Human cells have 46 chromosomes. By the end of interphase, how many chromosomes are present in one cell.

Electrophoresis is a technique commonly used in the lab to separate charged molecules, like DNA, according to size.

Gel electrophoresis is a technique commonly used in laboratories to separate charged molecules like DNA?, RNA? and proteins? according to their size.

Charged molecules move through a gel when an electric current is passed across it.

An electric current is applied across the gel so that one end of the gel has a positive charge and the other end has a negative charge.

The movement of charged molecules is called migration. Molecules migrate towards the opposite charge. A molecule with a negative charge will therefore be pulled towards the positive end (opposites attract!).

The gel consists of a permeable matrix, a bit like a sieve, through which molecules can travel when an electric current is passed across it.

Smaller molecules migrate through the gel more quickly and therefore travel further than larger fragments that migrate more slowly and therefore will travel a shorter distance. As a result the molecules are separated by size.

Gel electrophoresis and DNA

Electrophoresis enables you to distinguish DNA fragments of different lengths.

DNA is negatively charged, therefore, when an electric current is applied to the gel, DNA will migrate towards the positively charged electrode.

Shorter strands of DNA move more quickly through the gel than longer strands resulting in the fragments being arranged in order of size.

The use of dyes, fluorescent? tags or radioactive? labels enables the DNA on the gel to be seen after they have been separated. They will appear as bands on the gel.

A DNA marker with fragments of known lengths is usually run through the gel at the same time as the samples.

By comparing the bands of the DNA samples with those from the DNA marker, you can work out the approximate length of the DNA fragments in the samples.

How is gel electrophoresis carried out?

Preparing the gel

Agarose gels? are typically used to visualise fragments of DNA. The concentration of agarose used to make the gel depends on the size of the DNA fragments you are working with.

The higher the agarose concentration, the denser the matrix and vice versa. Smaller fragments of DNA are separated on higher concentrations of agarose whilst larger molecules require a lower concentration of agarose.

To make a gel, agarose powder is mixed with an electrophoresis buffer and heated to a high temperature until all of the agarose powder has melted.

The molten gel is then poured into a gel casting tray and a “comb” is placed at one end to make wells for the sample to be pipetted into.

Once the gel has cooled and solidified (it will now be opaque rather than clear) the comb is removed.

Many people now use pre-made gels.

The gel is then placed into an electrophoresis tank and electrophoresis buffer is poured into the tank until the surface of the gel is covered. The buffer conducts the electric current. The type of buffer used depends on the approximate size of the DNA fragments in the sample.

Preparing the DNA for electrophoresis

A dye is added to the sample of DNA prior to electrophoresis to increase the viscosity of the sample which will prevent it from floating out of the wells and so that the migration of the sample through the gel can be seen.

A DNA marker (also known as a size standard or a DNA ladder) is loaded into the first well of the gel. The fragments in the marker are of a known length so can be used to help approximate the size of the fragments in the samples.

The prepared DNA samples are then pipetted into the remaining wells of the gel.

When this is done the lid is placed on the electrophoresis tank making sure that the orientation of the gel and positive and negative electrodes is correct (we want the DNA to migrate across the gel to the positive end).

Separating the fragments

The electrical current is then turned on so that the negatively charged DNA moves through the gel towards the positive side of the gel.

Shorter lengths of DNA move faster than longer lengths so move further in the time the current is run.

The distance the DNA has migrated in the gel can be judged visually by monitoring the migration of the loading buffer dye.

The electrical current is left on long enough to ensure that the DNA fragments move far enough across the gel to separate them, but not so long that they run off the end of the gel.

Illustration of DNA electrophoresis equipment used to separate DNA fragments by size. A gel sits within a tank of buffer. The DNA samples are placed in wells at one end of the gel and an electrical current passed across the gel. The negatively-charged DNA moves towards the postive electrode. Image credit: Genome Research Limited

tank.

Answer: When studying the museum’s collection of plant fossils for information about the climate, Wing and Barclay start with plant leaves.

Roughly 56 million years ago, during a time called the Paleocene Eocene Thermal Maximum (PETM), Earth’s average temperature rose four to eight degrees Celsius in less than 10,000 years. The cause was geologic processes releasing trillions of tons of carbon dioxide into the atmosphere. The dramatic shift in global climate forced massive upheaval in ecosystems around the world.

“It’s the best analogue for the climate change we’re experiencing today,” Barclay said.

Fossil plants and their leaves from the PETM show that ecosystems shifted massively because of the rapid increase in global temperature. But global warming during the PETM did not come from humans. So, scientists today are working on ways to extrapolate information from that period and apply it to the even faster and more drastic events of today.

Answer:

D I believe

Explanation:

Proteins provides the building blocks for recovery and repair in forming new muscle

Answer:

The coefficient of variation in aboveground biomass of annuals decreased significantly with increasing annual and growing-season precipitation. Species richness of annuals increased significantly with increasing annual precipitation and growing-season precipitation.

Explanation:

Answer:

yes

Explanation:

Answer:

The test subject was therefore, Heterozygous

Answer:

third one

Explanation:

Answer:

The circadian rhythms are controlled by a part of the brain called the Suprachiasmatic Nucleus (SCN), or a group of cells in the hypothalamus that responds to light and dark signals. Thid happens when our eyes perceive light, causing our retinas send a signal to our SCN.

Answer: According to the biological species concept, organisms belong to the same species if they can interbreed to produce viable, fertile offspring. Species are separated from one another by prezygotic and postzygotic barriers, which prevent mating or the production of viable, fertile offspring. Speciation is the process by which new species form

Answer:

= # recombination/total progeny ×100

2.

No movement of water would have

occurred if they were isotonic.

3.

Answer:

columner and cuboidal epithelium

Answer:

Two rounds

Explanation:

Meiosis is characterized by one round of DNA replication followed by two rounds of cell division, resulting in haploid germ cells. Crossing-over of DNA results in genetic exchange of genes between maternal and paternal DNA.

Answer:

59 is false and 60 and true

Explanation: I think it is right sorry if it is wrong. I hope this helps

Answer: 1) True 2) True

Explanation:

Answer:

skeletal system, nervous system, and digestive system

Explanation:

our nervous system controls our every movement (walking) and skeletal because it makes up the frame work if not we would be total blobs of jello haha. anyways but then when your eating our digestive system when we swallow if goes through the whole phase of digestive system. and then it has to come out somehow so the digestive system at the end we go ahead and do our business.

hope this helps!

Answer:

the talus bone

Explanation:

hope it helps<3

mark me as brainliest

Answer:

increases body temperature

Explanation:

this is because when you shiver your blood vessels contract which then increases your body temperature  

If the environment gets cold, humans will often respond involuntarily by shivering in order to increase body temperature. So, the correct option is B.

An environment may be defined as anything that is present in the surroundings of living entities that is either biotic or abiotic.

The process of shivering causes the blood vessels to contract and relax at a rapid rate to maintain homeostasis. The signals of rapid contractions are sent by the hypothalamus through nerve impulses.

Therefore, the correct option for this question is B.

To learn more about Shivering, refer to the link:

https://brainly.com/question/14319427

#SPJ2

Answer:

b. Quadriplegia may occur when traumatic injury occurs along the upper vertebral column C1 to C7.

Explanation: is correct

Answer:

B

Explanation:

(thank you sunrise you've helped me with like 4 units now)

Answer:

Alternation of generations is the type of life cycle that occurs in those plants and algae in the Archaeplastida and the Heterokontophyta that have distinct haploid sexual and diploid asexual stages.

Explanation:

Answer:

During metaphase II, the centromeres of the paired chromatids align along the equatorial plate in both cells. Then in anaphase II, the chromosomes separate at the centromeres. The spindle fibers pull the separated chromosomes toward each pole of the cell.

Answer:

chlooplast

Explanation:

because those are the ones that are only in plants and they make photosynthesis

Explanation:

I think it should be C because increase in temperature increases molecular motion. Therefore the speed of the moving molecules of both enzymes as well as the substrate will be accelerated. This

will enhance the colliding probability for both enzyme active sites and substrate molecules and more collisions occur between the enzyme active sites and substrate molecules generate greater chances for the reaction to occur. This can continue up to a certain point, after which there is a rapid decline in enzyme activity. This point is referred to

as optimum temperature. When the temperature increases beyond the optimum temperature, the hydrogen bonds, ionic bonds and other weak chemical bonds of enzyme active sites may be disrupted.

This will result a change in the shape of the active site of enzyme which will alter the complementary nature of the active site of enzyme molecules. Therefore, the

complementary binding of enzyme active sites and substrate molecules will be prevented. The above event is called as denaturation of enzyme molecules.

Therefore the rate of enzyme catalyzed reaction or in this case, photosynthesis will start to decline when the temperature increases beyond the optimum temperature and stops completely at certain

temperature, although rate of collision will keep on increasing.

The researchers estimate that between 1990 and 2010, some 69 percent of the mass lost by the world's alpine glaciers can be traced to human influence – basically global warming. This 2013 file photo shows the Mendenhall Glaicer where it spills over the mountains above Mendenhall Lake in Juneau, Alaska.

Answer:

Human activity is playing an increasing role in the melting of glaciers, Austrian and Canadian scientists have found. One of the most disruptive effects of climate change, glacier retreat leads to rising sea levels, landslides and unpredictable availability of water downstream.

Explanation:

I hope it helpful to you.

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Answer:

its in the type of nutrience they have

Explanation:

Answer:

Plants provide oxygen so are vital to animals in order to survive. Many insects use plants to place their eggs: insects. Or even to protect themselves from the sun. Animals obtain part of their water intake through plants.

Explanation:

hope it helps