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The Microscope Is a Window into the Life of a Cell The light microscope was the first instrument that enabled scientists to view the cell Electron microscopes use streams of electrons focused with magnets to magnify specimens
more than 100,000 times A scanning electron microscope creates a three-dimensional view of specimen Cells The cell is the smallest and simplest unit of life
A cell is composed of an aqueous interior enclosed in a lipid-based plasma membrane Prokaryotes smaller, few/no organelles NO NUCLEUS Eukaryotes bigger, more organelles
Prokaryotes Most prokaryotes have a tough cell wall outside the plasma membrane Prokaryotes: bacteria and archea
Some bacteria have a slippery, protective layer called a capsule Eukaryotic Cells Are much bigger than prokaryotes have many organelles
Eukaryotes: Plants, animals, algae and other protists, Fungi Endosymbiosis Endo(inside) + Sym(same)+Bio(life) The idea that eukaryotic organelles were originally free-living
prokaryotes predation => symbiosis => organelles Endosymbiosis: the evidence The mitochondrion (plural: mitochondria) and chloroplasts reproduce on their own
Mitochondria and chloroplasts have own DNA DNA sequences more like bacteria than like the DNA in their cells nucleus Wrap DNA around different histone proteins
Also bacteria-like The Plasma Membrane Every cell has a plasma membrane that separates the cell from its surrounding environment
Phospholipid bilayer with embedded proteins Phospholipids Opposite behavior on ends Head loves water (hydrophilic) Tail hates water (hydrophobic)
The Plasma Membrane Controls the movement of molecules in & out: Brings necessary molecules in Passes waste out
Communicates with other cells Interacts with environment Anchors the cell in place Proteins of Plasma Membrane
Proteins in the phospholipid bilayer Transport, receptor, adhesion The fluid mosaic model: proteins drift inside the phospholipid bilayer
Eukaryotic Cells: The parts A cell is composed of an cytoplasm interior enclosed in a lipid-based plasma membrane Cytoplasm contains a thick fluid called cytosol, consisting of ions and biomolecules mixed in water An organelle is a cytoplasmic structure that performs
a unique function in the cell The nucleus contains the DNA enveloped in double membranes The mitochondrion (plural: mitochondria) provides the energy that fuels all cellular functions Ribosomes are important protein-manufacturing
organelles Eukaryote Nucleus: Where the DNA is DNA has instructions to make all the stuff for a cell to live, growing, or reproducing Stored as chromosomes
nuclear envelope - a double layer of membrane (outside of nucleus) The Nucleus Houses Genetic Material Nuclear pores are channels through the nuclear envelope
DNA info stays in the nucleus. RNA copies of that info The nuclear envelope contains nuclear pores RNA info will be read by ribosomes Endoplasmic Reticulum: makes stuff
endoplasmic reticulum (ER) a network of connected sacs and tubes made out of membranes smooth ER makes lipids and breaks down toxins for other cellular compartments and help break down toxic organic compounds in the cell
rough ER covered in ribosomes. Makes proteins dotted with ribosomes that produce proteins for Transport Vesicles: Move stuff A transport vesicle is a small sac of membrane used to move lipids, proteins, and
carbohydrates between cellular compartments The transport vesicle fuses with the membrane of the target destination in order to deliver its contents
Golgi Apparatus: Sorts/Ships stuff The Golgi apparatus directs proteins and lipids produced by the ER to their final destination (in or out of cell) addresses packages by adding specific chemical groups
Vesicles move the lipids and proteins from the ER to the Golgi apparatus Lysosomes: they break stuff apart Lysosomes use enzymes to break down macromolecules (big stuff) and release the
parts into the cytoplasm The interior of lysosomes is acidic (pH ~5) Vacuoles: breaking or storage Plant organelles called vacuoles act much like lysosomes to break down macromolecules
Vacuoles can also store ions, water-soluble molecules, and bad tasting compounds ((dont eat me) Vacuoles filled with water to help make the nonwoody parts of plant cells rigid
Mitochondria: the Power plant Uses food molecules to make ATP (energy) Plants also havecalled the chloroplast, which uses sunlight to make energy-storing molecules The mitochondrion is bound by double
membranes that form an intermembrane space Mitochondria Power the Cell The folds of the inner membrane form the cristae, which help to increase the surface
area for chemical reactions Mitochondria use chemical reactions to turn food molecules into ATP, which can be used to fuel the chemical reactions of the cell The process of turning food molecules into energy is called cellular respiration
Chloroplast: solar energy Chloroplast uses light to make ATP. (short lived energy source) Uses ATP from light with CO2 to make sugars Called photosynthesis; releases O2!!!
Sugars = longer term energy storage Sugars used by mitochondria of plant And everything else on earth!!! Cytoskeleton: bones of cell
Protein cylinders and filaments Microtubules (big) Intermediate filaments (medium) Microfilaments (small) Used to: help organelles move, strengthen
membrane, move entire Cilia and Flagella (microtubules used for swimming) Many protists and animals have cells covered in hairlike cilia
Microtubules inside cilia Motor proteins use ATP to bend cilia Cilia can be moved back and forth like oars Flagella: another way to swim flagellum (plural: flagella) has microtubules
inside (like cilia, but longer) Looks like a long tail. Is used to swim Used by bacteria, archaeans, and protists, and the sperm cells (plants and animals) Concept & Review
Questions Concept Quiz A. B. C.
D. Where is the secreted protein insulin synthesized? In the Golgi apparatus On the rough ER
On ribosomes in the cytoplasm In the nucleus Concept Quiz Two main types of cells are ______ and _______.
A. Prokaryotic; eukaryotic B. Bacterial; animal C. Nerves; muscles D. Plant; animal Concept Quiz
The boundary structure that physically defines a cell is the . A.Cell wall B.Selective permeability C.Plasma membrane
D.Protein coat Not Happy with your grade? Not understanding the material? Remember that the TLCC has
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