test 1 study guide

test 1 study guide - CELL STRUCTURE - Prokaryotes o Do not...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CELL STRUCTURE - Prokaryotes o Do not have membrane surrounding their DNA; lack a nucleus o Lack various internal structures bound with phospholipid membranes o Are small, ~1.0um in diameter o Have a simple structure, single cell o Composed of bacteria - Prokaryotic Cell Walls o Provide structure and shape and protect cell from osmotic forces o Assist some cells in attaching to other cells or in attaching to other cells or in eluding antimicrobial drugs o Not present in animal cells, so can target cell wall of bacteria with antibiotics o Bacteria and archaea have different cell wall chemistry o Bacterial cell walls Most have cell wall composed of peptidoglycan Peptidoglycan is composed of sugars, NAG, and NAM Chains of NAG and NAM attached to other chains by tetrapeptide crossbridges Bridges may be covalently bonded to one another Bridges may be held together by short connecting chains of amino acids Scientists describe two basic types of bacterial cell walls: Gram- positive and Gram-negative Gram-positive cell walls Relatively thick layer of peptidoglycan Contain unique polyalcohols called teichoic acids o Some covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan to cell membrane Retain crystal violet dye in Gram staining procedure; so appear purple Up to 60% mycolic acid in acid-fast bacteria helps cells survive desiccation Gram-negative cell walls Have only a thin layer of peptidoglycan Bilayer membrane outside the peptidoglycan contains phospholipids, proteins, and lipopolysaccharide (LPS) May be impediment to the treatment of disease Appear pink following Gram staining procedure - Prokaryotic Cytoplas mic Membranes o Structure 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Referred to as phospholipid bilayer; composed of lipids and associated proteins Approximately half composed of proteins that act as recognition proteins, enzymes, receptors, carriers, or Integral proteins Peripheral proteins Glycoproteins Fluid mosaic model describes current understanding o Function Energy storage Harvest light energy in photosynthetic prokaryotes Selectively permeable Naturally impermeable to most substances Proteins allow substances to cross membrane Occurs by passive or active processes Maintain concentration and electrical gradient Chemicals concentrated on one side of the membrane or the other Voltage exists across the membrane Passive processes Diffusion Facilitated diffusion Osmosis o Isotonic solution o Hypertonic solution o Hypotonic solution Active processes Active transport o Utilize permease proteins and expend ATP o Uniport o Antiport o Symport Group translocation Substance chemically modified during transport - Cytoplasm of Prokaryotes o Cytosol : liquid portion of cytoplasm o Inclusions : may include reserve deposits of chemicals o Endospores : unique structures produced by some bacteria that are a defensive strategy against unfavorable conditions
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 15

test 1 study guide - CELL STRUCTURE - Prokaryotes o Do not...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online