Figure 6-01

Investigating Cell Structure and Function 1. Cell Theory 2. Microscopy- a. History b. Types 3. Studying cell organelles Cell homogenization b. Cell Fractionation

LE 6-2 10 m Human height 1 m Length of some nerve and muscle cells Unaided eye Chicken egg 1 cm Frog egg 1 mm Measurements 1 centimeter (cm) = 10–2 meter (m) = 0.4 inch 1 millimeter (mm) = 10–3 m 1 micrometer (µm) = 10–3 mm = 10–6 m 1 nanometer (nm) = 10–3 µm = 10–9 m 100 µm Most plant and animal cells Light microscope 10 µm Nucleus Most bacteria Mitochondrion 1 µm Smallest bacteria Electron microscope 100 nm Viruses Ribosomes 10 nm Proteins Lipids 1 nm Small molecules Atoms 0.1 nm

Table 7.1 Different Types of Light Microscopy: A Comparison

Brightfield (unstained specimen) LE 6-3a Brightfield (unstained specimen) 50 µm Brightfield (stained specimen) Phase-contrast

Differential- interference- contrast (Nomarski) Fluorescence 50 µm LE 6-3b Differential- interference- contrast (Nomarski) Fluorescence 50 µm Confocal 50 µm

LE 6-4 Scanning electron microscopy (SEM) 1 µm Cilia Transmission electron microscopy (TEM) Longitudinal section of cilium Cross section of cilium 1 µm

LE 6-4a 1 µm Cilia Scanning electron microscopy (SEM)

Transmission electron microscopy (TEM) LE 6-4b Longitudinal section of cilium Cross section of cilium 1 µm Transmission electron microscopy (TEM)

ENDOPLASMIC RETICULUM (ER LE 6-9a ENDOPLASMIC RETICULUM (ER Nuclear envelope Flagellum Rough ER Smooth ER Nucleolus NUCLEUS Chromatin Centrosome Plasma membrane CYTOSKELETON Microfilaments Intermediate filaments Microtubules Ribosomes: Microvilli Golgi apparatus Peroxisome Mitochondrion Lysosome In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)

Inner Life of A Cell http://www.studiodaily.com/main/searchlist/6850.html

Differential centrifugation LE 6-5a Homogenization Tissue cells Homogenate Differential centrifugation

1000 g (1000 times the force of gravity) 10 min Supernatant poured LE 6-5b 1000 g (1000 times the force of gravity) 10 min Supernatant poured into next tube 20,000 g 20 min 80,000 g 60 min Pellet rich in nuclei and cellular debris 150,000 g 3 hr Pellet rich in mitochondria (and chloro- plasts if cells are from a plant) Pellet rich in “microsomes” (pieces of plasma membranes and cells’ internal membranes) Pellet rich in ribosomes

Cell Structure 1. Basic requirements to be a cell Cytoplasm DNA Ribosome Cell membrane Prokaryotic and eukaryotic cells 3. Limitations to cell size Lower limits Upper limits-SA/volume ratio

Prokaryotic and Eukaryotic Cells

A thin section through the bacterium Bacillus coagulans (TEM) LE 6-6 Pili Nucleoid Ribosomes Plasma membrane Cell wall Bacterial chromosome Capsule 0.5 µm Flagella A typical rod-shaped bacterium A thin section through the bacterium Bacillus coagulans (TEM)

Surface area increases while Total volume remains constant 5 1 1 Total surface area (height x width x number of sides x number of boxes) 6 150 750 Total volume (height x width x length X number of boxes) 1 125 125 Surface-to-volume ratio (surface area  volume) 6 1.2 6

An overview of animal cell structure Nucleus Ribosomes Endomembrane System RER & SER Vesicles Golgi apparatus Vacuoles Lysosomes 4. Mitochondria 5. Cytoskeleton

ENDOPLASMIC RETICULUM (ER LE 6-9a ENDOPLASMIC RETICULUM (ER Nuclear envelope Flagellum Rough ER Smooth ER Nucleolus NUCLEUS Chromatin Centrosome Plasma membrane CYTOSKELETON Microfilaments Intermediate filaments Microtubules Ribosomes: Microvilli Golgi apparatus Peroxisome Mitochondrion Lysosome In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)

Carbohydrate side chain LE 6-8 Outside of cell Carbohydrate side chain Hydrophilic region Inside of cell 0.1 µm Hydrophobic region Hydrophilic region Phospholipid Proteins TEM of a plasma membrane Structure of the plasma membrane

What is contained in the nucleus of a cell? DNA Chromosomes Genes R-rna All of the above

LE 6-10 Nucleus Nucleus 1 µm Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Surface of nuclear envelope Ribosome 1 µm 0.25 µm Close-up of nuclear envelope Pore complexes (TEM) Nuclear lamina (TEM)

What is the function of ribosomes? Protein synthesis DNA synthesis Intracellular digestion Transport of proteins outside of the cell

Ribosomes ER Cytosol Endoplasmic reticulum (ER) Free ribosomes Bound ribosomes Large subunit 0.5 µm Small subunit TEM showing ER and ribosomes Diagram of a ribosome

There is a difference in the make-up of cytoplasmic eukaryotic ribosomes and prokaryotic ribosomes True False

Proteins that are secreted from a cell are produced by: Membrane-bound ribosomes Free ribosomes

Secreted proteins are carried away from the ER by: The golgi apparatus Lysosomes Mitochondria vesicles

Smooth ER Nuclear Rough ER envelope ER lumen Cisternae Ribosomes Transitional ER Transport vesicle 200 nm Smooth ER Rough ER

A lysosome Mitochondria A storage vacuole The Golgi apparatus If a secreted protein needs to be chemically modified after it leaves the ER in a vesicle, it will go to: A lysosome Mitochondria A storage vacuole The Golgi apparatus

Nucleus Rough ER Smooth ER Nuclear envelope cis Golgi Transport vesicle Plasma membrane trans Golgi

Storage vacuole Mitochondria Lysosome Vesicles from either the ER or the Golgi that contain proteins involved in intracellular digestion fuse to form this cell organelle Storage vacuole Mitochondria Lysosome

Lysosomes are involved in destroying “worn out” cell organelles: True False

Up to 5 optional points You have 3 minutes to write a short answer to this question: Why is it important that the pH of a lysosome is acidic compared to the cytoplasm of the cell?

Phagocytosis: lysosome digesting food LE 6-14a Nucleus 1 µm Lysosome Lysosome contains active hydrolytic enzymes Food vacuole fuses with lysosome Hydrolytic enzymes digest food particles Digestive enzymes Plasma membrane Lysosome Digestion Food vacuole Phagocytosis: lysosome digesting food

two damaged organelles 1 µm LE 6-14b Lysosome containing two damaged organelles 1 µm Mitochondrion fragment Peroxisome fragment Lysosome fuses with vesicle containing damaged organelle Hydrolytic enzymes digest organelle components Lysosome Digestion Vesicle containing damaged mitochondrion Autophagy: lysosome breaking down damaged organelle

Malfunctions within a lysosome can cause diseases. True False

Vacuoles Can be formed by endocytosis May store substances the cell will need later Can be formed by vesicles joining together Can be filled with water All of the above

LE 7-14 50 µm Filling vacuole 50 µm Contracting vacuole

Lysosome Nucleus Vacuole Golgi apparatus mitochondria This cell organelle has a structure adapted for making ATP during cellular respiration. Lysosome Nucleus Vacuole Golgi apparatus mitochondria

Mitochondrion Intermembrane space Outer membrane Free ribosomes in the LE 6-17 Mitochondrion Intermembrane space Outer membrane Free ribosomes in the mitochondrial matrix Inner membrane Cristae Matrix Mitochondrial DNA 100 nm

The Cytoskeleton Made up of 3 elements a. Microtubules b. Microfilaments c. Intermediate filaments 2. Functions-diverse including maintaining cells shape; motility; contraction; and organelle movement

LE 6-20 Microtubule Microfilaments 0.25 µm

Table 6-1a

LE 6-22 Centrosome Microtubule Centrioles Longitudinal section of one centriole Microtubules Cross section of the other centriole

Cilia and Flagella Cell Movement

LE 6-23a Direction of swimming Motion of flagella 5 µm

Direction of active stroke Direction of recovery stroke LE 6-23b Direction of organism’s movement Direction of active stroke Direction of recovery stroke Motion of cilia 15 µm

Golgi apparatus Mitochondria RER Lysosome vacuole This cell organelle contains 2 compartments separated by a membrane, which is necessary for chemiosmosis to occur Golgi apparatus Mitochondria RER Lysosome vacuole

Which of the following statements is/are true? The cytoskeleton is composed of protein The cytoskeleton is involved in the segregation of chromosomes during mitosis The cytoskeleton can reorganize by polymerizing/depolymerizing A and B B and C All of the above

LE 6-24a Microtubules Plasma membrane Basal body 0.5 µm

Outer microtubule Plasma 0.1 µm doublet membrane Dynein arms Central LE 6-24b Outer microtubule doublet Plasma membrane 0.1 µm Dynein arms Central microtubule Cross-linking proteins inside outer doublets Radial spoke 0.5 µm

Effect of cross-linking proteins LE 6-25b Cross-linking proteins inside outer doublets ATP Anchorage in cell Effect of cross-linking proteins Wavelike motion

Organelle Movement Position of organelles not fixed in the cell

Vesicle ATP Receptor for motor protein Motor protein Microtubule (ATP powered) Microtubule of cytoskeleton

LE 6-21b Microtubule Vesicles 0.25 µm

Table 6-1c

Microfilaments (actin filaments) LE 6-26 Microvillus Plasma membrane Microfilaments (actin filaments) Intermediate filaments 0.25 µm

Table 6-1b

Muscle cell Actin filament Myosin filament Myosin arm LE 6-27a Muscle cell Actin filament Myosin filament Myosin arm Myosin motors in muscle cell contraction

Cortex (outer cytoplasm): gel with actin network LE 6-27b Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits Extending pseudopodium Amoeboid movement

Cytoplasmic streaming in plant cells LE 6-27c Nonmoving cytoplasm (gel) Chloroplast Streaming cytoplasm (sol) Vacuole Parallel actin filaments Cell wall Cytoplasmic streaming in plant cells

Dyneine walking is a key event in this cellular process: Chemiosmosis Amoeboid movement Cytokenesis Motility using flagella All of the above

Plant Cell Structure 1. All of the same organelles and structures that are in animals plus Cell wall Large central vacuole Chloroplasts

LE 6-9b Nuclear envelope Rough endoplasmic NUCLEUS reticulum Nucleolus Chromatin Smooth endoplasmic reticulum Centrosome Ribosomes (small brown dots) Central vacuole Golgi apparatus Microfilaments Intermediate filaments CYTOSKELETON Microtubules Mitochondrion Peroxisome Plasma membrane Chloroplast Cell wall Plasmodesmata Wall of adjacent cell In plant cells but not animal cells: Chloroplasts Central vacuole and tonoplast Cell wall Plasmodesmata

Central vacuole Plasma of cell membrane Secondary cell wall Primary Middle lamella 1 µm Central vacuole Cytosol Plasma membrane Plant cell walls Plasmodesmata

Central vacuole Cytosol Tonoplast Nucleus Central vacuole Cell wall Chloroplast 5 µm

Chloroplast Ribosomes Stroma Chloroplast DNA Inner and outer membranes LE 6-18 Chloroplast Ribosomes Stroma Chloroplast DNA Inner and outer membranes Granum 1 µm Thylakoid

LE 6-19 Chloroplast Peroxisome Mitochondrion 1 µm

Golgi apparatus Mitochondria RER Chloroplast 2 and 4 This cell organelle contains 2 compartments separated by a membrane, which is necessary for chemiosmosis to occur Golgi apparatus Mitochondria RER Chloroplast 2 and 4

Because plant cells have a large central water vacuole, they must also have: Chloroplasts Lysosomes Mitochondria A cell wall RER

Intermediate filaments Microtubules Dyneine walking All of the above Plays a role in cytoplasmic streaming, amoeboid movement, and muscle contraction: Microfilaments Intermediate filaments Microtubules Dyneine walking All of the above

These in class clicker questions are helpful Strongly Agree Agree Neutral Disagree Strongly Disagree

Cell Surrface Molecules/Connections Cell surface molecules (glycocalyx) Cell Connections-Plants Plasmodesmata 3. Cell connections-Animals Tight junctions Desmosomes Gap junctions

Proteoglycan complex EXTRACELLULAR FLUID Collagen fiber Fibronectin LE 6-29a Proteoglycan complex EXTRACELLULAR FLUID Collagen fiber Fibronectin Plasma membrane CYTOPLASM Integrin Micro- filaments

Cell walls Interior of cell Interior of cell 0.5 µm Plasmodesmata LE 6-30 Cell walls Interior of cell Interior of cell 0.5 µm Plasmodesmata Plasma membranes

LE 6-31 Tight junctions prevent fluid from moving across a layer of cells Tight junction 0.5 µm Tight junction Intermediate filaments Desmosome 1 µm Gap junctions Space between cells Plasma membranes of adjacent cells Gap junction Extracellular matrix 0.1 µm

LE 6-32 5 µm