DNA from the Beginning - An animated primer of 75 experiments that made modern genetics.
DNA from the Beginning is organized around key concepts. The science behind each concept is explained by: animation, image gallery, video interviews, problem, biographies, and links.
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DNA from the Beginning - An animated primer of 75 ...
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Genetics is the study of genes and heredity. It studies how living organisms, including people, inherit traits from their parents. Genetics is generally considered part of the science of biology. Scientists who study genetics are called geneticists.
What are genes?
Genes are the basic units of heredity. They consist of DNA and are part of a larger structure called the chromosome. Genes carry information that determine what characteristics are inherited from an organism's parents. They determine traits such as the color of your hair, how tall you are, and the color of your eyes.
What are chromosomes?
Chromosomes are tiny structures inside cells made from DNA and protein. The information inside chromosomes acts like a recipe that tells cells how to function. Humans have 23 pairs of chromosomes for a total of 46 chromosomes in each cell. Other plants and animals have different numbers of chromosomes. For example, a garden pea has 14 chromosomes and an elephant has 56.
What is DNA?
The actual instructions inside the chromosome is stored in a long molecule called DNA. DNA stands for deoxyribonucleic acid.
Gregor Mendel is considered the father of the science of genetics. Mendel was a scientist during the 1800s who studied inheritance by experimenting with pea plants in his garden. Through his experiments he was able to show patterns of inheritance and prove that traits were inherited from the parents.
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Biology for Kids: Genetics - ducksters.com
For over 150 years, Darwins hypothesis that all species share a common ancestor has dominated the creation-evolution debate. Surprisingly, when Darwin wrote his seminal work, he had no direct evidence for these genealogical relationships. Now, with online databases full of DNA-sequence information from thousands of species, the direct testing of Darwins hypothesis has finally commenced. More...
Authentic speciation is a process whereby organisms diversify within the boundaries of their gene pools, and this can result in variants with specific ecological adaptability. While it was once thought that this process was strictly facilitated by DNA sequence variability, Darwin's classic example of speciation in finches now includes a surprisingly strong epigenetic component as well. More...
One of the rapidly expanding and exciting research fields in molecular biology is the area of epigenetics. In the study of epigenetic modifications, scientists analyze DNA that has been modified in such a way that its chemistry is changed, but not the actual base pairs that make up the genetic code of the sequence. Its like a separate control code and system imposed upon and within the standard code of DNA sequence.
Because epigenetic modifications in the genome are related to gene expression, researchers have been using highly advanced technologies for comparing these differences in humans and chimps for regions of the genome that they both have in common. More... More...
Living things develop partly according to genetic instructions encoded on their DNA. The study of inheritance has widened the paradigms from genes to genomes, and now recent research indicates that critical biological information is carried from one generation to the next in systems additional to DNA, called epigenetic factors.
So, where did this information come from? More...
Genes could be thought of as brick molds, used to construct materials for building the physical structures of living organisms. They carry the codes to help make proteins, which then make up different cells that are combined together to form mega-structures called tissues.
New research has shed more light on how genes are used by cells to build the different tissues needed by complex living creatures. More...
Indiana University researchers discovered that certain genes used in developing horned beetle larvae are re-used later to make horns in their adult stage. The studys authors called the genes co-opted, indicating their belief that evolution decided to give them a secondary use. The authors suggestion that gene co-opting offers a possible explanation for the development of novel traits comes up short, however. More...
One of the past arguments for evidence of biological evolution in the genome has been the concept of pseudogenes. These DNA sequences were once thought to be the defunct remnants of genes, representing nothing but genomic fossils in the genomes of plants and animals. More...
Amazingly, scientists documented the activity of 2,082 distinct pseudogenes in the human genome whose aberrant levels of activity were directly associated with cancer-specific pathologies. More...
Proteins do most of the required metabolic tasks within each of the trillions of cells in the human body. However, only about four percent of human DNA contains coded instructions that specify proteins.
So what is the purpose of the remaining 96 or so percent? More...
A research team recently characterized a group of genes in humans and other mammals that not only defies evolutionary models but vindicates the Bibles prediction of the uniqueness of created kinds with distinct genetic features. More...
Cells rarely exist alone, which drives the evolution of diverse mechanisms for identifying and responding appropriately to the presence of other nearby cells. Filamentous fungi depend on somatic cell-to-cell communication and fusion for the development and maintenance of a multicellular, interconnected colony that is characteristic of this group of organisms. The filamentous fungus Neurospora crassa is a model for investigating the mechanisms of somatic cell-to-cell communication and fusion. N. crassa cells chemotropically grow toward genetically similar cells, which ultimately make physical contact and undergo cell fusion. Here, we describe the development of a Pprm1-luciferase reporter system that differentiates whether genes function upstream or downstream of a conserved MAP-Kinase (MAPK) signaling complex by using a set of mutants required for communication and cell fusion. The vast majority of these mutants are deficient for self-fusion and for fusion when paired with wild type cells. However, the ham-11 mutant is unique in that fails to undergo self-fusion, but chemotropic interactions and cell fusion are restored in ham-11 + wild-type interactions. In genetically dissimilar cells, chemotropic interactions are regulated by genetic differences at doc-1 and doc-2, which regulate pre-fusion non-self recognition; cells with dissimilar doc-1 and doc-2 alleles show greatly reduced cell fusion frequencies. Here, we show that HAM-11 functions in parallel with the DOC-1 and DOC-2 proteins to regulate activity of the MAPK signaling complex. Together our data support a model of integrated self and non-self recognition processes that modulate somatic cell-to-cell communication in N. crassa.
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Integration of Self and Non-self Recognition ... - genetics.org
Immunology is the study of the immune system. The immune system protects us from infection through various lines of defense. Molecular and cellular components make up the immune system. The function of these components is divided into non specific mechanisms, those which innate to an organism, and responsive responses which are adaptive to specific pathogens. Fundamental or classical immunology involves studying the components that make up the innate and adaptive immune system.
Innate immunity is the first line of defense and is non-specific that is the responses that are the same for all potential pathogens, no matter how different they maybe. Innate immunity includes physical barriers( e.g. skin, saliva etc) and cells (e.g. macrophages, neutrophils, basophils, mast cells etc). These components are ready to go and protect an organisms for the first few days of infection. Adaptive immunity is the second line of defense which involves building up memory of encountered response specific to the pathogen or foreign substance.
Adaptive immunity involves antibodies, which generally target foregin pathogens roaming free in the bloodstream. Also involved are T-cells, which are directed especially towards pathogens that have colonized cells and can directly kill infected cells or help control the antibody response.
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Immunology Department of Microbiology, Immunology and ...
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Cell Biology (CB), a journal of experimental cell investigation, publishes reviews, original articles and short communications on the structure, function and macromolecular organization of cells and cell components. Contributions focusing on cellular dynamics, motility and differentiation, particularly if related to cellular biochemistry, molecular biology, immunology, neurobiology, and developmental biology are encouraged. Manuscripts describing significant technical advances are also welcome. The topics related to this journal include but are not limited to:
Cell adhesion and motility
Cellular communication
Cell cycle and division
Cell growth, survival, and death
Cell structure and dynamics
Cellular disease mechanisms
Cytoskeleton and molecular motors
Gene expression and RNA metabolism
Methods and techniques
Organelle homeostasis
Protein and membrane trafficking
computational cell biology
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Cell Biology :: Science Publishing Group
Tooth, plural teeth, any of the hard, resistant structures occurring on the jaws and in or around the mouth and pharynx areas of vertebrates. Teeth are used for catching and masticating food, for defense, and for other specialized purposes.
The teeth of vertebrates represent the modified descendants of bony dermal (skin) plates that armoured ancestral fishes. A tooth consists of a crown and one or more roots. The crown is the functional part that is visible above the gum. The root is the unseen portion that supports and fastens the tooth in the jawbone. The root is attached to the tooth-bearing bonethe alveolar processesof the jaws by a fibrous ligament called the periodontal ligament or membrane. The neck of the root is embraced by the fleshy gum tissue (a specialized area of connective tissue covered with mucous membrane that lines the mouth cavity). The shape of the crown and root vary among different teeth and among different species of animals.
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human digestive system: The teeth
The teeth are hard, white structures found in the mouth. Usually used for mastication, the teeth of different vertebrate species are sometimes specialized. The teeth of snakes, for example, are very thin and sharp and usually curve backward; they function in capturing prey but
All true teeth have the same general structure and consist of three layers. In mammals an outer layer of enamel, which is wholly inorganic and is the hardest tissue in the body, covers part or all of the crown of the tooth. The middle layer of the tooth is composed of dentine, which is less hard than enamel and similar in composition to bone. The dentine forms the main bulk, or core, of each tooth and extends almost the entire length of the tooth, being covered by enamel on the crown portion and by cementum on the roots. Dentine is nourished by the pulp, which is the innermost portion of the tooth. The pulp consists of cells, tiny blood vessels, and a nerve and occupies a cavity located in the centre of the tooth. The pulp canal is long and narrow with an enlargement, called the pulp chamber, in the coronal end. The pulp canal extends almost the whole length of the tooth and communicates with the bodys general nutritional and nervous systems through the apical foramina (holes) at the end of the roots. Below the gumline extends the root of the tooth, which is covered at least partially by cementum. The latter is similar in structure to bone but is less hard than dentine. Cementum affords a thin covering to the root and serves as a medium for attachment of the fibres that hold the tooth to the surrounding tissue (periodontal membrane). Gum is attached to the adjacent alveolar bone and to the cementum of each tooth by fibre bundles.
Like most other mammals, humans have two successive sets of teeth during life. The first set of teeth are called primary, or deciduous, ones, and the second set are called permanent ones. Humans have 20 primary and 32 permanent teeth.
Primary teeth differ from permanent teeth in being smaller, having more pointed cusps, being whiter and more prone to wear, and having relatively large pulp chambers and small, delicate roots. The primary teeth begin to appear about six months after birth, and the primary dentition is complete by age 2 1/2; shedding begins about age 5 or 6 and is finished by age 13. The primary teeth are shed when their roots are resorbed as the permanent teeth push toward the mouth cavity in the course of their growth.
In humans the primary dentition consists of 20 teeth four incisors, two canines, and four molars in each jaw. The primary molars are replaced in the adult dentition by the premolars, or bicuspid teeth. The 12 adult molars of the permanent dentition erupt (emerge from the gums) behind the primary teeth and do not replace any of these, giving a total of 32 teeth in the permanent dentition. The permanent dentition is thus made up of four incisors, two canines, four premolars, and six molars in each jaw.
Incisor teeth are the teeth at the front of the mouth, and they are adapted for plucking, cutting, tearing, and holding. The biting portion of an incisor is wide and thin, making a chisel-shaped cutting edge. The upper incisors have a delicate tactile sense that enables them to be used for identifying objects in the mouth by nibbling. Next to the incisors on each side is a canine, or cuspid tooth. It frequently is pointed and rather peglike in shape and, like the incisors, has the function of cutting and tearing food.
Premolars and molars have a series of elevations, or cusps, that are used for breaking up particles of food. Behind each canine are two premolars, which can both cut and grind food. Each premolar has two cusps (hence the name bicuspid). The molars, by contrast, are used exclusively for crushing and grinding. They are the teeth farthest back in the mouth. Each molar typically has four or five cusps. The third molar in humans tends to be variable in size, number of roots, cusp pattern, and eruption. The number of roots for each type of tooth varies from one for incisors, canines, and premolars to two or three for molars.
The teeth of many vertebrates have been adapted for special uses. Rodents have curved incisors that are set deep in the jaws and which grow continually throughout life; hares and rabbits have similar teeth. The tusks of elephants are enlarged upper incisors. The tusks of the walrus are enlarged canines, as are those of the wild boar. In the pig the lower incisors lie close together and project forward to form a digging instrument. Baboons have enlarged canines for defense and display. Certain snakes have hollow teeth that function as needles to insert venom. The sawfish, the only animal with true teeth outside its mouth, uses the teeth on both sides of its snout to slash its prey. The forms, patterns, and arrangements of teeth in different species of animals are of great importance in determining their phylogenetic (taxonomic) relationships.
Caries, or tooth decay, is the most common disease of the teeth among humans. Apart from the common cold, it is perhaps the most frequent disease in contemporary society. Tooth decay originates in the buildup of a yellowish film called plaque on teeth, which tends to harbour bacteria. The bacteria that live on plaque ferment the sugar and starchy-food debris found there into acids that destroy the tooths enamel and dentine by removing the calcium and other minerals from them. Caries usually commences on surface enamel, especially in pits and fissures and between adjacent teeth. From the enamel the process of decay spreads to the underlying dentine, and may finally involve the tooth pulp. Aside from keeping the teeth clean through regular brushing and flossing, tooth decay can be greatly reduced by the addition of fluorides to drinking water. Caries is treated by removing decayed dental tissue and replacing it with inert filling substances.
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primate: Teeth
A dentition with different kinds of teeth (heterodonty)incisors, canines, and cheek teethis characteristic of all primates and indeed of mammals generally. Heterodonty is a primitive characteristic, and primates have evolved less far from the original pattern than most mammals. The principal changes are a
The teeth may be subject to certain irregularities in their alignment, such as an abnormality in the relationship between the teeth in opposing jaws (malocclusion). In a less-severe irregularity, one or more teeth may be out of alignment. Both types of problems are best treated early in life through the use of special fixed or removable appliances (i.e., braces).
Another common dental disorder is inflammation of the gum, or gingivitis. It usually commences at or close to the gum margin, often between adjacent teeth. Pockets form between the gum and the adjacent teeth, sometimes penetrating deeply into the tissues. This leads to further infection, with inflammation and bleeding from the infected gums. A principal cause of gingivitis is the buildup of plaque on teeth, which causes irritation of the gums and thus leads to their inflammation and infection.
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Tooth | anatomy | Britannica.com
Cell Definition
Cells are the basic unit of life. In the modern world, they are the smallest known world that performs all of lifes functions. All living organisms are either single cells, or are multicellular organisms composed of many cells working together.
Cells are the smallest known unit that can accomplish all of these functions. Defining characteristics that allow a cell to perform these functions include:
Below we will discuss the functions that cells must fulfill in order to facilitate life, and how they fulfill these functions.
Scientists define seven functions that must be fulfilled by a living organism. These are:
It is the biology of cells which enables living things to perform all of these functions. Below, we discuss how they make the functions of life possible.
In order to accomplish them, they must have:
The different cell types we will discuss below have different ways of accomplishing these functions.
Because of the millions of diverse species of life on Earth, which grow and change gradually over time, there are countless differences between the countless extant types of cells.
However, here we will look at the two major types of cells, and two important sub-categories of each.
Prokaryotes are the simpler and older of the two major types of cells. Prokaryotes are single-celled organisms. Bacteria and archaebacteria are examples of prokaryotic cells.
Prokaryotic cells have a cell membrane, and one or more layers of additional protection from the outside environment. Many prokaryotes have a cell membrane made of phospholipids, enclosed by a cell wall made of a rigid sugar. The cell wall may be enclosed by another thick capsule made of sugars.
Many prokaryotic cells also have cilia, tails, or other ways in which the cell can control its movement.
Prokaryote cell
These characteristics, as well as the cell wall and capsule, reflect the fact that prokaryotic cells are going it alone in the environment. They are not part of a multicellular organism, which might have whole layers of cells devoted to protecting other cells from the environment, or to creating motion.
Prokaryotic cells have a single chromosome which contains all of the cells essential hereditary material and operating instructions. This single chromosome is usually round. There is no nucleus, or any other internal membranes or organelles. The chromosome just floats in the cells cytoplasm.
Additional genetic traits and information might be contained in other gene units within the cytoplasm, called plasmids, but these are usually genes that are passed back and forth by prokaryotes though the process of horizontal gene transfer, which is when one cell gives genetic material to another. Plasmids contain non-essential DNA that the cell can live without, and which is not necessarily passed on to offspring.
When a prokaryotic cell is ready to reproduce, it makes a copy of its single chromosome. Then the cell splits in half, apportioning one copy of its chromosome and a random assortment of plasmids to each daughter cell.
There are two major types of prokaryotes known to scientists to date: archaebacteria, which are a very old lineage of life with some biochemical differences from bacteria and eukaryotes, and bacteria, sometimes called eubacteria, or true bacteria to differentiate them from archaebacteria.
Bacteria are thought to be more modern descendants of archaebacteria.
Both families have bacteria in the name because the differences between them were not understood prior to the invention of modern biochemical and genetic analysis techniques.
When scientists began to examine the biochemistry and genetics of prokaryotes in detail, they discovered these two very different groups, who probably have different relationships to eukaryotes and different evolutionary histories!
Some scientists think that eukaryotes like humans are more closely related to bacteria, since eukaryotes have similar cell membrane chemistry to bacteria. Others think that archaebacteria are more closely related to us eukaryotes, since they use similar proteins to reproduce their chromosomes.
Still others think that we might be descended from both that eukaryotic cells might have come into existence when archaebacteria started living inside of a bacterial cell, or vice versa! This would explain how we have important genetic and chemical attributes of both, and why we have multiple internal compartments such as the nucleus, chloroplasts, and mitochondria!
Eukaryotic cells are thought to be the most modern major cell type. All multicellular organisms, including you, your cat, and your houseplants, are eukaryotes. Eukaryotic cells seem to have learned to work together to create multicellular organisms, while prokaryotes seem unable to do this.
Eukaryotic cells usually have more than one chromosome, which contains large amounts of genetic information. Within the body of a multicellular organism, different genes within these chromosomes may be switched on and off, allowing for cells that have different traits and perform different functions within the same organism.
Eukaryotic cells also have one or more internal membranes, which has led scientists to the conclusion that eukaryotic cells likely evolved when one or more types of prokaryote began living in symbiotic relationships inside of other cells.
Organelles with interior membranes found in eukaryotic cells typically include:
As mentioned above, archaebacteria are a very old form of prokaryotic cells. Biologists actually put them in their own domain of life, separate from other bacteria.
Key ways in which archaebacteria differ from other bacteria include:
Archaebacterias unique chemical attributes allow them to live in extreme environments, such as superheated water, extremely salty water, and some environments which are toxic to all other life forms.
Scientists became very excited in recent years at the discovery of Lokiarchaeota a type of archaebacteria which shares many genes with eukaryotes that had never before been found in prokaryotic cells!
It is now thought that Lokiarchaeota may be our closest living relative in the prokaryotic world.
You are most likely familiar with the type of bacteria that can make you sick. Indeed, common pathogens like Streptococcus and Staphylococcus are prokaryotic bacterial cells.
But there are also many types of helpful bacteria including those that break down dead waste to turn useless materials into fertile soil, and bacteria that live in our own digestive tract and help us digest food.
Bacterial cells can commonly be found living in symbiotic relationships with multicellular organisms like ourselves, in the soil, and anywhere else thats not too extreme for them to live!
Plant cells are eukaryotic cells that are part of multicellular, photosynthetic organisms.
Plants cells have chloroplast organelles, which contain pigments that absorb photons of light and harvest the energy of those photons.
Chloroplasts have the remarkable ability to turn light energy into cellular fuel, and use this energy to take carbon dioxide from the air and turn it into sugars that can be used by living things as fuel or building material.
In addition to having chloroplasts, plant cells also typically have a cell wall made of a rigid sugars, to enable plant tissues to maintain their upright structures such as leaves, stems, and tree trunks.
Plant cells also have the usual eukaryotic organelles including a nucleus, endoplasmic reticulum, and Golgi apparatus.
For this exercise, lets look at a type of animal cell that is of great importance to you: your own liver cell.
Like all animal cells, it has mitochondria which perform cellular respiration, turning oxygen and sugar into large amounts of ATP to power cellular functions.
It also has the same organelles as most animal cells: a nucleus, endoplasmic reticulum, Golgi apparatus, etc..
But as part of a multicellular organism, your liver cell also expresses unique genes, which give it unique traits and abilities.
Liver cells in particular contain enzymes that break down many toxins, which is what allows the liver to purify your blood and break down dangerous bodily waste.
The liver cell is an excellent example of how multicellular organisms can be more efficient by having different cell types work together.
Your body could not survive without liver cells to break down certain toxins and waste products, but the liver cell itself could not survive without nerve and muscle cells that help you find food, and a digestive tract to break down that food into easily digestible sugars.
And all of these cell types contain the information to make all the other cell types! Its simply a matter of which genes are switched on or off during development.
1. Which of the following is NOT an essential function that all living things must perform?A. A living thing must reproduce.B. A living thing must be able to maintain its internal environment, regardless of external changes.C. A living thing must respond to changes in its environment.D. None of the above.
Answer to Question #1
D is correct. All of the above are essential functions of life!
2. Which of the following is NOT a type of prokaryotic cell?A. ArchaebacteriaB. Staphylococcus bacteriaC. Streptococcus bacteriaD. Liver cell
Answer to Question #2
D is correct. Liver cells are eukaryotic cells, like all cells from multicellular organisms!
3. Which of the following is NOT a eukaryotic cell organelle?A. PlasmidB. NucleusC. MitochondriaD. Chloroplast
Answer to Question #3
B is correct. Plasmids are pieces of DNA that are passed between prokaryotic cells. They are not organelles.
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Cell - Definition, Functions, Types and Examples | Biology ...
Section 1: Introduction to Cell Biology
1 Introduction to Cells
2 Evolution of Life on Earth
Section 2: Chemical and Physical Background
3 Molecules: Structures and Dynamics
4 Biophysical Principles
5 Macromolecular Assembly
6 Research Strategies
Section 3: Chromatin, Chromosomes, and the Cell Nucleus
7 Chromosome Organization
8 DNA Packaging in Chromatin and Chromosomes
9 Nuclear Structure and Dynamics
Section 4: Central Dogma: From Gene to Protein
10 Gene Expression
11 Eukaryotic RNA Processing
12 Protein Synthesis and Folding
Section 5: Membrane Structure and Function
13 Membrane Structure and Dynamics
14 Membrane Pumps
15 Membrane Carriers
16 Membrane Channels
17 Membrane Physiology
Section 6: Cellular Organelles and Membrane Trafficking
18 Posttranslational Targeting of Proteins
19 Mitochondria, Chloroplasts, Peroxisomes
20 Endoplasmic Reticulum
21 Secretory Membrane System and Golgi Apparatus
22 Endocytosis and the Endosomal Membrane
23 Processing and Degradation of Cellular Components
Section 7: Signaling Mechanisms
24 Plasma Membrane Receptors
25 Protein Hardware for Signaling
26 Second Messengers
27 Integration of Signals
Section 8: Cellular Adhesion and the Extracellular Matrix
28 Cells of the Extracellular Matrix and Immune System
29 Extracellular Matrix Molecules
30 Cellular Adhesion
31 Intercellular Junctions
32 Connective Tissues
Section 9: Cytoskeleton and Cellular Motility
33 Actin and Actin-Binding Proteins
34 Microtubules and Centrosomes
35 Intermediate Filaments
36 Motor Proteins
37 Intracellular Motility
38 Cellular Motility
39 Muscles
Section 10: Cell Cycle
40 Introduction to the Cell Cycle
41 G1 Phase and Regulation of Cell Proliferation
42 S Phase and DNA Replication
43 G2 Phase and Control of Entry into Mitosis
44 Mitosis and Cytokinesis
45 Meiosis
46 Programmed Cell Death
Glossary
Appendix
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Cell Biology - 9780323341264 | US Elsevier Health Bookshop
Page 1
Question 1 1.Which process best describes nonspecific internalization of dissolved substances outside the cell?
Question 2 2.The Fluid Mosaic Model describes proteins _____.
Question 3 3.Which of the following is NOT contained in a chloroplast?
Question 4 4.Which part of the endomembrane system is a site for protein synthesis?
Question 5 5.A sodium potassium pump is a type of...
Question 6 6.The packaging of proteins to be used outside the cell occurs in what organelle?
Question 7 7.What type of cell might have more smooth ER?
Question 8 8.Which does NOT describe the inner membrane of the mitochondria?
Question 9 9.Which of the following is NOT true of the endomembrane system
Question 10 10.What part of the mitochondria creates more space for cellular respiration?
Question 11 11.Which of the following statements about mitochondria and chloroplasts is true?
Question 12 12.Where does photosynthesis occur?
Question 13 13.Movement of cells in both prokaryotes and eukaryotes is accomplished by which of the following structures?
Question 14 14.Nuclear DNA exists as a complex of proteins called _ that condenses into _ during cellular division.
Question 15 15.Which of the following functions is carried out by intermediate filaments but not microtubules?
Question 16 16.The following cellular compartment(s) contain a lumen created by their membranes:
Question 17 17.Which of the following does NOT take place in the nucleus?
Question 18 18.Which of the following first binds to the mRNA message?
Question 19 19.Which of the following is true of the lysosome?
Question 20 20.A mass of cells is found in the sediment surrounding a thermal vent in the ocean floor. The salinity in the area is quite high. Microscopic examination of the cells reveals no evidence of membrane-enclosed organelles. What type of cell is this?
Question 21 21.Eukaryotic cells are thought to be derived from prokaryotic cells that underwent phagocytosis without digestion of the phagocytized cell. This mutualistic relationship is explained by the _ theory.
Question 22 22.Which part is a granum?
Question 23 23.Microfilaments are composed of
Question 24 24.Why does active transport require energy?
Question 25 25.After the bacteriophage uses its tail fibers to attach to the bacterial host, what will happen next in the lytic cycle?
Question 26 26.Which of the following tends to limit cell size?
Question 27 27.What is the function of a lysosome?
Question 28 28.Which of the following could trigger the lytic cycle of a bacteriophage?
Question 29 29.What is the cellular function of the RER?
Question 30 30.Which of the following describes a process that involves viral replications and assembly within a host, followed by bursting the host cell wall?
Choose your answers to the questions and click 'Next' to see the next set of questions. You can skip questions if you would like and come back to them later with the yellow "Go To First Skipped Question" button. When you have completed the practice exam, a green submit button will appear. Click it to see your results. Good luck!
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Cell Biology Chapter Exam - Study.com