Biology Ch. 4
Chloroplasts are found in __________.
Plants
Name four structures found in both prokaryotic and eukaryotic cells.
Plasma membrane, one or more chromosomes, cytosol, and ribosomes.
From which important class of biological molecules are the microtubules of the cytoskeleton made?
Protein
What is the function of ribosomes?
Protein synthesis
Which of the following is the building site for cellular proteins?
Ribosome
Extracellular matrix
The meshwork that surrounds animal cells, consisting of a web of protein and polysaccharide fibers embedded in a liquid, jelly, or solid,.
Which of the following is characteristic of all prokaryotes?
✅- Lack of a membrane-bound nucleus ❌- Multicellular ❌- True nucleus ❌- Golgi apparatus ❌- Membrane-bound organelles
A membrane is a fluid mosaic—fluid because the molecules can move freely past one another and mosaic because of the diversity of proteins that float like icebergs in the oily phospholipid sea.
**Just a note, not a question or flashcard**
Animal cells lack a cell wall, but most animal cells secrete a sticky coat called the extracellular matrix.
**Just a note, not a question or flashcard**
At the cellular level, we have a lot in common with a mushroom
**Just a note, not a question or flashcard**
Besides providing cellular energy, mitochondria and chloroplasts share another feature: They contain their own DNA that encodes some proteins made by their own ribosomes. Each chloroplast and mitochondrion contains a single circular DNA chromosome that resembles a prokaryotic chromosome. In fact, mitochondria and chloroplasts can grow and pinch in two, reproducing themselves as many prokaryotes do. This and other evidence indicate that they evolved from ancient free-living prokaryotes that established residence within other, larger host prokaryotes. This phenomenon, where one species lives inside a host species, is a special type of symbiosis. Over time, mitochondria and chloroplasts became increasingly interdependent with the host prokaryote, eventually evolving into a single organism with inseparable parts. The DNA found within mitochondria and chloroplasts likely includes remnants of this ancient evolutionary event.
**Just a note, not a question or flashcard**
Cells are the fundamental units of life, the smallest biological units that display all of life's characteristics. Despite their small size, animal and plant cells have a diverse array of organelles (or mini-organs) specialized for the tasks necessary to help cells survive and function. First, let's focus on organelles that are common between animal and plant cells, and then we'll cover a few additional organelles found only in plant cells. Let's start at the outside of a cell. All cells separate themselves from the external environment by a plasma membrane. A plasma membrane is a thin, double-layered wall that regulates the traffic of molecules into and out of the cell. You can think of a plasma membrane as similar to the walls of your house. The walls have windows and doors that can be opened to allow things in and out of the house. These windows and doors can be regulated-in other words, you can decide which windows and doors to open, and when to open them. Similarly, a plasma membrane has channels, comprised of proteins, which regulate the passage of specific molecules into and out of the cell. This creates a semi-permeable membrane between the inside, the cytoplasm, and the outside, the environment. The term "semi-permeable" refers to the fact that some substances can pass through the membrane while others cannot. Inside animal and plant cells, one of the most prominent organelles is the nucleus. The nucleus contains the DNA, the genetic information that controls the activity of the cell. You can think of the nucleus as the "brain" of the cell. The nucleus is surrounded by a membrane called the nuclear envelope. Like the plasma membrane, it functions to regulate the traffic of molecules. In this case, the nuclear envelope controls the flow of molecules between the nucleus and the rest of the cell. Many materials leaving the nucleus are sent through the endomembrane system. The endomembrane system is a network of organelles that make and distribute cellular products. These organelles include the endoplasmic reticulum, the Golgi apparatus, and lysosomes. Let's look at the specific function of each of these organelles. The endoplasmic reticulum, also called the "ER" for short, is the main manufacturing center of the cell. There are two kinds of ER in a cell: rough ER and smooth ER. Rough ER contains ribosomes on its outer surface, which give it a "rough" appearance under the microscope. Ribosomes are the organelles responsible for making proteins. If the endoplasmic reticulum is the "factory" of the cell, then ribosomes are the individual machines that manufacture items. Smooth ER is so named because it lacks ribosomes. Its main function is the construction of lipids. Items manufactured in the ER often go next to the Golgi apparatus. The Golgi apparatus is a refining and packaging center. In this organelle, proteins are modified, tagged, and sent to the appropriate areas of the cell. In many ways, the Golgi apparatus is like the "post office" of the cell, addressing proteins and then directing them to the correct location. The last organelle that we'll discuss from the endomembrane system is the lysosome. A lysosome is a membrane-enclosed sac of digestive enzymes. Its main function is to break down substances such as waste products or old organelles. The resulting molecules are often recycled and then used to make new compounds elsewhere in the cell. You can think of lysosomes as the "garbage disposals" of the cell. OK, let's move on and address two more organelles that are found in both animal and plant cells. Mitochondria are the main energy-producing organelles in cells. They are the primary site for cellular respiration, where energy from sugars and other food molecules is converted into ATP. ATP is a small molecule which cells can use to fuel most forms of work. Cells that use a lot of energy, such as those in our brain and muscles, have many mitochondria, which produce a lot of ATP. The last organelle we'll discuss that is common to both animal and plant cells is the cytoskeleton. The cytoskeleton is the support structure of a cell. As the name implies, you can think of the cytoskeleton as the skeleton or framework of the cell. It provides shape and a place to attach all of the other organelles so that they don't just float freely around the cell. The cytoskeleton is also used as a "highway system," with special proteins designed to ferry molecules along the cytoskeleton, like trucks on a road. Let's pause here and recap what we've discussed so far. If you're making a table, follow along and be sure that you have properly identified the function of each organelle. All cells separate themselves from the external environment with a semi-permeable plasma membrane, which regulates the flow of molecules in and out of the cell. Inside the cell, the nucleus contains the genetic information that directs the cell's activity. Extending from the nuclear envelope around the nucleus is the endoplasmic reticulum, also called the ER, which is the main manufacturing site for the cell. Rough ER contains ribosomes, which make proteins. The Golgi apparatus modifies and packages items. And lysosomes are membrane-bound sacs that digest and recycle waste products. Mitochondria produce ATP. Last, the cytoskeleton provides a framework for the cell. All of the organelles we've discussed so far are found in both plants and animals. Now let's discuss three other organelles found only in plant cells : the cell wall, the central vacuole, and chloroplasts. A cell wall is a rigid protective layer outside the plasma membrane. In plants, the cell wall is composed of a substance called cellulose. Have you ever peeled a string off a stalk of celery? That string is made up largely of cellulose from cell walls. Inside plant cells, the central vacuole is often the largest organelle. The central vacuole is a membrane-bound sac that functions as a storage center and helps to regulate the amount of water inside the cell. The third organelle unique to plants is the chloroplast, which is an energy-producing organelle found only in plant cells. What energy-producing organelle have we already discussed? Right, the mitochondria. Mitochondria are specialized for creating ATP from sugars. Chloroplasts, on the other hand, are specialized for using the energy in sunlight to make sugars. Do you see a connection here? Chloroplasts use light energy to make sugar and mitochondria use sugars to make ATP. Plant cells have both chloroplasts and mitochondria: chloroplasts to make sugars from sunlight and mitochondria that make ATP from these sugars. However, animal cells only have mitochondria, which means that they cannot make their own sugars. Thus, animals must eat plants or other animals to get sugars, which they can then use in mitochondria to make ATP. How's that table look now? Let's review what we've learned about plant cells. Plant cells have a cell wall that provides rigid support, a central vacuole for storage and water regulation, and chloroplasts to create chemical energy from light energy.
**Just a note, not a question or flashcard**
Consider this analogy: A eukaryotic cell is like an office building that is separated into cubicles. Within each cubicle, a specific function is performed, thus dividing the labor among many internal compartments. One cubicle may hold the accounting department, for example, while another is home to the sales force. The cubicle walls within eukaryotic cells are made from membranes that help maintain a unique chemical environment inside each cubicle. In contrast, the interior of a prokaryotic cell is like an open warehouse. The spaces for specific tasks within a prokaryotic warehouse are distinct, but they are not separated by physical barriers: Imagine desks for the sales and accounting departments arranged across an open floor.
**Just a note, not a question or flashcard**
Fibers made of the protein collagen (also found in your skin, cartilage, bones, and tendons) hold cells together in tissues and can also have protective and supportive functions. In addition, the surfaces of most animal cells contain cell junctions, structures that connect cells together into tissues, allowing the cells to function in a coordinated way.
**Just a note, not a question or flashcard**
Organisms are either single-celled, such as most prokaryotes and protists, or multicellular, such as plants, animals, and most fungi. Your own body is a cooperative society of trillions of cells of many specialized types
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Prokaryotic cells are simple cells that lack membrane-bound nuclei and complex organelles. Endoplasmic reticulum, microtubules, and the Golgi apparatus are unique to eukaryotic cells, and will not be found in prokaryotes. Prokaryotes do, however, contain ribosomes, though smaller than the ribosomes in eukaryotic cells.
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Surrounding the plasma membrane of a plant cell is a cell wall made from cellulose fibers, which are long chains of polysaccharides. The walls protect the cells, maintain cell shape, and keep cells from absorbing so much water that they burst. Plant cells are connected to each other by channels that pass through the cell walls, joining the cytoplasm of each cell to that of its neighbors. These channels allow water and other small molecules to move between cells, integrating the activities of a tissue.
**Just a note, not a question or flashcard**
The "rough" in rough ER refers to ribosomes that stud the outside of its membrane. One of the functions of rough ER is to make phospholipids that are inserted into the ER membrane. In this way, the ER membrane grows, and portions of it can bubble off and be transferred to other parts of the cell. The ribosomes attached to the rough ER produce proteins that will be inserted into the growing ER membrane, transported to other organelles, and eventually exported. Cells that secrete a lot of protein—such as the cells of your salivary glands, which secrete enzymes into your mouth—are especially rich in rough ER. STEP 1 some products manufactured by rough ER are STEP 2 chemically modified and then STEP 3 packaged into transport vesicles that are STEP 4 dispatched to other locations in the cell.
**Just a note, not a question or flashcard**
The "smooth" in smooth ER refers to the fact that this organelle lacks the ribosomes that populate the surface of rough ER. A diversity of enzymes built into the smooth ER membrane enables this organelle to perform many functions. One is the synthesis of lipids, including steroids. For example, the cells in ovaries or testes that produce the steroid sex hormones are enriched with smooth ER. In liver cells, enzymes of the smooth ER detoxify circulating drugs such as barbiturates, amphetamines, and some antibiotics (which is why antibiotics don't remain in the bloodstream for long after you stop taking them). As liver cells are exposed to a drug, the amounts of smooth ER and its detoxifying enzymes increase. This can strengthen the body's tolerance of the drug, meaning that higher doses will be required in the future to achieve the desired effect. The growth of smooth ER in response to one drug can also increase tolerance of other drugs. For example, abusing sleeping pills may make other useful drugs less effective by accelerating their breakdown in the liver.
**Just a note, not a question or flashcard**
The Caffeine that gives coffee a kick also protects coffee plants from Herbivores.
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The countless cells that exist on earth can be divided into two basic types: Prokaryotic cells and Eukaryotic cells.
**Just a note, not a question or flashcard**
The goal of antibiotics treatment is to knock out invading bacteria while doing no damage to the human host.
**Just a note, not a question or flashcard**
The key difference is that eukaryotic cells are partitioned by membranes into organelles. The membranes allow each organelle to maintain specific chemical conditions that favor the metabolic tasks performed there.
**Just a note, not a question or flashcard**
Without the cytoskeleton, your cells would collapse in on themselves, much like a building collapses when the infrastructure fails.
**Just a note, not a question or flashcard**
What is cellular respiration?
A process that converts the chemical energy of sugars and other food molecules to chemical energy in the form of ATP.
Bactericidal
A bactericidal antibiotic kills the bacteria. Penicillin is a bactericidal. A bactericidal usually either interferes with the formation of the bacterium's cell wall or its cell contents.
Bacteriostatic
A bacteriostatic stops bacteria from multiplying and interferes with cell replication. Disrupts DNA replication, protein production, metabolism.
Fluid mosaic
A description of membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules suspended in a fluid bilayer of phospholipid molecules.
Phospholipid bilayer
A double layer of phospholipid molecules (each molecule consisting of a phosphate group bonded to two fatty acids) that is the primary component of all cellular membranes. Suspended in the phospholipid bilayer of most membranes are proteins that help regulate traffic across the membrane.
Nuclear envelope
A double membrane, perforated with pores, that encloses the nucleus and separates it from the rest of the eukaryotic cell.
Lysosome
A membrane-enclosed sac of digestive enzymes. The enzymes and membranes of lysosomes are made by rough ER and processed in the Golgi apparatus. The lysosome provides a compartment where digestive enzymes can safely break down large molecules without unleashing the digestive enzymes on the cell itself. It is a digestive organelle in eukaryotic cells; contains enzymes that digest the cell's food and wastes.
Organelles
A membrane-enclosed structure with a specialized function within a eukaryotic cell. Prokaryotic cells do not have organelles.
Vesicles
A membranous sac in the cytoplasm of a eukaryotic cell. Sacs made of membrane that transfer membrane segments between organelles, like a mail cart delivering packages from one department to another. Together, these organelles form the Endomembrane system.
Cytoskeleton
A meshwork of fine fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules. It is a network of protein fibers extending throughout the cytoplasm. The cytoskeleton serves as both skeleton and "muscles" for the cell, functioning in support and movement. Without the cytoskeleton, your cells would collapse in on themselves. The cytoskeleton contains several types of fibers made from different types of protein. One important type of fiber forms microtubules, hollow tubes of protein. The other kinds of cytoskeletal fibers, called intermediate filaments and microfilaments, are thinner and solid.
What is the role of mRNA in making a protein?
A molecule of mRNA carries the genetic message from a gene (DNA) to ribosomes that translate it into protein.
Phospholipids
A molecule that is a part of the inner bilayer of biological membranes, having a hydrophilic head and a hydrophobic tail. The plasma membrane and other membranes of the cell are composed mostly of phospholipids. The structure of phospholipid molecules is well suited to their function as a major constituent of biological membranes. Each phospholipid is composed of two distinct regions—a "head" with a negatively charged phosphate group and two nonpolar fatty acid "tails." Phospholipids arrange themselves into a two-layer sheet called a phospholipid bilayer.
Rough Endoplasmic Reticulum (Rough ER)
A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm. Rough ER membranes are studded with ribosomes that make membrane proteins and secretory proteins. The rough ER constructs membrane from phospholipids and proteins.
Smooth Endoplasmic Reticulum (Smooth ER)
A network of interconnected membranous tubules in a eukaryotic cell's cytoplasm. Smooth ER lacks ribosomes. Enzymes embedded in the smooth ER membrane function in the synthesis of certain kinds of molecules, such as lipids.
Nucleoid
A non-membrane-enclosed region on a prokaryotic cell where the DNA is concentrated.
Nucleolus
A prominent structure within the nucleus, is the site where the components of ribosomes are made. The nucleolus is a structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins to make ribosomal subunits; consisting of parts of the chromatin DNA, RNA transcribed from the DNA, and proteins imported from the cytoplasm.
Domains
A taxonomic category above the kingdom level. The three domains of life are Archaea, Bacteria, and Eukarya.
Prokaryotic cells
A type of cell lacking a nucleus and other membrane-bound organelles. Prokaryotic cells are found only among organisms of the domains Bacteria and Archaea.
Eukaryotic cells
A type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles. All organisms except bacteria and archaea (including protist, plants, fungi, and animals) are composed of eukaryotic cells. Every organisms you can see with your own eyes is a eukaryote.
Central Vacuole
Another type of vacuole is a central vacuole, a membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, and development. A versatile compartment that can account for more than half the volume of a mature plant cell (Figure 4.16b). A central vacuole stores organic nutrients, such as proteins stockpiled in the vacuoles of seed cells. It also contributes to plant growth by absorbing water and causing cells to expand. In the cells of flower petals, central vacuoles may contain pigments that attract pollinating insects. Central vacuoles may also contain poisons that protect against plant-eating animals. Some important crop plants produce and store large amounts of toxic chemicals—harmful to animals that might graze on the plant but useful to us—such as tobacco plants (which store nicotine) and coffee and tea plants (which store caffeine).
Which of the following is a true statement about cilia and flagella?
Bacteria can have flagella but not cilia.
Which of the following is NOT a eukaryote?
Bacterium
Why does the phospholipid bilayer form the way it does?
Because the phospholid heads are hydrophilic and the tails are composed of lipids which are hydrophobic
Ribosomes
Builds proteins according to instructions from the genes. A cellular structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. The ribosomal subunits are constructed in the nucleolus and then transported to the cytoplasm where they act.
Chromosomes
Carries genes made of DNA. A gene-carrying structure found ion the nucleus of a eukaryotic cell and most visible when compacted during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. Each chromosome consists of one very long threadlike DNA molecule and associated proteins.
Which of the following is found in bacteria, plant, and animal cells?
Cell membrane
What polysaccharide is the primary component of plant cell walls?
Cellulose
Which of the following eukaryotic organelles is specific to plant cells?
Chloroplast
Chloroplasts
Chloroplasts are the photosynthetic organelles of plants and algae. They're an organelle found in plants and photosynthetic protists. Enclosed by two membranes, a chloroplast absorbs sunlight and uses it to power the synthesis of organic food molecules (sugars). A chloroplast is divided into compartments by membranes. The innermost compartment holds a thick fluid called stroma, which contains DNA, ribosomes, and enzymes. A network of sacs called thylakoids is suspended in the stroma. The sacs are often stacked like poker chips; each stack is called a granum (plural, grana). The grana are solar power packs, converting light energy to chemical energy.
Name three structures in plant cells that animal cells lack.
Chloroplasts, a central vacuole, and a cell wall
___________ and _____________ can reproduce themselves. They have their own DNA that evolved from ____________.
Chloroplasts; mitochondria; prokaryotes
What is the relationship between chromosomes, chromatin, and DNA?
Chromosomes are made of chromatin, which is a combination of DNA and proteins.
Compare and contrast cilia and flagella.
Cilia and flagella have the same basic structure, are made from microtubules, and aid in movement. Cilia are short and numerous and move back and forth. Flagella are longer, often occurring singly, and they undulate.
Antibiotics
Drugs that disable or kill infectious bacteria. Marvels of modern medicine. The first antibiotic to be discovered was penicillin in 1928.
After collecting samples of the material found growing on last month's leftovers at the back of your fridge, you realize that you have discovered a new type of organism. You find that the cells have distinct microscopic subunits within them. Further, several of these subunits seem to be involved in the production and transfer of certain molecules. One molecule appears after a messenger molecule is sent from a subunit to another one. The first molecule then travels to another location, where it is covered in membrane and (eventually) released from the cell. What type of cells do you think these are?
Eukaryotic
Cytoplasm
Everything within a eukaryotic cell inside the plasma membrane and outside the nucleus; consists of a semifluid medium (cytosol) and organelles; can also refer to the interior of a prokaryotic cell.
Cilia
Extensions from a eukaryotic cell that are generally shorter and more numerous than flagella and that propel the cell by moving in a coordinated back-and-fourth motion.
Flagilla
Extensions from a eukaryotic cell that propel the cell with an undulating, whiplike motion.
What structure is unique to animal cells?
Extracellular matrix
How can defective lysosomes result in excess accumulation of a particular chemical compound in a cell?
If the lysosomes lack an enzyme needed to break down the compound, the cell will accumulate an excess of that compound.
Explain what is wrong with the following statement: "Plant cells have chloroplasts, and animal cells have mitochondria."
It implies that plant cells do not have mitochondria, when in fact they do.
How DNA directs protein production
Like a company executive, the DNA doesn't actually so any of the work of the cell. Instead the DNA exectutive issues orders that result in work being done by the protein workers. STEP 1 DNA transfers its coded information to a molecule called messenger RNA (mRNA). Like a middle manager, the mRNA molecule carries the order to "build this type of protein." STEP 2 The mRNA exits the nucleus through pores in the nuclear envelope and travels to the cytoplasm, where it binds to a ribosome. STEP 3 The ribosome moves along the mRNA, translating the genetic message into a protein with a specific amino acid sequence. *In this way, information carried by the DNA can direct the work of the entire cell without the DNA ever leaving the protective confines of the nucleus. The pathway from DNA to RNA to protein, involving several organelles, illustrates the importance of the flow of information within living cells.
Which organelle is the recycling center of the cell?
Lysosome
Which of the following is common to both plant and animal cells?
Mitochondria
Which organelle(s) provide(s) the energy you use to read this sentence?
Mitochondria
How does an antibiotic zero in on its bacterial target among trillions of human cells?
Most antibiotics are so precise because they bind to structures found only in bacterial cells.
Which of the following lists the structures involved in protein synthesis and release in the correct order?
Nucleus, mRNA, and ribosome
Place the following cellular structures in the order they would be used in the production and secretion of a protein: Golgi apparatus, nucleus, plasma membrane, ribosome, transport vesicle.
Nucleus, ribosome, transport vesicle, Golgi apparatus, plasma membrane.
Ribosomes
Ribosomes are responsible for protein synthesis. In eukaryotic cells, the components of ribosomes are made in the nucleus and then transported through the pores of the nuclear envelope into the cytoplasm. It is in the cytoplasm that the ribosomes assemble and begin their work. Some ribosomes are suspended in the cytosol, making proteins that remain within the fluid of the cell. Other ribosomes are attached to the outside of the nucleus or an organelle called the endoplasmic reticulum (or ER), making proteins that are incorporated into membranes or secreted by the cell. Free and bound ribosomes are structurally identical, and ribosomes can switch locations, moving between the endoplasmic reticulum and the cytosol. Cells that make a lot of proteins have many ribosomes. For example, each cell in your pancreas that produces digestive enzymes may contain a few million ribosomes.
What makes rough ER rough?
Ribosomes attached to the membrane.
What is the structural difference between rough endoplasmic reticulum (ER) and smooth ER?
Rough ER has ribosomes, but smooth ER does not.
Which of the following is a site for lipid synthesis?
Smooth endoplasmic reticulum
What types of eukaryotic cells are flagellated?
Sperm
What is the relationship between the Golgi apparatus and the ER in a protein-secreting cell?
The Golgi apparatus receives proteins from the ER through vesicles, processes the proteins, and then dispatches them in vesicles.
Why do phospholipids spontaneously form into a bilayer when placed in water?
The bilayer structure shields the hydrophobic tails of the phospholipids from water while exposing the hydrophilic heads to water.
How do new living cells arise?
The cell theory states that all living things are composed of cells and that all cells come from earlier cells. So every cell in your body (and in every other living organism on Earth) was formed by division of a previously living cell.
Life begins at the cellular level
The cellular level
What does photosynthesis accomplish?
The conversion of light energy to chemical energy stored in food molecules.
Which of the following is a FALSE statement about prokaryotic and eukaryotic cells?
The cytoplasm is similar in size and function in eukaryotic and prokaryotic cells.
Endoplasmic Reticulum (ER)
The endoplasmic reticulum (ER) is one of the main manufacturing facilities within a cell. It produces an enormous variety of molecules. Connected to the nuclear envelope, the ER forms an extensive labyrinth of tubes and sacs running throughout the cytoplasm. A membrane separates the internal ER compartment from the cytosol. There are two components that make up the ER: rough ER and smooth ER. These two types of ER are physically connected but differ in structure and function. In eukaryotic cells. not prokaryotic.
Cytosol
The fluid part of the cytoplasm, in which organelles are suspended.
Nucleus
The most important organelle. Houses most of a eukaryotic cell's DNA. The nucleus is surrounded by a double membrane. A prokaryotic cell lacks a nucleus; its DNA is coiled into a "nucleus-like" region called the nucleoid, which is not partitioned from the rest of the cell by membranes. 1. An atom's central core, containing protons and neutrons. 2. The genetic control center of a eukaryotic cell.
Cell Theory
The theory that all living things are composed of cells and that all cells come from earlier cells.
Microtubules
The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight, hollow tube made of globular proteins called tubulins. Microtubules form the basis of the structure and movement of cilia and flagella. They're found in cilia and flagella.
Plasma membrane
The thin double layer of lipids and proteins that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which proteins are embedded. (regulates the traffic of molecules between the cell and its surroundings).
How is the nucleoid region of a prokaryotic cell different from the nucleus of a eukaryotic cell?
There is no membrane enclosing the prokaryotic nucleoid region
Endomembrane system
This system includes the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, lysosomes, and vacuoles. It is a network of organelles that partitions the cytoplasm of eukaryotic cells into functional compartments. Some of the organelles are structurally connected to each other, whereas others are structurally separate but functionally connected by the traffic of vesicles among them.
Vacuoles
Vacuoles are large vesicles with a variety of functions. They're a membrane-enclosed sac, part of the endomembrane system of a eukaryotic cell, having diverse functions.
If a house is an analogy for a cell, what part of a house corresponds to the cytoskeleton?
Walls
Chromatin
Within the nucleus, long DNA molecules and associated proteins form fibers called chromatin. Chromatin is the combination of DNA and proteins that constitutes chromosomes; often used to refer to the diffuse, very extended form taken by the chromosomes when a eukaryotic cell is not dividing. Each long chromatin fiber constitutes one chromosome. The number of chromosomes in a cell depends on the species.
Golgi apparatus
Working in close partnership with the ER, the Golgi apparatus, an organelle named for its discoverer (Italian scientist Camillo Golgi), receives, refines, stores, and distributes chemical products of the cell. You can think of the Golgi apparatus as a detailing facility that receives shipments of newly manufactured goods (proteins), puts on finishing touches, stores the completed goods, and then ships them out when needed. It is an organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.
If phospholipids are dropped into water,____________.
bilipid structures form with the hydrophilic heads pointing outward and the hydrophobic tails pointing inward
The fluid-mosaic model is ultimately the best depiction of the cell membrane because .
it shows that the phospholipids and proteins within the layers are able to move
DNA is located in the ___________, and its message reaches the ribosome via the __________.
nucleus; nuclear pores
Ribosomes "dock" with rough endoplasmic reticulum to produce __________ .
proteins that will be exported from the cell
