Midterm 2 (Ch.5-11) Flashcards
The cell
The basic unit of life (but remember viruses)Unicellular and multi-cellular organisms>200 cell types in humansAll cells share basic components
The microscope
• The light microscope • Electron microscope : can be used for viruses and very small things • Anton Van Leewenhoek (1632-1723) ○ Father of microbiology ○ First one to observe blood cells and capillaries.
Phospholipids
• The plasma membrane separates the cell from its environment • Consists of a bilayer, mostly of phospholipids • Proteins allow communication between the outside and inside “world” • Fluid Mosaic Model: Membrane components are mobile
The prokaryotic cell
No real nucleusLittle internal organization Much smaller than eukaryotes
The eukaryotic cell
• DNA contained in the nucleus • Membrane enclosed organelles • Internal compartments of special functions
The cell nucleus, the ‘office’ of the cell
Contains the DNASurrounded by a double membrane nuclear envelope The envelope contains pores for molecule transport
The endoplasmatic reticulum, the ‘factory’ of the cell
Interconnected tubes and flattened sacs-Rough ER Site of the ribosomes Site for membrane- and secreted proteins-Smooth ER Makes membrane vesicle
The Golgi apparatus, the ‘shipping department’ of the cell
Stacked flattened membrane sacsContain enzymes to breakdown macromoleculesRelease simple sugars, amino-acids and fats to be recycledTo clear cell of damaged organellesAs source of foodTo destroy invading bacteria or viruses
Vesicles, movement in the cell
Membrane-enclosed sacsTransport vesicles for substance movement from location to location
The lysosomes , the ‘clean-up crew’ of the cell
Specialized structure in plants and fungi Breaks down substancesAdds specific chemical groupsTargets them to their destinations
The central vacuole, the storage of the cell
Small spherical organelles Processes new proteins and lipids Stores chemicals for later use Fills with water to provide rigidity
The mitochondrion, the power plant of the cell
Double-membrane organelleInner membrane folded into cristae Harnesses energy from chemical breakdown Site for cellular respiration – ATP production(Converts Sugars into CO2 and H2O)
The chloroplast, the site of photosynthesis
Double-membrane organelleContains grana made of cylindrical sheets called thylakoids Converts CO2 and H2O into sugars using lightChlorophyll enables photosynthesisChlorophyll are embedded in the thylakoid membranes
The cytoskeleton, for the shape and movement of the cell
Gives the cell its shapeProvides internal supportIs responsible for movement Microtubules radiate out from the center
Cytoskeleton components
–Microtubules Microtubules radiate out from the center Used as tracks for vesicle movement A helical polymer of tubulin monomers Grow or shrink by adding or losing monomers–Intermediate filaments Ropelike filaments Provide structural support–Microfilaments Smallest diameter Made of actin monomers Involved in cell crawling
The amoeba
MicrofilamentsInvolved in cell crawling
Cilia and flagella
Cilia beat in unison like oars Flagella beat like whips
The bacterial flagellum
Very different from eukaryotic flagella H+ ions pumped out of the cellH+ ion entry causes the motion Flagellum rotates like a propeller*run– no change in direction *tumble– change in direction
Evolution of organelles
Organelles evolved from prokaryotes engulfing other cells Mitochondria and chloroplasts formedendosymbiotic relationship with the host Eukaryotes most likely evolved from prokaryotesLarger prokaryotes ingested smaller prokaryotesOrganelles evolved from other cells
The plasma membrane, gate and gatekeeper
All cells have plasma membraneSeparates the cell from its environmentServes as selectively permeable barrierBiologically important molecules transported across the membraneHydrophobic phospholipid bilayerBarrier to movement: Large and charged moleculesSmall molecules can passhydrophobic molecules can pass
Transport (passive)
concentration gradients: areas of abundance to scarcityPassive transportDownhill in energyMovement from high to low concentration
Transport (active)
concentration gradients: areas of abundance to scarcityactive transportRequires added energyMovement from low to high concentrationEnergy derided from ATPProduces a concentration gradient
What does DNA turn into and so on… (DOGMA of Biology)
DNA to RNA to Protein
Passive transport
Small molecules diffuse through membranes ( Phospholipid Bilayer)Larger molecules and ions enter through protein carriers(Channel proteins and Carrier proteins)
Active transport
Active carriers use energy from ATP Energy changes the shape of the carrier Produces a concentration gradient
Active carrier proteins
Movement of molecules across a membrane, up a concentration gradient Use energy from breakdown of ATPSodium-potassium pump as an example
Osmosis
Water moving passively across the membrane
Exocytosis
Release of substances from the cell Vesicles fuse with plasma membrane Fusion with the membrane causes release
Endocytosis
Inward budding of the membrane»_space;>Forms a vesicle 1. Non-specific endocytosis: pinocytosis (‘cell drinking’)2. Specific endocytosis: receptor-mediatedReceptors select targeted substances Only these substances are pull into the cell
Phagocytosis
Ingestion of entire cells: ‘cell-eating’Membrane receptors identify the bacterium (for example) Pseudopodia extend around the bacterium
Receptors for cell signaling
*hydrophobic – signaling molecules can pass through the plasma membrane and directly affect processes inside the cell. *hydrophilic– signaling molecules cannot pass through the plasma membrane and must bind receptors at the cell surface to indirectly affect processes inside the cell. Cell-surface receptors Intracellular receptors
Metabolism
The sum of all chemical reactions in the bodyTransfers energy following the laws of thermodynamics
Laws of Thermodynamics
First law: Energy cannot be either created or destroyedSecond law: When reactions occur, they become more disordered
Metabolism (Anabolism and Catabolism)
The sum of all chemical reactions within living cellsAnabolism:Biosynthetic reactions to create complex molecules out of smaller compoundsCatabolism:Break down reactions of complex molecules to release energy**ATP: the universal energy carrier Energy-storing molecules in all cells
The Carbon Cycle and Energy
All living organisms require energy to survive Sun is source of most energy on EarthLight energy is used by producers to synthesize sugars Plants and cyanobacteria perform photosynthesisFor non-photosynthesizing organisms (mostly consumers), energy is acquired from food moleculesCarbon dioxide and food molecules are involved in this energy transfer
Using energy from food
Energy transfer in non-living organisms can be explosive (combustion)Energy transfer in cells is controlledCarbon in wood + O2»»CO2 + H2O + energy Carbon in food + O2»»> CO2 + H2O + energy
Electron transfer
Capturing energy requires electron transferReaction that transfer electrons are called redox (Reduction/Oxidation)Oxidation: loss of electronsReduction: gain of electrons
Chemical reactions and thermodynamics
Some chemical reactions need a ‘jump-start’ to proceed Activation energy: the energy needed to ‘jump-start’ a reaction
Enzymes
Enzymes are biological catalysts
Enzymes speed up reactions
They lower the energy of activation They increase the speed of the reaction
The structure of enzymes
Very specific for specific reactionsTheir 3D shape determines their function Active site is the region where substrate binds Induced fit: active site ‘molds’ around substrate
Enzymes in metabolism
Metabolic pathways in the body usually involve several reactionsThere may be several intermediates Each intermediate has its own enzyme
