cell unit learning goal 2: describe cell organelles and their functions within the cell
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Cell Unit• Learning Goal 2: Describe cell organelles and their functions within the cell.
Prokaryotic Cells
Believed to be the first cells to evolve.
Lack a membrane bound nucleus and organelles.
Genetic material is naked in the cytoplasm
Ribosomes are only organelle.
Eukaryotic Cells
• “True nucleus”; contained in a membrane bound structure.
• Membrane bound organelles.
• Thought to have evolved from prokaryotic cells.
Prokaryotic vs. Eukaryotic
CellSize of the Cell http://learn.genetics.utah.edu/content/begin/cells/scale/
Cell Structure http://learn.genetics.utah.edu/content/begin/cells/insideacell/
Cell Wall
• The main function of the cell wall is to provide support and protection for the cell.
• Found in plant and prokaryotic cells.
• Formed from cellulose molecules.
Cytoplasm
• Location of growth, metabolism, and replication.
• Is a gel-like matrix of water, enzymes, nutrients, wastes, and gases and contains cell structures.
Ribosomes
• Translate the genetic code to assemble proteins.
• Found attached to the Rough endoplasmic reticulum or free in the cytoplasm.
Ribosome
Rough Endoplasmic ReticulumRough E.R.
Network of continuous tubes, studded with ribosomes.
Manufactures, processes, and transports proteins for export from cell.
Continuous with nuclear envelope.
Endoplasmic Reticulum
Smooth Endoplasmic ReticulumSmooth E.R.
• Similar in appearance to rough ER, but without the ribosomes.
• Contains a collection of enzymes that perform specialized tasks.
Lysosome
• Single membrane bound structure.
• Found mostly in animal cells.
• Contains digestive enzymes that break down cellular waste, old cell parts, and nutrients for use by the cell.
Lysosome
Golgi Apparatus (Complex)
• Modifies, sort, and package proteins and lipids made by the ER.
Golgi Apparatus
Mitochondria
• Membrane bound organelles that are the site of cellular respiration (ATP production)
• Powerhouse of the cell.
Mitochondria
Nucleus
• Double membrane-bound control center of cell.
• Brain of the cell.• Contains nearly all of
the cell’s DNA.
Nucleus
Parts of the nucleus: Chromatin - genetic material of cell in its non-dividing
state. Chromosomes – Condensed chromatin ready for cell
division.
Figure 2: Different levels of DNA condensation. (1) Double-strand DNA. (2) Chromatin strand (DNA with histones). (3) Chromatin during interphase with centromere. (4) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (5) Chromosome during metaphase.
Parts of the nucleus:
Nucleolus - dark-staining structure in the nucleus that plays a role in making ribosomes
Nuclear envelope - double membrane structure that separates nucleus from cytoplasm.
Centrioles
• Found only in animal cells.
• Self-replicating• Made of bundles of
microtubules.• Help in organizing cell
division.
Cytoskeleton
Solid rods of globular proteins.
cytoskeleton offers support to cell structure.
Cell membrane
Endoplasmicreticulum
Microtubule
Microfilament
Ribosomes Mitochondrion
Section 7-2
Figure 7-11 Cytoskeleton
Chloroplast
Site of photosynthesis
Membrane bound structure.
Contains chlorophyll
Chloroplast
Vacuole
• Store water and nutrients needed by the cell.
• Help support the shape of the cell.
• Plants have a large central vacuole.
• Other types of cells have a much smaller vacuole.
Animal Vacuole
Plant Cell Vacuole
Cell Membrane
Plasma (Cell) Membrane Is a Fluid Mosaic
• The plasma membrane is a selectively semipermeable barrier– controls the passage of substances into and out of the cell.
• Fluid Mosaic composed of Phospholipids, Proteins, Cholesterol, Glycolipids, and Glycoproteins.
Phospholipid BilayerPhopholipids are the main components of membranes. They arrange themselves in abilayer, with their water-hating tails facing each other, and their water-loving heads facing the outside of the cell on one side, and the inside of the cell on the other side.
Phospholipid
Phospholipid Bilayer
Membrane Proteins Roles of
membrane proteins include:
•Structural
•Enzyme
•Transport
•Cell- recognition
Types of TransportTypes of Transport
Transport Across the MembraneDiffusion • a substance moving from an area of high concentration of
the substance to a region of low concentration of the substance until it reaches equilibrium.– This is a passive process that does not require an energy
input.
DiffusionDiffusion
DiffusionDiffusion
Facilitated Diffusion
• Transport Proteins – channels for
substances to enter or exit the cell through passive diffusion.
– No Energy Required
Active Transport
• Active Transport– Substances move from a region of low
concentration on one side of the membrane to a region of high concentration on the other side.
• Active Transport Requires Energy
Osmosis: Diffusion of Water• Osmosis is the
diffusion of water, across a semipermeable membrane.– from a region of high
concentration of water to a region of low concentration of water, until equilibrium of water on both sides of the membrane is reached.
OsmosisOsmosis
Osmoregulation: Control of H2O Balance in Cells
• Tonicity: the movement of water into and out of cells in response to the water concentration on the outside of the cell. – Water moves from where it is in high concentration to where it is in low
concentration until an equilibrium of the water concentration is reached.
Transport of Large Molecules Across the Membrane
• Endocytosis – Large substances enter the cell through phagocytosis, cell “eating” or pinocytosis, cell “drinking”.
• Exocytosis – vesicles fuse with the plasma membrane and its contents are ejected from the cell
Animal Cell
Centrioles
Nucleolus
Nucleus
Nuclearenvelope
Rough endoplasmic reticulum
Golgi apparatus
Smooth endoplasmicreticulum
Mitochondrion
CellMembrane
Ribosome(free)
Ribosome(attached)
Section 7-2
Figure 7-5 Plant and Animal Cells
Plant Cell
Nuclearenvelope
Ribosome(attached)
Ribosome(free)
Smooth endoplasmicreticulum
Nucleus
Rough endoplasmic reticulum
Nucleolus
Golgi apparatus
Mitochondrion
Cell wall
CellMembrane
Chloroplast
Vacuole
Section 7-2
Figure 7-5 Plant and Animal Cells
Prokaryotes Eukaryotes
Cell membraneContain DNA
NucleusEndoplasmic reticulum
Golgi apparatusLysosomesVacuoles
MitochondriaCytoskeleton
Animal Cells Plant Cells
Centrioles
Cell membraneRibosomes
NucleusEndoplasmic reticulum
Golgi apparatusLysosomesVacuoles
MitochondriaCytoskeleton
Cell WallChloroplasts
Section 7-2
Venn Diagrams
Animal Cell vs. Plant Cell
Http://:micro.magnet.fsu.edu/cells/html
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