Cells: The Living Units

• is the "father of microscopy" 
• it was Hooke who coined the term "cell" to describe the basic unit of life
• 1st observed a plant cells (cork) with a crude microscope in the late 1600s

• 1830s
• boldly asserted that all living things are composed of cells

cells arise only from other cells

• 1. the plasma membrane
• 2. the Cytoplasm
• 3. the nucleus

are firmly embedded in or strongly attached to the lipid bilayer

• are not embedded in the lipid bilayer at all
• they attach rather loosley to the membrane surface

span the whole width of the membrane and protrude from both sides (trans = across)

• is one result of the movement of molecules (High concentration → Low Concentration)
• is passive transport, does not require energy
• Ex. Oxygen, Carbon, Fat-soluble molecules can pass freely through the lipid bilayer of the PM

the diffusion of water molecules across a selectively permeable memebrane

Diffusing through the plasma membrane by moving through a specific integral protein

• other integral proteins move molecules across the PM against their concentration gradient
• requires energy

is the mechanism by which large particles and macromolecules enter cells

deforms the membrane to form a membrane-walled sac

• Phagocytosis
• Pinocytosis
• Receptor-mediated endocytosis

is a mechanism by which substances move from the cytoplasm to the outside of the cell

• "cell forming material"
• is the part of the cell that lies internal to the plasma membrane and external to the nucleus

• 1. Cytosol
• 2. Organelles
• 3. Inclusions

• is the jellylike, fluid containing substances within which the other cytoplasmic elements are suspended
• made up of water, ions, and many enzymes
• in many cells, makes up half the volume of the cytoplasm

• Mitochondria 
• Ribosomes
• RER
• SER
• Golgi Apparatus
• Lysosomes
• Peroxisomes
• Cytoskeleton
• Centrioles

• Protein Synthesis
• constructed of proteins plus ribosomal RNA
• not membrane bound

• DNA→RNA→mRNA→protein
• DNA→RNA = Transcription
• RNA→mRNA = Post Transcripted Modification
• mRNA→Protein = Translation

• is literally the "network within the cytoplasm"
• is an extensive system of membrane-walled envelopes and tubes that twists through the cytoplasm

• float freely within the cytosol
• make the soluble proteins that function in the cytosol itself

genetic material in the cell nucleus (DNA), whose instruction are carried to the ribosomes by messenger molecules

• A. the protein product is contained in secretory vesicles; these vesicles ultimately release their contents to the cell's exterior by exocytosis
• B. the membrane of the vesicle fuses to and contributes to the plasma membrane
• C. the vesicle leaving the golgi apparatus is a lysosome, that remains inside the cell

• are spherical, membrane-walled sacs containing many kinds of digestive enzymes
• enzymes called acid hydrolase, can break down almost all large biological molecules
• AKA "demolition crew", because they break apart and digest unwanted substances

• there ability to move
• their internal organization (prokaryotic vs eukaryotic)
• their metabolic activities

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• Sperm + Oocytes = Zygote
• Zygote→Blastocyte (hollow ball)

• Prokaryotic: only domains: bacteria and archaea
• Eukaryotic cells: Plant and Animal kingdoms, including the fungi

consists of a single enclosed compartment that is surrounded by a plasma membrane, lacks a defined nucleus, and has relatively simple organization

• contain a defined membrane-bound nucleus, the nucleus segregates the cellular DNA from the rest of the cell
• can be either unicellular or multicellular

is the control of water balance in animals

translation

• the processes of ribosomes
• kills bacteria by stopping the protein they need in order to survive

• equal concentration of ions in solution and cell
• equilibrium 

• High concentration of ions in solution than in cell
• Solvent will go out of cell, cells will shrivel/shrink

• Lower concentration of ions in solution than in cell
• solvent will go into cell, cells will enlarge

• "Cell Skeleton"
• is an elaborate network of rods running throughout the cytosol
• Supports the cell's structures and generates various cell movement
• not membrane bound

• 1. Microfilaments
• 2. Intermediate Filaments
• 3. Microtubules

the thinnest elements of the cytoskeleton, are strands of protein actin

are tough, insoluble protein fibers, with a diameter between those of microfilaments and microtubules

the elements with the largest diameter, are hollow tubes made of spherical protein subunits called tublins

• is a spherical structure in the cytoplasm near the nucleus
• not membrane bound
• it consists of an outer cloud of protein called the centrosome matrix and an inner pair of centrioles 

• are temporary structures in the cytoplasm that may or may not be present in a given cell type
• Ex. pigments, crystals of protein, and food stores (Lipid Droplets and Glycosomes)

• are spherical drops of stored fat
• look like lysosomes, but can be distinguished by their lack of a surrounding membrane

• "sugar-containing bodies"
• store sugar in the form of glycogen, which is a long branching chain of glucose molecules, the cell's main energy source

• "little nut"
• is the control center of the cell 
• its genetic material, deoxyribonucleic acid (DNA), directs the cell's activities by providing the instructions for protein synthesis

the nucleus is surrounded by a nuclear envelope that consists of two parallel membranes separated by a fluid-filled space

• there may be one or several within a cell nucleus
• contains parts of several different chromosomes and serves as the cell's "ribosome-producing machine"
• More Specific: it has hundreds of copies of the genes that code for ribosomal RNA and serves as the site where the large and small subunits of ribosomes are assembled

• Thymine (T)
• Adenine (A)
• Cytosine (C)
• Guanine (G)

46 chromosome

is the series of changes a cell undergoes from the time it forms until it reproduces itself

a sequence of DNA that gives rise to a protein or functional RNA

• most free radicals are produced in the mitochondria, the organelle with the highest rate of metabolism
• scientist propose that a decrease in energy production by free-radical damaged mitochondria weakens and ages the cells

• propose that aging is programmed into our genes
• telomeres structures that limit the max number of times cells can divide (cap the ends of chromosomes)
• Telomerase is an enzyme that prevents telomeres from degrading by adding more repeating DNA to the ends (occurs in germ-line cells and cancer cells)

a pictorial representation of chromosomes within a individual

• is the complete set of an organism's genes
• located mainly on chromosomes in the cell's nucleus

• is made of chromatin, a combo of DNA and protein molecules
• are not visible in the cell until cell division