4.1 - 4.13 Structure and function of plants

• structure of cell plant

  A) nucleus

  B) nucleolus

  C) Smooth endoplasmic reticulum

  D) ribosomes

  E) cytoplasm

  F) plasmodesmata

  G) plasmalemma

  H) cell wall

  I) chromoplast

  J) microtubule

  K) mitochondrion

  L) Lysosome

  M) Golgi apparatus

  N) chloroplast

  O) vacuole

  P) tonoplast

  Q) rough endoplasmic reticulum

  
• Starch

  • stores energy
  • made of 2 polysaccharides
  • amylose
  • amylopectin
  • laid down in successive rings that form starch granules
• amylose

  • unbranched and coiled glucose molecules
  • 1-4 glycosidic bonds
  • compact
• amylopectin

  • branched chain of glucose
  • 1-4 and 1-6 glycosidic bonds
  • rapidly digested
• Cellulose

  • component of cell walls and composed of long, unbranched chains of beta glucose joined by glycosidic bonds
  • microfibrils are made of long cellulose chains linked together by hydrogen bonds formed between adjacent chains
  • provides structural support
• Secondary cell wall

  • formed between primary cell wall and cell membrane
  • only begins to gropw when cell has stopped growing
  • made of parellel layers of microfibrils of cellulose, with other polysaccharide additions
• Vascular bundle

  A) sclerenchyma

  B) vascular bundle

  C) ground tissue

  D) xylem

  E) phloem

  
• Xylem

  • function is to transport water and inorganic ions
  • form hollow tubes of dead cells and secondary wall has lignin
• Phloem

  • transports organic solutes via translocation
  • made of living cells lined end to end forming a sieve tube element, with surrounding companion cells
• Sclerenchyma

  • function is to support the plant
  • fibres are tapered at the ends and are made with dead cells whose cell walls have lignin
• Lignin

  • polysaccaride
  • makes cell walls less flexible and more rigid
  • adds strength to vascular bundle
• Sustainability

  • plant material is renewable and sustainable
  • bio diesel replacing diesel and is made from synthesised ethanol from fermented plants
  • plant fibre strength can replace oil based plastics
  • plant based plastics are biodegradable
  • fibres can be used to male materials
  • starch can be used to make bioplastics and bioethanol
  • plants can have antimicrobial and therapeutic properties
• Cell wall

  • surrounds outside of the cell surface membrane
  • made of cellulose
  • strengthens and supports cell
  • prevents it changing shape
  • contains pores to allow movement of substances
• Chloroplast

  • small flattened structure contains a double membrane
  • inne rmebrane stacked into thykaloid
  • contains chlorophyll
  • green pigment
  • absorbs light for photosynthesis
• Amyloplast

  • synthesises and stores starch and breaks down to glucose when required
• Vacuole

  • membranous sac containing sap
  • contains dissolved sugars and salts for the cell
  • function is to allow the cell to become turgid and also to isolate unwanted chemicals from the rest of the cell
• Tonoplast - membrane surrounding a vacuole
• Plasmodesmata

  • channels of cytoplasm
  • passes between adjacent walls of plant cells that allows fast communication and exchange of substances between cells
• Pits - sections of cell walls the allow for fluid exchange and communication with adjacent cells
• Middle lamellam - pectin layer between adjacent plant cells, sticking cell walls togethert
• movement of water and dissolved inorganic ions is through the transpiration stream
• Water in plants is required to keep cells turgid and as a reactant
• when cells dont have enough water, they lose water and the plant wilts

  ->

  reduces surface area of leaves exposed to sunlight and can reduce plants overall height

  ->

  overall reduces amount they can photosynthesise; less sunlight is absorbed by chlorophyll
• Ions required for plant growth and development

  • nitrate ions
  • calcium ions
  • phosphate ions
  • magnesium ions
• Nitrate ions in plants

  • make nucleotide bases in DNA and amino acids
• Calcium ions in plants

  • needed to form calcium pectate for the middle lamella
• Phosphate ions in plants - used to make ADP and ATP
• Magnesium ions in plants - needed to produce chlorophyll
• optimum conditions for bacteria

  • warmth
  • moisture
  • nutrients
  • optimum pH
  • oxygen