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What is a Eukaryotic Cell?
Chapter 5 Objectives:
Eucaryotic Cells & Microorganisms
EUKARYOTES - CELLS WITH PARTS Eukaryotes are what you think of when you think of a classic "cell." There are cells without organized nuclei or organelles that are called prokaryotes.
The possibilities are endless. Eukaryotes are cells that can do anything. They are the cells that have helped organisms advance to new levels of specialization beyond imagination. You wouldn't be here if eukaryotic cells did not exist. What makes a eukaryotic cell? Let's watch.
(1) Eukaryotic cells have an organized nucleus with a nuclear envelope. They have a "brain" for the cell. They have a discreet area where they keep their DNA. It is also said that they have a "true nucleus."
(2) Eukaryotic cells usually have organelles.
(3) Although limited in size by the physics of diffusion, eukaryotic cells can get very large. There are even some extreme examples called plasmodial slime molds that can be a meter wide. The cell is multi-nucleated (many nuclei) and it gets huge. Generally, eukaryotic cells are a couple hundred times the size of a prokaryotic cell.
(4) Eukaryotic cells have extra stuff going on and extra parts attached. Since they have organelles and organized DNA they are able to create parts. One example is the flagellum (a tail-like structure to help it move). They could also create cilia (little hairs that help scoot the cell through the water). In the invertebrate section, we talk about nematocysts that are cells with little harpoons for catching prey. The list is endless.
Form & Function of the Eukaryotic Cell
The cell structures common to all eukaryotes are the cell membrane, a membrane-enclosed nucleus with nucleolus inside, vacuoles, mitochondria, endoplasmic reticulum, Golgi apparatus, and a cytoskeleton. Cell walls, chloroplasts, and locomotor organs are present in some eukaryote groups.
I. External Structures:
Flagella and Cilia: Locomotor Appendages:
- Provide locomotion. Flagella are common in protozoa, algae, and few fungal and animal cells.
- Eukaryotic flagella are different from prokaryotic flagella: eukaryotic flagellum is 10x thicker, structurally more complex, and covered by an extension of the cell membrane. Eukaryotic flagella also contains regularly spaced hollow tubules--called microtubules--that extend along their entire length.
- In vertebrates only the sperm cells have flagella
- Cilia are found only in certain protozoa and animal cells. Cilia is shorter than flagella and more numerous. Cilia function in motility, feeding, and filtering.
-many protozoans are covered with cilia and move quickly
Glycocalyx:
- The glycocalyx is the outermost boundary of most eukaryotic cells that comes in direct contact with the environment. It is usually composed of polysaccharides and appears in a network of fibers, a slime layer or a capsule much like the glycocalyx of prokaryotes. Glycocalyx means "sweet husk."
- Its functions are adherence to environmental surfaces, the development of biofilms and mats, and reception of chemical signals from the environment and /or other organisms.
- The glycocalyx is supported by either a cell wall or a cell membrane.
- Cell surface markers (antigens) are part of the glycocalyx
this is how our immune system distinguishes self and nonself.
Boundary Structures:
Cell Wall:
- Found in fungi, plants, and most algae have a cell wall, but protozoa, a few algae, and all animal cells don't (they only have a membrane).
- The cell wall is rigid and provides structural support and shape. Fungi have a thick inner layer of polysaccharides fibers composed of chitin or cellulose and a thin outer layer of mixed glycans. Plants use cellulose for their cell wall.
Cytoplasmic Membrane:
- Made of a bilayer of phospholipids in which protein molecules are embedded. The cytoplasmic membrane of eukaryotes is similar in function to that of prokaryotes, but it differs in composition, possessing sterols as additional stabilizing agents.
- The cytoplasmic membrane is relatively rigid, which strengthens the stability on eukaryotic membranes. This is important especially to those cells without cell walls (i.e. protozoa, a few algae, and all animal cells).
II. Internal Structures:
Nucleus: Control Center:
- Compact sphere that is the most prominent organelle of eukaryotic cells. The control center (governs and regulates all cell activity). The nucleus contains the cell's chromosomes (the cell's genetic information) which are
not visible until they coil during mitosis. Chromosomes are only coiled up when getting ready to divide, they are normally unbound in the nucleus.
- The nucleus is separated from the cytoplasm by an external boundary called a nuclear envelope, which is composed of two parallel membranes separated by a narrow space and perforated with pores. The pores serve as passageways for molecules to go between the nucleus and cytoplasm.
- The main body of the nucleus consists of the nucleolus, which is the site for ribosomal RNA synthesis and ribosomes assembly.
Endoplasmic Reticulum: A Passageway into the Cell:
- A series of tunnels used in transport and storage.
- Two kinds of endoplasmic reticulum:
- appears as parallel, flat pouches bounded by membranes
- Rough endoplasmic reticulum (RER), which originates from the outer membrane of the nuclear envelope and extends in a continuous network through the cytoplasm. It's rough due to the ribosomes partly attached to its membrane surface. Proteins synthesized on the ribosomes are shunted into the RER for packaging and transport. transport materials from the nucleus to the cytoplasm and ultimately to the cells exterior.
- Smooth endoplasmic reticulum (SER) is a closed tubular network without ribosomes. It functions in nutrient processing and also in synthesis and storage of lipids and other non-protein macromolecules. SER lack ribosomes making it have the smooth shape it does.
Golgi Apparatus: A Packaging and Distribution Machine:
- The "packaging and distribution center" (the site where proteins are modified, stored, and packaged for transport to their final destinations which can be within or outside of the cell).
- Consists of a stack of flattened sacs called cisternae (looks like pita bread), which have cavities like the endoplasmic membrane, but the cisternae don't form a continuous network.
- The Golgi apparatus is always closely associated with the endoplasmic reticulum in its location and function. The endoplasmic reticulum buds off protein packets called transitional vesicles that are picked up by the Golgi apparatus, which modifies the proteins, then pinches them off as finished condensing vesicles that are transported to organelles or secreted outside the cell.
Lysosymes:
- The garbage men of the cell.
- Vesicles originating from the Golgi apparatus that contain a variety of enzymes.
- They're involved in intracellular digestion of food particles and in protection against invading microbes.
- White blood cells have lots of lysosomes.
Vacuoles:
- A membrane-bound sac of fluid or solid particles to be excreted, digested, or stored.
- Formed in phagocytic cells (certain white blood cells and protozoa).
Mitochondria: Energy Generators of the Cell:
- Function in energy production: generates energy in the form of ATP (adenosine triphosphate) for all cellular activities.
- Consists of an outer membrane and an inner, folded membrane with folds called cristae.
- The cristae membranes hold the enzymes and electron carriers of aerobic respiration, which is an oxygen-using process that extracts chemical energy contained in nutrient molecules and stores it in the form of high energy molecules (i.e. ATP).
- The spaces around the cristae are filled with a fluid called the matrix, which holds prokaryote-sized ribosomes and DNA.
-The higher the cells energy needs the more mitochondria it has.
- Has the instructions within itself, is able to divide and copy themselves (therefore, they divide independently).
- Believed to have once been free-living bacteria
Chloroplasts: Photosynthesis Machines:
- Found in algae and plant cells.
- Capable of photosynthesis (i.e. converting the energy of sunlight into chemical energy). This makes them the primary producers of organic nutrients upon which almost all other organisms ultimately depend.
- Chloroplast also produces oxygen gas.
- Resemble mitochondria, but chloroplasts are larger and more varied in shape.
- Most chloroplasts are composed of two membranes, one enclosing the other. The outer membranes covers an inner membrane that's folded into small sacs called thylakoids and stacked on each other into grana. These structures carry the green pigment chlorophyll.
- Believed to have once been cyanobacteria
Ribosomes: Protein Synthesizers:
- Present in both eukaryotes and prokaryotes, but eukaryote ribosomes are larger (80S).
- They originate in the nucleus and the rough endoplasmic reticulum. Both types of ribosomes are necessary components of protein synthesis. Ribosomes are composed of rRNA and proteins. Larger than prokaryotic ribosomes. They are attached to the ER in the cytoplasm. Are the peptide assembly site.
- 80s ribosomes on ER and in cytoplasm
- 70s ribosomes in chloroplasts and mitochondria (like bacteria)
- Made in the nucleolus from rRNA and protein
Cytoskeleton: A Support Network:
- Maintains the shape of cells.
- Produces movement of cytoplasm within the cell, movement of chromosomes at cell division, and in some groups, movement of the cell as a unit. WBC, macrophages, use pseudopods to move around.
- The cytoskeleton is the flexible framework of proteins.
The micro-filaments (strands of protein actin that attach to the cell membrane) and micro-tubules (long, hollow tubes that maintain the shape of eukaryotic cells that lack
cell walls, such as protozoa) form the network through the cytoplasm.
Eucaryotic cells have membrane-bound organelles, which are never present in procaryotes. Such compartmentalization allows a wide variety of cellular functions to occur in specialized areas of the cell.
Q: What is not a cytoplasmic organelle present in all eucaryotic organisms?
a. endoplasmic reticulum
b. cytoskeleton
c. mitochondria
A: B cytoskeleton
Form and Function of the Eucaryotic Cell: Internal Structures
The genome of eucaryotes is located in the nucleus, aspherical structure surrounded by a double membrane. The nucleus also contains the nucleolus, site of rRNA synthesis. Eucaryote DNA, or chromatin, is organized into chromosomes at cell division.
All eucaryotes cycle between a haploid state and a diploid state at some point in their life cycle. Most fungi, many algae, and some protozoa are haploid except in their zygote stage.
Plants and animals, as will as some protozoa and algae, are diploid for most of their life cycles, but their gametes (reproductive cells) are always haploid.
Microscopic eucaryotes reproduce asexually by mitosis and sexually by meiosis.
Flagella: are long, sheathed cylinder containing micro-tubules in a 9+2 arrangement. It's main function is motility.
Q: What are the only human cells that have flagella?
Q: What statement regarding procaryotic and eucaryotic Flagella is correct?
a. Both possess an external covering
b. The motion of both types is the same
c. Both function in locomotion
A: C Both function in locomotion
Structure Flowchart
Eucaryotic cell
Videos showing protozoans moving with flagella and cilia.
- Identify the different parts/structures of a eukaryotic cell, along with each structure's functions.
- Identify the different kinds of eukaryotic microbes.
- Identify the different kingdoms of eukaryotes, with each kingdom's morphology, nutritional mode/distribution, method of reproduction, importance, and major groups.
Eucaryotic Cells & Microorganisms
EUKARYOTES - CELLS WITH PARTS Eukaryotes are what you think of when you think of a classic "cell." There are cells without organized nuclei or organelles that are called prokaryotes.
The possibilities are endless. Eukaryotes are cells that can do anything. They are the cells that have helped organisms advance to new levels of specialization beyond imagination. You wouldn't be here if eukaryotic cells did not exist. What makes a eukaryotic cell? Let's watch.
(1) Eukaryotic cells have an organized nucleus with a nuclear envelope. They have a "brain" for the cell. They have a discreet area where they keep their DNA. It is also said that they have a "true nucleus."
(2) Eukaryotic cells usually have organelles.
- Example: They have mitochondria for energy production, chloroplasts for photosynthesis, and many other parts that make the cells a self-sufficient organism
(3) Although limited in size by the physics of diffusion, eukaryotic cells can get very large. There are even some extreme examples called plasmodial slime molds that can be a meter wide. The cell is multi-nucleated (many nuclei) and it gets huge. Generally, eukaryotic cells are a couple hundred times the size of a prokaryotic cell.
(4) Eukaryotic cells have extra stuff going on and extra parts attached. Since they have organelles and organized DNA they are able to create parts. One example is the flagellum (a tail-like structure to help it move). They could also create cilia (little hairs that help scoot the cell through the water). In the invertebrate section, we talk about nematocysts that are cells with little harpoons for catching prey. The list is endless.
Form & Function of the Eukaryotic Cell
The cell structures common to all eukaryotes are the cell membrane, a membrane-enclosed nucleus with nucleolus inside, vacuoles, mitochondria, endoplasmic reticulum, Golgi apparatus, and a cytoskeleton. Cell walls, chloroplasts, and locomotor organs are present in some eukaryote groups.
I. External Structures:
Flagella and Cilia: Locomotor Appendages:
- Provide locomotion. Flagella are common in protozoa, algae, and few fungal and animal cells.
- Eukaryotic flagella are different from prokaryotic flagella: eukaryotic flagellum is 10x thicker, structurally more complex, and covered by an extension of the cell membrane. Eukaryotic flagella also contains regularly spaced hollow tubules--called microtubules--that extend along their entire length.
- In vertebrates only the sperm cells have flagella
- Cilia are found only in certain protozoa and animal cells. Cilia is shorter than flagella and more numerous. Cilia function in motility, feeding, and filtering.
-many protozoans are covered with cilia and move quickly
Glycocalyx:
- The glycocalyx is the outermost boundary of most eukaryotic cells that comes in direct contact with the environment. It is usually composed of polysaccharides and appears in a network of fibers, a slime layer or a capsule much like the glycocalyx of prokaryotes. Glycocalyx means "sweet husk."
- Its functions are adherence to environmental surfaces, the development of biofilms and mats, and reception of chemical signals from the environment and /or other organisms.
- The glycocalyx is supported by either a cell wall or a cell membrane.
- Cell surface markers (antigens) are part of the glycocalyx
this is how our immune system distinguishes self and nonself.
Boundary Structures:
Cell Wall:
- Found in fungi, plants, and most algae have a cell wall, but protozoa, a few algae, and all animal cells don't (they only have a membrane).
- The cell wall is rigid and provides structural support and shape. Fungi have a thick inner layer of polysaccharides fibers composed of chitin or cellulose and a thin outer layer of mixed glycans. Plants use cellulose for their cell wall.
Cytoplasmic Membrane:
- Made of a bilayer of phospholipids in which protein molecules are embedded. The cytoplasmic membrane of eukaryotes is similar in function to that of prokaryotes, but it differs in composition, possessing sterols as additional stabilizing agents.
- The cytoplasmic membrane is relatively rigid, which strengthens the stability on eukaryotic membranes. This is important especially to those cells without cell walls (i.e. protozoa, a few algae, and all animal cells).
II. Internal Structures:
Nucleus: Control Center:
- Compact sphere that is the most prominent organelle of eukaryotic cells. The control center (governs and regulates all cell activity). The nucleus contains the cell's chromosomes (the cell's genetic information) which are
not visible until they coil during mitosis. Chromosomes are only coiled up when getting ready to divide, they are normally unbound in the nucleus.
- The nucleus is separated from the cytoplasm by an external boundary called a nuclear envelope, which is composed of two parallel membranes separated by a narrow space and perforated with pores. The pores serve as passageways for molecules to go between the nucleus and cytoplasm.
- The main body of the nucleus consists of the nucleolus, which is the site for ribosomal RNA synthesis and ribosomes assembly.
Endoplasmic Reticulum: A Passageway into the Cell:
- A series of tunnels used in transport and storage.
- Two kinds of endoplasmic reticulum:
- appears as parallel, flat pouches bounded by membranes
- Rough endoplasmic reticulum (RER), which originates from the outer membrane of the nuclear envelope and extends in a continuous network through the cytoplasm. It's rough due to the ribosomes partly attached to its membrane surface. Proteins synthesized on the ribosomes are shunted into the RER for packaging and transport. transport materials from the nucleus to the cytoplasm and ultimately to the cells exterior.
- Smooth endoplasmic reticulum (SER) is a closed tubular network without ribosomes. It functions in nutrient processing and also in synthesis and storage of lipids and other non-protein macromolecules. SER lack ribosomes making it have the smooth shape it does.
Golgi Apparatus: A Packaging and Distribution Machine:
- The "packaging and distribution center" (the site where proteins are modified, stored, and packaged for transport to their final destinations which can be within or outside of the cell).
- Consists of a stack of flattened sacs called cisternae (looks like pita bread), which have cavities like the endoplasmic membrane, but the cisternae don't form a continuous network.
- The Golgi apparatus is always closely associated with the endoplasmic reticulum in its location and function. The endoplasmic reticulum buds off protein packets called transitional vesicles that are picked up by the Golgi apparatus, which modifies the proteins, then pinches them off as finished condensing vesicles that are transported to organelles or secreted outside the cell.
Lysosymes:
- The garbage men of the cell.
- Vesicles originating from the Golgi apparatus that contain a variety of enzymes.
- They're involved in intracellular digestion of food particles and in protection against invading microbes.
- White blood cells have lots of lysosomes.
Vacuoles:
- A membrane-bound sac of fluid or solid particles to be excreted, digested, or stored.
- Formed in phagocytic cells (certain white blood cells and protozoa).
Mitochondria: Energy Generators of the Cell:
- Function in energy production: generates energy in the form of ATP (adenosine triphosphate) for all cellular activities.
- Consists of an outer membrane and an inner, folded membrane with folds called cristae.
- The cristae membranes hold the enzymes and electron carriers of aerobic respiration, which is an oxygen-using process that extracts chemical energy contained in nutrient molecules and stores it in the form of high energy molecules (i.e. ATP).
- The spaces around the cristae are filled with a fluid called the matrix, which holds prokaryote-sized ribosomes and DNA.
-The higher the cells energy needs the more mitochondria it has.
- Has the instructions within itself, is able to divide and copy themselves (therefore, they divide independently).
- Believed to have once been free-living bacteria
Chloroplasts: Photosynthesis Machines:
- Found in algae and plant cells.
- Capable of photosynthesis (i.e. converting the energy of sunlight into chemical energy). This makes them the primary producers of organic nutrients upon which almost all other organisms ultimately depend.
- Chloroplast also produces oxygen gas.
- Resemble mitochondria, but chloroplasts are larger and more varied in shape.
- Most chloroplasts are composed of two membranes, one enclosing the other. The outer membranes covers an inner membrane that's folded into small sacs called thylakoids and stacked on each other into grana. These structures carry the green pigment chlorophyll.
- Believed to have once been cyanobacteria
Ribosomes: Protein Synthesizers:
- Present in both eukaryotes and prokaryotes, but eukaryote ribosomes are larger (80S).
- They originate in the nucleus and the rough endoplasmic reticulum. Both types of ribosomes are necessary components of protein synthesis. Ribosomes are composed of rRNA and proteins. Larger than prokaryotic ribosomes. They are attached to the ER in the cytoplasm. Are the peptide assembly site.
- 80s ribosomes on ER and in cytoplasm
- 70s ribosomes in chloroplasts and mitochondria (like bacteria)
- Made in the nucleolus from rRNA and protein
Cytoskeleton: A Support Network:
- Maintains the shape of cells.
- Produces movement of cytoplasm within the cell, movement of chromosomes at cell division, and in some groups, movement of the cell as a unit. WBC, macrophages, use pseudopods to move around.
- The cytoskeleton is the flexible framework of proteins.
The micro-filaments (strands of protein actin that attach to the cell membrane) and micro-tubules (long, hollow tubes that maintain the shape of eukaryotic cells that lack
cell walls, such as protozoa) form the network through the cytoplasm.
Eucaryotic cells have membrane-bound organelles, which are never present in procaryotes. Such compartmentalization allows a wide variety of cellular functions to occur in specialized areas of the cell.
Q: What is not a cytoplasmic organelle present in all eucaryotic organisms?
a. endoplasmic reticulum
b. cytoskeleton
c. mitochondria
A: B cytoskeleton
Form and Function of the Eucaryotic Cell: Internal Structures
The genome of eucaryotes is located in the nucleus, aspherical structure surrounded by a double membrane. The nucleus also contains the nucleolus, site of rRNA synthesis. Eucaryote DNA, or chromatin, is organized into chromosomes at cell division.
All eucaryotes cycle between a haploid state and a diploid state at some point in their life cycle. Most fungi, many algae, and some protozoa are haploid except in their zygote stage.
Plants and animals, as will as some protozoa and algae, are diploid for most of their life cycles, but their gametes (reproductive cells) are always haploid.
Microscopic eucaryotes reproduce asexually by mitosis and sexually by meiosis.
Flagella: are long, sheathed cylinder containing micro-tubules in a 9+2 arrangement. It's main function is motility.
Q: What are the only human cells that have flagella?
Q: What statement regarding procaryotic and eucaryotic Flagella is correct?
a. Both possess an external covering
b. The motion of both types is the same
c. Both function in locomotion
A: C Both function in locomotion
Structure Flowchart
Eucaryotic cell
- Appendages
- Flagella
- Cilia
- Surface structures
- Glycocalyx
- Capsules
- Slimes
- Cell wall-Outer support
- Cytoplasmic membrane
- Nucleus
- Nuclear envelope
- Nucleolus
- Chromosomes
- Cytoplasm
- Organelles
- Endoplasmic reticulum
- Mitochondria
- Chloroplasts
- Golgi complex
- Lysosomes
- Vacuoles
- Organelles
- Cytoskeleton
- Micro-tubules Micro-filaments
- Ribosomes
Videos showing protozoans moving with flagella and cilia.
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I was wondering if anyone cold tell me the dirrerence?
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| angieatkin | Lynn Marguilis | 0 | Jan 28 2008, 3:37 PM EST by angieatkin | ||
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lynn marguilis endosymbiosis
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