Cell structure (Plants and Prokaryotes)

• Rigid structure • Made from cellulose. • Freely permeable so substances can pass into/out of cell. • Provides shape. • Acts as a defence mechanism against invading pathogens.

Membrane lined sacs in cytoplasm containing cell sap/sugars + AA Large permanent vacuole —> maintenance of turgor so that contents of cell push against cell wall and maintain a rigid framework for the cell. Membrane called tonoplast (selectively permeable)

• Double membrane structure • Fluid enclosed in chloroplast = stroma. • Internal network of membranes ~form flattened sacs called thylakoids. • Granum = several thylakoids stacked together • Grana joined by membranes called lamellae. • Grana contain chlorophyll pigments (where light-dependent reactions occur) • Starch grains = strach produced by photosynthesis • Contain DNA + proteins so able to make own proteins.

Site of photosynthesis Internal membranes = large SA –> absorb as much sunlight as possible

Earliest forms of life on Earth. 3.5 billion years ago. Known as extremophiles (live in salt lakes + hydrothermal vents)

Large circular strand of DNA Extra genes found in plasmids Genes often grouped into operons.

Smaller than eukaryotes 70S Necessary for protein synthesis.

Cell walls made from peptidoglycan (murein)

Thinner and no 9+2 arrangement. Energy to rotate filament supplied from process of chemiosmosis not from ATP. The flagellum is attached to cell membrane of a bacterium by a basal body and rotated by a molecular motor. Molecular motor causes hook to rotate giving the filament a whip-like movement which propels the cell.

Slimy layer made of proteins. Prevents bacteria from desiccating (drying out). Protects bacteria against the hosts immune system.

Plasmids —> small loops of DNA which only carry few genes. Occurs in varying numbers.

Binary fission vs a/sexual reproduction 70S vs 80S ribosomes