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sergeinik [125]
2 years ago
13

1. Answer the following using complete sentences. a. Give an example of a situation or problem that would be difficult to test w

ithout a model and describe the model you would use. b. Describe a situation from the news or recent history where scientists were called upon to provide explanations of events and offer possible solutions to problems. c. Choose an industry or business. Decide what areas of scientific study they should support and state why you think so. d. Describe one way in which the quality of human life is based on the quality of a natural ecosystem. e. Give an example of a technology or problem that has recently become widespread. Discuss the impact of this technology or problem and contrast that to the way you think others may view the technology or problem.
Biology
1 answer:
FrozenT [24]2 years ago
7 0

Answer:

These principles are at work in the fundamental elements of the scientific method, ... that could possibly explain your results; and things you thought of that you've ... If you make a theory, for example, and advertise it, or put it out, then you must also put ... One author of a historical study of research groups in the chemical

You might be interested in
Explain how we know that DNA breaks and rejoins during recombination.
alisha [4.7K]

Answer:

It occurs through homologous recombination

Explanation:

GENERAL RECOMBINATION OR HOMOLOGIST

           Previously we defined its general characteristics. We will now describe a molecular model of this recombination, based on the classic Meselson and Radding, modified with the latest advances. Do not forget that we are facing a model, that is, a hypothetical proposal to explain a set of experimental data. Not all points of this model are fully clarified or demonstrated:

           Suppose we have an exogenote and an endogenote, both consisting of double helices. In recombination models, the exogenote is usually referred to as donor DNA, and the endogenote as recipient DNA.

1) Start of recombination: Homologous recombination begins with an endonucleotide incision in one of the donor double helix chains. Responsible for this process is the nuclease RecBCD (= nuclease V), which acts as follows: it is randomly attached to the donor's DNA, and moves along the double helix until it finds a characteristic sequence called c

Once the sequence is recognized, the RecBCD nuclease cuts to 4-6 bases to the right (3 'side) of the upper chain (as we have written above). Then, this same protein, acting now as a helicase, unrolls the cut chain, causing a zone of single-stranded DNA (c.s. DNA) to move with its 3 ’free end

2) The gap left by the displaced portion of the donor cut chain is filled by reparative DNA synthesis.

3) The displaced single chain zone of the donor DNA is coated by subunits of the RecA protein (at the rate of one RecA monomer per 5-10 bases). Thus, that simple chain adopts an extended helical configuration.

4) Assimilation or synapse: This is the key moment of action of RecA. Somehow, the DNA-bound RecA c.s. The donor facilitates the encounter of the latter with the complementary double helix part of the recipient, so that in principle a triple helix is formed. Then, with the hydrolysis of ATP, RecA facilitates that the donor chain moves to the homologous chain of the receptor, and therefore matches the complementary one of that receptor. In this process, the chain portion of the donor's homologous receptor is displaced, causing the so-called "D-structure".

It is important to highlight that this process promoted by RecA depends on the donor and the recipient having great sequence homology (from 100 to 95%), and that these homology segments are more than 100 bases in length.

Note that this synapse involves the formation of a portion of heteroduplex in the double receptor helix: there is an area where each chain comes from a DNA c.d. different parental (donor and recipient).

5) It is assumed that the newly displaced chain of the recipient DNA (D-structure) is digested by nucleases.

6) Covalent union of the ends originating in the two homologous chains. This results in a simple cross-linking whereby the two double helices are "tied." The resulting global structure is called the Holliday structure or joint.

7) Migration of the branches: a complex formed by the RuvA and RuvB proteins is attached to the crossing point of the Holliday structure, which with ATP hydrolysis achieve the displacement of the Hollyday crossing point: in this way the portion of heteroduplex in both double helices.

8) Isomerization: to easily visualize it, imagine that we rotate the two segments of one of the DNA c.d. 180o with respect to the cross-linking point, to generate a flat structure that is isomeric from the previous one ("X structure").

9) Resolution of this structure: this step is catalyzed by the RuvC protein, which cuts and splices two of the chains cross-linked at the Hollyday junction. The result of the resolution may vary depending on whether the chains that were not previously involved in the cross-linking are cut and spliced, or that they are again involved in this second cutting and sealing operation:

a) If the cuts and splices affect the DNA chains that were not previously involved in the cross-linking, the result will be two reciprocal recombinant molecules, where each of the 4 chains are recombinant (there has been an exchange of markers between donor and recipient)

b) If the cuts and splices affect the same chains that had already participated in the first cross-linking, the result will consist of two double helices that present only two portions of heteroduplex DNA.

8 0
3 years ago
Which of the following are important features for transcription?
devlian [24]

Answer:

The correct answer will be option-A and B.

Explanation:

Transcription is a process which synthesizes a complementary molecule of DNA which acts a messenger called RNA.

The gene contains a sequence of the nucleotide at the beginning of gene called promoter sequence. The promoter sequence has the ability to attach an RNA synthesizing enzyme called RNA polymerase.

The RNA polymerase is the enzyme which synthesizes the RNA molecules using a single strand of DNA called template strand.  RNA polymerase binds nucleotide at 3' end of the strand thus proceeding the strand in 5' to 3' direction.  

The promoter and RNA polymerase begins the process of transcription and thus option-A and B is the correct answer.

6 0
3 years ago
Which one of these is involved in adaptive and humoral immunity?
SpyIntel [72]

Answer:

(d). B-cells.

Explanation:

Adaptive immunity can be described as immunity which develops in response to exposure to a pathogen (or foreign molecule). throughout the life. It is divided into two types, humoral immunity and cell-mediated immunity.

Humoral immunity is mediated by B cells that secrete antibodies against particular antigens. These antibodies recognize and neutralize the antigens and activate cell-mediated immunity, which is mediated by T cells.  

Thus, the correct answer is option (d).

4 0
3 years ago
I'll give likes and thank yous and try to give brainiest! Which of the following organisms are capable of self feritlization?
tino4ka555 [31]

Answer:

A. Plants.

Hope it helps! =)

Brainliest?

8 0
2 years ago
List and explain the 3 paths natural selection can take.
evablogger [386]

Answer:

1. Stabilizing Selection  

2. Directional Selection  

3. Disruptive Selection  

Explanation:

Stabilizing Selection  

This type of natural selection occurs when there are selective pressures working against two extremes of a trait and therefore the intermediate or “middle” trait is selected for. If we look at a distribution of traits in the population, it is noticeable that a standard distribution is followed:

Example:  For a plant, the plants that are very tall are exposed to more wind and are at risk of being blown over. The plants that are very short fail to get enough sunlight to prosper. Therefore, the plants that are a middle height between the two get both enough sunlight and protection from the wind.

Directional Selection  

This type of natural selection occurs when selective pressures are working in favour of one extreme of a trait. Therefore when looking at a distribution of traits in a population, a graph tends to lean more to one side:

Example: Giraffes with the longest necks are able to reach more leaves to each. Selective pressures will work in the advantage of the longer neck giraffes and therefore the distribution of the trait within the population will shift towards the longer neck trait.

Disruptive Selection  

This type of natural selection occurs when selective pressures are working in favour of the two extremes and against the intermediate trait. This type of selection is not as common. When looking at a trait distribution, there are two higher peaks on both ends with a minimum in the middle as such:

Example: An area that has black, white and grey bunnies contains both black and white rocks. Both the traits for white and black will be favored by natural selection since they both prove useful for camouflage. The intermediate trait of grey does not prove as useful and therefore selective pressures act against the trait.

6 0
2 years ago
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