The linking number (Lk) of a closed-circular, double-stranded DNA molecule is changed by: a. breaking a strand, b. unwinding or rewinding the DNA, c. then rejoining it.

Answers

Answer 1

The linking number of a closed-circular, double-stranded DNA molecule is changed by breaking a strand, unwinding or rewinding the DNA, and then rejoining it. Each of these manipulations alters the degree of supercoiling, which in turn affects the Lk of the molecule.

The linking number (Lk) of a closed-circular, double-stranded DNA molecule is a topological property that describes the number of times the two strands of DNA are intertwined around each other. It is important to note that the Lk of a DNA molecule is conserved, meaning that it cannot be changed unless some sort of topological manipulation is performed on the molecule.


Breaking a strand of DNA will alter the Lk of the molecule, as it changes the number of times the strands are intertwined. For example, if one strand of a double-stranded DNA molecule is broken, the two strands will separate, and the linking number will decrease by one. This is because the number of times the strands are intertwined is reduced by one, as the broken strand is no longer intertwined with the intact strand.

Unwinding or rewinding the DNA molecule can also alter its linking number. This is because the Lk of a DNA molecule is directly proportional to its degree of supercoiling. When the DNA molecule is unwound, the number of times the strands are intertwined is reduced, and the Lk decreases accordingly. Conversely, when the DNA molecule is rewound, the number of times the strands are intertwined increases, and the Lk increases accordingly.

If the DNA molecule is broken and then re-joined after unwinding or rewinding, the linking number will be restored to its original value, as long as the strands are rejoined in the correct orientation. This is because the act of rejoining the broken strand will restore the degree of supercoiling to its original value, and the Lk will be conserved.

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Related Questions

How is the brain involved with the senses and what is the relationship to the wat a personreacts to objects?

Answers

Answer:

The senses are the components of our nervous system that capture stimuli from the environment for transmission to the brain, and it is there where the information is processed to issue a response. All sensations are electrical signals that travel through neurons which form a network that communicates all organs with the center of the nervous system, and communicate with each other to transmit the electrical impulse through a process known as synapsis.

Explanation:

The brain is an organ that controls the activity of the body, both its conscious and unconscious functions. It is located in the head and corresponds, therefore, to the encephalon of humans and other vertebrates and is subdivided into forebrain, midbrain and hindbrain.  

The brain acts on the rest of the organism by generating muscle activity or by the production and secretion of chemicals called hormones. Thereby the brain controls responses to changes in the environment. Some basic types of response such as reflexes may be mediated by the spinal cord or peripheral ganglia, but sophisticated intentional control of behavior based on complex sensory information requires the integration of information.

The thalamus, which is located in the central part of the brain, processes and coordinates the messages from the senses that it receives from the body. Five senses are considered to exist: sight, touch, smell, taste and hearing. For that, the information perceived from the outside must reach the brain.

The senses are the components of our nervous system that capture stimuli from the environment for transmission to the brain, and it is there where the information is processed to issue a response. Therefore, all sensations perceived from the outside are electrical signals that travel through neurons. For example, the eyes transform light signals into electrical impulses, which travel to the brain where they are transformed into electrical signals.

Neurons form a network that communicates all organs with the center of the nervous system, and communicate with each other to transmit the electrical impulse through a process known as synapsis, which is mediated by molecules called neurotransmitters. Since the electrical impulse cannot jump directly from one neuron to another, these neurotransmitters are needed. When the active neuron produces them, the next neuron in the network detects them and becomes electrically charged. Once this has happened, it produces neurotransmitters again so that the next one becomes electrically activated. This is how the electrical impulse reaches the brain.

When alleles are neither dominant or recessive, so both alleles are expressed, is
called what?
I

Answers

Answer:

hmoocigtoos

Explanation:

homocigotios

WILL GIVE BRANLIEST. 30 POINTS

Explain the three ways genetic variation can occur in a population. ​

Answers

1. caused by mutation
2. random mating
3.random fertilization
4.recombination between homologous chromosomes during meiosis
hope this helps!

ILL GIVE U BRAINLYIST

Answers

Answer:

D.

Explanation:

That is where it demonstrates how the word is said. it's easy to identify this because the pronunciation always comes right after the word itself in the definition.

Answer:hbhh

FffcffExplanation:

most common type of arch, loop and whorl?

Answers

Answer:

yes

Explanation:

most common pattern being found in 65 to 70 percent of all fingerprints

If you were an Amazon ant, how would you eat?
a. You would cultivate a special fungus
b. You would feed off the nectar produced by caterpillars
c. You would consume the pheromones produced by
other ants
d. You would be fed by "slave" ants from other species

Answers

Answer:

A

Explanation:

you have make your own cultivation so that you will no any else where for food

Fill in the blanks the world banks the word bank is on the picture provided below :)

Answers

Answer:

1 is pioneer species 2 is limiting factor 3 is ecological succession

Explanation:

Answer:

1) pioneer

2) limiting factor

3) ecological succession

During the process of photosynthesis, green plants produce...
(1) sunlight
(3) nitrogen
(2) methane
(4) sugar

Answers

Answer:

4

Explanation:

Plants are autotrophs, which means they produce their own food. They use the process of photosynthesis to transform water, sunlight, and carbon dioxide into oxygen, and simple sugars that the plant uses as fuel

Why type of cells in your body are created through the cell cycle and mitosis?​

Answers

Mitosis is a way of making more cells that are genetically the same as the parent cell. It plays an important part in the development of embryos, and it is important for the growth and development of our bodies as well. Mitosis produces new cells, and replaces cells that are old, lost or damaged. Hope I helped! ^^

__________________________________________________________

有糸分裂は、親細胞と遺伝的に同じであるより多くの細胞を作る方法です。それは胚の発達において重要な役割を果たしており、私たちの体の成長と発達にとっても重要です。有糸分裂は新しい細胞を生成し、古い、失われた、または損傷した細胞を置き換えます。私が助けてくれたらいいのに! ^^

The daughter cells from mitosis are called diploid cells. Diploid cells have two complete sets of chromosomes. Since the daughter cells have exact copies of their parent cell's DNA, no genetic diversity is created through mitosis in normal healthy cells.

Hello can someone help?
Im confused

Answers

Answer:

Maybe B

Explanation:

Hi! I'm not sure... If you want to take the risk, go ahead... But IF it's correct pls mark me the brainliest

Describe the basic structure of the cell membrane with regard to specific molecules. What is it made out of?

Answers

Answer: The cell membrane is made up of phospholipids and the overall name is the Phospholipid bi-layer

Explanation:

The cell membrane has two rows of phospholipids.  A phospholipid is broken into two parts, the heads and tails.  The heads are hydrophilic (water-loving) and point to the outside and inside regions making the inner and outer wall, while the tails are hydrophobic (water-hating) and face each other to make the inside of the membrane.  There are also molecules of cholesterol and proteins throughout the membrane.

Phospholipids are the building blocks of a cell membrane. A single phospholipid molecule consists of two ends: the head and the tail.

What are phospholipids?

Phospholipids are amphiphilic molecules with both hydrophobic and hydrophilic fatty acid chains.

They are found in all living organisms as the primary components of cell membranes. Nature contains a variety of phospholipid classes with varying polar moieties.

Phospholipids are glycerol esters, fatty acid esters, phosphoric acid esters, and other alcohol esters.

Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine are the most common phospholipids.

The phospholipid bilayer, which forms a stable barrier between two aqueous compartments, is the membrane's fundamental structure.

These compartments are the inside and outside of the cell in the case of the plasma membrane.

Thus, this is the basic structure of the cell membrane with regard to specific molecules.

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Which of the following has the highest reproductive potential?
O a. bacteria
O b. cattle
O c. humans
O d. elephants

Answers

Answer:

A. Bacteria

Explanation:

I asked my teacher hahahahahahahaha

Bacteria as the highest reproductive potential. Hence option a is correct.

What is reproductive potential?

Reproductive potential is defined as the proportional ability of a species to reproduce itself under ideal circumstances. The maximum number of children that a particular organism can produce is known as its reproductive potential. Compared to other species, some have substantially higher reproductive capacity.

When people reproduce more frequently, sooner in life, and at higher rates, their reproductive potential rises. The largest influence on reproductive capacity is early pregnancy. Every living thing must be able to reproduce. All living things produce additional organisms that resemble them.

Thus, bacteria as the highest reproductive potential. Hence option a is correct.

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What happens during translation?
a. Messenger RNA is made from a DNA code.
b. The cell uses a messenger RNA code to
make proteins.
c. Transfer RNA is made from a messenger
RNA code.
d. Copies of DNA molecules are made.

Answers

The cell uses mRNA to code new proteins

How are gay marriaged babys made to be biological?

Answers

Answer:

if its a couple with a trans man (female to male) they can have a baby if they havent had surgery.

a trans woman (male to female) can also have a biological baby with a woman if they havent had surgery.

They could also have had a baby in a past relationship though it wont be biological to the other parent.

Crocuses can bloom in the winter, while dahlias bloom in the fall. This is due to different responses to daylight length or _________.
A. Sun rays
B. Photoperiodism
C. phototropism
D. geotropism

Answers

Answer:

It's becoz of sun rays.....

While exploring a rock formation, Hiroto finds a rock that has footprints pressed into it. A geologist tells Hiroto that the rock is millions of years old. Which of these claims
is correct about Hiroto's find?
It is not a fossil because footprints are not fossils.
It is not a fossil because only whole organisms are fossils.
It is a fossil only if Hiroto finds actual parts of the organism in rocks nearby.
It is a fossil because footprints of organisms from million of years ago are considered to
be fosss

Answers

Answer:

5 is the answer

Explanation:

Answer:

message me on ig

Explanation:

she.hatezay ill help you there

1. What does H.I.P.P.O. stand for? Habitat destruction, Invasive species, pollution, population Increase and
over population
over production
over use
over exploitation

Answers

Human,increase population and Overharvesting

What makes echinoderms unique to all other animals? (think of systems/structures they
have that no other animal has!)

Answers

Although these spines may look like components of an exoskeleton at first glance, echinoderms do not have an exoskeleton. This is partly due to their symmetry and their spiny endoskeleton.

2. Which atom in the water molecule is negatively charged?

Answers

Answer:

oxygen atom

Explanation:

The unequal sharing of electrons gives the water molecule a slight negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms. When a neutral molecule has a positive area at one end and a negative area at the other, it is a polar molecule.

Answer:

The oxygen

Hydrogen is positive

Explanation:

Your body uses feedback mechanisms to help maintain a stable internal environment called homeostasis. Changes can come from outside or inside the body and the body must respond to these adverse changes to return to a steady state. One such example is what happens when you go for a run on a hot summer day and your body temperature increases. According to the diagram, one of the mechanisms used to cool down is vasodilation. Similar mechanisms are also used when your body temperature drops due to a cold environment. Which of these would NOT help return a body to homeostasis by increasing body temperature?
A) shivering
B) vasoconstriction
C) muscles contract
D) increasing blood pressure

Answers

Answer:

Option D increasing blood pressure.

Explanation:

Increasing blood pressure

What is feedback mechanism in homeostasis?

Homeostasis is generally maintained by a negative feedback loop that includes a stimulus , sensor , control center , and effector . Negative feedback serves to reduce an excessive response and to keep a variable within the normal range.

What are the two feedback mechanisms which work to maintain homeostasis?

Homeostasis typically involves negative feedback loops that counteract changes of various properties from their target values, known as set points. In contrast to negative feedback loops, positive feedback loops amplify their initiating stimuli, in other words, they move the system away from its starting state.

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Global measurements indicate that, in the late 2000s, sea levels steadily rose. Rising sea
levels lead to the migration of marshlands further inland. The environmental changes
caused by rising sea levels have the potential to?
O increase the stability of marsh habitats.
decrease the stability of marsh habitats.
O increase the biodiversity of organisms in marsh habitats.
alternately increase and decrease the biodiversity of marsh habitats.

Answers

Answer:

My Game is José Fernando Tengo 12 YEARS OLD

The environmental changes caused by rising sea levels have the potential to alternately increase and decrease the biodiversity of marsh habitats.

What is Biodiversity?

Sum total of all the varieties of living organisms in a particular space, is known as its biodiversity.

As the sea levels steadily rose, it will firstly increase the biodiversity of marsh habitats, but sea level constantly rising, will affect its biodiversity, and organism that is native to marshy habitat should be eliminated while those organisms that are able to survive in inland habitat will migrate into it, overall causing the decrease meant of biodiversity of marshy habitat.

Therefore, the environmental changes caused by rising sea levels have the potential to alternately increase and decrease the biodiversity of marsh habitats.

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How many total ATOMS are represented?

2Fe(NO3)2

Answers

i think 2 atoms

one is 2Fe

second is NO3

I NEED HELP! Complete the table of the following element. Element: Chlorine Symbol: Cl


number of Protons:

Neutrons:

Electrons:

Atomic Number:

Atomic Mass:

Answers

Answer:

For example, the atomic mass of chlorine (Cl) is 35.45 amu because chlorine is composed of several isotopes, some (the majority) with an atomic mass of 35 amu (17 protons and 18 neutrons) and some with an atomic mass of 37 amu (17 protons and 20 neutrons).

Hope it helped!!!

:

Protons :17
Neutrons:17
Electrons:17
Atomic number:17
Atomic mass:(protons +neutrons) 17+17=34

Lack of medical knowledge

Answers

Ah Yes the lack of medical knowledge something I have

Please help me out!

Which of the following is NOT true about the chromosomes in your body?

-Include 46 total chromosomes
-Include 2 sex chromosomes
-Exist in 46 pairs
-Exist in 23 pairs

Answers

Answer:

Exist in46 pairs

Explanation:

How many valence electrons does this atom have? How do you know?

Answers

Answer:

5 valence electrons

Explanation:

valence electrons are the electrons at the ends of atom or in the valence cell. so there are 5 valence electrons.

Which generalization can be made from the data in the table?
1.The higher the temperature, the fewer chirps there will be in 10 seconds.
2.The chirps occur closer together as the temperature increases.
3.The chirps become farther apart as the temperature increases.
4.There is no relationship between temperature and the time between chirps.

Answers

I think it's the third one. But I'm not sure. Hope this helps

The generalization that can be made is: 2.The chirps occur closer together as the temperature increases.

Generalization is a statement you state after making an inference from an observation. For example, we can make a generalization by observing or analyzing the data from the experiment conducted which are given in the table.

From the table given, there seems to be a trend that can be observed. Temperature seems to influence the number of seconds between each chirp of the cricket.

A closer observation of the trend from the data given shows that in general, as the temperature was increased, the seconds between chirps seem to shorten.

Therefore, we make a generalization stating that: "2.The chirps occur closer together as the temperature increases."

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What are the answers for questions 4 and 5?

Answers

Answer:

4. D (enzymes 1 and 3 works equally well in an acidic and alkaline environment respectively)

5. C. 2; 7; 9.5

Explanation:

The image attached to this question shows a graphical representation of the pH ranges for three enzymes. According to the image;

- Enzyme 1 reached its peak reaction rate at pH 2 (acidic)

- Enzyme 2 reached its peak reaction rate at pH 7 (neutral)

- Enzyme 3 reached its peak reaction rate at pH 9.5 (basic)

This result means that enzymes 1, 2 and 3 will work well and effectively at an acidic, neutral and alkaline environment respectively. Likewise, the optimal pH level for enzymes 1, 2 and 3 are 2; 7; and 9.5 respectively.

Describe the two signals and pathways that are activated when you touch something and experience pain

Answers

The medial thalamus projects to widespread areas of the forebrain, including the somatosensory cortex. Thus there are two major ascending pathways for pain: a direct lateral spinothalamic pathway and an indirect medial spinoreticulothalamic pathway.

I don’t understand this so please help

Answers

Answer:

all I see is dots lines and circles

Explanation:

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