a tour of the cell, cont…
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A Tour of the Cell, cont…. Last Time : The Nucleus and the Endomembrane System Today : Other Organelles and the Cytoskeleton. Cells need energy to work. Figure 6.8 The structure and hydrolysis of ATP. - PowerPoint PPT PresentationTRANSCRIPT
A Tour of the Cell, cont…
Last Time: The Nucleus and the Endomembrane System
Today: Other Organelles and the Cytoskeleton
Cells need energy to work
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Sunlight photosynthesis ⏐ → ⏐ ⏐ ⏐ ⏐ glucose
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Glucose cell respiration ⏐ → ⏐ ⏐ ⏐ ⏐ ATP
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ATP hydrolysis ⏐ → ⏐ ⏐ ⏐ ADP + energy
Figure 6.8 The structure and hydrolysis of ATP
Chloroplasts in plant cells convert sunlight into chemical energy that will
be used to make ATP
ATP is manufactured through cellular respiration that takes place in the mitochondria
Peroxisomes
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H2 +O2 → H2O2
H2O2 +H2 → 2H2O
The cytoskeleton
MicrofilamentsActin
Two intertwined strands
• maintain cell shape by resisting tension
Actin subunit
Protein subunits
Structure
Functions
• motility via pseudopodia • muscle contraction
• cell division in animals
7 nm
Intermediate filamentsKeratin, others
Fibers wound into thick cables
• anchor nucleus and some other organelles
Microtubules-tubulin and -tubulin dimers
Hollow tube
Keratin subunits Tubulin dimer
• maintain cell shape by resisting compression
• motility via flagella/cilia
• move chromosomes during cell division
• move organelles
10 nm 25 nm
3 types of cytoskeletal structures
Structure of kinesin
Tail
Stalk
Head
Motor molecules like kinesin, myosin, and dynein work with the cytoskeleton to produce
movement
Transport vesicle
Kinesin
Microtubule
ATP ADP+Pi
Kinesin "walks" along a microtubule track
ATP ADP+Pi
Microfilaments and Intermediate Filaments
Networks of filaments near the plasma membrane help to maintain a cell’s shape
Microfilaments aid in motility
Centrosome containing a pair of centrioles
Microtubules often grow out from the region called the centrosome
Cilia Flagella
Cilia and Flagella move the entire cell
TEM of flagella
Microtubule doublet
Cell membrane
Central pair
Outer doublet
Dynein
Spoke
Cilia and Flagella have a “9 +2” arrangement of microtubule doublets
Bend
The motor protein Dynein “walks” along the microtubules within the flagella on one side,
causing bending
Figure 7.23 A comparison of the beating of flagella and cilia
Plant cells are surrounded by cell walls made of cellulose
Plasmodesmata connect adjacent plant cells
Animal cells are connected through Intercellular junctions
Review of an animal cell
(centrioles)
Review of a plant cell