Given the enormous heterogeneity of antigen receptors expressed on the populations of naive B and T lymphocytes, the adaptive immune response relies on a process whereby the rare lymphocyte that binds to the antigen is first induced to proliferate, before it can perform its effector function. For B cells, there is a clever mechanism that ensures that the specificity of the antibody secreted by the plasma cell will recognize the same pathogen that initially stimulated the B cell antigen receptor and induced B cell proliferation. This mechanism is:
Answer:
The naïve B cell expresses a membrane-bound form of the antibody as a receptor and secretes that same antibody when it differentiates into a plasma cell.
Explanation:
Naive B cell is a type of B cell that has still not been exposed to the antigen. The B cell receptors (BCRs) are transmembrane proteins composed of 1-a surface immunoglobulin molecule capable of recognizing the antigen, and 2-two transmembrane subunits that transduce the signal. When a B cell binds to antigen with its BCR, the B cell will proliferate and differentiate into a plasma cell. This plasma cell then releases antibodies, which are soluble forms of the BCR where the transmembrane domain that anchors the antibody protein to the membrane of the B cell is eliminated.
Fertilization, Fruit and Seed Formation x3 3. a. name the two processes that lead to seed formation in flowering
Answer:
Pollination, the transfer of pollen from flower-to-flower in angiosperms or cone ... In angiosperms, the process of seed development begins with double ...
Missing: x3 | Must include: x3
Cells control or regulate the flux through metabolic pathways by means of I. allosteric control of enzymes. II. covalent modification of enzymes. III. genetic control of the concentrations of enzymes. IV. genetic expression of allosteric regulators.
Answer:
I, II, III
Explanation:
Allosteric regulation is a common mechanism of regulation of enzyme activity, which generally involves key enzymes in metabolic pathways. Allosteric modulation occurs when a substance/molecule called 'allosteric regulator' binds to an enzyme at a site other than the enzyme's active site, thereby triggering a conformational change in the enzyme and thus affecting its activity. Moreover, covalent modifications such as phosphorylation, acetylation, methylation, etc, are also involved in the regulation of enzymatic activity in metabolic pathways. For example, phosphorylation is a type of reversible covalent modification of proteins consisting of the addition of phosphate groups at specific amino acid residues (i.e., serine, threonine, and tyrosine) by specific enzymes known as protein kinases. Phosphorylation alters the three-dimensional (3D) structure of proteins, thereby turning the substrate or cellular pathway to active and/or inactive. Finally, both transcriptional and post-transcriptional mechanisms are also able to control the expression of enzymes involved in signaling pathways. Transcriptional mechanisms are capable of limiting the amount of mRNA that is produced from a given gene (in this case, an enzyme encoding gene), whereas post-transcriptional mechanisms such as, for example, RNA interference pathways, control the translation of messenger RNA (mRNA) molecules into proteins.
Compared with a eukaryotic cell, a prokaryotic cell Select one:______
a. lacks organelles beyond ribosomes.
b. is larger.
c. does not require energy.
d. is not living.
e. has no method of movement.
The Calvin Cycle can best be described as which type of reaction?
Answer:
In plants, carbon dioxide (CO2) enters the chloroplast through the stomata and diffuses into the stroma of the chloroplast—the site of the Calvin cycle reactions where sugar is synthesized. ... This type of reaction is called a reduction reaction, because it involves the gain of electrons.
what kind of mutation occurred when the DNA strand changed from AATCGTCCG TO AATAGTCCG?
Answer:
Missense Mutation
Explanation:
AAT CGT CCG to AAT AGT CCG where CGT has become AGT is a point mutation. If a point mutation changes the amino acid, it’s called a missense mutation. In this case CGT (arginine) has become AGT (serine).
A small group of mice are released on an island without mice but with abundant food for mice and no predators. After the population size stabilizes for several years, a hurricane drastically reduces it. We can now say that:________.
A) the biotic potential of the population has been reduced.
B) its new population size is a result of density-dependent regulation.
C) its new population size is a result of density-independent regulation.
D) it can now act as a sink metapopulation.
The correct answer is option C) The new mice population size is a result of density-independent regulation.
The carrying capacity might be affected by different factors, known as limiting factors, which might be a result of the population density (for example, competition) or might be density-independent. This last case refers to dense-independent factors, and among these, we can mention human impact or natural disasters (fires, volcanic eruption, flooding). Natural disaster causes damages in an ecosystem, reducing the available resources such as food or shelter, and consequently decreases the number of individuals. Natural disasters reduce the carrying capacity of the environment
In the exposed example, mice got to stabilize on the island. The population had enough food and no predators. But the occurrense of the huricane reduced drastically the population size. This is an example of a natural dissaster acting as a limiting dense-independent factor affecting the population size.
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Cystathioninuria can be caused by two different mutations in the enzyme cystathionase. Cystathioninuria caused by mutation 1 can be overcome by providing cells with increasing concentrations of the coenzyme pyridoxal phosphate. Which of the following statements describe the most likely changes in the binding affinities of the two mutant enzymes?
A. Both mutant enzymes have lost the ability to bind the substrates.
B. The enzyme with mutation 1 has lost the ability to bind to the substrates, whereas the enzyme with mutation 2 has lost the ability to bind to pyridoxal phosphate.
C. The enzyme with mutation 1 has decreased affinity for pyridoxal phosphate, whereas the enzyme with mutation 2 has lost the ability to bind to the substrates.
D. Both mutant enzymes have lost the ability to bind pyridoxal phosphate.
Answer:
C. The enzyme with mutation 1 has decreased affinity for pyridoxal phosphate, whereas the enzyme with mutation 2 has lost the ability to bind to the substrates.
Explanation:
A coenzyme is an organic cofactor that binds with an enzyme in order to initiate or aid the function of the enzyme. A coenzyme binds to the active site of the enzyme (where the reaction occurs), thereby triggering its activation by modifying protein structure during the reaction. Some examples of coenzymes include Coenzyme A and Adenosine triphosphate (ATP). Pyridoxal phosphate is a coenzyme (it is the active form of vitamin B6) that is required for the function of cystathionase. Moreover, cystathionase is an enzyme that enables cells the synthesis of cysteine from methionine (transsulfuration pathway). The binding of pyridoxal phosphate to the enzyme increases the binding affinity of the enzyme for the substrate, thereby influencing its activity. In this case, it is expected that mutation 1 reduces the binding affinity of the enzyme to the cofactor, and thereby the cofactor is required at a higher concentration to restore normal enzyme activity.
What is the function of the dendrites of a neuron?
Phân tích các quy luật hoạt động thần kinh cấp cao ở trẻ và vận dụng trong thiết lập thói quen học tập và kỉ luật ở học sinh tiểu học.
Answer:
very different than ducks do u want it is not the
what is counter current mechanism?
“The mechanism that the kidneys use to concentrate urine is called the counter current mechanism.”
A postsynaptic neuron has three presynaptic inputs - from neurons X, Y and Z. When X, Y, and Z are stimulated simultaneously, the postsynaptic neuron reaches threshold and undergoes an action potential. What is this process called?
Answer:
Summation
Explanation:
Presynaptic neurons release chemical signals called neurotransmitters into the synaptic cleft in order to trigger graded potentials in the postsynaptic neuron. Some neurotransmitters produce excitatory post-synaptic potentials, whereas other neurotransmitters generate inhibitory post-synaptic potentials. Summation refers to the process that determines whether an action potential is generated by the combined effects of excitatory and/or inhibitory signals. The summation can be temporal or spatial regarding the number of cells communicating with the neuron. Temporal summation occurs when a presynaptic terminal is stimulated repeatedly in rapid succession. On the other hand, spatial summation occurs when excitatory potentials fire from different presynaptic neurons.
The meaning of ALARA in radiation?
Answer:
The guiding principle of radiation safety is “ALARA”. ALARA stands for “as low as reasonably achievable”.
A boatload of Swedish tourists, all of whom bear the MM blood group, is marooned on Haldane Island, where they are met by an equally sized population of Islanders, all bearing blood group NN. In time, the castaways become integrated into Island society. Assuming random mating, no mutation, no selection (based on blood group), and no genetic drift, what would you expect the blood group distribution to be among 4000 progeny of the new Haldane Island population
Answer:
1000 MM individuals; 2000 MN individuals; 1000 NN individuals
Explanation:
The Hardy-Weinberg principle states that, under certain conditions, the frequency of alleles and genotypes in a sexually reproducing population will remain constant over generations. The Hardy-Weinberg assumptions include random mating, sexual reproduction, and the absence of evolutionary forces such as mutation, natural selection, and genetic drift (as in the example above). Under these conditions, the frequency of alleles and genotypes in a population will not change and tend to the equilibrium. In this case, under Hardy-Weinberg equilibrium, the frequency of the M allele or 'p' must be equal to 0.5, and the frequency of the N allele or 'q' must be equal to 0.5 (i.e., the sum of all allele frequencies in the population must be equal to 1). Moreover, the frequencies of the genotypes will be p², 2pq, and q² >> p² (MM genotype) = (0.5)² = 0.25; q² (NN genotype) = (0.5)² = 0.25; and 2 x p x q (MN genotype) = 2 x 0.5 x 0.5 = 0.50. In consequence, under Hardy-Weinberg equilibrium, in a population of 4000 diploid individuals (8000 alleles), we have
- 4000 M alleles (M = 0.5) and 4000 N alleles (N = 0.5);
- 1000 MM individuals [p² >> (0.5)² = 0.25]; 2000 MN individuals (2pq >> 2 x 0.5 x 0.5 = 0.5) and 1000 NN individuals [q² >> (0.5)² = 0.25].
What is the fubtion of the nerves
Answer:
carry messages to and from the brain and spinal cord and the rest of the body
OR
it is a bundle of fibers that receives and sends message between the body and the brain
Answer:
The nervous system is the body's primary governing, regulating, and communication system. It is the hub of all mental activity, such as thinking, learning, and remembering. The nervous system, together with the endocrine system, is in charge of regulating and maintaining homeostasis.
OAmalOHopeO
Two species have homologous structures. What do these homologous structures show about the evolutionary relationship between the two species?
What variable should Anurag change in his experiment
Answer:
For geological carbon sequestration, the reaction of aqueous CO2 with silicate rock permits carbonate formation, achieving permanent carbon sequestration.A
Explanation:
The image below shows a club fungus. A club fungus has an erect, above-ground fruiting body and long, branching, underground hyphae.
How do the structures of the fruiting body and hyphae relate to their functions?
A.
The fruiting body is tall to allow for spore dispersal, while the hyphae are branched to increase the absorption of nutrients.
B.
The fruiting body is curved to help the uptake of decaying plant material, while the hyphae are long to increase gas exchange.
C.
The fruiting body is tall to maximize photosynthesis, while the hyphae are branched to support the release of waste products.
D.
The fruiting body is curved to improve absorption of water, while the hyphae are long to allow for reproduction.
Answer:
The fruiting body is curved to improve absorption of water, while the hyphae are long to allow for reproduction.May 12, 2020
Explanation:
If it helps you mark me as a brainleast
Answer:
Explanation:
d
What is a function of the integumentary system?
1 forms blood clots
2 grows new tissue
3 absorbs water
4 break down chemical bonds in food
Answer:
absorbs water is a function of the integumentary system. hope it help you.
A function of the integumentary system is to grow new tissues. Thus, the correct option B.
What is the Integumentary system?The integumentary system may be defined as a unique type of system that primarily consists of the skin, hair, nails, and exocrine glands. It is the set of organs that construct an outermost layer of an animal or human body.
The integumentary system plays a significant role in the growth of new tissues within the body. The cells of the skin generally hold the mechanism of renewal or replacement of injured or damaged cells which are present on the epidermis part of a specific organ.
The integumentary system also protects the body from infections, and injuries provide defense against pathogens, etc.
Therefore, a function of the integumentary system is to grow new tissues. Thus, the correct option B.
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What is the function of the mitochondria?
A. Stores the cell's DNA
B. Builds proteins
C. Produces energy for the cell by respiration
OD. Stores the cell's glucose
Reset Selection
Answer:
Produces energy for the cell by respiration
Explanation:
The glucose obtained from food is broken down to pyruvic acid in the cytoplasm. This pyruvic acid is broken down into oxygen, water and energy rich ATP molecules in the Mitochondria.
What do MSDS sheets do, in your own words
Answer: The MSDS lists the hazardous ingredients of a product, its physical and chemical characteristics (e.g. flammability, explosive properties), its effect on human health, the chemicals with which it can adversely react, handling precautions, the types of measures that can be used to control exposure
Explanation:
Ecosystems rely on interdependence between species to keep balance. Which of the following is a threat to a stable
ecosystem?
A. Loss of biodiversity
B. High biodiversity
C. Low biodiversity
D. Increase in biodiversity
Answer:
loss of biodiversity
Explanation:
Biodiversity- refers to the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life.
loss in biodiversity affect food chains greatly
thanks
hope it helps
During the performance of the simple staining procedure, you failed to heat fix your E-coli smear preparation. Upon microscopic examination , how would you expect this slide to differ from the correctly prepared slides ?
OMG I'm a business study Student so I really don't know about this stuff
What will the percentage of cytosine be in this segment of DNA?
Answer:
15%
Together, adenine and thymine compose 70% of the segment. This means that 30% of the section is composed of guanine-cytosine pairs. Since these two bases will be equal in quantity, 15% of the DNA section will be cytosine bases.
What happens during rusting of an iron nail?
1 sulfur and oxygen combine to form a sulfur dioxide coating
2 iron and oxygen combine to form iron oxide
3 sulfur, iron, and oxygen combine to form iron sulfoxide
4 iron and sulfur combine to form iron sulfide
Answer: the correct answer is B number 2
Explanation: I just answered this question
A large section of tropical rainforest is cleared to build roads for mining. Select the least likely outcome of this habitat fragmentation from the options below. a.) Species that require open grazing areas may not survive. b.) Species will quickly adapt and re-populate the area. c.) The environment on the habitat edges will support different plants and animals. d.) Subpopulations of species may emerge.
Answer:
B
Explanation:
B - Species, especially ones with small niches, that looses their niches will likely die out or move to another location. Roads Will, in general, also disrupt the ecosystem (or the remains of it) and its inhabitants, which might lead to migration once again. That would be my reasoning at least. (:
function of graffian follicle
Answer:
It provides for the maturation and release of a fertilizable oocyte
Explanation:
let me know if you have any questions
A man bought a goldfish in a pet shop. Upon returning home, he put the goldfish in a bowl of recently boiled water that had been cooled quickly. A few minutes later the fish was found dead. Explain what happened to the fish
Answer:
lack of oxygen in the water
Explanation:
The fish most likely died from lack of oxygen in the water. This is because fishes actually use their gills to extract and breathe in the oxygen from the water while also expelling carbon dioxide from their lungs. Similar to how humans breathe. When the water was boiled it caused the dissolved gases to be expelled, which includes oxygen. Therefore, without the necessary oxygen in the water, the fish ultimately suffocated.
Boiling the water reduce its amount of dissolved oxygen which is needed by the fish to breathe, that's why the fish died after few minutes.
What is dissolved oxygen?Dissolved oxygen is the amount of oxygen present in the water.
The organisms live to consume dissolved oxygen to breathe.
The amount of dissolved oxygen is high in the current water like rivers than in the still water like pond.
If the amount of DO is high in the water, it causes bubble gas disease in the aquatic organisms.
If the amount of DO is low in the water than, fishes and other aquatic organism cant survive due to low oxygen level.
Thus, boiling the water reduce its amount of dissolved oxygen which is needed by the fish to breathe, that's why the fish died after few minutes.
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which life cycle stage is found in plants but not animals
Answer:
Multicellular haploidOAmalOHopeO
Plants have multicellular haploid and multicellular diploid stages in their life cycle.
Gametes develop in the multicellular haploid gametophyte . Fertilization gives rise to a multicellular diploid sporophyte, which produces haploid spores via meiosis.What is multicellular haploid stage?The haploid multicellular stage produces specialized haploid cells by mitosis that fuse to form a diploid zygote.The zygote undergoes meiosis to produce haploid spores. Each spore gives rise to a multicellular haploid organism by mitosis.To know more about diploid stage here
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Why is it important to have a taxonomy or classification of types of collection and how does that help us understand the development of collection strategies, technologies, collection planning, and methods of collection
Answer:
Classifying and characterizing various types of collection helps us to identify and understand the capabilities and limitations of each type.
Explanation:
By understanding these factors, we are better able to request support, layer collections, and provide a complete collection plan that best addresses our intelligence gaps. Collection strategies ultimately start with these gaps. By understanding all of your available collection capabilities, you can more effectively manage these assets to accomplish the mission. In most cases, you will not be able to have every type of asset or collection medium under the sun, so it becomes even more critical to understand the strengths and weaknesses of those available. Doing so will help a collection manager most effectively utilize the assets available to them to accomplish the collective organizational mission or end state. Without characterization and classification, you cannot fully understand and thus employ the myriad of tools available effectively (Found on a site not mine)
Taxonomy allows us to organize and categorize collections based on their characteristics, which makes it easier to understand the various types of collections that exist and to compare them.
What is taxonomy?All of the world's plants, animals, and microorganisms are included in taxonomy, which is the science of naming, describing, and classifying species.
For a number of reasons, taxonomy, or the classification of collection kinds, is crucial.
Secondly, taxonomy enables us to classify and organize collections based on their traits, which facilitates comprehension of the numerous sorts of collections that exist and allows for simpler comparison.
To ensure that collections are properly managed, preserved, and available for future generations, taxonomy is an essential tool for understanding the development of collection strategies, technologies, planning, and techniques of collecting.
Thus, it is important to have a taxonomy or classification of types of collection.
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