Cells and Organelles

what is karyokinesis ?

(nuclear division of chromosomes).

What is a feulgen stain?

Feulgen stain is a staining technique discovered by Robert Feulgen and used in histology to identify chromosomal material or DNA in cell specimens. It is darkly stained. The principle of Feulgen stain is to dissociate the two strands of DNA through hydrolysis by a solution of molar HCl which destroys the purine bases. HCl separates the two purine bases of DNA: adenine, guanine

What is the function of collagen and what cells produce them?

Fibroblasts are cells that produce collagen. When they are produced they are secreted as long woven fibers called collagan fibrils. Collagen fibrils is what gives humans so much of their strength and rigidity.

What is the significance of fibronectin when they connect integrins to the network of proteoglycans and collagen in the ECM?

Fibronectin connects integerins to the network of proteoglycans and collagen with the extraceullar matrix. These connections help in the transduction of extracellular signals, such that they can travel through the integrins and into the cell.

What are fibronectin?

Fibronectin is a protein in the ECM that connects integrins to the network of proteoglycans and collagen in the ECM.

What is the important pattern seen in flagella and cilia and what is an axoneme?

Flagella and Cilia have a "9+2" pattern. This entire picture of the 9+2 arrangement along with the proteins constitutes what is called an axoneme.

There are two main ways animal cells extracellular matrix connect to the cytoskeleton. They are ____

Focal adhesions connect the ECM to actin-based microfilaments in the cytoskeleton. Hemidesmosomes connect the ECM to the keratin intermediate filaments of the cytoskeleton.

What are food vacuoles?

Food vacuoles are temporary food holders. These form when cells take-up nutrients via endocytosis mechanisms, and all the nutrient vesicles fuse together. temporary receptacles of nutrients; merge with lysosomes which break down food Food vacuoles will eventually merge with lysosomes such that the acidic lysosomal enzymes can digest the nutrients within the food vacuole.

keratin is ....

For example, keratin is an important intermediate filament protein in skin, hair, and nails which helps in the cellular structure of these important outer features. Keratins represent a predominant type of intermediate fiber. Keratins are actually a diverse family of over 20 proteins that provide protection against abrasion and prevent water loss in epidermal cells.

There are four main ways animal cells can connect to one another, and they have a range of benefits. what are they?

Four main ways animal cells can connect to one another: 1. Tight junctions 2. Anchor Junctions a. Desomosome Junctions b. Adheren Junctions 3- Gap junctions

What is freeze fracture?

Freeze fracture is a specialized preparation technique that splits a membrane along the middle of the phospholipid bilayer. In this technique, e can study the bilayer. The interior and exterior are surely NOT symmetrical. The freeze-fracture studies provided the first direct evidence of integral proteins in many biological membranes.

What does the Smooth ER do in the liver and what is cytochrome 450?

In the liver, the Smooth ER contains a large amount of cytochrome 450 and participates in detoxifying certain drugs. The cytochrome 450 catalyzes reactions to decrease drug toxicity. The hepatocyte (liver cell) is involved with drug detoxification, thus has a high % of smooth ER.

Gap junctions are...

Gap junctions allow the passage of ions and small molecules between cells. Gap Junctions allows communication to occur between cells. We see membrane proteins that surround a pore that will allow substances such as small molecules, amino acids, and ions to pass. The proteins of gap junctions are called connexins. Many types of tissue such as muscle and heart contain these junctions. Gap junctions are responsible for the heart's coordinated beat.

Cells often communicate with each other and are not isolated. What are a few intracellular junctions?

Gap junctions, Rapid exchange, Plasmodesmata (in plants), Tight Junctions "Zona Occludens", and desmosomes.

What are osteoclasts?

Osteoclasts are cells that break down bone, these are a fine example of a multinucleated cell. Multinucleated cells can often be found under pathological conditions such as in a malignant (cancerous tumor).

What is the Tay-Sachs disease?

In Tay-Sachs disease, a critical lysosomal enzyme is deficient...lipids cannot be digested, and cells become "engorged" and neuronal function suffers...the child dies before age 4.

what is the glycoclayx?

In a transmission electron microscope study, we would see the external of the cell showing a "fuzzy" area. This is the glycocalyx. It essentially is the carbohydrate chains covalently linked to the transmembrane proteins and/or phospholipids on the outer portion. It has many negatively charged sulfate and carboxyl groups. They are involved with making up receptors that participate in functions such as cell recognition, hormone response, and adhesion. It's a carbohydrate coat that covers outer face of cell wall of some bacteria and outer face of plasma membrane (some animal cells). It consists of glycolipids (attached to plasma membrane) and glycoproteins (such as recognition proteins). It may provide adhesive capabilities, a barrier to infection, or markers for cell-cell recognition.

Centrioles are involved with the creation of spindle apparatus for cell division, what else are they important for?

In addition to centrioles being involved with cell division, the mother centriole can attach to the cell membrane. Here, the mother centriole can form a basal body, which can produce a cilium or a flagellum for the cell.

What happens to the products that went inside the golgi apparatus?

In general, products secreted by the Golgi tend to travel to their destined locations such as the cytosol, cell membrane, extracellular environment (via exocytosis), into a lysosome, or into a vacuole.

Which types of hormones are fast and slow acting?

In general, steroids are slow-acting hormones this is because since they can cross the lipid membrane, they have to do the job of giving their effects themselves at the translation and transcription level, which is a slow process. Fast-acting hormones are peptide hormones that are made of amino acids. They bind to membrane-bound receptors which is a relatively quick process because they trigger secondary messengers which do the job for the peptide hormone and this is pretty quick. This is a relatively quick process because second messengers like cAMP amplify the cascade. You can have many proteins phosphorylated in a short amount of time, leading to a quick cellular reaction. In contrast, a steroid hormones such as testosterone must diffuse through the membrane and act on a receptor in the cytosol or nucleus of the target cell. To have its effects on the cell, testosterone must affect gene expression by regulating transcription. It does so by binding to a hormone response element on the DNA. Then protein products are made from the targeted genes, leading to a cellular response. As you can imagine, it takes a relatively long time (usually hours) to make new proteins in this fashion, which is why it is slow-acting.

In plants, hemicellulose and pectin are made by what?

In plants, hemicellulose and pectin are made by the Golgi apparatus. Both hemicellulose and pectin contribute to the plant cell wall.

What are 3 places ribosomes can be found?

Ribosomes can be: a) Attached to the Endoplasmic Reticulum b) Attached to the Nuclear Envelope c) Freely suspended in the cytosol.

What are ribosomes made of?

Ribosomes consist of two subunits which are made in the nucleolus of the cell. The subunits are made separately in the nucleolus and exported to the cytoplasm for final assembly. The large and small subunit join together by binding an mRNA strand.

What are the three main destinations for the material being shipped out of the trans-Golgi?

There are three main destinations for the material being shipped out of the trans Golgi: Inside the cell...many are released in vesicles destined to be delivered to the lysosomes. The Plasma Membrane...many molecules are shipped to be used for repair to the membrane, for cell signaling purposes, etc. Outside the cell...such as the release of the hormone insulin

What is actin?

Thin filament protein. Twisted into a double helix and appears like a double-stranded chain of pearls. Contains the myosin-binding site. Actin plays a critical role in cytokinesis and phagocytosis. In most eukaryotic cells, actin is the most abundant protein, and participates in more protein-protein interactions than any other protein.

Two types of integral proteins that are involved with facilitated transport are...

Two types of integral proteins that are involved with facilitated transport are 1.Channel protein 2. carrier proteins.

Which types of transport DO NOT require energy?

Type of Transport where no energy is required: simple diffusion channel proteins carrier proteins (depends, can also require energy) passive diffusion porins ion channels aquaporins

What are the 5 important types of vaculoes?

Types of Vacuoles: 1. Transport vacuoles 2. food vacuoles 3. Central vacuoles 4. storage vacuoles 5. contractile vacuoles.

Which types of transport REQUIRE ENERGY?

Types of transport that are energy requiring: Active transport-both primary and secondary transport Sodium-potassium pump cytosis- both endocytosis and exocytosis phagocytosis pinocytosis receptor-mediated endocytosis

Proteins that enter the lumen of the rough ER have one of two fates, what are they?

Ultimately, proteins that enter the lumen of the rough ER will have one of two fates: they will either become a part of the cell membrane (as an integral or peripheral membrane protein), or they will leave the cell altogether (via exocytosis). In this way, the rough ER allows for increased eukaryotic complexity because it helps to distinguish between proteins that should leave the cell and those that should remain inside.

What are vacuoles?

Vacuoles are another organelle found within all plant and fungal cells, as well as some animal, protist, and rarely bacterial cells. Vacuoles are found in both animal and plant cells but are much larger in plant cells. Vacuoles form as the result of many membrane vesicles fusing together.

Vacuoles form as the result of _____

Vacuoles form as the result of many membrane vesicles fusing together.

Do prokayotes have any membranous organelles?

eukaryotes contain membrane-bound organelles; Prokaryotic cells do not.

What is the extracellular matrix?

extracellular matrix (ECM) primarily functions to provide mechanical support in the area between adjacent animal cells. The ECM has carbohydrates, an extensive network of fibrous structural proteins, and adhesion proteins.

Do fungi and plant cells contain centrosomes?

fungi and most plant cells do not contain a centrosome as their MTOC. We typically refer to their MTOCs just as 'MTOCs.'

In the golgi apparatus, further modification can occur such as phosphorylation, what is the point of this?

glycoproteins from the rough ER can undergo phosphorylation in the Golgi complex. These "tags" help the "mailroom" direct the "product" to the correct location

How do these carbohydrate chains attach to proteins?

glycosylation is the process by which a carbohydrate is covalently attached to an organic molecule, creating structures such as glycoproteins and glycolipids which are chains of oligosaccharides or polysaccharides. They are very abundant on the surface of the cell, and their interactions contribute to the overall stability of the cell by serving cell recognition services, modulating the function of membrane proteins that act as receptors (The head of the oligosaccharide serves as a binding partner in receptor activity.)

What is amphipathic?

having both hydrophilic and hydrophobic parts

What are ion channels?

ion channels are the passage of ions across membrane. Ion channels are also known as gated channels that can be seen in the nervous system and muscular system. There are three types of ion gated channels: 1. Voltage Gated Ion Channels 2. Ligand Gated Channels 3. Mechanically gated channels

How do these glycoproteins/oligosccharides attach on to the proteins?

1) via the nitrogen atom on the side chain of asparagine (called the N-linkage) 2) via the oxygen atom on the side chain of theonine or serine (called the O-linkage) The site of glycosylation depends on the sequence of amino acids surrounding (asparagine, serine, and theonine) It also depends on the type of cell producing the protein on the overall structure of the protein.

N-linked glycosylation and O-linked glycosylation doesn't happen in the same place, explain where each occurs.

1- N-linked glycosylation begins at the endoplasmic reticulum and is completed at the Golgi apparatus. 2- O-linked glycosylation taken place entirely in the Golgi apparatus.

Summarize how glycosylation occurs and be specific on each location.

1- Ribosomes attached to the cytoplasmic side of the rough ER synthesize proteins. As the proteins move into the lumen of the ER, special enzymes attach oligosaccharides via N-linkages. 2- The proteins move out of the lumen of the ER and into the cytoplasm where they travel to the golgi apparatus. Inside the golgi apparatus, the N-linked sugars are modified and the O-linked glycosylation occurs. Once the golgi apparatus modifies and sorts the glycoproteins, it directs them to their correct locations, such as lysososmes, secretory granules, or the plasma membrane.

Properties of the plama membrane (plasmalemma)?

1. Allows the cell to maintain homeostasis (steady state of equilibrium) 2. Allows ions and other solutes to be transported in or out and contains ion channels and many proteins 3. This plasma or cell membrane contains phosphilipids, cholesterol, proteins, glycoproteins. This selective barrier regulates materials from passing into or out of the cell.

What are microfilaments?

1. Microfilaments: Microfilaments are the smallest, and are composed of a double helix of two actin filaments. They are mainly involved in cell movement and can quickly assemble, and disassemble. Functions of Microfilaments: 1. Cyclosis (cytoplasmic streaming) - 'stirring of the cytoplasm', organelles and vesicles travel on microfilament "tracks". This is important in cell movement. For example, cyclosis (or cytoplasmic streaming) is a cytoplasmic movement process that relies upon actin-based microfilaments. Here, organelles and vesicles travel throughout the cytoplasm on microfilament "tracks." 2. Cleavage furrow- during cell division, actin microfilaments form contractile rings that split the cell For example, animal cells form cleavage furrows to divide. Cleavage furrows contain contractile rings of microfilaments that pinch the cytoplasms into two separate cells (cytokinesis). 3. Muscle contraction - actin microfilaments have directionality, allowing myosin motor proteins to pull on them for muscle contraction. For example, actin-based microfilaments have directionality; therefore, they can create "one-way streets" for a motor protein called myosin. Muscle cells can contract because of myosin and actin microfilaments.

What are the three important types of gated channels?

1. Voltage-gated ion channels: they respond to the difference in membrane potential Voltage-gated ion channels are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel. The membrane potential alters the conformation of the channel proteins, regulating their opening and closing. 2. ligand-gated channels: This is where an external ligand like a chemical binds to the receptor on the protein in order for the channel to open and close. Ligand-gated ion channels bind neurotransmitters and open in response to ligand binding. These channels control synaptic transmission between two neurons or between a neuron and a muscle. 3. mechanically-gated channels: these channels respond to pressure, vibration, temperature, etc. A mechanically gated channel opens because of the physical distortion of the cell membrane. Many channels associated with the sense of touch (somatosensation) are mechanically gated. For example, as pressure is applied to the skin, these channels open and allow ions to enter the cell

What is a centrosome?

A centrosome is an organelle found in animal cells, and it is a type of MTOC. Centrosomes are near an animal cell's nucleus.

centrosome vs centrioles

A centrosome is an organelle that is found close to the nucleus within the cytoplasm of cells. Centrosomes are key to the division of cells and produce the spindle fibers that are required during metaphase of mitosis. Each centrosome consists of two centrioles that are orientated at right-angles to each other. Each centriole is a cylindrical array of 9 microtubules.

What are peripheral membrane proteins?

A peripheral membrane protein is the other type of membrane protein found associated with cell membranes. These do not extend through the entire bilayer - instead, peripheral membrane proteins are on the periphery. The periphery could mean the polar heads of the phospholipid bilayer, partially inserted into the membrane, or attached to one of the hydrophilic surfaces of an integral membrane protein. These proteins are generally hydrophilic since they are exposed on the outside of the cell membrane in the aqueous environment.

How is a phagosome formed?

A phagosome is formed by the fusion of the cell membrane around a microorganism or senescent cell ( a cell that no longer divides). This phagosome fuses with the lysosome and the enzymes begin digestion.

What's the difference between vacuoles and vesicles?

A vesicle is a small, membrane bound, chemically neutral and temporary container, used to pass its contents across organelle and cell plasma membranes. A vacuole is larger, a membrane bound organelle, present in plant and fungal cells and in some bacterial, protist, and animal cells.

What are the four main functions of the plasma membrane?

A) Physical barrier: partitions substances on the inside vs. outside B) Cell communications: think receptors!! C) Selective Structure: regulates ion and molecule flow D) Protection and Support: maintains cell integrity

what are ATPases?

ATPases are a class of enzymes that catalyze the decomposition of ATP into ADP and a free phosphate ion

What is active transport?

Active transport occurs when particles travel against their concentration gradient (from low to high concentration). These processes require an energy input, and the energy source dictates whether it will be primary or secondary active transport. Active transport primarily relies upon carrier proteins that change their shape.

Adheren Junctions are....

Adherens junctions - similar in structure and function to desmosomes, but connects neighboring cells via actin microfilaments.

What are the two important types of peripheral membrane proteins?

Adhesion proteins and Cellular recognition proteins are types of peripheral proteins.

What are adhesion proteins?

Adhesion proteins attach adjacent cells to other things (like other cells), and they also act as anchors for the cytoskeleton (internal filaments and tubules) for stability. Adhesives (like tape) stick to other things. Think of adhesion proteins as the tape that sticks cellular components together. Some adhesion proteins are truly peripheral (many lipoproteins), while some extend completely through the phospholipid membrane and would not be considered peripheral.

What is the Endosymbiotic Theory?

Although most DNA is packaged in chromosomes, mitochondria and chloroplasts have a small amount of their own DNA. Mitochondrial DNA is double-stranded, but circular. This has led scientists to believe that mitochondria originated from an ancestral aerobic prokaryotic bacterium...This bacterium adapted to a symbiotic relationship with an ancestral host cell. This is the Endosymbiotic Theory. Mitochondria are self-replicating too, with an average life span of about 10 days. The endosymbiotic theory deals with the origins of mitochondria and chloroplasts, two eukaryotic organelles that have bacteria characteristics. Mitochondria and chloroplasts are believed to have developed from symbiotic bacteria

What are nuclear pores?

Although the nuclear envelope separates the cytosol from the nucleoplasm, specific molecules need to travel in and out of the nucleus. These molecules are usually related to DNA replication and transcription. Nuclear pores are holes in the nuclear envelope allowing for molecules to travel in and out. For example, messenger ribonucleic acid (mRNA), the product of transcription, exits the nucleus via nuclear pores.

How do amoebas move and what type of microfilaments or microtubules does it involve for its movement?

Amoebas move by pseudopodia and this movement also involves actin and myosin.

What is the endomembrane system?

An endomembrane system is a group of organelles and membranes that work together to modify, package, and transport proteins and lipids that are entering or exiting a cell. Together, the endomembrane system includes the nucleus/nuclear envelope, rough and smooth ERs, Golgi apparatus, lysosomes, vacuoles, and cell membranes. Cells have extensive sets of intracellular membranes, which together compose the endomembrane system. The endomembrane system includes the endoplasmic reticulum (ER), Golgi Apparatus, and lysosomes. Vescicles also allow exchange of membrane components with a cell's plasma membrane.

Since animal cells don't have cell walls, what do they have instead?

Animal cells do not have cell walls because they secrete collagen and have an extracellular matrix. Both plants and animals have ECM. The cell wall of plant cells is a type of extracellular matrix. In animals, the ECM can surround cells as collagen fibrils that contact the cells on all sides, or as a sheet called the basement membrane that cells 'sit on'

Aquaporins are....

Aquaporin is a specific type of porin that work through faciliated diffusion in order to allow water to flow through channels, so water can flow more rapidly that simple diffusion alone. They are abundant in kidney and plant roots.

Carrier proteins...

Carrier protein is a type of integal protein involved in facilitated transport Carrier proteins change their shape to facilitate the movement of molecules through the protein. These are different from the protein channels we discussed above because they do not face extracellular and intracellular environments at the same time. Instead, they only face one side at a time. They change shape when their specific molecule binds, causing them to face the other side to help transport the mocleule to the other side.

what are cell membranes?

Cell membranes are boundaries that hold all of the critical cellular contents inside, protecting them from the surrounding environment. In general, cell membranes contain three main things: 1. phospholipids, 2. cholesterol 3. proteins

How do cell walls form in plants, fungi, bacteria, and archaea and what building blocks form cell walls in each organism?

Cell walls in plants, fungi, bacteria, and archaea form as cells secrete their respective carbohydrate building blocks into the extracellular environment. This means that each cell wall is composed of different building blocks. plant cell walls contain cellulose, so plant cells will secrete cellulose to make their cell wall. Fungi cell walls contain chitin. Bacteria cell walls have peptidoglycan. Archaea cell walls have indiscriminate polysaccharides.

What are cell walls?

Cell walls only exist in plants, fungi, bacteria, and archaea. They are unique carbohyrate-based structures that lie above the cell membrane. They provide structural support, protection, and an enhanced degree of filteration for what enters and exits the cell. In this way they act similar to animal cells extracellular matrix.

cell to cell junctions connect ______.

Cell-cell junctions connect adjacent cells.

What are cell-matrix junctions?

Cell-matrix junctions allow the extracellular matrix outside of cells to connect the cytoskeleton that lie in the inside of animal cells.

Cells have shape, can move and have the ability to communicate. A system of tubules and filaments comprise the cytoskeleton. The cell organelles can be membranous such as the mitochondria or lysosome or be non-membranous such as the ribosomes.

Cells have shape, can move and have the ability to communicate. A system of tubules and filaments comprise the cytoskeleton. The cell organelles can be membranous such as the mitochondria or lysosome or be non-membranous such as the ribosomes.

What kind of cells would contain lots of ribosomes?

Cells making an enzyme will have a lot of enzymes.

Cells regulate how substances cross the cell membrane to travel in and out of the cell.

Cells regulate how substances cross the cell membrane to travel in and out of the cell. small, hydrophobic, uncharged (regardless of polarity), nonpolar particles ( like carbon dioxide and oxygen) can travel directly across the phospholipid bilayer. Note polar molecules can cross the membrane but they have to be very small and uncharged. Everything else requires transporter (large, polar, charged molecules)

What types of cells show an abundance of smooth ER?

Cells that are active in the synthesis of cholesterol, triglycerides, and steroids show an abundance of smooth ER.

What organs contain the most mitochondria?

Cells usually possess a high number of mitochondria, but kidneys and heart have enormous numbers of mitochondria!! Heart has the most; kidneys are second for those who are curious. A liver cell might have 2,000, but a heart cell has 5,000 mitochondria.

What are cellular recognition proteins?

Cellular recognition proteins are peripheral membrane proteins that help cells recognize each other. They have carbohydrate chains (glycoproteins) that are used by cells to recognize each other. This is how cells identify (or recognize) each other when they come in contact. Recognition proteins usually interact with receptor proteins. Recognition proteins are attached to a short carbohydrate chain called an oligosaccharide so hence they are a type of glycoprotein.

What are central vacuoles?

Central vacuoles are very large organelles, and they tend to occupy the majority of a plant cell interior. Central vacuoles often carry out the same functions as an animal cell lysosome within a plant. They can also act as a storage vacuole. Central vacuoles have a specialized membrane called the tonoplast, they exert turgor when filled, which helps to maintain cell rigidity.

What is a tonoplast?

Central vacuoles have a specialized membrane called the tonoplast, they exert turgor when filled, which helps to maintain cell rigidity.

Main difference between channel proteins and carrier proteins?

Channel proteins face the extracellular and intracellular environments of the cell at the same time. Carrier proteins: do not face extracellular and intracellular environments at the same time. Instead, they only face one side at a time. They change shape when their specific molecule binds, causing them to face the other side.

Channel proteins are a type of integral protein involved in facilitated transport, how?

Channel proteins face the extracellular and intracellular environments of the cell at the same time. They are like tunnels that have been dug through the membrane, and they usually allow the passage of hydrophilic (water-soluble), small, polar molecules and charged ions.

What is a chloroplast?

Chloroplast is a plant organelle and the site of photosynthesis. It contains the green pigment chlorophyll which absorbs light energy to convery carbon dioxide into water, oxygen, and sugar. Like the mitochondria, it contains their own circular DNA. Inside the chloroplast, we find flattened sacs called thylakoids. These thylakoids may be stacked like pancakes..each stack is called a grana. The fluid outside the thylakoids is called stroma, which as the DNA, enzymes, and ribosomes. Like the mitochondria, they have a double membrane. Thylakoids contain hundreds of different proteins and is still being investigated

What are chloroplasts?

Chloroplasts exist in select eukaryotic cells, such as plant cells and some protists like algae. Animal, fungal, and prokaryotic cells do not contain chloroplasts. The central role of a chloroplast is to carry out photosynthesis.

Chromatin can be either heterochromatin or euchromatin, what's the difference?

Chromatin can be either heterochromatin or euchromatin. Heterochromatin is dark-staining and much is found near the nuclear envelope. It is condensed and not actively transcribed. The euchromatin is the light area...less dense...less compact and has genes that are actively transcribing. In most cells, more of the DNA is found in euchromatin than heterochromatin.

What is cilia and flagells composed of?

Cilia and flagella are composed of microtubules and motor proteins are used for movement.

What are cilia and flagella?

Cilia and flagella are projections from the cell. They are made up of microtubules , as shown in this cartoon and are covered by an extension of the plasma membrane. They are motile and designed either to move the cell itself or to move substances over or around the cell.

What are cilia and flagella?

Cilia and flagella are projections from the cell. They are made up of microtubules , they are covered by an extension of the plasma membrane. They are motile and designed either to move the cell itself or to move substances over or around the cell.

Do cilia and flagella have the same structure as the basal body they stem from?

Cilia and flagella have a slightly different structure than the basal body they stem from because cilia and flagella have an outer ring of nine microtubule doubles, and two singles at the center - this is also known as a 9 + 2 array. On the other hand, the basal body's structure is known as triplet of microtubules because they have a 9 x 3 array of microtubules. Look at diagram.

Clathrin is the is the best-studied coat protein. How does it work?

Coat protein on cell membrane receptors, it provides the mechanism to covert a planar membrane into a spherical structure (vesicle), the receptor provides the specificity. It plays a major role in the formation of coated vesicles.

What are cyanobacteria?

Cyanobacteria give us oxygen! They represent the only form of oxygenic photosynthetic bacteria known to date. These bacteria contain chlorophyll, and perform photosynthesis similar to plants. Cyanobacteria are mainly found in water, but can be found on corals, rocks, and even land. Cyanobacteria used to be called blue-green algae, but we try to avoid it. Remember, these cyanobacteria are from Kingdom Monera and represent prokaryotes. Prokaryotes are unicellular, and lack a membrane-bound nucleus, mitochondria, and other membrane-bound organelles.

What is cytosis?

Cytosis refers to the processes cells use to facilitate the bulk transport of large, polar (hydrophilic) molecules. Types of cytosis include: 1. Phagocytosis 2. Pinocytosis 3. receptor-mediated endocytosis 4. Exocytosis All of these types of bulk transport cytosis are high energy-intensive requiring processes.

DNA is like the instruction manual that cellular factories reply upon to make products (proteins). but HOW?

DNA is like the instruction manual that cellular factories reply upon to make products (proteins). The DNA is "read" through two processes, called transcription and translation, hence allowing for the creation of the cellular factory's proteins.

In a cell, where does DNA exist?

DNA lies within eukaryotic cells in a particular "room" called the nucleus

What are desmosomes?

Desmosomes are anchor junctions that are like staples that hold adjacent cells together. They provide robust mechanical stability and are present in tissues subject to mechanical stress. Desmosomes are different from tight junctions because they extend across the cell membranes and connect to the cytoskeleton inside the cell. They connect adjacent cells together via intermediate filaments. Desmosomes remind me of "staples"...they fasten the cells together into strong sheets...some scientists call them a "spot-weld". They can attach muscle cells to one another. Desmosomes have intermediate filaments which are very strong, they are common in epithelia that need to withstand abrasian such as skin. As a future doctor, you might be interested to known that some people produce antibodies against the proteins that make up the desmosome. In a skin disease called Pemphigus Vulgaris, we see a disruption of cell adhesion. Many blisters form and loss of extracellular fluid occurs. This can be fatal if not treated. Usually, a steroidal agent can control the pathology.

What is colchicine?

Drugs such as colchicine disrupts the microtubules and is used to treat gout. Microtubules disruptions blocks white blood cell migration which is responsible for inflammation. Gout is a painful inflammation of the big toe and foot caused by defects in uric acid metabolism resulting in deposits of the acid and its salts in the blood and joints. Make sure you understand that colchicine is a "Mitotic poison"...it messes up the microtubules. Thus, I hope you can see that mitosis would be halted!!

what is bulk transport?

During bulk transport, larger substances or large packages of small molecules are transported through the cell membrane, also known as the plasma membrane, by way of vesicles - think of vesicles as little membrane sacs that can fuse with the cell membrane. bulk transport cytosis are high energy-intensive requiring processes.

What is responsible for the bending movement of cilia and flagella?

Dynein, one of the molecular motors, is responsible for the bending movements of the cilia and flagella.

How does the structure of centrioles look like?

Each centrosome has two centrioles at 90 degree angles. Each individual centriole is a hollow cylinder made of nine triplets of microtubules (9 x 3 array).

What occurs in endocytosis?

Endocytosis occurs whenever the cell membrane forms a plasma membrane-bound package (vacuole or vesicle) around something extracellular the cell wants to internalize. In other words, endocytosis transports molecules into the cell. Endocytosis is an integral part of the endomembrane system Basic process: 1. The plasma membrane of the cell invaginates (folds inward), forming a pocket around the target particle or particles. 2. The pocket then pinches off with the help of specialized proteins, leaving the particle trapped in a newly created vesicle or vacuole inside the cell. Endocytosis can be further subdivided into the following categories: 1. phagocytosis, 2. pinocytosis 3. receptor-mediated endocytosis.

Over 40 different enzymes are found and are particularly abundant in cells with high phagocytic activity. What are some types of enzymes found in phagocytotic cells?

Enzymes include proteases, nucleases, phosphotases, and sulfatases, etc.

What are epithelial cells?

Epithelial cells are cells that come from the surfaces of your body such as your skin, blood vessels, urinary tract, or organs. They serve as a barrier between the inside and outside of your body, and protects it from viruses. Epithelial cells secrete the layer of extracellular matrix called basal lamina.

Both eukaryotic cells and prokaryotes contain ribosomes; although, their structures are slightly different. how?

Eukaryotic ribosomes have two subunits. One subunit is 60 S, while the other is 40 S (the unit "S" tells how heavy/dense a molecule is). These subunits come together to form a complete 80 S eukaryotic ribosome. Each of the subunits is produced in the nucleoplasm, coming together in the cytosol of the cell. Prokaryotic ribosomes also have two subunits. They have a 50 S subunit and a 30 S subunit. The subunits come together in the prokaryotic cytosol, and they form a 70 S prokaryotic ribosome.

What are some examples of types of lipids that are created by the smooth endoplasmic reticulum?

Examples of common lipids is cholesterol, steroids, waxes, phospholipids, and fat-soluble vitamins

What is exocytosis?

Exocytosis is the opposite of endocytosis. In other words, exocytosis occurs when materials exit the cell. Exocytosis is an essential part of vesicle secretion from the Golgi apparatus Cells must take in certain molecules, such as nutrients, but they also need to release other molecules, such as signaling proteins and waste products, to the outside environment. How does it work? The vesicles that come out of the golgi apparatus contain proteins made specifically by the cell for release to the outside environment. These contents canbe for signaling molecules, or wastes that the cell needs to dispose of, such as the leftovers that remain after a phagocytosed particle has been digested. These vesicles are transported to the edge of the cell, where they can fuse with the plasma membrane and release their contents into the extracellular space. Some vesicles fuse completely with the membrane and are incorporated into it, while others follow the "kiss-and-run" model, fusing just enough to release their contents ("kissing" the membrane) before pinching off again and returning to the cell interior. Exocytosis (exo = external, cytosis = transport mechanism) is a form of bulk transport in which materials are transported from the inside to the outside of the cell in membrane-bound vesicles that fuse with the plasma membrane. Examples of exocytosis: Exocytosis require ATP. It is when molecules are secreted by the fusion of vesicle with the plasma membrane. The release of the contents goes to the extracellular space without compromising cell membrane (plasma membrane) integrity. Beta cells of the pancrease make insulin and secrete it into the blood by exocytosis. Exocytosis is triggered in many cells by a brief release of Ca2+ ions in the cytosol. Neurotransmitters released into the synaptic cleft is done by exocytosis.

The three types of facilitated transport methods are....

Facilitated transport can be uniport (one molecule moving in one direction), symport (several molecules moving in one direction), or antiport (several molecules moving in opposite directions).

The Rough Endoplasmic Reticulum helps a protein undergo glycosylation because...

Glycosylation is a process in which carbohydrate components are added to proteins. It is an important and highly regulated mechanism of secondary protein processing within cells. It plays a critical role in determining protein structure, function and stability. Structurally, glycosylation is known to affect the three dimensional configuration of proteins. This modification serves various functions. For instance, some proteins do not fold correctly unless they are glycosylated. It plays a critical role in determining protein structure, function and stability. Structurally, glycosylation is known to affect the three dimensional configuration of proteins.

Summary of hormones; steroid vs non steroid?

Hormones work by binding to protein receptors either inside target cells or on their plasma membranes. The binding of a steroid hormone (they are lipid soluble so they can cross the plasma membrane and do the work themselves, so it takes longer) forms a hormone-receptor complex that affects gene expression in the nucleus of the target cell. The binding of a non-steroid hormone (they are not fat soluble because they are made out of amino acids, so they send a signal to other guys to do the job nice and quickly) activates a second messenger that affects processes within the target cell.

What is an inclusion?

Inclusion are the nonliving components of a cell. Inclusions include: a) pigments-melanin pigment in skin and hair b) Lipid droplets in fat cells c) Glycogen granules in liver and skeletal muscle cells d) Vacuoles..membrane bound vecles..more prominent in plants. They can be used for storage e) crystals..likely remnants of certain proteins

large, hydrophilic, polar molecules pass through the phospholipid bilayer through....

Integral proteins allow largers, hydrophilic, polar molecules to pass through the phospholipid bilayer through Facilitated transport.

What are integral/transmembrane proteins?

Integral proteins are embeded inside the membrane. A type of integral protein is called transmembrane proteins, they traverse the entire phospholipid bilayer. These proteins are amphipathic, with nonpolar parts that contact the fatty acids and polar parts that extend out into the aqueous environment.

What do integral/transmembrane proteins function to do?

Integral/ transmembrane proteins may function in cell signaling, but most tend to transport large, polar (hydrophilic) molecules across the cell membrane.

What are some of the key roles of integrin in the extracellular matrix?

Integrins: 1- they connect the collagen to the extracellular matrix hence helping in extracellular matrix adhesion. 2- integrins are transmembrane proteins that send signals to the cell about its extracellular environment. 3- integrins signals the cells on how to respond to the extraceullar environemnt by telling the cell whether it should grow, divide, differentiate, or undergo programmed cell death (apoptosis)

In cancer cells, the nucleolus is hypertrophic, what does this mean?

Interestingly, in cancer cells, the nucleolus is often hypertrophic meaning increased in size. But, be careful. Large nucleoli are not only encountered with rapidly growing malignant tumors, but are found in cells that are actively synthesizing proteins.

What are intermediate filaments?

Intermediate filaments are about 10 nm diameter and provide tensile strength for the cell.

What are intermediate filaments?

Intermediate filaments are between microfilaments and microtubules in size (intermediate-sized). Unlike microfilaments, they do not assemble and disassemble nearly as quickly as the actin filaments that make-up microfilaments hence they are more stable which makes them longer lasting and for this reason they contribute to to the structural support of cells. They are more "permanent" structures compared to microfilaments and microtubules. After cell death, they are often still seen. Intermediate filaments anchors the nucles in place and provides much structural support for the cell. They also make up the framework of the nuclear envelope. Intermediate filaments embed themselves into cell junctions, like desmosomes and hemidesmosomes. For this reason, they tend to associate with the cellular membrane. For example, keratin is an important intermediate filament protein in skin, hair, and nails which helps in the cellular structure of these important outer features. Lamins are a type of intermediate filament which helps to make up the nuclear lamina, a network of fibrous intermediate filaments that support the nucleus and nuclear activities.

What is a senescent cell?

It is a cell that no longer divides.

What is the nucleoplasm?

Just like the cell contains cytoplasm which consists of everything within the cell (cytosol and organelles) so does the nucleus. The nucleus contains an aqueous medium called the nucleoplasm. DNA is located floating in the nucleoplasm in a certain region called the nucleoid region.

What is karyoplasm?

Karyoplasm simply forms the contents of the nucleus. It is the protoplasm that constitues the nucleus of the cell. Karyoplasm is also known as the nucleoplasm and it is the liquid content of the cell nucleus.

What are laminin?

Laminin is a protein that behaves similarly to fibronectin. They influence cell differentiation, adhesion, and movement. It is a biologically active component of the basal lamina.

What CANNOT freely cross the phospholipid bilayer?

Large, hydrophilic, polar molecules cannot travel directly across the bilayer- they need help from integral proteins. Note the inside of the phospholipid bilayer is hydrophobic, so no hydrophilic or polar molecule can pass through it.

What is myosin?

Like the motor protein dynein, myosin is another motor protein that loves to walk. However, it is a microfilament-based and not microtubule-based like dynein. Myosin "walks" along the actin filaments. Recall, this is seen in muscle contraction. I hope you remember that actin and myosin filaments slide past one another.

Lipoproteins are a type of ______ protein

Lipoproteins are a type of adhesion protein Recall that lipids are nonpolar, hydrophobic molecules. As a result, they travel through the blood in structures called lipoproteins. Lipoproteins contain a coat of phospholipids, cholesterol, and proteins. Lipoproteins also have a lipid core that contains more cholesterol and triglycerides. In this way, the hydrophobic lipids can travel through aqueous environments (like blood) by traveling in lipoproteins

Lysosomes Vs. Peroxisomes.

Lysosomes Vs. Peroxisomes.

How are lysosomes formed?

Lysosomes are formed by budding from the Golgi Complex.

What is a lysosome?

Lysosomes are membrane bound organelles that: 1. Lysosomes are formed from the fusion of vesicles from the Golgi complex with endosomes. Endosomes are vesicles that are formed by endocytosis as a section of the plasma membrane pinches off and is internalized by the cell. In this process, extracellular material is taken up by the cell. 2. break down substances through hydrolysis (they contain acidic hydrolytic/digestive enzymes that are designed to function at a low pH) that are taken up into lysosomes through endocytosis. 3. They carry out autophagy (the breakdown of the cell's own machinary for recycling) to break down nutrients, bacteria, and other cellular debris. A lysosome is a membrane-bound organelle that hydrolyzes (breaks down) substances. 4. They particupate in apoptosis which is programmed cell death of a cell when they release their contents into the cell. 5. Lysosomes are part of the endomembrane system 6. Neutrophils and macrophages are loaded with lysosomes 7. Lysosomes have a pH of about 5 within lysosomal lumen, and they are usually spherical in shape. 8. Lysosomes will digest: a) Microorganisms like fungi or bacteria b) Cellular debris such as old cells c) Old organelles such as mitochondria 9. *** Any leaked lysosomes are normally harmless to the cell since the cytosol has a pH of about 7.2 and will make lysosomal enzymes inactive.

What do lysosomes do?

Lysosomes break down macromolecules into their constituent parts, which are then recycled. These membrane-bound organelles contain a variety of enzymes called hydrolases that can digest proteins, nucleic acids, lipids, and complex sugars. The lumen of a lysosome is more acidic than the cytoplasm. This environment activates the hydrolases and confines their destructive work to the lysosome. In plants and fungi, lysosomes are called acidic vacuoles. Lysosomes are formed by the fusion of vesicles that have budded off from the trans-Golgi. The sorting system recognizes address sequences in the hydrolytic enzymes and directs them to growing lysosomes. In addition, vesicles that bud off from the plasma membrane via endocytosis are also sent to lysosomes, where their contents — fluid and molecules from the extracellular environment — are processed. The process of endocytosis is an example of reverse vesicle trafficking, and it plays an important role in nutrition and immunity as well as membrane recycling. Lysosomes break down and thus disarm many kinds of foreign and potentially pathogenic materials that get into the cell through such extracellular sampling

Polysaccharides and glycosaminoglycans are made by what?

Many of the cells polysaccharides are made by the Golgi and most of the glycosaminoglycans of the extracellular matrix.

When are membrane phospholipids most stable? What is the structure of a phospholipid?

Membrane phospholipids are most stable when organized in a lipid bilayer. As you can see, each phospholipid molecule of the lipid bilayer is made up of this polar head group and two long nonpolar fatty acyl traits projecting inward. The phospholipid is composed of both a hydrophilic area and a hydrophobic area. Therefore, the molecule is amphipathic. Hopefully you can see that the protein components can span the entire length (integral) or are simply attached to the cytosolic side (peripheral). Since most integral proteins span the entire length, we refer to them often as transmembrane proteins. These transmembrane proteins are often quite long and can fold while forming channels that allow the passage of specific ions or molecules.

What are the three types of membrane proteins that can be found in the cell membrane?

Membrane proteins come in three types: 1. peripheral 2. integral 3. transmembrane (this is a TYPE of integral protein) 1. peripheral (loosely attached to one side surface) 2. integral (embeds inside membrane) 3.transmembrane (all the way through, both sides - this is a TYPE of integral)

How are cell membranes synthesized?

Membranes and their constituent proteins are assembled in the ER. This organelle contains the enzymes involved in lipid synthesis, and as lipids are manufactured in the ER, they are inserted into the organelle's own membranes. This happens in part because the lipids are too hydrophobic to dissolve into the cytoplasm. Similarly, transmembrane proteins have enough hydrophobic surfaces that they are also inserted into the ER membrane while they are still being synthesized. Here, future membrane proteins make their way to the ER membrane with the help of a signal sequence in the newly translated protein. The signal sequence stops translation and directs the ribosomes — which are carrying the unfinished proteins — to dock with ER proteins before finishing their work. Translation then recommences after the signal sequence docks with the ER, and it takes place within the ER membrane. Thus, by the time the protein achieves its final form, it is already inserted into a membrane The proteins that will be secreted by a cell are also directed to the ER during translation, where they end up in the lumen, the internal cavity, where they are then packaged for vesicular release from the cell. The hormones insulin and erythropoietin (EPO) are both examples of vesicular proteins.

Microfilaments are built from what?

Microfilaments are built from actin (a globular protein)

What are microfilaments?

Microfilaments are fine, thread-like protein fibers, 3-6 nm in diameter. They are composed predominantly of a contractile protein called actin, which is the most abundant cellular protein. Microfilaments' association with the protein myosin is responsible for muscle contraction. Microfilaments can also carry out cellular movements including gliding, contraction, and cytokinesis.

what are Microtubule Organizing Centers (MTOCs?

Microtubule Organizing Centers (MTOCs) are in eukaryotic cells. MTOCs create, extend, and organize the cell's microtubules

There are microtubule motor proteins and microfilament motor proteins, what are they?

Microtubule motor proteins: Dynein and kinesins Microfilament motor proteins: Myosin is the motor, actin filaments are the tracks along which myosin moves, and ATP is the fuel that powers movement.

Rank the diameter sizes between microfilaments, intermediate filaments, and microtubules from largest to smallest.

Microtubules > intermediate filaments > microfilaments.

What are microtubules?

Microtubules are cylindrical tubes, 20-25 nm in diameter. They are composed of subunits of the protein tubulin--these subunits are termed alpha and beta. Microtubules act as a scaffold to determine cell shape, and provide a set of "tracks" for cell organelles and vesicles to move on. Microtubules also form the spindle fibers for separating chromosomes during mitosis. When arranged in geometric patterns inside flagella and cilia, they are used for locomotion.

What are microtubules?

Microtubules are the largest in size out of all three cytoskeletal components. They function by: 1. Giving structural integrity to cells as part of the cytoskeleton. 2. They participate in cell division by helping forming the spindle apparatus, which guides chromosomes to opposite ends of the cell during karyokinesis. 3. Microtubules also help form cilia and flagella Microtubules are hollow and have walls made out of tubulin protein dimers. This means they have a alpha-tubulin and beta-tubulin combined together. Microtubules are similar to microfilaments in the sense that they can grow and shrink rapidly, which is due to tubulin dimer addition/subtraction. the tubulin dimers that make up a microtubule also have directionality, much like the actin monomers in a microfilament.This means that they have two ends that are structurally different from one another.

Which of the three cytoskeletal polymers is the strongest?

Microtubules are the strongest of the cytoskeletal polymers. Most cells would lose their shape if microtubules are depolymerized!! Microtubules are organized to suit the needs of each cell. A mature neuron for example, uses microtubules for strenth, while a young neuron uses microtubules to help with movement.

Microtubules created by MTOCs form a ________, which guides chromosomes to opposite ends of the cell during __________

Microtubules created by MTOCs form a spindle apparatus, which guides chromosomes to opposite ends of the cell during karyokinesis

What is special about mitochondria and chloroplasts?

Mitochondria and chloroplasts were once likely prokaryotes that got ingested by larger cells...this was the Endosymbiont Theory.

What are Dyneins and kinesins?

Molecular motors are enzymes that will walk along microtubules and they include dyneins and kinesins. These molecules can generate enough force to literally walk across the microtubule. Dynein "walking" is responsible for the bending movement of the cilia and flagella.

What are molecular motors and what do they include?

Molecular motors are enzymes that will walk along microtubules. These molecular motors include Dyneins and kinesins. These molecules can generate enough force to literally walk across the microtubules.

Oligosaccharide vs polysaccharides?

Monosaccharides combine to make up more complex carbs. Oligosaccharides are typically made up of less than 20 monosaccharides, whereas polysaccharides can be made of even more.

What is the nuclear lamina?

Net like array of protein intermediate filament called lamins that maintains the shape of a nucleus by supporting nuclear envelope.

Nuclear lamina vs nuclear matrix?

Nuclear Lamina- a netlike array of protein intermediate filaments made out of lamins that maintains the shape of the nucleus by mechanically supporting the nuclear envelope. Nuclear matrix- a framework of fiber extending throughout the nuclear interior.

What do the pores of the nuclear envelope do?

Nuclear envelopes contains pores used for importing and exporting materials such as proteins or RNA.

What is a catalase?

One enzyme in particular I want you to know about is known as a catalase. Catalase will break down H2O2, hydrogen peroxide, which is harmful to cells.

What does secondary active transport rely on?

One important point to note is that secondary active transport relies on primary active transport to create the initial concentration gradient. In other words, if a secondary active transport pump is to pump some molecule against its concentration gradient, it needs to use the energy another molecule releases as it flows down its concentration gradient. That second molecule had its concentration gradient established by primary active transport.

What are examples of cells that are multinucleated and cells that have no nucleus?

Osteoclasts, skeletal muscle cells, and hepatocytes (liver cells) are examples of multinucleated cells. Red blood cells, platelets (thrombocytes)-which are involved with blood clotting, are examples of cells with no nucleus.

What plays a role in the aging process?

Oxidative damage to mitochondria has been proposed to play a role in the aging process.

Passive Diffusion is a type of facilitated diffusion...

Passive diffusion describes a type of facilitated transport of particles down their concentration gradient (from high to low concentration). Passive diffusion does not require energy, and it usually relies upon channel proteins. They are called facilitated because proteins facilitate their transport. It is different from passive diffusion because passive diffusion doesn't require a protein to help transport.

What are non steroid hormones?

Peptide hormones and are made of amino acids. They are water soluble but they are not fat soluble, so they cannot diffuse across the plasma membrane of target cells. Instead, a peptide hormone binds to a receptor on the cell membrane. The binding of the hormone triggers an enzyme inside the cell membrane. The enzyme activates another molecule, called the second messenger, which influences processes inside the cell. Most endocrine hormones are peptide hormones image: A non-steroid hormone binds with a receptor on the plasma membrane of a target cell. Then, a secondary messenger affects cell processes.

Peroxisomes...

Peroxisomes are membrane bound organells that share a similar function to lysosomes because they are responsible for breaking things apart (hydrolysis), but they are also very different. 1. Peroxisomes are not part of the endomembrane system 2. Peroxisomes do not receive vesicles from the Golgi apparatus, instead the ROUGH ENDOPLASMIC RETICULUM MAKES THEM 3. Peroxisomes DO NOT participate in apoptosis 4. Peroxisomes are organelles that mainly break down toxic substances, fatty acids, and amino acids. 5. The by-product of peroxisomes can generate hydrogen peroxide, which is very toxic because hydrogen peroxide can produce reactive oxygen species (ROS). ROS can then create free radicals, which can damage the nuclear DNA or phospholipid bilayers which can all cause cancer. But since peroxisomes create hydrogen peroxide, they also create an enzyme called catalase, which converts dangerous hydrogen peroxide radicals into harmless water and oxygen. 6. Peroxisomes are commonly found in the liver and kidney, sites of filtration where a lot of toxic substances are found. 7. Peroxisomes can break down proteins, although that role is usually carried out by lysosomes.

What are peroxisomes?

Peroxisomes contain enzymes that oxidize certain molecules normally found in the cell, notably fatty acids and amino acids. Those oxidation reactions produce hydrogen peroxide, which is the basis of the name peroxisome. Peroxisomes are spherical organelles that are membrane-bound and contain over 40 oxidative enzymes including catalase. Peroxisomes contain enzymes involved with lipid metabolism. The beta oxidation of long chained fatty acids, of 18 carbons or longer, are done by peroxisomal enzymes. These enzymes are different from those of the mitochondria. These fatty acids are made shorter, then subsequently shuttled to the matrix of the mitochondria for oxidation. Interestingly, the peroxisome also makes H2O2, hydrogen peroxide. H2O2 detoxifies substances such as ethanol and even kills microorganisms. The excess H2O2i broken down by catalase. This is often a very confusing point that I find student don't clearly understand. They do self-replicate, but unlike the mitochondria lack their own DNA. Hence, they must import the needed proteins for self-replication. Also, mitochondria generate ATP, peroxisomes do not.

What is phagocytosis?

Phagocytosis is a type of endocytosis where a cell engulfs undissolved solid materials. During phagocytosis, the cell membrane will project outward to wrap around the solid it wants to internalize. Phagocytosis is known as cellular eating. Phagocytosis (literally, "cell eating") is a form of endocytosis in which large particles, such as cells or cellular debris, are transported into the cell. We've already seen one example of phagocytosis, because this is the type of endocytosis used by the macrophage in the article opener to engulf a pathogen. Single-celled eukaryotes called amoebas also use phagocytosis to hunt and consume their prey. Once a cell has successfully engulfed a target particle, the pocket containing the particle will pinch off from the membrane, forming a membrane-bound compartment called a food vacuole. The food vacuole will later fuse with an organelle called a lysosome, the "recycling center" of the cell. Lysosomes have enzymes that break the engulfed particle down into its basic components (such as amino acids and sugars), which can then be used by the cell.

What is pinocytosis?

Pinocytosis is similar to phagocytosis. This type of endocytosis is known as cellular drinking because the cell will pinch inward (invaginate) such that it can engulf dissolved materials (liquids). Pinocytosis occurs in many cell types and takes place continuously, with the cell sampling and re-sampling the surrounding fluid to get whatever nutrients and other molecules happen to be present. Pinocytosed material is held in small vesicles, much smaller than the large food vacuole produced by phagocytosis.

What is plasodesmata?

Plasmodesmata which are intracellular channels that connect plant cells. Water and small molecules can pass freely between the cells. These microscopic channgels traverse the cell wall of plants and some algal cells.

Porins are used in passive diffusion...

Porins are channel proteins used in passive diffusion because they are usually not specific for just one type of molecule. Most of the time, they allow any hydrophilic or polar molecule that fits to pass through.

What is primary active transport?

Primary active transport uses the energy released from ATP hydrolysis to pump molecules against their concentration gradient.

What happens to the products from the golgi apparatus that are destined for the cell membrane?

Products destined for the cell membrane utilize transport vesicles that fuse with the cell membrane. The products will often include integral/peripheral membrane proteins, and phospholipids and cholesterol (which lie in the vesicle bilayer itself).

What happens to products that are destined to be secretion products after they are done being modified in the golgi apparatus?

Products that are destined for secretion travel in vesicles that empty into the extracellular environment (exocytosis). Secretion products need to accumulate within the Golgi before secretion. Secretion products do not undergo regular production, so it is more efficient to send many of the products at one time whenever another cell needs them. Remember that exocytosis is BULK TRANSPORT, where many things are transported AT ONCE and this whole process is energy-requiring. These products may include transport proteins and hormones

Prokaryotic cells do not contain membrane-bound nuclei. So where do prokaryotes keep their DNA?

Prokaryotes house most of their genetic material in a dense and irregularly shaped region within the cytoplasm known as the nucleoid.

What is the fluid mosaic model?

Proteins in the phospholipid bilayer can floate in this bilayer sea much like an iceberg. This model is called the fluid mosaic model. Proteins literally float in a lateral motion along the plane of the membrane. Lipids and many membrane proteins are in constant lateral motion.

What are enzymes?

Proteins that speed up chemical reactions. A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction.

What type of protein exists in the extracellular matrix between cells?

Proteoglycans are a class of glycoproteins that exist in the ECM between cells.

What are proteoglycans?

Proteoglycans are a class of glycoproteins that exist in the ECM between cells. These types of glycoproteins are unique because they have a lot of carbohydrates relative to the amount of actual protein they contain.

What's the function of proteoglycans in the extracellular matrix?

Proteoglycans are a major component of the animal extracellular matrix, the "filler" substance existing between cells in an organism

Protoplasm is....

Protoplasm is the living substance of the cell and it includes: a) Cytoplasm b) Karyoplasm (aka Nucleoplasm)

What are protosomes?

Protosomes are protein complexes found in the cytoplasm about the size of a ribosomal subunit (small). They degrade denatured or unneeded proteins. Think of proteosomes as the quality control protein department. Lysosomes do the bulk of the job, but these organelles assist with primarily individual proteins. Recent studies have shown that they remove abnormal or misfolded proteins and use ATP to dirve the needed conformational changes in their subunits. It has a very cool structure, note the four stacked rings!

Are ribosomes found in prokaryotes or eukaryotes?

Ribosomes are found in both prokaryotes and eukaryotes.

What are ribosomes?

Ribosomes are known as the "Protein Factories" that are made of rRNA and over 80 different proteins. This is the site of protein synthesis.

What is rapid exchange?

Rapid exchange occurs between gap junctions. Cyclic AMP which is involved with cell signal transduction can easily move. Gap junctions are responsible for the heart's coordinated beat.

What are receptor (integral) proteins?

Receptor proteins (integral) receive chemical signals from the extracellular environment through the binding site for hormones or other trigger molecules. When these proteins receive such a signal, the protein triggers secondary responses within the cell. Many peptide hormones act as chemical trigger molecules for receptor proteins.

Clathrin is involved in receptior mediated endocytosis...

Receptor-mediated endocytosis is a form of endocytosis in which receptor proteins on the cell surface are used to capture a specific target molecule. The receptors, which are transmembrane proteins, cluster in regions of the plasma membrane known as coated pits. This name comes from a layer of proteins, called coat proteins, that are found on the cytoplasmic side of the pit. Clathrin is the best-studied coat protein. When the receptors bind to their specific target molecule, endocytosis is triggered, and the receptors and their attached molecules are taken into the cell in a vesicle. The coat protein called clathrin participate in this process by giving the vesicle its rounded shape and helping it bud off from the membrane. Receptor-mediated endocytosis allows cells to take up large amounts of molecules that are relatively rare (present in low concentrations) in the extracellular fluid Although receptor-mediated endocytosis is intended to bring useful substances into the cell, other, less friendly particles may gain entry by the same route. Flu viruses, diphtheria, and cholera toxin all use receptor-mediated endocytosis pathways to gain entry into cells.

What is receptor-mediated endocytosis?

Receptor-mediated endocytosis is a type of endocytosis that occurs whenever a specific molecule binds to a peripheral membrane receptor protein. Certain peptide hormones target cells via this mechanism. Why peptide hormones? Remember peptide hormones are made from amino acids, so they cannot pass through the phospholipid bilayer, (they aren't lipid-soluble but they are hydrophilic) they have to attach to an external peripheral membrane receptor protein. The binding of the hormone triggers an enzyme inside the cell membrane. The enzyme activates another molecule, called the second messenger, which influences processes inside the cell. This whole process is relatively fast and cellular response and action happens quite quickly. In cell-mediated endocytosis, we see the capture of macromolecules using receptor proteins in the cell membrane. These receptor molecules associate with the macromolecules and then become associated intracellularly as well using a molecule called clathrin. Hormones, growth factors, antibodies, even antigens are bound at the cell surface. A region of the cell membrane called a coated pit is lined by a later of proteins. Upon binding, the coated pit forms a vesicle!! You need not to know any details, but clathrin is a major player in cell-mediated endocytosis.

what are oligosaccharides?

Remember carbohydrate components are also known as oligosaccharides in which they are just carbohydrates containing 3-10 sugar units. Polysaccharides are the same except they have more than 20 sugar units attached.

What's another way of saying impermeable?

Resistant to

While ribosomes are responsible for protein synthesis, they do not function in the subsequent packaging or modification of those proteins. So where do the packaging and modification occur?

Ribosomes float freely in the cytosol or attach to the rough endoplasmic reticulum (ER). Ribosomes that freely float in the cytosol tend to make proteins that function within the cytosol of the cell. Ribosomes that bind to the rough Endoplasmic Reticulum will synthesize proteins into it, such that the proteins can undergo modifications.

What is the function of ribosomes?

Ribosomes function in protein translation (protein synthesis). Ribosomes are macromolecules that do not contain a membrane, and they are not organelles.

What is secondary active transport?

Secondary active transport uses energy obtained from a source other than ATP. The energy this type of transport uses will usually come from the free energy released as other molecules spontaneously flow down their concentration gradient

The molecules that can directly cross the phospholipid bilayer can do so through what process.....

Small, uncharged, hydrophobic, nonpolar particles (eg. carbon dioxide and oxygen) can travel directly across the phospholipid bilayer via a process known as simple diffusion. Simple diffusion is the flow of substances down their concentration gradient (from high to low) in a non-energy consuming process. Simple diffusion does not utilize any proteins to help the particles cross the membrane. Osmosis is a type of simple diffusion

Glyoxysomes are............

Specialized variations of peroxisomes, called glyoxysomes, exist in the germinating seeds of some plants. In plant cells of germinating seeds, peroxisomes are called glyoxysomes. They modify the by-products of photorespiration.

What are contractile vacuoles?

Specific single-celled organisms have contractile vacuoles, which collect and pump excess water out of the cell. Contractile vacuoles operate to prevent the cell from bursting (lysis). Contractile vacuoles utilize active transport in organisms that live in freshwater environments.

What are steroid hormones?

Steroid hormones are made of lipids, such as phospholipids and cholesterol. They are fat soluble, so they can diffuse across the plasma membrane of target cells and bind with receptors in the cytoplasm of the cell or even the receptors in the nuecleus itself. The steroid hormone and receptor form a complex that moves into the nucleus and influences the expression of genes, essentially acting as a transcription factor and do the work themselves at the transcriptional and translational level to affect gene expression and essentially send their message. (This is a slow process) Examples of steroid hormones include hormones made by the adrenal cortex, mineralcorticoids (aldosterone), glucocorticoids (cortisol), and androgens, as well as the sex hormones made from testes and ovaries like estrogen, progesterone, and testosterone. image: A steroid hormone crosses the plasma membrane of a target cell and binds with a receptor inside the cell.

What are storage vacuoles?

Storage vacuoles store starches, pigments, and toxic substances.

Summary of three types of cytoskeletons

Summary of three types of cytoskeletons

There are three types of fibers that create a complex network in the cytoskeleton, what are they?

The Cytoskeletan is a complex network of: a) Microfilaments (actin) b) Microtubules c) Intermediate filaments They determine the shape of cells and play an important role in movement of organelles, vesicles, as well as entire cell movement. As you know, sperm cells can swim and white blood cells crawl across cell surfaces to destory invaders. These cells are powered and guided by the cytoskeleton. The cytoskeleton polymers are composed of many subunit proteins, and is always reorganizing itself. Sometimes it loses subunits, other times it gains subunits. Microtubules are involved with "molecular motors"...attaching to organelles and vesicles as well as chromosomes to help pull them apart.

How are organelle membranes maintained?

The ER, Golgi apparatus, and lysosomes are all members of a network of membranes, but they are not continuous with one another. Therefore, the membrane lipids and proteins that are synthesized in the ER must be transported through the network to their final destination in membrane-bound vesicles. Cargo-bearing vesicles pinch off of one set of membranes and travel along microtubule tracks to the next set of membranes, where they fuse with these structures. Trafficking occurs in both directions; the forward direction takes vesicles from the site of synthesis to the Golgi apparatus and next to a cell's lysosomes or plasma membrane. Vesicles that have released their cargo return via the reverse direction. The proteins that are synthesized in the ER have, as part of their amino acid sequence, a signal that directs them where to go, much like an address directs a letter to its destination. Soluble proteins are carried in the lumens of vesicles. Any proteins that are destined for a lysosome are delivered to the lysosome interior when the vesicle that carries them fuses with the lysosomal membrane and joins its contents. In contrast, the proteins that will be secreted by a cell, such as insulin and EPO, are held in storage vesicles. When signaled by the cell, these vesicles fuse with the plasma membrane and release their contents into the extracellular space.

What is the golgi apparatus?

The Golgi apparatus is like the mailroom in a cellular factory. Their goal is to transport various substances in vesicles (cis face is for incoming vesicles, trans face for secretory vesicles). Has flattened sacs known as cisternae The Golgi consists of flattened sacs called cisternae (these look like pancakes). Incoming vesicles from the ER enter the lumen of the Golgi apparatus at the cis face; this is the cisternae that is found closest to the rough and smooth ER. Once the products enter the Golgi lumen, they travel from one cisterna to the next, undergoing further modifications. For example, glycoproteins from the rough ER can undergo phosphorylation in the Golgi complex. These "tags" help the "mailroom" direct the "product" to the correct location. Eventually, vesicles containing manipulated rough/smooth ER products will exit the Golgi apparatus at the trans face. The trans face is the cisternae that lies farthest away from the rough and smooth ER (and therefore closer to the cell membrane) The Golgi apparatus functions as a molecular assembly line in which membrane proteins undergo extensive post-translational modification. Many Golgi reactions involve the addition of sugar residues to membrane proteins and secreted proteins. The carbohydrates that the Golgi attaches to membrane proteins are often quite complex, and their synthesis requires multiple steps. In electron micrographs, the Golgi apparatus looks like a set of flattened sacs. Vesicles that bud off from the ER fuse with the closest Golgi membranes, called the cis-Golgi. Molecules then travel through the Golgi apparatus via vesicle transport until they reach the end of the assembly line at the farthest sacs from the ER — called the trans-Golgi. At each workstation along the assembly line, Golgi enzymes catalyze distinct reactions. Later, as vesicles of membrane lipids and proteins bud off from the trans-Golgi, they are directed to their appropriate destinations — either lysosomes, storage vesicles, or the plasma membrane

What is the golgi apparatus?

The Golgi is like one big warehouse..where sorting and shipping occur. It reminds me of Mimeo...the company that ships our DAT destroyer books to you. The Golgi apparatus is responsible for transporting, modifying, and packaging proteins and lipids into vesicles for delivery to targeted destinations. It is located in the cytoplasm next to the endoplasmic reticulum and near the cell nucleus. The golgi apparatus is stacks of membranous "sacs" that is involved with the synthesis of carbohydrates and in the modification of proteins. For example, carbohydrates are added to the protein by Golgi enzymes. In other words, post translational modification and "packaging" of proteins occur here. Some proteins are glycosylated...we add sugars, while other proteins have sugars removed.

What does the abundance of smooth ER in a cell depend on?

The abundance of smooth ER in a cell depends on the functions of that cell. For example, a human liver is heavily involved with detoxification, so its cells tend to contain many smooth ER.

What is the basal lamina?

The basal lamina is a layer of extracellular matrix secreted by epithelial cells, on which the epithelium sits. It is often incorrectly referred to as the basement membrane, since it is not the traditional plasma membrane that we have come to know and love.

What are cells?

The basic functionl units of complex organisms are cells.

There are two types of hormones, steroid hormones, and non-steroid hormones, what is the difference between them along with their function?

The binding of a steroid hormone forms a hormone-receptor complex that affects gene expression in the nucleus of the target cell. The binding of a peptide hormone activates a second messenger that affects processes within the target cell

What is collagen?

The most common fibrous structural protein in the ECM is a protein called collagen. Cells called fibroblasts produce collagen.. Once secreted, collagen will form long woven fibers called collagen fibrils. Collagen fibrils is what gives human tissues so much of their strength and rigidity.

What is the cell theory?

The cell theory says living things: 1. contain one or more cells; therefore, the cell is the basic unit of life. 2. New cells must arise from pre-existing cells. The coordinated effort of cells allows living organisms to carry out all their amazing functions. 3. Cells act like factories that make proteins. In cellular factories, the cell membrane acts as the building, the DNA acts as the instruction manual for building the products, and ribosomes act like workers.

During cell division, when does the centrosome replicate and why is it essential?

The centrosome will replicate during S phase of interphase, which is essential because we need one centrosome for each daughter cell after cell division, as well as for proper spindle apparatus functioning.

What is cytoplasm?

The cytoplasm involves the contents of the cell excluding the nucleus.

Differentiate between cytosol and cytoplasm.

The cytoplasm is mainly water, and various organic and inorganic substances are disssolved or even suspended. The fluid suspension is the cytosol. The cytosol is the aqueous intracellular fluid, while the cytoplasm is everything within the cell (cytosol and organelles). If the cytoplasm were a stew, the cytosol would be the broth.

What is the cytoskeleton?

The cytoskeleton is unique to eukaryotic cells. It is a dynamic three-dimensional structure that fills the cytoplasm. This structure acts as both muscle and skeleton, for movement and stability. The long fibers of the cytoskeleton are polymers of subunits. The primary types of fibers comprising the cytoskeleton are microfilaments, microtubules, and intermediate filaments.

What is the cytoskeleton of the cell?

The cytoskeleton lies within the cytoplasm of both eukaryotic and prokaryotic cells. In eukaryotic cells, the cytoskeleton has microfilaments, intermediate filaments, and microtubules. A microscopic network of actin filaments and microtubules in the cytoplasm of many living cells that gives the cell shape and coherence.

What is the cytosol and cytoplasm?

The cytosol is the aqueous intracellular fluid (the liquid) the cytoplasm is everything within the cell (cytosol and organelles) (liquid + chicken and veggies).

What is the drug Taxol often used for?

The drug often used for ovarian and breast cancer is Taxol. This drug will bind to the microtubules and prevent them for disassociating. Another clever way to stop mitosis. Recall, a cancer or malignancy represents an uncontrolled mitosis.

How does the golgi apparatus and the endoplasmic reticulum work together?

The endoplasmic reticulum is a series of membranes found throughout the cell that are connected to the nucleus. The endoplasmic reticulum can be smooth or rough. A smooth endoplasmic reticulum (SER) does not have ribosomes attached whereas a rough endoplasm reticulum (RER) does. The membranes of the endoplasmic reticulum form sacs called cisternae. Proteins are folded in the cisternae spaces called lumen. Additionally, the smooth endoplasmic reticulum forms lipids and steroids. When enough proteins have been created a vesicle is pinched off of the membrane. This transition vesicle then moves through the cytoplasm from the endoplasmic reticulum to the Golgi apparatus. The Golgi apparatus then packages, transports, distributes, or stores the contents of the vesicle. After the Golgi apparatus does its work on the contents of the vesicle, a secretory vesicles is created and pinched off into the cytoplasm. The contents of the secretory vesicle are delivered to where they are needed within the cell.

What is integrin?

The extracellular matrix is mainly composed of collagen and they function by connecting to the cells it surround, hence facilitating the adhesion of extracellular matrix. These connections are made possible via proteins called integrins.

What is glycocalyx?

The glycocalyx is a coat of glycolipids and glycoproteins that covers the surface of bacterial cell walls, as well as some animal cell membranes. In all, the glycocalyx can provide adhesive capabilities, a protective barrier to infection, and act as markers for cell-cell recognition.

Where does the material that went to the Golgi apparatus come from?

The material that went to the Golgi Apparatus comes from the endoplasmic reticulum. The endoplasmic reticulum is the largest membranous system in the cell. It occupies about 50% of the total membrane volume. It has two components: a) Smooth ER b) Rough ER

What is the mitochondria?

The mitochondria is the powerhouse of the cell. It contains enzymes specialized in making ATP and carrying out aerobic respiration. They can have a shape that is round or elongated. Animals and plants contain mitochondria. Often can be visible with a light microscope. In the picture you can see that this is a 2D picture, thus it was taken with a TEM (transmission electron microscope). Note the cristae...foldings of the inner membrane, which greatly increases the surface area.

What is the nuclear envelope?

The nuclear envelope sets the borders of a eukaryotic nucleus. The nuclear envelope is the nucleus' membrane. The nuclear envelope is a set of two phospholipid bilayers, one inner and one outer. The area between the outer and inner membranes is called the perinuclear space .

What is the nucleus?

The nucleus is the largest organelle of the cell. In the eukaryotic organism, most of the genes are found here ( a small smount is found in the mitochondria and chloroplasts.) It is enclosed by the nuclear envelope, which is a double membrane. Inside the nucleus, DNA is organized into units called chromosomes. The chromosomes are made of proteins and DNA called a chromatin complex. For humans we have 46 chromosomes in the nucleus, normally. The germ cells...sperm and eggs, have 23 chromosomes.

Describe the structure of the the "nucleus membrane"

The nucleus membrane consists of TWO phospholipid bilayers, one inner and one outer. In between these two phospholipid layers, there is a space called the perinuclear space.

What is the nucleus?

The nucleus' primary function is to house and protect the DNA. It also has various molecules that aid in DNA replication and transcription, both of which occur inside the nucleus.

What are the three major compounds of the nucleus?

The nucleus, bounded by a pair of lipid membranes has three major components: A) Nucleolus: rRNA synthesis B) Chromatin: genetic material C) Nucleoplasm: the content of the nucleus, excluding the nucleolus

Explain the parts of a mitochondria.

The outer membrane allows the passage of small molecules and ions. The inner membrane is higly folded and is a closed space, even to small ions! The inner mitochondrial matrix is where the electron transport chain that makes up almost 90% of the ATP is found. The matrix of mitochondria is enclosed by the inner membrane. This might sound confusing so lets have a look in the picture. Matrix: Kreb Cycle (TCA cycle) and Fatty Acid Oxidative processes occur...contains many enzymes, ribosomes, and mitochondrial DNA. Very gel-like and viscous.

What is the pericentriolar material of a centrosome?

The pericentriolar material of a centrosome is a matrix of proteins that surround the centrioles. These proteins play a role in microtubule nucleation, which is the process where several tubulin dimers come together to form a microtubule. Similarly, the pericentriolar material is involved with securing microtubules to the centrosome.

What is the plasma membrane (plasmalemma)?

The plasma membrane also known as plasmalemma, seperates the cytoplasm from its extracellular environment.

What enters through the nuclear pores?

The proteins enter the nucleoplasm (from the cytosol) via nuclear pores, and rRNA synthesis occurs via transcription directly within the nucleus.

what is the rough endoplasmic reticulum?

The rough ER is continuous with the outer membrane of the nuclear envelope, which means the ER lumen is continuous with the perinuclear space. The rough ER membrane appears "rough" because its surface contains ribosomes. The ribosomes attach to cytoplasmic side of the rough ER and translate proteins into the lumen, which mechanistically looks similar to threading a string through a button

Once in the rough ER lumen, the protein will be manipulated to prepare it to be delivered to other organelles. What kind of manipulations will occur by the rough ER?

The rough endoplasmic reticulum helps the protein undergo certain manipulations that will help them in their life. One important manipulation is glycosylation which attach a carbohydrate chain (oligosaccharides or polysaccharides) which helps the protein gets tagged so it can go to its next proper location.

Summary of Rough Endoplasmic Reticulum ...

The rough endoplasmic reticulum is continous with the outer membrane of the nuclear envelope and is "rough" because it has ribosomes embedded in it. Protein synthesis by the embedded ribosomes are sent into the lume (inside of the rough ER) for modifications ( like glycosylation). Afterwards, they are either sent out fo the cell or becomes part of the cell membrane. The two main functions of the rough endoplasmic reticulum are the production of A) mitochondria and proteins secreted by the cell. B) hydrogen peroxide and steroid hormones secreted by the cell. Part of the rough endoplasmic reticulum is continous with the nuclear envelope. In an avergae liver cell, almost 15 million ribosomes are present. Ribosomes on the Rough ER are "membrane bound" and are involved in protein synthesis. Cells that make enzymes such as pancreas and those of the GI tract have abundant Rough ER. The rough ER works with the ribosome and continues the protein assembly. In most cases, proteins are moved to the Golgi complex for final modification and "finishing". They are either conveyed in vesicles or moved directly between the ER and Golgi complex befor ebeing delivered to their specific locations.

The SMOOTH endoplasmic reticulum...

The smooth ER is a little different than the rough ER because it is not associated with ribosomes, and therefore is not involved in protein synthesis. The smooth ER is usually not continuous with the outer membrane of the nuclear envelope. The central role of the smooth ER is to synthesize lipids (fats), steroid hormones, detoxify cells, and in some cases, store ions. Remember that steroid hormones are lipid-soluble hence they are made of lipids. This is different from peptide hormones which are made out of amino acids. It's important to see that smooth ER doesn't make peptide hormones. The lipids and steroids produced by a smooth ER are essential molecules for energy storage, membrane structure (cholesterol), and hormone communication. The abundance of smooth ER in a cell depends on the functions of that cell. For example, a human liver is heavily involved with detoxification, so its cells tend to contain many smooth ER. The Smooth ER is also involved with holding and releasing Calcium ions in a controlled manner, and released when needed. It is specialized in skeletal muscles and called the sarcoplasmic reticulum. The Smooth ER is also involved in steroid biosynthesis and detoxification of drugs and poisons.

What is the top example of a primary active transport?

The sodium-potassium (Na+/K+) pump is a typical example of primary active transport because it hydrolyzes ATP The Na⁺/K⁺ pump exchanges three Na⁺ out of a cell for two K⁺ into a cell. In doing so, the pump consumes one ATP molecule, which is why the pump is also an ATPase (ATP hydrolysis enzyme). ATP hydrolysis powers this exchange, as both Na⁺ and K⁺ travel against their concentration gradient by primary active transport.

What are centrioles?

The spindle apparatus is a important structure in cells that guide chromosomes to opposite ends of the cell during karyokinesis in cell division. The centrosome is a special microtubule organizing center that helps to create the microtubules needed for this. The centrosome has two centrioles that are specialized cylinders of microtubules inhabiting the centrosome. Each centrosome has a mother and daughter centriole, oriented at a ninety-degree angle. They are involved with the formation of the spindle apparatus, and each centriole is a hollow cylinder made of nine triplets of microtubules (9 x 3 array).

If prokaryotes do not have membrane bound organelles, then where do their ribosomal subunits get formed?

The subunits come together in the prokaryotic cytosol, and they form a 70 S prokaryotic ribosome.

What happens to the products from the golgi apparatus that are destined for the lysosome?

The trans face of the Golgi apparatus secretes vesicles that can also travel to the lysosome (some plant cells have vacuoles instead of lysosomes). These trans-Golgi vesicles tend to contain enzyme proteins that the lysosome uses to carry out specific functions.

What are the three main sections of the golgi apparatus?

Three main sections of the golgi apparatus: 1. Cis Golgi: molecules go in 2. Main Golgi: molecules get processed 3. Trans Golgi: molecules go outward The apparatus has three primary compartments, known generally as "cis" (cisternae nearest the endoplasmic reticulum), "medial" (central layers of cisternae), and "trans" (cisternae farthest from the endoplasmic reticulum).

What are tight junctions aka Zona Occludens....

Tight junctions are also known as Zona Occludens are protein junctions that provide a water-tight seal between cells. They ensure that materials must enter the cells (diffusion or active transport) to pass through the tissue. Tight junctions are characteristic of cells lining the digestive tract, where materials are required to pass through cells (not between them) before they can travel into the blood. Tight junctions, also known as Zona Occludens, forms tight seals around cells to prevent contents from leaking. They allow skin cells, for example, to make us watertight, and maintain the integrity of the epithelial barrier. The intestinal barrier is maintained by tight junctions. The complex protein structures that regulate the permeability of the intestine is clearly one example of their importance. Chronic diseases such as Celiac disease or inflammatory bowel diseases involves a "leaky" intestinal barrier.

What are transport vacuoles?

Transport vacuoles move materials from one organelle to another; or, from organelles to the plasma membrane. In this way, transport vacuoles are mainly just large transport vesicles.

What are organelles?

Within cells, we find metabotically active structures that are involved in performing many functions. These structures are called organelles.

What is the nucleolus?

a small dense spherical structure in the nucleus of a cell during interphase, it works to make ribosomes so it is also known as the ribosome production factory. It is a non-membranous organelle. One or more may be found within the nucleus, but rarely beyond three. In addition to rRNA synthesis, the assembly of large and small ribosomal subunits occurs here. Small amounts of DNA are present, but not stain with Feulgen stain.

The cytoskeleton consits of...?

microfilaments, intermediate filaments, and microtubules. These are in order from smallest diameter to the largest diameter

Where are central vacuoles found?

occupy the majority of a plant cell interior.

Do organelles have membranes?

organelles are like the "rooms" of a cellular factory. Just like a cell, these organelles are also enclosed by a phospholipid bilayer to keep the materials they contain inside (organelles are membrane-bound). In other words, organelle membranes prevent organelle contents from spilling into the cytosol.

What is the pathway order between the Rough ER, Golgi complex, and the cytosol?

pathway order between the Rough ER, Golgi complex, and the cytosol

what is microtubule nucleation and where does it occur?

pericentriolar material of a centrosome is a matrix of proteins that surround the centrioles. These proteins play a role in microtubule nucleation, which is the process where several tubulin dimers come together to form a microtubule

What are connexins?

protein subunits of gap junctions

Where does transcription occur in eukaryotes?

proteins enter the nucleoplasm (from the cytosol) via nuclear pores, and rRNA synthesis occurs via transcription directly within the nucleus.

What do ribosomal subunits contain?

rRNA and and proteins

What happens after proteins enter the nuclear pores?

rRNA synthesis occurs in the nucleus after proteins enter through the nuclear pores. Once the proteins and rRNA are both floating around in the nucleoplasm, they assemble into ribsomoal subunits. The ribosomal subunits then exit the nucleus and enter the cytosol via the nuclear pores. Once in the cytosol, the subunits assemble into a complete ribosome.

The space inside an endoplasmic reticulum is called the lumen. The word lumen is not unique to an ER - a lumen is just the inside space of a hollow structure. There are two different ER types in a eukaryotic cell, what are they?

rough endoplasmic reticulum and smooth endoplasmic reticulum

What is included in the endomembrane system?

the endomembrane system includes the 1. nucleus/nuclear envelope, 2. rough and smooth ERs 3. Golgi apparatus, 4. lysosomes, 5. vacuoles, 6. cell membrane