biofinalch7.txt

• Bacteria, archaea
• Absence of membrane-bound nucleus
• Dna in nucleoid
• Extensive internal membranes only in photosynthetic species, limited types and numbers of organelles
• Cytoskeleton limited in extent, relative to eykaryotes
• Small
• Single, circular chromosome
• Have plasmids – genes physically independent of main, cellular chromosome
• Have ribosomes

• DNA inside nucleus, membrane bound, plasmids rare.
• Large number and many types of organelles
• Cytoskeleton extensive, found throughout volume of cell
• large

• Nucleus –
• have genetic information, assembly of ribosome subunits, structural support. Membrane double envelope, openings called nuclear pores, components of chromosomes, nucleolus, nuclear lamina

have complec of RNA and proteins, function is protein synthesis

function protein synthesis and processing, components – ribosome’s attached, single membrane that contains receptors for entry of selected proteins

function protein processing (glycosylation) components – stack of flattened cisternae, single membrane contains receptors for products of rough ER

lipid synthesis, have network of branching sacs, enzymes for synthesizing lipids, single membrane containing enzymes for synthesizing phospholipids

digesting and recycling, single membrane with proton pumps

– oxidation of fatty acids, ethanol, or other compounds, has enzymes that catalyze oxidation reactions, single membrane with transporters for selected macromolecules

storage of oils, carbohydrates, water, or toxins, has single membrane with transporters for selected molecules

ATP production, double membrane (inner contains enzymes for ATP production) has enymes that catalyze REDOX reactions

production of ATP and sugars via photosynthesis, have pigments and enzymes, double membrane and membrane-bound sacs in interior

structural support, movement of materials, movement of whole cell (some), has actin, intermediate filaments and microtubules

selective permeability, maintains intracellular environment, phospholipid bilayer with transport ad receptor proteins, single membrane

protection and structural support, has carbs fibers running through carb or protein matrix

proteins bound for the endomembrane sustem have a molecular zip code analogous to the nuclear localization signal

• (1) Signal sequence synthesized by ribosome (2) signal sequence binds to signal recognition particle (SRP) (3) signal recognition particle binds to SRP receptor in ER membrane (4) SRP is released and protein synthesis continues, and protein enters the ER, (5) signal sequence is removed and protein synthesis is complete
• (1) ribosome synthesizes the ER signal sequence (2) signal sequence binds to a signal recognition particle (SRP) – a complex of RNA and protein, (3) ribosome + signal sequence + SRP complex attaches to an SRP receptor in the ER membrane, (4) receptor and SRP connect, the SRP is released, (5) signal sequence is removed and protein synthesis is complete

secretion of intracellular molecules (hormones, collagen), contained within membrane-bounded vesicles, to the outside of the cell by fusion of vesicles to the plasma membrane

• Endocytosis –
• general term for pinching off of the plasma membrane that results in the uptake of material from outside the cell. Includeds phagocytosis, pinocytosis, and receptor-mediated endocytosis

uptake by a cell of small particles or cells by pinching off the plasma membrane to form small membrane-bound vesicles, one type of endocytosis

process by which damaged organelles are surrounded by a membrane and delivered to a lysosome to be destroyed

uptake by a cell of extracellular fluid by pinching off the plasma membrane to form small membrane-bound vesicles, type of endocytosis

maintain cell shape by resisting tension (pull), move cells via muscles contraction or cell crawling, divide animal cells in two, move organelles and cytoplasm in plants, fungi, and animals, actin subunits, strands in double helix

maintain cell shape by resisting tension (pull), anchor nucleus and some other organelles, subunit keratin or vimentin or lamin, fibers wound into thicker cables

maintain cell shape by resisting compression (push), move cells via flagella or cilia, move chromosomes during cell division, assist formation of cell plate during plant cell division, move organelles, provie tracks for intracellular transport, alpha and beta tubulin dimers, hollow tube

• • Light capturing reactions occur in internal membranes of the chloroplast that are organized into structures called thylakoids in stacks known as grana
• • Calvin cycle takes place in a fluid portion of chloroplast called stroma
• • Light energy is transformed to chemical energy. A pigment molecule in an antenna complex absorb a photon, energy is transferred to the reaction center, where excited elctron is transferred to an electron acceptor, reducing it
• • Photosystem II, high-energy electrons accepted by pheophytin and passed along an electron transport chain, releasing energy that pumps protons across thylakoid membrane, creating ATP. PS II takes electrons from water, releasing oxygen and protons.
• • Photosystem I,, high-energy electrons accepted by iron and sulfur containing proteins and passed to NADP+ forming NADPH
• • Z scheme connects PHII and I (electron transport chain)
• • Calvin cycle starts when CO2 is attached to a five carbon compound called RuMP in a reaction catalyzed by the enzyme rubisco.
• • Six carbon compound results immediately splits in half to form two 3-phosphoglycerate, reduced to G3P
• • Some G3P used to synthesize glucose and fructose, rest regenerate RuBP to redo cycle
• •

•Fix CO2 to organic acids, before it is transferred to rubisco. As a result, they can increase Co2 levels in their tisues, reducing the effect of photorespiration and allowing photosynthesis to continue when stomata close