cell (learning objectives)
TRANSCRIPT
1. Understand & describe the basic components necessary for a functional cell. 2. Review the order of appearance of cells on earth and explain the
endosymbiotic theory. 3. Compare and contrast prokaryotic and eukaryotic cells 4. Review the emergent functional properties of a eukaryotic cells. 5. Review the structure of membranes and explain the importance of different
proteins for creating intracellular membranous compartments where different cellular functions can take place.
6. Identify the components of the cytoskeleton and their role in cellular structural support, movement, and communication.
7. Describe the flow of genetic information within a living cell from DNA into proteins and the processes involved.
8. Explain the structure and role of membranes in compartmentalization of eukaryotic cell functions.
9. Identify the cellular organelles of the endomembrane system and the role of each in the manufacture and breakdown of important cellular molecules and intracellular trafficking of biomolecules.
10.Identify the cellular organelles that are involved in energy transformation and recycling of matter and the forms of energy and matter they transform.
11.Identify peroxisomes and their cellular function. 12.Explain the source and importance of the extracellular matrix and intercellular
junctions.
Cell (Learning Objectives)
Cell (Outline) - Components of a functional cell - Major Events in the History of Earth: abiotic and biotic phases;
anaerobic and aerobic atmosphere - Prokaryotic cells impact on the biosphere - Origin of Eukaryotic cells - Emergent properties of eukaryotic cells: animal and plant cells - Role of cellular membranes: external and internal - Cytoskeleton: structure and functions - Flow of genetic information: DNA to protein - The endo-membrane system - Other organelles: Fatty acid metabolism and Energy Processing - Cell surface and extracellular matrix
Components of a functional cell
• Boundary-membrane • Cytoplasm: Cytosol (soluble components)
& particulates • DNA-information • Ribosomes-protein synthesis
Major Events in the History of Earth Cenozoic
Humans
Land plants
Animals
Multicellular eukaryotes
Single-celled eukaryotes
Origin of solar system and Earth
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2
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3
Proterozoic eon
Archaean eon
Atmospheric oxygen
Prokaryotes
Anaerobic
Aerobic
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Prokaryotic Cell Structure
Evolution of larger Eukaryotic cells increase in
surface area/volume ratio
“The Endo-symbiotic Theory”
Cenozoic
Humans
Land plants
Animals
Multicellular eukaryotes
Single-celled eukaryotes
Origin of solar system and Earth
1
2
4
3
Proterozoic eon
Archaean eon
Atmospheric oxygen
Prokaryotes
• For single-celled organisms- - physical force of diffusion of material in and out of
the cells. - Increase in size is limited by surface area : volume ratio
• For multi-cellular organisms - Number of cells increases size. - Individual cells vary in size
Size Limitations
Engulfing of photosynthetic prokaryote
Chloroplast
Mitochondrion
Some cells
Host cell
Mitochondrion
Host cell Engulfing of aerobic prokaryote
Ancestral eukaryotic cells two or more prokaryotic cells in a state of endo-symbiosis:
• animal cell- 2 different prokaryotes
• plant cell- 3 different prokaryotes
Differ in - size - complexity - internal membrane, creating
organelles
(Sub-cellular compartments where different cell functions of eukaryotic cells are carried out)
Comparing Prokaryotic and Eukaryotic Cells
Emergent Properties of Eukaryotic cells
Functions – Structural support, movement, and
communication – Manufacturing of molecules – Breakdown of molecules – Energy processing
Eukaryotic cells structures and organelles
specialize for functions
A. Plasma membrane - Boundary of the cell - Surrounds the cytoplasm - Selective barrier - Allows passage of oxygen, nutrients, and wastes.
B. Internal membranes of eukaryotes
Partitioning the cell into compartments
- Sites of metabolic
reactions, enzymes - Local environments
that facilitate specific metabolic functions
The cytoskeleton is a network of protein fibers that functions in cell structural support and motility
Cytoskeleton
Microfilament
Actin subunit
7 nm
Intermediate filament
Fibrous subunits
10 nm
Microtubule
Tubulin subunit
25 nm
Nucleus
Nucleus
Cytoskeleton fibers
Microtubules: cell shape, movement of organelles, chromosome separation during cell division, and cilia and flagella (hollow/tubulin)
Microfilaments three-dimensional network just inside the
plasma membrane (actin) Actin and myosin/cell motility and cytoplasmic flow http://staffa.wi.mit.edu/microscopy/macrophage.shtml http://www.nytimes.com/2009/06/09/science/09cell.html?_r=1 Intermediate filaments They reinforce cell shape and fix
organelle location (keratin)
Components of the cytoskeleton pull past each other
Vesicles or organelles carried to various destinations along “monorails’ of microtubules.
The Flow of Genetic Information: The “Central Dogma” of Molecular Biology
The sequence of bases in DNA determines the sequence of amino acids in proteins - DNA codes for the production of messenger RNA. - Messenger RNA codes for the production of protein. - Proteins do not code for the production of protein, RNA or DNA
• Home of most genetic material (DNA)
• Double membrane with pores, nuclear envelope
• Shape maintained by nuclear lamina, a network of protein filaments
Nucleus
The Nucleus: • Site of transcription of messenger RNA
(mRNA) The nucleolus • Site of ribosomal RNA (rRNA)synthesis
and ribosome assembly
Ribosomes • Made of rRNA and protein. • two subunits that combine to carry out protein
synthesis • Number of ribosomes vary between cells • Free and bound ribosomes (to endoplasmic
reticulum)
The Endomembrane System Sub-cellular components
Nuclear envelope Endoplasmic reticulum Golgi apparatus Vesicles Lysosomes Vacuoles Plasma membrane
Function - Sites of certain metabolic functions in the cell (Synthesis, modification, & breakdown of macromolecules) - Regulation of protein traffic within the cell
Two connected regions of ER that differ in structure and function. – Smooth ER
(No ribosomes) – Rough ER
(bound ribosomes) are attached to the outside
Smooth ER Contains enzymes for – synthesis of lipids, phospholipid, steroids – Metabolism of carbohydrates – Detoxification of poison – Storage of Ca+2 for in muscle cells (necessary
for contraction)
Rough ER (membrane factory) - Produces proteins and membranes for
transport by vesicles, destined for secretion - Membrane-embedded and secretory proteins - Site of protein glycosylation (glycoproteins)
Transport vesicle buds off
Secretory protein inside trans- port vesicle
Glycoprotein Polypeptide
Ribosome
Sugar chain
Rough ER
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2
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The Golgi Apparatus • Finishing, sorting, and shipping cell products • Transport vesicles from the ER travel to the Golgi
apparatus for modification of their contents • Extensive in cells specialized for secretion. http://vcell.ndsu.edu/animations/proteintrafficking/movie-
flash.htm
Lysosomes • Digestive compartment within the cells. Membrane-
bounded sacs of hydrolytic enzymes that digests large particles made of macromolecules: proteins, fats, polysaccharides, and nucleic acids.
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter5/animations.html#
Vacuoles
• Larger versions of vesicles • Many functions in cell maintenance
– Food vacuoles – Contractile vacuoles, found in freshwater
protists, pump excess water out of the cell. – Central vacuoles- mature plant cells storage
of some pigments.
Other Membranous Organelles not part of the endomembrane system
• Peroxisomes – generate and degrade H2O2 in performing various
metabolic functions – Fatty Acid metabolism
• Mitochondria and chloroplasts- sites of energy transformation from one form to another and of recycling of matter - Mitochondria (respiration) are present in animal &
plant cells - Chloroplasts (photosynthesis) only in plant cells
Peroxisomes
• A single membrane • Abundant in liver and
kidney - breakdown of fatty
acids for transport to mitochondria for fuel
- detoxify alcohol and other harmful compounds.
- Conversion of fatty acids in seeds to sugars.
Mitochondria and Chloroplasts
• Contain their own ribosomes and cytosol • Contain small quantities of DNA that direct
the synthesis of the polypeptides produced by these internal ribosomes.
• Grow and reproduce as semi-autonomous organelles
• Not part of the endomembrane system
• Matrix-contains DNA and ribosomes
• Cristae-contains enzymes for ATP generation during cellular respiration
Mitochondria Video (4)
Chloroplasts • Present in plants and eukaryotic algae are the • Sites of photosynthesis-production of sugar from
CO2 and water (high levels of the green pigment chlorophyll)
• Mitochondria and chloroplasts - dynamic structures. - mobile and move around the cell along
tracks in the cytoskeleton. - have double membranes.
Cytoplasmic Streaming Video Campbell
Review of Functional Compartments of Eukaryotic cells
• Structural support, movement, and communication: cytoskeleton, plasma membrane, and cell wall
• Manufacturing: nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus • Breakdown of molecules: lysosomes, vacuoles, and
peroxisomes
• Energy processing: chloroplasts & mitochondria
• Cell wall in some organisms proteins and polysaccharides, in plant cells
• The extracellular matrix (ECM) proteins and polysaccharides, in animal cells
• Extracellular components and connections between cells help coordinate cellular activities
Cell Surfaces
Polysaccharide molecule
Carbo- hydrates
Proteoglycan molecule
Core protein
A proteoglycan complex
Functions of the ECM include – Support – Adhesion – Movement – Regulation
EXTRACELLULAR FLUID
Microfilaments
Collagen fiber
Connecting glycoprotein
Integrin
Plasma membrane
Glycoprotein complex with long polysaccharide
CYTOPLASM