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• Cell


  • Smallest, basic unit of life that is responsible for all of life's processes
  • Smallest unit that can live on its own
• Domains of life


  • Eubacteria
  • Archaebacteria
  • Eukarya
• Eubacteria


  • Prokaryotic
  • Largest domain of life: all bacteria except archaebacteria
  • Cannot be seen by the naked eye
• Archaebacteria


  • Prokaryotic
  • Inhabit some of the most extreme environment on the planet – extremophiles
• Eukarya

  • Eukaryote
  • Multicellular: Animalia, Plantae, Fungi
  • Unicellular: Protista
• Nucleus


  Control center of the cell – contains genetic materials
• Plant Cells vs. animal cells

  Animal cells do not contain chloroplasts, not surrounded by cell walls and vacuoles are smaller in animal cells
• Nuclear membrane


  • Protects The Genetic Material
  • Exchange of material between nucleus and rest of the cell occurs through nuclear pores
  • Main determinant whether the cell is eukaryotic or prokaryotic
• Prokaryote vs Eukaryote


  • No true nucleus = no nuclear membrane
  • DNA is condensed in a nucleoid
  • Carry extrachromosomal plasmids
  • With true nucleus = with nuclear membrane
  • No membrane bound organelles
  • With membrane bound organelles – mitochondria, lysosomes, endoplasmic reticulum, Golgi apparatus
  • 30 s + 50 s = 70s
  • 40s + 60s = 80s
  • 60s subunit is inhibited by shiga toxin of shigella
  • Bacteria (monera/archaea)
  • Plants, animal, fungi
  • Circular DNA (Except Borrelia burgdorferi)
  • Continuous genome
  • Linear DNA
  • Segmented genome
  • Unicellular always
  • Unicellular or multicellular
• Nucleoli/Nucleolus

  • Site of ribosomal assembly
  • Contains enzymes involved in the synthesis of DNA and RNA
• Nucleoplasm


  Liquid part of the nucleus
• Chromatin/Chromosomes

  • Organized structural unit
  • Chromatin: threadlike, cell is not dividing
  • Chromosomes: rodlike, involved in cell division
  • XX – female
  • XY – male
  • Histones: small basic proteins that converts chromatin to chromosomes via condensation
  • Histone (simple protein) + DNA = nucleosome (conjugated protein)
  • Telomeres: end portions of DNA chromosomes that do not code for proteins
  • Main cause of age-related breakdown of cells
  • Short telomerase = no cell reproduction = degeneration
  • Related to immortality of cancerous cells
• Cell membrane

  • Outermost structure of the cell that decides its contour
  • Semipermeable – contains phospholipids (main structural component). Glycoprotein, glycolipids, cholesterol (for fluidity and consistency), arachidonic acid
  • Receptors: integral or peripheral
  • Lipid rafts

  
• Fluid mosaic model


  • Describes the fluidity of the cell membrane – constantly moving
  • Cholesterol modulates membrane fluidity in a bidirectional manner
• Cell membrane composition

  • Plants: Cellulose
  • Bacteria: Peptidoglycan
  • Fungi: Ergosterol
  • Animals: Phospholipid bilayer
  • Exoskeleton of crustaceans and arthropods: Chitin
• Passive transport vs Active transport

  • Passive: along a conc gradient, does not require energy, simple diffusion vs facilitated
  • Active: against a conc gradient, requires energy, primary: require energy (Na/K ATPase), secondary: uses conc gradient created by primary active transport (SGLT2 in kidneys)
• Cytoplasm


  Liquid part of the cell
• Cytosol

  • Semi-transparent fluid that suspends other elements
  • Site of Glycolysis, Glycogenesis, Fatty acid synthesis
• Cytoskeleton


  • Scaffolds of the cell: helps maintain the shape and internal organization of the cells
  • Involved in cell division and movement
• Inclusions

  • Non-membrane bound
  • Nutrients and cellular by-products – pigment granules, glycogen granules, lipid granules
  • Hemosiderin: breakdown products of hemoglobin, "wear-and-tear pigments"
  • Anthracotic pigments: carbon + pyrenes in lungs
• Organelles


  Cellular organs
• Ribosomes


  • Not enclosed by a membrane
  • Scattered around the cell
  • rRNA + protein
  • For protein synthesis (translation)
  • Binding sites: Shine-Dalgarno (prokaryotes), Kozak (Eukaryote)
• Endoplasmic reticulum


  • System of fluid filled cisterns
  • Rough ER – protein synthesis
  • Smooth ER – lipid synthesis, detoxification
• Golgi apparatus

  • Stacks of flattened sacs/cisterns
  • Packagers of the cells – store, modify, package proteins
  • Post-translational modification
• Lysosomes


  • Bags containing digestive enzymes/hydrolases
  • Scavengers: digest worn out cells, suicidal bags, demolition bags
  • Site of autolysis

  
• Peroxisomes

  • Contains oxidative enzymes
  • Microbodies
  • For detoxification – degrade H2O2

  
• Mitochondria


  • Powerhouse of the cell: site of ATP synthesis
  • Has its own mitochondrial DNA
  • ATP: form of energy in the body; produced via oxidative phosphorylation
  • Site of Beta-oxidation, Electron transport/Respiratory chain, Oxidative Phosphorylation, Kreb's cycle, Ketogenesis

  
• Chloroplast

  • Contains chlorophyll
  • Has its own DNA
  • Photosynthesis, MEP pathway

  
• Cell division

  • Interphase – preparation, metabolic phase
  • G1/Gap 1/Growth phase: aka preDNA phase; longest phase in cell division
  • S phase: DNA replication phase
  • G2 phase: DNA supercoils and condenses; repair of DNA; machinery of mitosis is assembled; duplication of organelles
  • G0: dormancy
  • Mitosis – Division of nucleus
  • Prophase: chromosomal formation
  • Metaphase: chromosomal alignment by spindle fibers (composed of tiny microtubules)
  • Anaphase: chromosomal migration
  • Telophase: nuclear membrane reconstitution
  • Cytokinesis – division of cytoplasm; total separation of the cell
• Mitosis vs Meiosis

  • Mitosis: Cell multiplication, Cytoplasmic divisions, For somatic cells, Produces 2 diploid cells (2n)
  • Meiosis: Cell division, Cytoplasmic (meiosis 1) + nuclear divisions (meiosis 2), For gametes, Produces 4 haploid cells (n)
• Binary fission

  • Asexual process that produces identical offspring
  • FtsZ protein: similar to tubulin in eukaryotes – ring composed of repeating units of proteins, triggers the accumulation of other proteins that work together to acquire and bring new membrane and cell wall materials to the site
• Binary fission process

  1. Replication of the circular prokaryotic chromosome begins at the origin of replication and continues in both directions at once

  2. Cells begin to elongate and the FtsZ proteins migrate toward the midpoint of the cell

  3. Duplicated chromosomes separate and continue to move away from each other towards the opposite ends of the cell. FtsZ proteins form a ring around the periphery of the midpoint between chromosomes

  4. FtsZ directs the formation of a septum that divides the cell. Plasma membrane and cell wall materials accumulate

  5. After the septum is complete, the cell pinches in 2, forming 2 daughter cells. FtsZ is dispersed throughout the cytoplasm of the new cells
• Carbohydrates


  • Contains C, H, O
  • Formerly known as hydrates of carbon; but not all carbohydrates follow the (CH2O)2 empirical formula
  • Polyhydroxyaldehydes or polyhydroxyketones or substances that yield these molecules upon hydrolysis
  • Produced by plants via photosynthesis
  • Building blocks: monosaccharides bound by glycosidic bonds

  
• Functions of carbohydrates

  • In Plants: Structural element as cellulose, Energy reserve as starch
  • In Animals: Energy via carbohydrate oxidation, Short-term energy reserve as glycogen, Source of carbon atoms for the synthesis of other biochemical substances, Structural components of cell membranes (with lipids), Cell-cell and cell-molecule recognition process (with proteins)
• Stereoisomerism

  • Chirality: "handedness", in which a carbon has 4 different groups attached
  • Mirror images: reflection of an object in a "mirror"
  • Achiral: superimposable mirror images without chiral centers
  • Chiral: Nonsuperimposable mirror images: not all points coincide when the 2 molecules are laid upon each other
  • L/D stereoisomers: handedness of a molecules based on the penultimate carbon; based on structure
  • +/-: based on the bending of a plane of polarized light = based on optical activity(has one direction only)
  • Stereoisomers: same molecular formula and structural formula but difference spatial orientation
  • Enantiomers: nonsuperimposable mirror image stereoisomers
  • Diastereomers: nonsuperimposable non mirror image stereoisomers
  • Epimers: differ on one chiral carbon configuration
• Fisher projection


  • 2D structural notation; chiral centers are the intersection of vertical and horizontal lines
  • Functional groups of high priority are written at the top
  • Vertical lines are atoms placed in the same plane of the paper; horizontal lines are atoms directed out of the page
  • Uses L and D system based on glyceraldehyde enantiomers

  
• Classification of carbohydrates by molecular size

  • Monosaccharides: single unit
  • Disaccharide: 2
  • Oligosaccharide: 3-10 monosaccharide units
  • Polysaccharide: polymeric carbohydrate that contains many monosaccharides covalently bonded to each other
• Monosaccharides

  • Aka simple sugars
  • Pure: water soluble, white, crystalline solids
  • Cannot be broken down into simpler substances via hydrolysis
  • Almost all monosaccharides are right-handed
  • All are reducing sugars
  • All have mutarotation

  
• Classification of monosaccharides

  • Based on functional group (other than the hydroxy): Aldose, Ketose
  • Based on number of carbons: Hexose, Diose, Triose, Tetrose, Pentose, Sialic acid

  
• 1. glyceraldehyde


  • Intermediates of glycolysis
  • Converted to pyruvate