4/12/17. Cells. Cell Structure. Ch. 2 Cell Structure and Func.on. Range of Cell Sizes BIOL 100

Transcription

1 Ch. 2 Cell Structure and Func.on BIOL 100 Cells Fundamental units of life Cell theory All living things are composed of one or more cells. The cell is the most basic unit of life. All cells come from pre-existing cells. Except possibly viruses Minimal Cell Plasma membrane Phospholipid bilayer Cytoplasm Space inside cell excluding Genetic information DNA Cell Structure Range of Cell Sizes 10 m 1 m 100 mm (10 cm) 10 mm (1 cm) 1 mm 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm Human height Length of some nerve and muscle cells Chicken egg Frog egg Most plant and animal cells Nucleus Most bacteria Viruses Ribosome Proteins Lipids 0.1 nm Atoms Unaided eye Mycoplasmas (smallest bacteria) Small molecules Light microscope Electron microscope 1

2 Two Cell Types Prokaryotic Bacteria Archaea Eukaryotic Everything else Prokaryotic Cells Average 2 µm to 8 µm long No Nucleoid (nuclear region) Bacterial cell wall Peptidoglycan Limited organelles Prokaryotic vs. Eukaryotic Prokaryotic cells Eukaryotic cells DNA in nucleoid region within membrane-bound Size much smaller much larger Organization always single-celled often multicellular Organelles only one type of organelle many types of organelles Figure 4.2 2

3 The Eukaryotic Cell Much larger 10x length 1000x volume Nucleus present Variety of membranous cellular organelles tiny specialized organs Vary in cellular metabolism Dependent on internal cellular membranes Increase areas of specialization nuclear pores DNA nuclear envelope nucleolus cytoskeleton rough endoplasmic plasma membrane transport vesicle mitochondria smooth endoplasmic free ribosomes cytosol lysosomes Golgi complex The Eukaryotic Cell Cytosol aqueous jelly-like fluid excluding bathes organelles should not be confused with the cytoplasm Cytosol fills cytoplasm The Eukaryotic Cell Plasma membrane outer lining of the cell phospholipid bilayer imbedded with proteins contains cholesterol controls entry and exit of many compounds Components of eukaryotic cells other organelles cytosol cytoskeleton plasma membrane 3

4 Multicellular Eukaryotes Plant No centrioles Cell wall (cellulose) Chloroplast Central vacuole Golgi apparatus Cell wall NUCLEUS: Nuclear envelope Chromosome Nucleolus Central vacuole Chloroplast Plasmodesmata Rough endoplasmic Smooth endoplasmic CYTOSKELETON: Microtubule Intermediate filament Microfilament Peroxisome Plasma membrane Cell wall of adjacent cell Multicellular Eukaryotes Animal Paired centrioles No cell wall Flagella in some (movement) Contractile vacuole No chloroplasts Rough endoplasmic Lysosome Centriole Peroxisome CYTOSKELETON: Microtubule Intermediate filament Microfilament Smooth endoplasmic NUCLEUS: Nuclear envelope Chromosomes Nucleolus Golgi apparatus Plasma membrane Rough endoplasmic Smooth endoplasmic NUCLEUS: Nuclear envelope Chromosomes Nucleolus Lysosome Centriole Peroxisome CYTOSKELETON: Microtubule Intermediate filament Microfilament Golgi apparatus Plasma membrane 4

5 Nucleus Control center of the cell Contains DNA Nucleus Two membranes of nuclear envelope Nucleus Nucleolus Chromatin Pore Endoplasmic Two subunits Made of ribosomal (r)rna and proteins Assemble amino acids into polypeptides Using transfer (t)rna Every cell has ribosomes! ER Cytoplasm Endoplasmic (ER) Free ribosomes Bound ribosomes Large subunit Small subunit Endoplasmic Reticulum Rough ER (due to ribosomes) Makes membrane bound proteins Makes secretory proteins Smooth ER Synthesis of lipids In the liver, helps regulate blood sugar Drug breakdown Storage of calcium Amount of Smooth ER or Rough ER in the cells depends on the function of the cell Smooth ER Rough ER Nuclear envelope 5

6 Receives and modifies substances manufactured in the ER Finishes, sorts and ships products Contents may either leave the cell or become part of the cell s organelles or membrane The Golgi Complex Golgi complex 1. Transport vesicle from RER fuses with Golgi 2. Protein undergoes more processing in Golgi cisternae cisternal space vesicle Side chains are edited (sugars may be to cytosol 3. Proteins are trimmed, phosphate sorted and groups added). for export to plasma shipped out of cell membrane Lysosomes Digestive enzymes (hydrolytic) in a membranous sac Only work in a very acidic environment Stuff that needs to be broken down is brought into the membranous sac (recycling) Engulfing bacteria Fusing with food vacuoles Embryonic development (programmed cell death) lysosome worn-out digestive organelle enzymes 1. Lysosome fuses with worn-out organelle. 2. Organelle broken down. 5. Usable molecules recycled to make new organelles. 3. Small molecules returned to cytosol. 4. Waste molecules expelled from cell. Mitochondria Energy converting organelle Cellular Respiration Converting chemical energy in food to chemical energy of ATP for cellular work Mitochondria 6

7 4/12/17 Mitochondria and Energy Double membrane two compartments (outer and inner membranes) Intermembrane space between the membranes where H+ build up occurs food oxygen Cristae increase surface area for ATP outer membrane inner membrane water carbon dioxide ATP production ATP Synthase is embedded here Mitochondrial matrix The Citric Acid Cycle is located here The Cytoskeleton Internal Scaffolding (a)microfilaments web of protein strands (b) Intermediate filaments(c) Microtubules Microfilaments Intermediate filaments 7 nm Microtubules 10 nm 25 nm Main function: changes Main function: in cell shape maintenance of cell shape Provides structure Main functions: maintenance of cell shape, movement of organelles, cell mobility (cilia and flagella) Facilitates the movement of materials inside the cell Facilitates cell movement. Plant Cells Like animal cells, have: Nucleus RER Golgi Plasma membrane Plant cells have a cell wall, chloroplasts, and a central vacuole, while animal cells do not. cytoskeleton cell wall chloroplast central vacuole nuclear envelope nuclear pores DNA nucleolus rough endoplasmic smooth endoplasmic free ribosomes Golgi complex cytosol plasma membrane mitochondrion mitochondria Do NOT possess lysosomes 7

8 Plant Cells 3 structures not found in animal cells: a cell wall cellulose a large central vacuole provides turgor pressure chloroplasts carry out photosynthesis Plant cells have a cell wall, chloroplasts, and a central vacuole, while animal cells do not. cytoskeleton cell wall chloroplast central vacuole nuclear envelope nuclear pores DNA nucleolus rough endoplasmic smooth endoplasmic free ribosomes Golgi complex cytosol plasma membrane mitochondrion Stores water and nutrients degrades waste products like lysosome in animal cells Central Vacuole Cell Wall Gives the plant structural strength helps regulate the intake and retention of water. 8

9 Chloroplasts Sites of photosynthesis Double membrane like mitochondria Internal space like mitochondria Contain stacks of thylakoids (not like mito) water carbon dioxide minerals outer membrane inner membrane sugar (food) oxygen Structures in Plant and Animal Cells 9