Plant Cell Structure Topic 4.4a

Specification topic 4  2 Compare the ultrastructure of plant cells (cell wall, chloroplasts, amyloplasts, vacuole, tonoplast, plasmodesmata, pits and middle lamella) with that of animal cells.

Introduction  What is the significance of trees growing so tall?  Be above competitors for more light for photosynthesis.  How are plants able to grow so tall?  Cellulose cell walls  Columns and tubes  Strengthened with lignin

Plant cell structure  Are plants eukaryotes or prokaryotes?  Differences between eukaryotes and prokaryotes:  Size  Nuclei- prokaryote cells lack it  Membrane bound organelles- prokaryotes lack them  Mesosomes- only prokaryotes have them  Size of ribosomes  Cell wall structure  DNA: circular/ linear

Plant cells  Which organelles do you recognize?  Which organelles do plant cells have in common with animal cells?

Activity 4.13 Plant and Animal Cells 

Structures found in both plant and animal cells StructureDescriptionSketchFunction Cell membrane Phospholipids bilayer, proteins embedded, glycoproteins and glycolipids Control what enters and leave the cell Nucleus Round, double membrane bound organelle, pores Genetic store; transcription Nucleolus Dense body in nucleus Produces ribosomes Ribosome Non-membrane bound Translation

Structures found in both plant and animal cells StructureDescriptionSketchFunction RibosomeNon-membrane bound, two subunits, rRNA and protein Translation ERMembrane bound interconnected tubular cisternae Synthesis of steroids/ lipids RERMembrane bound interconnected flattened cisternae, with ribosomes on surface Synthesis, folding and transport of protein GolgiStacks of curved flattened cisternae, vesicles, lysosomes Protein modification

Structures found in both plant and animal cells StructureDescriptionSketchFunction mitochondionDouble membrane, inner membrane folded into cristae; circular DNA, small ribosomes Aerobic respiration Lysosome (disputed if in plant cells) Round, membrane bound, containing hydrolytic enzymes Break down of worn out organelles, food/bacteria, cells programmed to die

Structures found in plants only StructureDescriptionSketchFunction VacuoleFluid filled surrounded by tonoplast membrane Involved in maintaining turgidity, storage of water, ions and sugars Cell wallCellulose microfibrils stuck together with a glue of hemicellulose and pectins; Pits: an area, indent, in the cell wall where only the first layer is deposited Structural support- strong but flexible chloroplastDouble membrane, flattened disk shaped, Stroma, thylakoid membranes stacked in grana, chlorophyll in thylakoid membrane Photosynthesis

Structures found in plants only StructureDescriptionSketchFunction amyloplastMembrane bound organelle, containing starch granules Synthesis and storage of starch LamellaPectin layer between cells Holds cells together/ allows plasmodesmata to form plasmodesmaNarrow fluid filled channels through cell wall, linking the cytoplasm of two cells Allow transfer of material from one cell to another

Structures found in animal cells only StructureDescriptionSketchFunction centriolesHollow cylinder of 9 protein microtubules, pair of centrioles at right angles, Spindle formation/ organisation

 Which organelles are membrane bound?  ER, Golgi, vacuole, nucleus, mitochondria, chloroplasts  Which have double membranes?  Mitochondria, choloroplasts, nucleus, amyloplasts  Which organelles are involved in protein production/ transport?  Nucleus, rER, Golgi, vesicles