Explanation:
Human immunodeficiency virus type 1 (HIV-1) enters target cells by first binding to the primary receptor CD4 and then to a coreceptor, generally one of the chemokine receptors CCR5 and CXCR4 (4). CD4 binding induces structural changes in the envelope (Env) glycoprotein that form and expose the coreceptor binding site. There are two main interactions between Env and coreceptor (13, 14, 25, 50, 51): the base of the third variable loop (V3) engages the N terminus of the coreceptor, while the crown of the V3 loop that includes the highly conserved GPGR/Q arch motif binds to the extracellular loops of the coreceptor, with the second extracellular loop of the coreceptor being particularly important (16, 25, 35, 48, 62). Although some HIV-1 strains are able to use a variety of different G protein-coupled receptors to gain entry into CD4+ cell lines, the great majority of these viruses use CCR5 and/or CXCR4 as coreceptors to infect primary cells (3, 4, 10, 23, 47, 66). CCR3, GPR15, APJ, and FPRL-1 are among the most frequently used alternative coreceptors when overexpressed on cell lines (11, 26, 43, 47, 57). Rare cases of HIV-1 strains that are able to use FPRL-1 and GPR1, but not CCR5 or CXCR4, have been reported (57); however, their in vivo relevance remains unknown.
To characterize the biological processes underlying HIV/simian immunodeficiency virus (SIV) transmission, we recently developed an experimental strategy that permits the identification, enumeration, and molecular cloning of transmitted/founder (T/F) viruses (28, 53). This strategy, which employs single-genome amplification (SGA) and direct amplicon sequencing of HIV/SIV RNA or DNA from the plasma or infected cells, makes it possible to infer the nucleotide sequence of the viral strain(s) that initiated productive infection weeks earlier (1, 28, 29, 37, 53, 58, 67). An important prediction of this approach has been that inferred T/F viruses are fully functional and encode all proteins necessary to establish a new infection. Indeed, this prediction has been borne out in numerous studies, which have shown that T/F viral genes as well as full-length genomes are biologically active. Sets of T/F Envs have been shown to mediate efficient virus entry in single-round infection assays, and they invariably use CCR5 as a coreceptor (28, 34). Similarly, T/F infectious molecular clones (IMCs) of HIV-1, SIVmac and SIVagm all produce replication competent virus that grow to high titers in primary CD4+ T cells (22, 38, 54).
MATERIALS AND METHODS
Amplification of the HIV-1 env gene. Serial plasma samples collected from an acutely infected plasma donor, ZP6248, were purchased from ZeptoMetrix. A total of seven plasma samples were collected between 12 February and 9 March 1997, and viral loads (VLs) were determined by the COBAS Amplicor HIV-1 monitor test.
Sequence analysis. All SGA amplicons were sequenced directly by cycle sequencing and dye terminator methods using an ABI 3730xl genetic analyzer (Applied Biosystems, Foster City, CA). Individual sequences were assembled and edited using the Sequencher program 4.7 (Gene Codes, Ann Arbor, MI). The env sequences were aligned using CLUSTAL W (60), and manual adjustment for optimal alignment was done using MASE (20).
What portion of the DNA molecule is variable and serves as the “GENETIC CODE
Cellular Respiration occurs in which organelle?
a. ribosome
B. golgi
c.nucleus
d.mitochondria
Answer:
the answer d. mitochondria
the image of an object which is 10cm from a lens is formed on the same side as the object. If the image is 10cm behind the object, Find the focal length of the lens.
Answer:
Focal length is 6.67 cm.
Explanation:
Object distance, u, from the lens = 10 cm
Image distance, v, to the lens = 10 cm + 10 cm
= 20 cm
Apply the lens formula to determine the focal length, f, of the lens.
[tex]\frac{1}{f}[/tex] = [tex]\frac{1}{u}[/tex] + [tex]\frac{1}{v}[/tex]
= [tex]\frac{1}{10}[/tex] + [tex]\frac{1}{20}[/tex]
= [tex]\frac{2 + 1}{20}[/tex]
[tex]\frac{1}{f}[/tex] = [tex]\frac{3}{20}[/tex]
Find the inverse of both sides, so that;
f = [tex]\frac{20}{3}[/tex]
= 6.67
f = 6.67 cm
The focal length of the lens is 6.67 cm.
According to the law of conservation of mass, which statement is true?
Question 1 options:
Mass can be created by chemical reactions.
The mass of the products in a chemical reaction do not have to equal the mass of the reactants.
Mass can neither be created nor destroyed.
Mass can only be destroyed by physical transformations.
Answer:
3 Mass can neither be created nor destroyed.
Explanation:
Not number 1 because The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. Not 2 One of these is called the law of conservation of mass , which states that during a chemical reaction, the total mass of the products must be equal to the total mass of the reactants. not 4 go back to number 1 and look why so its 3
what do Entropy mean
Answer:
lack of order or predictability; gradual decline into disorder.
Explanation:
Answer:
Entropy means the amount of energy in a system that is unable to work
(randomness)
In other words, how are we speeding up the effects of the competitive exclusion principle and thereby altering the outcome of that ecosystem's natural succession
Answer: Overgrazing, overfishing, and forest fires
Explanation:
Competitive exclusion principle two species which have the same ecological niche cannot exists together as such species will be competing for the same resources. The species which is superior over the other will receive the resources and the other species having no competitive advantage will not survive in future.
According to the given situation, human being is the most superior species on earth and have competitive advantage of thinking ability and intelligence over other species. Succession are the changes that occur in the biotic community of an ecosystem with respect to time.
The human beings can speed up the effects of the competitive exclusion principle by various ways: Overgrazing, overfishing, and forest fires. The overgrazing of the cattle in the field can remove the vegetation cover of the region and the land will become barren so instead of progressive succession in terms of vegetation cover the succession will again re-initiate in terms of primary succession if environment supports.
Overfishing can cause the exclusion of some valuable species of fish and there will not be evolution of such species and will alter the outcome of natural succession.
Forest fires can affect both floral and faunal species some species may tolerate the fire and will survive and some precursors like roots of the plants can support new individual plants. This will again alter the outcome of natural progressive succession in an ecosystem.
Which of the following items may be on the laboratory bench to while doing la work?
Answer:
Disinfection needs to happen after any spill as well as after every work shift. The CDC recommends the use of a ten percent bleach solution as the standard for disinfection, but other products might be preferred for your lab.
Explanation:
What type of duck only has 2 legs DONT LOOK IT UP
Answer:
dont all ducks have 2 legs?
an egg cell in a gorilla contains 24 chromosomes. When the egg cell is fertilized, which of the following occurs?
A.
The 24 original chromosomes replicate, resulting in 48 chromosomes in the fertilized egg.
B.
The 24 original chromosomes split at the centromere, resulting in 48 chromosomes in the fertilized egg.
C.
The nucleus of a sperm cell fuses with the nucleus of the original egg cell, resulting in 48 chromosomes in the fertilized egg.
D.
The nucleus of another egg cell pairs with the nucleus of the original egg cell, resulting in 48 chromosomes in the fertilized egg.
Answer:
Its C
Explanation:
DNA from 2 parents, 24 from each parent is combined into one with 48 chromosomes. Hopefully, that makes sense and is correct.
What 2 properites are needed to figure out the effect of a force on acceleration of an object?
Question 1 options:
both magnitude and direction
both velocity and momentum
both force and gravity
both speed and movement
Answer:
B. Velocity and Momentum
Explanation:
I majored in Biology
What living systems have distinct structures and sets of functions? Be sure to refer to class notes for 2.02.
Question 1 options:
cells
tissue
All of the listed answers have distinct structures and sets of functions
organisms
Answer
Estoy muy triste por tener que regalar a mi perro
In tomatoes, a heterozygous plant with normal fruit and purple stems is crossed with a recessive plant having fasciated fruit and green stems. The following distribution of offspring is observed:
normal fruit, purple stems 38.5% fasciated fruit, green stems 38.5%
normal fruit, green stems 11.5%
fasciated fruit, purple stems 11.5%
What conclusion can be made regarding the loci for fruit shape and stem color? HINT determine the RF
What the loci and RF here mean? How to answer this question?
Answer:
Recombination frequency, P = 0.23.
If the recombination frequency is < 50%, genes are linked. A RF of 23% tells us that these two genes are in the same chromosome, close enough to be linked.
1% of recombinations = 1 map unit23% = 23 map unitsThe genes for stem color and fruit type seem to be in the same chromosome, linked and 23 MP apart.
Explanation:
In the present example, the genes for stem color and fruit type seem to be linked.
To know if two genes are linked, we must observe the progeny distribution. If individuals, whos genes assort independently, are test crossed, they produce a progeny with equal phenotypic frequencies 1:1:1:1. If we observe a different distribution, that is that phenotypes appear in different proportions, we can assume that genes are linked in the double heterozygote parent.
In this way, we might verify which are the recombinant gametes produced by the di-hybrid, and we will be able to recognize them by looking at the phenotypes with lower frequencies in the progeny.
The following distribution of offspring is observed:
normal fruit, purple stems 38.5% fasciated fruit green stems 38.5% normal fruit, green stems 11.5% fasciated fruit, purple stems 11.5%38.5% + 38.5% + 11.5% + 11.5% = 100%
N (total number of individuals in the progeny) = 100
number of individuals with normal fruit, purple stems 38.5 number of individuals with fasciated fruit green stems 38.5 number of individuals with normal fruit, green stems 11.5 number of individuals with fasciated fruit, purple stems 11.5To calculate the recombination frequency we will make use of the next formula: P = Recombinant number / Total of individuals. The genetic distance will result from multiplying that frequency by 100 and expressing it in map units (MU).
P = Recombinant number / Total of individuals.
P = 11.5 + 11.5 / 100
P = 0.23
We need to know that 1% of recombinations = 1 map unit = 1cm. Also, the maximum recombination frequency is always 50%. This means that if the recombination frequency is < 50%, genes are linked. A RF of 23% tells us that these two genes are in the same chromosome, close enough to be linked. FR 23% = 23 UM.
Order the following words from smallest to largest. Cell, atom, organ, tissue, electron element, molecule, organ system, organism, macromolecule.
Answer:
Electron, Atom, Element, Molecule, Macromolecule, Cell, Tissue, Organ, Organ Systems, Organism
Explanation:
Electron, atom, element, molecule, macromolecule, cell, organ, organ system, organism.
In the organization of life, it is usually arranged from the smallest to the most complex.
The electrons: This is the negative part of an atom that revolves round the nucleus of an atom.
The atom: This is the smallest unit of an element.
The element: This is a substance that is made up of atoms and cannot be further broken down.
The molecule: This is made up of elements that are usually held together by a chemical bond.
The macromolecule: This is a large molecule .which consists of smaller molecules combine together.
The cell: This is the structural and functional unit found in a living organism.
The organ: This is made up of a collection of tissues that carry out the same function.
The organ system: This is made up of different organs that work together to perform a similar function.
The organism: This can either be animal or plants that are capable of functioning independently.
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Which two processes are responsible for the formation of fog?
Answer:
Explanation:
evaporation
What are the energy producing organelles and under what conditions do they produce energy
Answer: mitochondria are the site of aerobic respiration, for which of course, they require oxygen.
Explanation: mitochondria are the site of aerobic respiration and energy production for which they require a supply of oxygen
The energy-producing organelle is the mitochondria, and the mitochondria make the energy in the aerobic cellular respiration where the cell uses oxygen and makes the energy that is the ATP.
What is the function of the mitochondria?The mitochondria are cellular organelles in which energy is produced, which happens when the cell gets enough oxygen and the glucose is broken down completely to form ATP. The ATP is formed due to the proper oxygenation of the glucose, and the proton gradient is formed. The proton gradient gives the energy to the cell for energy production, and the energy is used by the cell for the overall body metabolism and growth.
Hence, the energy-producing organelle is the mitochondria, and the mitochondria makes the energy in the aerobic cellular respiration where the cell uses oxygen and makes the energy that is the ATP.
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Which of the following is false about DNA?
A. DNA is made up of units called nucleotides.
B. Any base can pair to any other base.
C. DNA contains the instructions to make proteins.
D. DNA is found in a cell's nucleus.
Answer:
b. any base pair can pair to any other base
Explanation:
Any base pair cannot pair with any other base, Adenine pairs with thymine and cytosine pairs with guanine.
• The hereditary material in humans and almost all of the living species is known as DNA or deoxyribonucleic acid.
• The majority of the DNA is present within the nucleus of the cell.
• DNA comprises the instructions to make proteins that helps to perform essential functions within the body of an organism.
• Within the DNA, information is stored in the form of a code formed of four chemical bases, that is, Adenine, guanine, cytosine, and thymine.
• The base pairs present within the DNA pairs up with each other, that is, adenine pairs with thymine only, and guanine pairs with cytosine, no other kind of pairing is found within the DNA. Each base of also attached with a molecule of phosphate and sugar.
• Together, a phosphate, base, and sugar are known as a nucleotide.
Thus, statement B is incorrect.
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What do you think the term genetic variation means? How does genetic variation
help a species survive?
Answer:
Genetic variation means that a specific gene has various alleles. ... Genetic variation makes it possible for a species to exhibit various traits related to that specific gene. Having a variety of traits can help species adapt to different environmental conditions over time.
Explanation:
Genetic variation is the presence of differences in sequences of genes between individual organisms of a species.
It enables natural selection, one of the primary forces driving the evolution of life.What is genetic variation?Genetic variation is a term used to describe there variation in the DNA sequence in each of the genomes.Genetic variation is the result of the alleles of genes.Genetic variation is important in evolution.To know more about genetics here
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what is sexual reproduction?
Answer:
Hey!
Explanation:
Erm maybe look it up, itll give you a straight answer and I feel like you asked this to see what we answer
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Do you think humans go through a simple life cycle? Explain your reasoning.
Answer: no
Explanation: we complex
Which is larger? 1 meter or 2 feet
Answer:
1 meter
Explanation:
1 meter=3 feet and 3 inches
and 3 ft is bigger than 2 ft
Explain why lamarckism is currently not a widely accepted theory
Answer:
Its not really taught in schools that much.
Explanation:
Write a 5-sentence paragraph to explain how energy and work are related. Give an example of that.
Tell me one thing you know that makes prokaryotic DNA different than eukaryotic DNA.
Answer:
Prokaryotic DNA can be found in the cytoplasm whereas eukaryotic DNA is found in the nucleus, enclosed by the nuclear membrane. Prokaryotic DNA is organized into a single circular chromosome and eukaryotic DNA is organized into several linear chromosomes. The amount of eukaryotic DNA is higher than prokaryotic DNA.
Explanation:
please give me a heart
gene expression is a regulated process due to the fact that-
Answer:
-almost all the cells of your body contain the exact same DNA.
Explanation:
Gene regulation is how a cell controls which genes, out of the many genes in its genome, are “turned on”.
Answer:
Genes are regulated to preserve energy and space.
Explanation:
The process of expressing genes is an energy-requiring process since it requires the breaking and synthesis of proteins. When genes are regulated energy is saved as only the gene required to perform a certain job is turned on and after the function is completed it is turned off. Therefore, continuous protein synthesis is not required to express the genes at all times.If the genes were not regulated i.e., turned off and turned on at required times then it would take a never-ending spree of gene expression which in turn would require a lot of time in transcription and translation.For more information:
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Can someone help on this science question for BRAINLIEST please.
Answer:
most at of earth s water is salt water found in oceans
What's a chromosome
Identify two functions of mitosis.
Cells need to divide in order to maintain our bodies cell count and cell growth and cells in our bodies are
constantly dying and need to be replaced.
b. Consider a teenager going through puberty. Describe how cells in his body could be performing
each of the two functions you identified in part a.
Answer:
id nnshsubxbdhsjjsndhdhdhsbd
Which of the following food groups is most commonly used as a source of high-protein hay, and as a nitrogen-rich green fertilizer, rather than primarily as human food?
peas
green beans
soy beans
alfalfa
Answer:
Soy Beans
Explanation:
Answer:
the answer is alfalfa
Explanation:
The theory that Evolution results from a slow genetic change in a population is...
A Convergent Equilibrium
B Co - evolution
C Gradualism
D Puncuated Equilibrium
Drag the inputs and outputs of cellular respiration to their correct
place.
Answer:
Inputs are: Glucose
Output are; carbon dioxide, ATP and heat
Explanation:
Cellular respiration is the metabolic process by which cells of living organisms breakdown glucose molecules to release energy (ATP). Cellular respiration, which is a must for every living organism uses oxygen (aerobic) to break down glucose (C6H12O6) into carbon dioxide (CO2) and water (H2O).
Based on the question asked, the inputs of cellular respiration are GLUCOSE AND OXYGEN while the outputs are CO2, H2O, ATP and HEAT give out. The general chemical equation is as follows:
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP