Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 6: A tour of the Cell, Link Title - Coggle Diagram
Chapter 6: A tour of the Cell
Concept 1-Biologists use microscopes and biochemistry to study cells
Microscopy:
Development of instruments extend human senses.
3 Important parameters of microscopy
-Magnification: Ratio of objects image size to real size vs. specimen
-Resolution: Measure of the clarity of the image.
-Contrast: Visible difference in brightness between parts of the sample
Light Microscope
: visible light passed through glass lens.
-Bend light= Image magnified
Electron Microscope:
focus beam of electrons through the specimen.
Scanning Electron:
Uses a beam of electrons on the surface of the specimen (3-D View).
Transmission Electron:
Beam of electrons to view internal structures of cells.
Cell Fractionation:
Takes cells apart and separates the major organelles.
-Centrifuge fractionate cells into component parts (differential centrifugation).
6.6-The cytoskeleton is a network of fibers that organizes structures and activities in the cell
Cytoskeleton: gives the cell shape and mechanical support, especially in animal cells that lack walls.
anchors organelles + holds enzymes in place,
enables cell motility, whole-cell movement and the transport of materials inside the cell.
Components of the Cytoskeleton
Three main types of fibers:
-Microtubules:thick hollow rods made of tubulin; shape the cell, guide organelle movement. They grow from the centrosome, which contains centrioles in animal cells.
-Microfilaments (Actin Filaments):thin rods made of actin; bear tension, support the cell’s shape, and form structures like microvilli.
-Intermediate Filaments: medium-sized fibers made of proteins like keratin; provide long-term support and hold organelles, such as the nucleus, in place.
Cilia and Flagella
-Flagella moves with a tail-like, wave motion (ex: sperm)
-Cilia beat back and forth like oars and can move fluids across tissues (ex: clearing mucus in the trachea)
Concept 2-Eukaryotic cells have internal membranes that compartmentalize their functions
Prokaryotes
-Small, simple
No membrane bound organelles (No ER or Golgi Apparatus)
-DNA concentrated in region that is not membrane enclosed: Nucleotide
Eukaryotes
-Large, complex
Has membrane bound organelles ( has no nucleus)
All cells have
Ribosomes
Genetic Material
Cytoplasm or Cytosol
Cell Membrane
Plasma Membrane
: selectively parable membrane
Ribosomes
: Protein synthesis
Chromosomes
: carry genes in form of DNA
Endomembrane system:
(Prokaryotes don't have)
Membrane Bound organelles -> Transfer through vesicles
Nuclear Envelope
Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Vacuoles
Plasma membrane
Concept 3-The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes
Nucleus:
Contains most genes in the Eukaryotic cell ( located in Mitochondria + Chlorplast)
Nucleus
: Structures within non-dividing nucleus
Type of RNA called Ribosomal RNA(rRNA) synthesized forms genes i the DNA.
mRNA:
carries info from the DNA; Transported to the cytoplasm via nuclear pores.
Ribosomes:
Complexes made of ribosomes RNA+ Proteins, carryout protein synthesis.
Build proteins into 2 cytoplasmic regions.
Structural Identities
Free Ribosomes :
Are suspended into Cytosol.
Bound Ribosomes:
are attached to outside of the endoplasmic reticulum or nuclear envelope.
Proteins imported from cytoplasm are assembled w/ rRNA into large and small subunits of ribosomes.
Nuclear Envelope:
Encloses the nucleus, separate contents from cytoplasm (double membrane)
Nuclear Lamina:
Lines nuclear side of envelope, protein filaments maintain shape of nucleus by mechanical support. EX: In animal cells called intermediates filaments;
-Nuclear lamina+ matrix helps organize genetic material so if functions efficiently
DNA-> Chromosomes
DNA+ Proteins-> Chromatin
Pore Complex:
Intricate protein structure plays a role in cells by regulating entry and exit of protein + RNA + Macromolecules.
Concept 4-The endomembrane system regulates protein traffic and performs metabolic functions
Endomembrarane system:
nuclear envelop,
endoplasmic reticulum,
Golgi Apparatus,
lysosomes,
Varies vacuoles + Vesicles
Plasma Membrane
Golgi Apparatus,
Synthesis of proteins, transports of proteins into membrane + organelles or out of the cell, metabolism, + movement of lipids, + detoxification of poisons.
Endoplasmic Reticulum:
Extensive network of membranes accounts for more that ½ total membrane in many eukaryotic cells.
Cisternae
: Network of membranous tubules + sacs
Smooth endoplasmic
: outer surface lacks ribosomes
Rough Endoplasmic:
Studded w/ ribosomes on outer surface of the membrane.\
Functions of Smooth ER’s
Synthesis of lipids- including oils, steroids, and new membrane phospholipids
Metabolism of carbohydrates
Detoxification of drugs + poisons
Storage of calcium ions Ex: in muscles, making them more water-soluble +easier to flush from the body
Functions of Rough ER’s
Many cells secrete proteins produced by ribosomes attached to rough ER.\
Certain pancreatic cels synthesized the proteins insulin in the ER and secrete hormones into the bloodstream
Most secretory proteins: Glycoproteins ( proteins w/ carbohydrates covalently bonded to them)
Transport vesicles: vesicles in the transit from one part of the cell to another(membrane factory for the cell)
Golgi Apparatus
Golgi Apparatus: warehouse for receiving, sorting, shipping, + even some manufacturing
•products of ER, proteins, are modified + stored sent to other destinations.
manufacturers some macromolecules Ex: Pectins + other noncellulose polysaccharides made
in Golgi + added to the plant cell w/ cellulose.
2 - Sides of Golgi Stack = cis face"on the same side" located near ER + trans face “on opposite side" gives vise to vesicles that pinch off and travel to other sites.
Ex: glycoproteins formed in ER have carbohydrates modified, first in ER itself, then as they Pass through Golgi.
•gives vise to vesicles that pinch off i travel to other sites.
Ex: Pectins + other noncellulose polysaccharides made
in Golgi + added to the plant cell w/ cellulose.
Lysosomes membrane sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules.
lysosomal enzymes work best in acidic environments found in lysosomes.
• Hydrolytic enzymes + lysosomal membranes made by rough
Lysosomes
carry-out intracellular digestion in a variety of circumstances.
Phagocytosis
: Amoebas + unicellular protists eat by engulfing smaller organisms or food particles.
Food-vacuoles f
uses w/ a lysosome, whose enzymes digest the food.
Digestion products simple sugars, amino acids, + other
monomers. = Pass into the cytosol = become nutrients for the
cell .
macrophages
macrophages: type af white blood cell helps defend the body.
• hydrolytic enzymes recycle cell's own
organic materials = autophagy: damaged organelle or small amount of cytosol becomes surrounded by
double membrane.
Ex: human liver cell = recycles half of its macromolecules each week.
Vacuoles
Vacuoles: large vesicles derived from the ER + Golgi apparatus.
vacuolar membrane selective in transporting solutes; = Solution inside vacuole differs in composition from cytosol: contractile: pump excess, H2O out of cells, maintaining suitable concentration of ions + molecules. inside
Plants: Small vacuoles hold reserves of important organic compounds; help protect plants against herbivores by storing compounds, unpalatable to animals.
Central vacuoles: develops by the coalescence of smaller vacuoles. (major role in growth of plant cells).
Cell sap: plant cells main repository of inorganic ions
Ex: Potassium + Chloride.
6.5-Mitochondria and chloroplasts change energy from one form to another
Mitochondrias
: sites of cellular respirations, process uses O to generate ATP by extracting energy from sugar, fats, and fuels
thylakoids: form flattened, interconnected sacs.
Stroma: fluid inside outside the thylakoids.
Plastids: costery velated plant organelles.
Granum: thylakoids stacked like polar chips
Chloroplasts
- found in plants + algae, sites for photosynthesis.
• converts solar energy to chemical energy.
endosymbiont theories: an early ancestor of eukaryotic cells engulfed in O using nonphotosynthetic prokaryotic cells
Engulfed cells→ relationship w/ host cell was enclosed = endosymbiont (cell living within another cell)
-have 2 membranes surrounding them
•contain ribosomes, as well as circular DNA molecules associated w/ inner membranes.
are autonomous (somewhat independent ) organelles that grow and reproduce w/in cells.
found in nearly all eukaryotic cells , including plants, animals, fungi, + most protists
some cell = single large mitochondria → # correlates with the cell level of single metabolic activity.
Ex: Cells that move or contrast have proportionally more mitochondria per vol. then less active cells.
2 membranes encrusting mitochondria is a phospholipid bilayer
Cristae: outer membrane is smooth, inner membrane is convoluted.
mitochondrial matrix: enclosed by the inner membrane.
6.7-Extracellular components and connections between cells help coordinate cellular activities
Extracellular Components & Connections- Structures outside the plasma membrane (ex- cell membrane)
Cell Walls (Plants, Some Protists, Fungi, Bacteria)
Functions
Protects cell
Maintains shape
Prevents excessive water uptake
Helps plant stand upright
Structure:
Made of cellulose microfibrils in a matrix of polysaccharides & proteins
Primary cell wall: thin, flexible, forms first
Middle lamella: pectin-rich “glue” between cells
Secondary cell wall: thick, strong layer added after growth
Extracellular Matrix of Animal Cells
Main Components:
Collagen: strong structural protein (40% of body’s protein)
Proteoglycans: core protein + many carbohydrate chains
Fibronectin: connects ECM to cell surface via integrins
Integrins: membrane receptors linking ECM ↔ cytoskeleton
Cell Junctions
Purpose: Connect and communicate between neighboring cells
In Plants:
Plasmodesmata: channels through cell walls; connect cytoplasm of adjacent cells for transport of water, ions, and small molecules
In Animals:
Tight Junctions: seal cells together; prevent leakage (ex: intestinal lining)
Desmosomes: anchor cells together; provide mechanical strength
Gap Junctions: communication channels; allow ions & small molecules to pass (similar to plasmodesmata)
6.8-A cell is greater than the sum of its parts
A Cell Is Greater Than the Sum of Its Parts- Cellular life depends on the coordination and interaction of all cell structures and processes.
Integration of Structure and Function- Each organelle has a specific role, but cell function emerges from their cooperation.
-Structure and function are closely related at every level of organization.
Macrophage (Immune Cell)
Process: Defends body by engulfing and digesting bacteria
Coordination Among Components:
Cytoskeleton (actin filaments): moves cell and forms pseudopodia to capture bacteria
Link Title