AP Bio Ch. 6.5 - 6.6
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AP Bio Ch. 6.5 - 6.6

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AP Bio Ch. 6.5 - 6.6 AP Bio Ch. 6.5 - 6.6 Presentation Transcript

  • Mitochondria, Chloroplasts, Peroxisomes, & the Cytoskeleton 6.5-6.7
  • Mitochondria & Chloroplasts are special… Not part of the endomembrane system because… They both have 2 membranes separating their insides from the cytosol Have their own ribosomes Contain small amounts of their own DNA to make some of their own membrane proteins Grow and reproduce independently of the cell
  • Mitochondria Found in eukaryotic cells of plants, animals, fungi, and protists More active cells have more mitochondria Very small - ~ 1-10 microns
  • Structure of Mitochondria 2 membranes Smooth outer membrane Convoluted inner membrane Folds called cristae This membrane creates 2 spaces inside the mitochondrion Space between outer & inner membrane = intermembrane space Space inside inner membrane = matrix Matrix has enzymes , DNA, ribosomes Lots of folds means lots of membrane surface for cell respiration to occur
  • Chloroplasts One of a family of plant organelles called plastids Amyloplast – store starch Chromoplast – pigments that color fruits and flowers Chloroplast – contain the pigment chlorophyll & enzymes for photosynthesis Very small ~ 2 microns Found in green parts of plants
  • Structure of Chloroplasts  Double membrane with narrow intermembrane space  Inside is second membrane system – flattened discs called thylakoids Stacks of thylakoids are called grana Fluid inside grana called stroma Stroma contains DNA, enzymes for photosynthesis, ribosomes
  • Quick Think Describe at least 2 things that mitochondria and chloroplasts have in common. Explain why mitochondria and chloroplasts are not part of the endomembrane system.
  • Peroxisomes  Single membrane  Contain enzymes that transfer hydrogen from other molecules to oxygen to produce H2O2 as a by-product.  Contains enzymes that then break down H2O2 into water.
  • Peroxisomes Many different functions Some are used to break down fatty acids Those in the liver detoxify alcohol
  • The Cytoskeleton Cytoskeleton - a network of fibers that runs through the cell Helps organize the inside of the cell Made up of 3 types of tubes: Microtubules Microfilaments Intermediate filaments
  • Cytoskeleton Functions Supports cell Maintains cell shape (important for animal cells since no cell wall) Can be dismantled and reformed quickly so cells can change shape
  • Cytoskeleton Function Aides in cell motility -2 types of motility: Whole cell movement - the cytoskeleton interacts with motor proteins to allow the cell to move along fibers outside the cell Movement of organelles and vesicles within the cell - internal parts move along filaments of cytoskeleton Sperm around an egg
  • Cytoskeleton Structure Microtubules - thickest Microfilaments - thinnest (aka actin filaments) Intermediate filaments - mid sized
  • Microtubules Hollow Made of a protein called tubulin Give shape & support to cell Allows for organelles to move along them Separate chromosomes during cell division Grow out of centrosomes in many cells
  • Cilia & Flagella  Specialized arrangement of microtubules makes flagella & cilia beat  Internal structure of both the same Core of microtubules surrounded by plasma membrane 9 doublets of microtubules arranged in a ring Wagon wheel proteins that connect each doublet Motor proteins between each doublet Whole thing anchored to cell at the basal body
  • Cilia & Flagella Flagella on sperm Cilia on cells in the throat move mucus along Cilia in reproductive tract of females moves egg toward uterus Lots of unicellular eukaryotes use cilia and flagella for movement in aquatic environments
  • Microfilaments (Actin Filaments) Solid Built from a protein called actin Help support cell’s shape Have an important role in muscle contraction
  • Intermediate Filaments Specialized for bearing tension Made up of keratin proteins More diverse than the other 2 More permanent than the other 2 Skin is dead cells full of keratin proteins Keep certain organelles, like nucleus, locked in place Maintain shape of cell, especially odd shapes like neurons
  • Quick Think – complete the table Main features Main functions Microtubules Hollow, thickest, tubulin support for cell, organelles move along it’s tracks, cilia & flagella Microfilaments Thinnest, solid actin Support cell shape, muscle contraction Intermediate filaments In between size, diverse structure, more permanent, keratin Lock certain organelles in place, maintain irregular cell shapes
  • Quick Think There are many different cell types, even within the same organism. Cells vary in size, shape, structure, and function. This is part of the diversity of life. Which aspects of cells best reveal their evolutionary unity? What are some examples of specialized cellular modifications?