the Cell

Chapter 3
Cytoplasmic Organelles and the
Nucleus
What general features can be
identified in this “typical”
generalized cell?
Cells
• Structural unit of all living things
• 50 – 100 trillion cells in human body
• 200 different cell types that vary in size,
shape, function
• A cells SHAPE reflects its function
Erythrocytes
Diversity of Cell
Structure and Function
Fibroblasts
Epithelial cells
(a) Cells that connect body parts, form linings, or transport gases
Skeletal
muscle
cell
Smooth
muscle cells
(b) Cells that move organs and body parts
Fat cell
Nerve cell
(e) Cell that gathers information and controls
body functions
Macrophage
Sperm
(c) Cell that stores
nutrients
(d) Cell that fights disease
(f) Cell of reproduction
A Tour Inside a Cell
Nucleus
• Porous phospholipid
membrane
• Inner membrane lined
with intermediate
filaments (nuclear lamina)
that maintains shape
• ER often is an extension
of the nuclear membrane
• Contain DNA of
eukaryotic cells – “brain”
of cell
A single strand of DNA can be 3
meters long. How does all that DNA
fit?
Condensation of Eukaryotic
Chromosomes
Nucleosome = DNA coils
around histone proteins
Chromatin = supercoiled
nucleosomes
Looped Domains =
supercoiled chromatin
Chromosome =
supercoiled looped
domains
Ribosomes
•Assembles amino acids into polypeptide chain, which
eventually folds into functional protein
•Made of rRNA and protein
•2 subunits: large and small
Nucleolus
•Located inside nucleus
•makes ribosomal subunits by
combining rRNA and proteins
imported from cytoplasm
•subunits leave nuclear pore and assembles into a
ribosome in the cytoplasm
What is the endomembrane
system?
• System of membrane-bound organelles in cells
that work cooperatively together to create
secretory proteins, membrane-bound proteins,
or plasma membrane proteins
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Nucleus
ER
Golgi
Transport Vesicles
Lysosomes
Peroxisomes
Vacuoles
Plasma Membrane
Rough Endoplasmic Reticulum
RER w/ bound ribosomes
Space w/in ER = cisternae space
Fcn: to fold and modify secretory proteins (glycoproteins)
within cisternae space
-attaches carbohydrates
called oligosaccharides to
growing and folding
polypeptide chain
-- vesicles bud off from
RER and delivers
glycoprotein to Golgi
Smooth ER
Rough ER
Ribosomes
Protein being made
inside ER
mRNA
outside
ER
Ribosome
outside
ER
Interior of
rough ER
Vesicle
Rough ER
Golgi Apparatus
Adds “ID”
tags (like
groups) and uses these to
Accepts
vesicles
fromphosphate
RER (cis side)
“sort” proteins into different vesicles
Adds and removes monomers of sugar (small subunits) from
glycoproteins
Dispatches vesicles w/glyco-proteins for shipping (trans side)
Protein inside
Golgi apparatus
Golgi apparatus
Vesicle
Vesicle
Cytoskeleton
Golgi apparatus
3 destinations for proteins within
Golgi vesicles
1) Secreted from cell
2) Remains within vesicles  vacuole,
lysosome, peroxisome
3) Protein becomes part of plasma
membrane
Vesicle
Plasma membrane
Proteins
Protein Synthesis and Export of Proteins
Cisterna
Rough ER
Proteins in cisterna
Phagosome
Membrane
Vesicle
Lysosomes containing acid
hydrolase enzymes
Vesicle incorporated
Pathway 3
into plasma membrane
Coatomer
coat
Golgi
apparatus
Pathway 2
Secretory vesicles
Pathway 1
Plasma membrane
Proteins
Secretion by exocytosis
Extracellular fluid
Vacuoles
- Stores water, organic compounds, ions,
waste
- Supplemental role in endo and exocytosis
as a “vesicle”
Lysosomes
• Membrane-bound sac
of digestive enzymes
• Acidic env’t
maintained by
pumping H+ ions from
cytoplasm
• Digests food, worn
out cell parts,
programmed cell
death (webbing b/t
fingers, tadpole tails)
Lysosome
Damaged
mitochondrion
Peroxisome
• Breaks down toxic substances in liver
• Breaks down fatty acids into
carbohydrates for use in CR
• In breakdown process, oxygen and
hydrogen combine to create  H2O2
• Peroxide = metabolic waste
Smooth ER
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ER w/o ribosomes
Makes lipids, oils, steroids
Helps break down CHO
Detoxifies drugs by adding –OH groups 
water soluble toxins  flushed from body
Mitochondria
Mitochondria
- Cellular Respiration site
- requires oxygen (O2) to
make ATP from glucose
(C6H12O6)
- ATP is the energy form
used for cellular work
- CO2 and H2O is
produced as waste and
bi-product of cellular
respiration
Oxygen is delivered to our
mitochondria from the air and carbon
dioxide is released back as waste.
Which system is responsible for this
function?
Mitochondrion
Inner membrane
Outer membrane
ATP
Cytoskeleton
Network of fibers in the cytoplasm that
a) maintains cell shape/mechanical
support
b) anchors and/or moves organelles
c) helps w/ cell motility
3 components
1) microtubules
2) microfilaments
3) intermediate filaments
Microtubule
Cytoskeleton
Intermediate Microfilament
filament
Microtubules
Structure:
Hollow tube made up of α
and β tubulin polypeptide
25 nm diameter
Compression Resistent 
supports cell shape
Forms spindle fibers for
separation of
chromosomes, makes up
centrioles, and cilia/flagella
Microtubule
9 sets of 3 arrangement
(ring formation)
Ex. Centrioles, spindle
fibers, basal body of
cilia and flagella
9 + 2 arrangement (9
doublets surrounding
a pair in the center)
Ex. Cilia and Flagella
Radial Spokes and Dynein Arms of
Microtubule
• Dynein arms “walk”
along the
microtubules to bend
and move flagella,
using ATP energy
Microfilaments
AKA: actin fibers
Structure: twisted double chain of
actin protein that forms a solid rod
7 nm diameter
Tension resistent (protects against
“pulling” forces)
Makes up microvilli core, contracts
muscles, causes cytoplasmic
streaming and pseudopod
extensions in cells
Intermediate Filaments
• In btwn microtubules and
microfilaments in size (10 nm)
• Fixes positions of organelles
• Organelles w/motor proteins
can move by “walking” along
intermediate filaments (as if
along a track)
• Helps to maintain cell shape
Glycolipid and glycoproteins = Glycocalyx
Plasma Membrane
A cell boundary that selectively controls the
movement of substances into and out of the cell =
Selective Permeability Transmembrane/Integral
Glycoproteins
protein
Cholesterol
Made up of a
“mosaic” or
collection
Glycolipid
Peripheral/Surface
Proteins
Phospholipids
Why do cells need to increase
permeability rate of the plasma
membrane?
Outside of cells bathed in interstitial fluid
• Nutrient rich “soup”
– Amino acids, sugars, fats, vitamins,
hormones, proteins, salt, waste,
neurotransmitters
• Cells need to absorb what they need from
this fluid AND remove waste in an efficient
manner as needed
One method: microvilli
Microvilli
Fingerlike-extensions of plasma
membrane
Supported by actin (microfilament)
core
Microvilli and the
glycocalyx help cells
“stick” together
(imagine your fingers
interlocked and covered in
sugar)
Increases cell’s surface
area relative to its
volume, to increase
absorptive and expelling
properties
Race to the Board – Cell Drawing
• Class divided into two teams to draw a cell, with
all of its organelles. All organelles covered in
lecture must be represented in the illustration.
• No use of notes allowed. Must be done from
memory.
• All organelles must be accurately drawn, labeled
with correct spelling.
• Proper scientific illustration protocol must be
followed.