What Is The Outermost Boundary Of An Animal Cell
Chapter 3: Introduction to Cell Structure and Function
three.3 Eukaryotic Cells
By the cease of this section, you will be able to:
- Describe the structure of eukaryotic establish and animal cells
- State the role of the plasma membrane
- Summarize the functions of the major cell organelles
- Describe the cytoskeleton and extracellular matrix
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At this point, information technology should be clear that eukaryotic cells have a more complex structure than practise prokaryotic cells. Organelles allow for various functions to occur in the cell at the same time. Before discussing the functions of organelles within a eukaryotic prison cell, let united states of america start examine 2 of import components of the cell: the plasma membrane and the cytoplasm.
What structures does a institute jail cell have that an animal cell does not have? What structures does an animal cell take that a constitute jail cell does not have? Institute cells have plasmodesmata, a jail cell wall, a large central vacuole, chloroplasts, and plastids. Animal cells have lysosomes and centrosomes.
The Plasma Membrane
Like prokaryotes, eukaryotic cells have a plasma membrane (Figure 3.9) made up of a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding surround. A phospholipid is a lipid molecule composed of two fatty acid chains, a glycerol backbone, and a phosphate group. The plasma membrane regulates the passage of some substances, such as organic molecules, ions, and water, preventing the passage of some to maintain internal conditions, while actively bringing in or removing others. Other compounds move passively across the membrane.
The plasma membranes of cells that specialize in absorption are folded into fingerlike projections called microvilli (atypical = microvillus). This folding increases the surface expanse of the plasma membrane. Such cells are typically found lining the small intestine, the organ that absorbs nutrients from digested nutrient. This is an excellent instance of form matching the function of a structure.
People with celiac illness take an allowed response to gluten, which is a protein found in wheat, barley, and rye. The allowed response amercement microvilli, and thus, afflicted individuals cannot absorb nutrients. This leads to malnutrition, cramping, and diarrhea. Patients suffering from celiac illness must follow a gluten-free diet.
The Cytoplasm
The cytoplasm comprises the contents of a cell between the plasma membrane and the nuclear envelope (a construction to be discussed shortly). Information technology is made up of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals. Fifty-fifty though the cytoplasm consists of 70 to 80 percentage water, it has a semi-solid consistency, which comes from the proteins inside it. Yet, proteins are non the only organic molecules found in the cytoplasm. Glucose and other simple sugars, polysaccharides, amino acids, nucleic acids, fat acids, and derivatives of glycerol are found at that place as well. Ions of sodium, potassium, calcium, and many other elements are besides dissolved in the cytoplasm. Many metabolic reactions, including poly peptide synthesis, take identify in the cytoplasm.
The Cytoskeleton
If you were to remove all the organelles from a jail cell, would the plasma membrane and the cytoplasm be the just components left? No. Within the cytoplasm, at that place would yet be ions and organic molecules, plus a network of protein fibers that helps to maintain the shape of the cell, secures sure organelles in specific positions, allows cytoplasm and vesicles to move within the jail cell, and enables unicellular organisms to move independently. Collectively, this network of protein fibers is known every bit the cytoskeleton. There are 3 types of fibers within the cytoskeleton: microfilaments, too known as actin filaments, intermediate filaments, and microtubules (Figure 3.x).
Microfilaments are the thinnest of the cytoskeletal fibers and part in moving cellular components, for example, during prison cell partition. They besides maintain the structure of microvilli, the extensive folding of the plasma membrane found in cells dedicated to absorption. These components are likewise common in muscle cells and are responsible for muscle cell contraction. Intermediate filaments are of intermediate bore and take structural functions, such as maintaining the shape of the cell and anchoring organelles. Keratin, the compound that strengthens pilus and nails, forms one type of intermediate filament. Microtubules are the thickest of the cytoskeletal fibers. These are hollow tubes that tin can dissolve and reform rapidly. Microtubules guide organelle movement and are the structures that pull chromosomes to their poles during cell sectionalization. They are as well the structural components of flagella and cilia. In cilia and flagella, the microtubules are organized equally a circle of nine double microtubules on the outside and ii microtubules in the center.
The centrosome is a region near the nucleus of animal cells that functions equally a microtubule-organizing center. Information technology contains a pair of centrioles, two structures that lie perpendicular to each other. Each centriole is a cylinder of ix triplets of microtubules.
The centrosome replicates itself before a cell divides, and the centrioles play a role in pulling the duplicated chromosomes to contrary ends of the dividing cell. Nevertheless, the exact function of the centrioles in cell partition is non clear, since cells that take the centrioles removed can however divide, and institute cells, which lack centrioles, are capable of cell partitioning.
Flagella and Cilia
Flagella (atypical = flagellum) are long, hair-similar structures that extend from the plasma membrane and are used to move an entire cell, (for case, sperm, Euglena). When nowadays, the cell has just one flagellum or a few flagella. When cilia (singular = cilium) are present, yet, they are many in number and extend along the entire surface of the plasma membrane. They are short, pilus-similar structures that are used to motion entire cells (such as paramecium) or motion substances along the outer surface of the cell (for instance, the cilia of cells lining the fallopian tubes that motility the ovum toward the uterus, or cilia lining the cells of the respiratory tract that move particulate thing toward the throat that mucus has trapped).
The Endomembrane System
The endomembrane arrangement (endo = within) is a group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins. Information technology includes the nuclear envelope, lysosomes, vesicles, endoplasmic reticulum and the Golgi apparatus, which we volition cover shortly. Although not technically inside the jail cell, the plasma membrane is included in the endomembrane organization considering, every bit you volition meet, it interacts with the other endomembranous organelles.
The Nucleus
Typically, the nucleus is the most prominent organelle in a cell. The nucleus (plural = nuclei) houses the cell's DNA in the form of chromatin and directs the synthesis of ribosomes and proteins. Let united states await at it in more than item (Figure 3.11).
The nuclear envelope is a double-membrane structure that constitutes the outermost portion of the nucleus (Figure 3.11). Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers.
The nuclear envelope is punctuated with pores that command the passage of ions, molecules, and RNA between the nucleoplasm and the cytoplasm.
To understand chromatin, it is helpful to showtime consider chromosomes. Chromosomes are structures within the nucleus that are made up of DNA, the hereditary textile, and proteins. This combination of DNA and proteins is chosen chromatin. In eukaryotes, chromosomes are linear structures. Every species has a specific number of chromosomes in the nucleus of its body cells. For example, in humans, the chromosome number is 46, whereas in fruit flies, the chromosome number is eight.
Chromosomes are simply visible and distinguishable from one some other when the cell is getting fix to split up. When the cell is in the growth and maintenance phases of its life cycle, the chromosomes resemble an unwound, jumbled bunch of threads.
We already know that the nucleus directs the synthesis of ribosomes, but how does information technology practice this? Some chromosomes have sections of DNA that encode ribosomal RNA. A darkly stained surface area within the nucleus, called the nucleolus (plural = nucleoli), aggregates the ribosomal RNA with associated proteins to assemble the ribosomal subunits that are then transported through the nuclear pores into the cytoplasm.
The Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a series of interconnected membranous tubules that collectively modify proteins and synthesize lipids. Withal, these two functions are performed in separate areas of the endoplasmic reticulum: the rough endoplasmic reticulum and the polish endoplasmic reticulum, respectively.
The hollow portion of the ER tubules is called the lumen or cisternal space. The membrane of the ER, which is a phospholipid bilayer embedded with proteins, is continuous with the nuclear envelope.
The crude endoplasmic reticulum (RER) is and then named because the ribosomes fastened to its cytoplasmic surface give information technology a studded appearance when viewed through an electron microscope.
The ribosomes synthesize proteins while attached to the ER, resulting in the transfer of their newly synthesized proteins into the lumen of the RER where they undergo modifications such as folding or addition of sugars. The RER too makes phospholipids for cell membranes.
If the phospholipids or modified proteins are not destined to stay in the RER, they volition be packaged within vesicles and transported from the RER by budding from the membrane. Since the RER is engaged in modifying proteins that will be secreted from the cell, it is abundant in cells that secrete proteins, such as the liver.
The smooth endoplasmic reticulum (SER) is continuous with the RER simply has few or no ribosomes on its cytoplasmic surface. The SER'southward functions include synthesis of carbohydrates, lipids (including phospholipids), and steroid hormones; detoxification of medications and poisons; alcohol metabolism; and storage of calcium ions.
The Golgi Apparatus
Nosotros have already mentioned that vesicles can bud from the ER, just where do the vesicles go? Before reaching their final destination, the lipids or proteins inside the transport vesicles need to be sorted, packaged, and tagged and so that they wind up in the correct identify. The sorting, tagging, packaging, and distribution of lipids and proteins accept place in the Golgi apparatus (as well called the Golgi torso), a series of flattened membranous sacs.
The Golgi apparatus has a receiving face most the endoplasmic reticulum and a releasing face up on the side away from the ER, toward the cell membrane. The transport vesicles that form from the ER travel to the receiving face, fuse with it, and empty their contents into the lumen of the Golgi apparatus. As the proteins and lipids travel through the Golgi, they undergo further modifications. The most frequent modification is the addition of brusque chains of sugar molecules. The newly modified proteins and lipids are then tagged with modest molecular groups to enable them to be routed to their proper destinations.
Finally, the modified and tagged proteins are packaged into vesicles that bud from the opposite face of the Golgi. While some of these vesicles, send vesicles, deposit their contents into other parts of the cell where they will be used, others, secretory vesicles, fuse with the plasma membrane and release their contents exterior the cell.
The amount of Golgi in different cell types once again illustrates that course follows part within cells. Cells that engage in a great bargain of secretory action (such as cells of the salivary glands that secrete digestive enzymes or cells of the immune organization that secrete antibodies) have an abundant number of Golgi.
In plant cells, the Golgi has an additional part of synthesizing polysaccharides, some of which are incorporated into the cell wall and some of which are used in other parts of the cell.
Lysosomes
In animal cells, the lysosomes are the jail cell'south "garbage disposal." Digestive enzymes inside the lysosomes assist the breakup of proteins, polysaccharides, lipids, nucleic acids, and fifty-fifty worn-out organelles. In single-celled eukaryotes, lysosomes are important for digestion of the food they ingest and the recycling of organelles. These enzymes are active at a much lower pH (more acidic) than those located in the cytoplasm. Many reactions that take place in the cytoplasm could not occur at a low pH, thus the advantage of compartmentalizing the eukaryotic cell into organelles is credible.
Lysosomes besides use their hydrolytic enzymes to destroy disease-causing organisms that might enter the cell. A good example of this occurs in a group of white blood cells chosen macrophages, which are role of your trunk'southward immune system. In a procedure known as phagocytosis, a section of the plasma membrane of the macrophage invaginates (folds in) and engulfs a pathogen. The invaginated section, with the pathogen within, then pinches itself off from the plasma membrane and becomes a vesicle. The vesicle fuses with a lysosome. The lysosome'southward hydrolytic enzymes then destroy the pathogen (Effigy 3.fifteen).
Vesicles and Vacuoles
Vesicles and vacuoles are membrane-jump sacs that function in storage and ship. Vacuoles are somewhat larger than vesicles, and the membrane of a vacuole does non fuse with the membranes of other cellular components. Vesicles can fuse with other membranes inside the cell system. Additionally, enzymes within establish vacuoles can intermission down macromolecules.
Why does the cis face of the Golgi not face the plasma membrane?
<!– Because that confront receives chemicals from the ER, which is toward the heart of the cell. –>
Ribosomes
Ribosomes are the cellular structures responsible for protein synthesis. When viewed through an electron microscope, gratuitous ribosomes appear equally either clusters or single tiny dots floating freely in the cytoplasm. Ribosomes may be attached to either the cytoplasmic side of the plasma membrane or the cytoplasmic side of the endoplasmic reticulum. Electron microscopy has shown that ribosomes consist of large and small subunits. Ribosomes are enzyme complexes that are responsible for protein synthesis.
Because poly peptide synthesis is essential for all cells, ribosomes are plant in practically every cell, although they are smaller in prokaryotic cells. They are particularly abundant in immature red claret cells for the synthesis of hemoglobin, which functions in the transport of oxygen throughout the body.
Mitochondria
Mitochondria (singular = mitochondrion) are ofttimes called the "powerhouses" or "energy factories" of a cell considering they are responsible for making adenosine triphosphate (ATP), the cell's principal energy-carrying molecule. The germination of ATP from the breakdown of glucose is known every bit cellular respiration. Mitochondria are oval-shaped, double-membrane organelles (Effigy 3.17) that have their own ribosomes and Deoxyribonucleic acid. Each membrane is a phospholipid bilayer embedded with proteins. The inner layer has folds chosen cristae, which increase the area of the inner membrane. The area surrounded by the folds is chosen the mitochondrial matrix. The cristae and the matrix accept different roles in cellular respiration.
In keeping with our theme of form post-obit function, information technology is important to signal out that muscle cells have a very high concentration of mitochondria because muscle cells demand a lot of free energy to contract.
Peroxisomes
Peroxisomes are modest, round organelles enclosed by single membranes. They bear out oxidation reactions that break down fatty acids and amino acids. They as well detoxify many poisons that may enter the torso. Alcohol is detoxified past peroxisomes in liver cells. A byproduct of these oxidation reactions is hydrogen peroxide, HtwoOtwo, which is contained inside the peroxisomes to prevent the chemical from causing harm to cellular components outside of the organelle. Hydrogen peroxide is safely broken down by peroxisomal enzymes into water and oxygen.
Fauna Cells versus Found Cells
Despite their fundamental similarities, at that place are some striking differences between creature and plant cells (see Tabular array 3.1). Animal cells have centrioles, centrosomes (discussed under the cytoskeleton), and lysosomes, whereas constitute cells do not. Plant cells have a cell wall, chloroplasts, plasmodesmata, and plastids used for storage, and a large central vacuole, whereas animal cells do not.
The Cell Wall
In Figure 3.8b, the diagram of a plant cell, you see a construction external to the plasma membrane called the jail cell wall. The jail cell wall is a rigid covering that protects the cell, provides structural support, and gives shape to the cell. Fungal and protist cells likewise have cell walls.
While the chief component of prokaryotic prison cell walls is peptidoglycan, the major organic molecule in the plant cell wall is cellulose, a polysaccharide made upwards of long, straight bondage of glucose units. When nutritional data refers to dietary fiber, information technology is referring to the cellulose content of food.
Chloroplasts
Like mitochondria, chloroplasts besides accept their own Deoxyribonucleic acid and ribosomes. Chloroplasts function in photosynthesis and can be found in eukaryotic cells such every bit plants and algae. In photosynthesis, carbon dioxide, water, and light energy are used to make glucose and oxygen. This is the major deviation between plants and animals: Plants (autotrophs) are able to brand their own food, like glucose, whereas animals (heterotrophs) must rely on other organisms for their organic compounds or food source.
Like mitochondria, chloroplasts have outer and inner membranes, merely within the space enclosed past a chloroplast'south inner membrane is a set of interconnected and stacked, fluid-filled membrane sacs called thylakoids (Effigy 3.18). Each stack of thylakoids is called a granum (plural = grana). The fluid enclosed by the inner membrane and surrounding the grana is called the stroma.
The chloroplasts contain a green pigment chosen chlorophyll, which captures the energy of sunlight for photosynthesis. Similar institute cells, photosynthetic protists also have chloroplasts. Some bacteria besides perform photosynthesis, but they practice not accept chloroplasts. Their photosynthetic pigments are located in the thylakoid membrane inside the prison cell itself.
Development in Activeness
Endosymbiosis: Nosotros accept mentioned that both mitochondria and chloroplasts contain Dna and ribosomes. Have you lot wondered why? Strong evidence points to endosymbiosis as the explanation.
Symbiosis is a relationship in which organisms from ii separate species live in close association and typically exhibit specific adaptations to each other. Endosymbiosis (endo-= within) is a human relationship in which one organism lives inside the other. Endosymbiotic relationships abound in nature. Microbes that produce vitamin One thousand live inside the human being gut. This human relationship is benign for usa because we are unable to synthesize vitamin K. It is also beneficial for the microbes because they are protected from other organisms and are provided a stable habitat and abundant food past living within the large intestine.
Scientists accept long noticed that bacteria, mitochondria, and chloroplasts are similar in size. We also know that mitochondria and chloroplasts have Dna and ribosomes, just as bacteria do and they resemble the types found in bacteria. Scientists believe that host cells and bacteria formed a mutually beneficial endosymbiotic relationship when the host cells ingested aerobic bacteria and cyanobacteria simply did not destroy them. Through development, these ingested bacteria became more specialized in their functions, with the aerobic leaner becoming mitochondria and the photosynthetic bacteria condign chloroplasts.
The Central Vacuole
Previously, we mentioned vacuoles as essential components of plant cells. If you look at Figure iii.8b, y'all will see that found cells each have a large, central vacuole that occupies most of the prison cell. The central vacuole plays a key role in regulating the prison cell'due south concentration of water in irresolute environmental atmospheric condition. In establish cells, the liquid inside the central vacuole provides turgor pressure, which is the outward force per unit area caused by the fluid inside the prison cell. Have you ever noticed that if you forget to water a constitute for a few days, it wilts? That is because as the water concentration in the soil becomes lower than the water concentration in the plant, water moves out of the central vacuoles and cytoplasm and into the soil. As the fundamental vacuole shrinks, it leaves the cell wall unsupported. This loss of support to the cell walls of a plant results in the wilted appearance. Additionally, this fluid has a very biting gustation, which discourages consumption past insects and animals. The central vacuole also functions to store proteins in developing seed cells.
Extracellular Matrix of Fauna Cells
Most fauna cells release materials into the extracellular space. The main components of these materials are glycoproteins and the protein collagen. Collectively, these materials are called the extracellular matrix (Figure 3.nineteen). Not only does the extracellular matrix hold the cells together to form a tissue, merely information technology as well allows the cells within the tissue to communicate with each other.
Blood clotting provides an example of the role of the extracellular matrix in cell communication. When the cells lining a blood vessel are damaged, they display a protein receptor called tissue factor. When tissue factor binds with another factor in the extracellular matrix, information technology causes platelets to adhere to the wall of the damaged blood vessel, stimulates adjacent smooth muscle cells in the blood vessel to contract (thus constricting the blood vessel), and initiates a series of steps that stimulate the platelets to produce clotting factors.
Intercellular Junctions
Cells tin also communicate with each other by direct contact, referred to as intercellular junctions. There are some differences in the ways that institute and fauna cells do this. Plasmodesmata (atypical = plasmodesma) are junctions between plant cells, whereas animal cell contacts include tight and gap junctions, and desmosomes.
In general, long stretches of the plasma membranes of neighboring constitute cells cannot bear upon ane another because they are separated by the cell walls surrounding each cell. Plasmodesmata are numerous channels that pass between the cell walls of side by side plant cells, connecting their cytoplasm and enabling betoken molecules and nutrients to be transported from jail cell to prison cell (Figure 3.xxa).
A tight junction is a watertight seal between ii adjacent brute cells (Figure 3.20b). Proteins agree the cells tightly against each other. This tight adhesion prevents materials from leaking betwixt the cells. Tight junctions are typically found in the epithelial tissue that lines internal organs and cavities, and composes nigh of the skin. For case, the tight junctions of the epithelial cells lining the urinary bladder foreclose urine from leaking into the extracellular infinite.
Also found only in animate being cells are desmosomes, which act like spot welds between adjacent epithelial cells (Figure 3.xxc). They keep cells together in a sheet-like germination in organs and tissues that stretch, like the peel, heart, and muscles.
Gap junctions in brute cells are like plasmodesmata in plant cells in that they are channels between side by side cells that let for the transport of ions, nutrients, and other substances that enable cells to communicate (Effigy 3.20d). Structurally, however, gap junctions and plasmodesmata differ.
Jail cell Component | Role | Nowadays in Prokaryotes? | Present in Animal Cells? | Present in Establish Cells? |
|---|---|---|---|---|
| Plasma membrane | Separates cell from external environment; controls passage of organic molecules, ions, h2o, oxygen, and wastes into and out of the cell | Yes | Yes | Aye |
| Cytoplasm | Provides construction to cell; site of many metabolic reactions; medium in which organelles are found | Yes | Yeah | Yes |
| Nucleoid | Location of DNA | Aye | No | No |
| Nucleus | Cell organelle that houses Deoxyribonucleic acid and directs synthesis of ribosomes and proteins | No | Yes | Yeah |
| Ribosomes | Poly peptide synthesis | Yep | Yes | Yep |
| Mitochondria | ATP production/cellular respiration | No | Yes | Yes |
| Peroxisomes | Oxidizes and breaks down fatty acids and amino acids, and detoxifies poisons | No | Yes | Yep |
| Vesicles and vacuoles | Storage and send; digestive function in plant cells | No | Yes | Aye |
| Centrosome | Unspecified role in cell division in beast cells; organizing center of microtubules in creature cells | No | Aye | No |
| Lysosomes | Digestion of macromolecules; recycling of worn-out organelles | No | Aye | No |
| Cell wall | Protection, structural support and maintenance of cell shape | Yes, primarily peptidoglycan in leaner only not Archaea | No | Yes, primarily cellulose |
| Chloroplasts | Photosynthesis | No | No | Yes |
| Endoplasmic reticulum | Modifies proteins and synthesizes lipids | No | Yes | Yes |
| Golgi apparatus | Modifies, sorts, tags, packages, and distributes lipids and proteins | No | Aye | Yep |
| Cytoskeleton | Maintains cell's shape, secures organelles in specific positions, allows cytoplasm and vesicles to move within the jail cell, and enables unicellular organisms to move independently | Aye | Yep | Aye |
| Flagella | Cellular locomotion | Some | Some | No, except for some plant sperm. |
| Cilia | Cellular locomotion, move of particles along extracellular surface of plasma membrane, and filtration | No | Some | No |
Section Summary
Similar a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes, simply a eukaryotic prison cell is typically larger than a prokaryotic cell, has a true nucleus (meaning its Deoxyribonucleic acid is surrounded past a membrane), and has other membrane-jump organelles that allow for compartmentalization of functions. The plasma membrane is a phospholipid bilayer embedded with proteins. The nucleolus within the nucleus is the site for ribosome assembly. Ribosomes are found in the cytoplasm or are attached to the cytoplasmic side of the plasma membrane or endoplasmic reticulum. They perform protein synthesis. Mitochondria perform cellular respiration and produce ATP. Peroxisomes break downward fat acids, amino acids, and some toxins. Vesicles and vacuoles are storage and transport compartments. In plant cells, vacuoles besides help pause downwards macromolecules.
Animal cells likewise have a centrosome and lysosomes. The centrosome has 2 bodies, the centrioles, with an unknown role in jail cell division. Lysosomes are the digestive organelles of animate being cells.
Plant cells take a cell wall, chloroplasts, and a central vacuole. The plant cell wall, whose principal component is cellulose, protects the prison cell, provides structural back up, and gives shape to the cell. Photosynthesis takes place in chloroplasts. The primal vacuole expands, enlarging the prison cell without the need to produce more cytoplasm.
The endomembrane system includes the nuclear envelope, the endoplasmic reticulum, Golgi appliance, lysosomes, vesicles, as well as the plasma membrane. These cellular components work together to change, package, tag, and transport membrane lipids and proteins.
The cytoskeleton has three different types of poly peptide elements. Microfilaments provide rigidity and shape to the cell, and facilitate cellular movements. Intermediate filaments bear tension and anchor the nucleus and other organelles in place. Microtubules help the cell resist compression, serve as tracks for motor proteins that move vesicles through the cell, and pull replicated chromosomes to reverse ends of a dividing jail cell. They are also the structural elements of centrioles, flagella, and cilia.
Animal cells communicate through their extracellular matrices and are connected to each other by tight junctions, desmosomes, and gap junctions. Establish cells are connected and communicate with each other by plasmodesmata.
cell wall: a rigid cell roofing made of cellulose in plants, peptidoglycan in bacteria, non-peptidoglycan compounds in Archaea, and chitin in fungi that protects the cell, provides structural support, and gives shape to the cell
central vacuole: a large plant cell organelle that acts as a storage compartment, water reservoir, and site of macromolecule degradation
chloroplast: a plant cell organelle that carries out photosynthesis
cilium: (plural: cilia) a short, hair-like construction that extends from the plasma membrane in large numbers and is used to move an entire prison cell or move substances along the outer surface of the cell
cytoplasm: the unabridged region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in the gel-like cytosol, the cytoskeleton, and diverse chemicals
cytoskeleton: the network of protein fibers that collectively maintains the shape of the cell, secures some organelles in specific positions, allows cytoplasm and vesicles to move inside the cell, and enables unicellular organisms to move
cytosol: the gel-like material of the cytoplasm in which cell structures are suspended
desmosome: a linkage between adjacent epithelial cells that forms when cadherins in the plasma membrane adhere to intermediate filaments
endomembrane organisation: the group of organelles and membranes in eukaryotic cells that piece of work together to modify, package, and send lipids and proteins
endoplasmic reticulum (ER): a series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids
extracellular matrix: the material, primarily collagen, glycoproteins, and proteoglycans, secreted from animal cells that holds cells together as a tissue, allows cells to communicate with each other, and provides mechanical protection and anchoring for cells in the tissue
flagellum: (plural: flagella) the long, hair-similar construction that extends from the plasma membrane and is used to motility the cell
gap junction: a aqueduct betwixt two next animal cells that allows ions, nutrients, and other low-molecular weight substances to laissez passer betwixt the cells, enabling the cells to communicate
Golgi apparatus: a eukaryotic organelle made upward of a serial of stacked membranes that sorts, tags, and packages lipids and proteins for distribution
lysosome: an organelle in an animal prison cell that functions every bit the prison cell'due south digestive component; it breaks down proteins, polysaccharides, lipids, nucleic acids, and even worn-out organelles
mitochondria: (singular: mitochondrion) the cellular organelles responsible for carrying out cellular respiration, resulting in the production of ATP, the jail cell's main energy-carrying molecule
nuclear envelope: the double-membrane structure that constitutes the outermost portion of the nucleus
nucleolus: the darkly staining trunk inside the nucleus that is responsible for assembling ribosomal subunits
nucleus: the cell organelle that houses the prison cell's Dna and directs the synthesis of ribosomes and proteins
peroxisome: a small, round organelle that contains hydrogen peroxide, oxidizes fatty acids and amino acids, and detoxifies many poisons
plasma membrane: a phospholipid bilayer with embedded (integral) or attached (peripheral) proteins that separates the internal contents of the jail cell from its surrounding surroundings
plasmodesma: (plural: plasmodesmata) a channel that passes between the prison cell walls of side by side plant cells, connects their cytoplasm, and allows materials to be transported from prison cell to cell
ribosome: a cellular construction that carries out protein synthesis
crude endoplasmic reticulum (RER): the region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification
polish endoplasmic reticulum (SER): the region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates, lipids, and steroid hormones; detoxifies chemicals like pesticides, preservatives, medications, and environmental pollutants, and stores calcium ions
tight junction: a firm seal between 2 side by side animate being cells created by poly peptide adherence
vacuole: a membrane-bound sac, somewhat larger than a vesicle, that functions in cellular storage and transport
vesicle: a small, membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane and the membranes of the endoplasmic reticulum and Golgi apparatus
Media Attribution
- Figure iii.xi: modification of work by NIGMS, NIH
- Figure 3.xiii: modification of work by NIH; calibration-bar data from Matt Russell
- Figure 3.14: modification of work by Louisa Howard; scale-bar information from Matt Russell
- Figure iii.sixteen: modification of piece of work by Magnus Manske
- Effigy 3.17: modification of work by Matthew Britton; calibration-bar data from Matt Russell
- Figure 3.20: modification of work by Mariana Ruiz Villareal
Source: https://opentextbc.ca/biology/chapter/3-3-eukaryotic-cells/
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