chapter 3 cytoplasmic organelles and the nucleus
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Chapter 3 Cytoplasmic Organelles and the Nucleus. What general features can be identified in this “typical” generalized cell?. A Tour Inside a Cell (video). Cells. Structural unit of all living things 50 – 100 trillion cells in human body - PowerPoint PPT PresentationTRANSCRIPT
Chapter 3Cytoplasmic Organelles and the Nucleus
What general features can be identified in this “typical”
generalized cell?
A Tour Inside a Cell (video)
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
Fibroblasts
Erythrocytes
Epithelial cells
Macrophage
Nerve cell
Fat cell
Sperm
Skeletalmusclecell
Smoothmuscle cells
(a) Cells that connect body parts, form linings, or transport gases
(c) Cell that stores nutrients
(b) Cells that move organs and body parts
(d) Cell that fights disease
(e) Cell that gathers information and controls body functions
(f) Cell of reproduction
Diversity of Cell Structure and Function
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– Nucleus– ER– Golgi– Transport Vesicles– Lysosomes– Peroxisomes– Vacuoles– Plasma Membrane
Rough Endoplasmic ReticulumRER 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
Rough ER
Smooth ER
Ribosomes
Interior of rough ER
Protein being made inside ER
mRNA outside ER
Ribosome outside ER
Vesicle
Rough ER
Golgi Apparatus
Accepts vesicles from RER (cis side)
Adds and removes monomers of sugar (small subunits) from glycoproteins
Adds “ID” tags (like phosphate groups) and uses these to “sort” proteins into different vesicles
Dispatches vesicles w/glyco-proteins for shipping (trans side)
Protein inside Golgi apparatus
VesicleGolgi apparatus
Golgi apparatus
Vesicle
Cytoskeleton
3 destinations for proteins within Golgi vesicles1) Secreted from cell2) Remains within vesicles vacuole,
lysosome, peroxisome3) Protein becomes part of plasma
membrane
Vesicle Plasma membrane
Proteins
Protein Synthesis and Export of Proteins
Secretion by exocytosisExtracellular fluid
Plasma membrane
Vesicle incorporatedinto plasma membrane
Coatomercoat
Lysosomes containing acidhydrolase enzymes
PhagosomeProteins in cisterna
Membrane
Vesicle
Pathway 3
Pathway 2Secretory vesicles
Proteins
Pathway 1
Golgi apparatus
Cisterna Rough ER
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
• ER w/o ribosomes• Makes lipids, oils, steroids• Helps break down CHO• Detoxifies drugs by adding –OH groups
water soluble toxins flushed from body
Smooth ER
MitochondriaMitochondria- 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?
MitochondrionInner membrane
Outer membrane
ATP
Cytoskeleton
Network of fibers in the cytoplasm that a) maintains cell shape/mechanical supportb) anchors and/or moves organelles c) helps w/ cell motility
3 components1) microtubules2) microfilaments3) intermediate filaments
Intermediate filament
MicrofilamentCytoskeleton
Microtubule
Microtubules
Structure:Hollow tube made up of α
and β tubulin polypeptide 25 nm diameterCompression Resistent
supports cell shapeForms spindle fibers for
separation of chromosomes, makes up centrioles, and cilia/flagella
Microtubule9 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 fibersStructure: twisted double chain of
actin protein that forms a solid rod7 nm diameterTension 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
Plasma MembraneA cell boundary that selectively controls the movement of substances into and out of the cell = Selective Permeability
Made up of a “mosaic” or collection
Phospholipids
Cholesterol
Peripheral/Surface Proteins
GlycoproteinsTransmembrane/Integral protein
Glycolipid
Glycolipid and glycoproteins = Glycocalyx
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
MicrovilliFingerlike-extensions of plasma membrane
Supported by actin (microfilament) core
Increases cell’s surface area relative to its volume, to increase absorptive and expelling properties
Microvilli and the glycocalyx help cells “stick” together (imagine your fingers interlocked and covered in sugar)
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.