The endosymbiotic theory proposed that the mitochondria and the chloroplast evolve from some types of bacteria which the eukaryotic cells engulfed.
The endosymbiotic theory tries to explain how the eukaryotic cells came into existence from prokaryotic cells. According to this theory, the eukaryotic organelles like the mitochondria and the chloroplasts were actually free living prokaryotes and were taken in one after the other via endosymbiosis.
This theory has been backed by evidences which establish the phylogenetic similarity between mitochondria and bacteria and also between chloroplast and cyanobacteria. The evidences include the presence of circular DNA in both chloroplast as well as the mitochondria and also the fact they divide by binary fission like bacteria.
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The effect of disorder of checkpoints proteins and cell cycle regulation
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Answer:
LEARNING OBJECTIVES
Identify important checkpoints in cell division
Explain how errors in cell division are related to cancer
The length of the cell cycle is highly variable, even within the cells of a single organism. In humans, the frequency of cell turnover ranges from a few hours in early embryonic development, to an average of two to five days for epithelial cells, and to an entire human lifetime spent in G0 by specialized cells, such as cortical neurons or cardiac muscle cells. There is also variation in the time that a cell spends in each phase of the cell cycle. When fast-dividing mammalian cells are grown in culture (outside the body under optimal growing conditions), the length of the cycle is about 24 hours. In rapidly dividing human cells with a 24-hour cell cycle, the G1 phase lasts approximately nine hours, the S phase lasts 10 hours, the G2 phase lasts about four and one-half hours, and the M phase lasts approximately one-half hour. In early embryos of fruit flies, the cell cycle is completed in about eight minutes. The timing of events in the cell cycle is controlled by mechanisms that are both internal and external to the cell.
Explanation:
Regulation of the Cell Cycle by External Events
Both the initiation and inhibition of cell division are triggered by events external to the cell when it is about to begin the replication process. An event may be as simple as the death of a nearby cell or as sweeping as the release of growth-promoting hormones, such as human growth hormone (HGH). A lack of HGH can inhibit cell division, resulting in dwarfism, whereas too much HGH can result in gigantism. Crowding of cells can also inhibit cell division. Another factor that can initiate cell division is the size of the cell; as a cell grows, it becomes inefficient due to its decreasing surface-to-volume ratio. The solution to this problem is to divide.
Whatever the source of the message, the cell receives the signal, and a series of events within the cell allows it to proceed into interphase. Moving forward from this initiation point, every parameter required during each cell cycle phase must be met or the cycle cannot progress.
Regulation at Internal Checkpoints
It is essential that the daughter cells produced be exact duplicates of the parent cell. Mistakes in the duplication or distribution of the chromosomes lead to mutations that may be passed forward to every new cell produced from an abnormal cell. To prevent a compromised cell from continuing to divide, there are internal control mechanisms that operate at three main cell cycle checkpoints. A checkpoint is one of several points in the eukaryotic cell cycle at which the progression of a cell to the next stage in the cycle can be halted until conditions are favorable. These checkpoints occur near the end of G1, at the G2/M transition, and during metaphase
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Question 3
Earth's plates move due to a convection celin
A the Earth's crust
B. the Earth's mantle.
the Earth's inner core.
D. the Earth's outer core.
Answer:B
Explanation:Earth’s core that cause the molten rock in the mantle layer to move, and it moves in a pattern.
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How did scientists begin to Mark divisions in the geologic time scale in response to a change they discovered in the geologic record
Answer:
Scientists began to mark division on the geologic time scale when patterns and similarities started emerging from archeological studies. Patterns such as the discovery of fossils that were formed within the same period.
Explanation:
Geologists who study matter that make up the Earth's crust (whether solid gaseous or liquid), as well as matter from other terrestrial planets and the processes that influence the formation and condition of this matter, are called geologists.
They have successfully calibrated history into various phases of time intervals. These intervals are event-based intervals. For example, you have Eons, Eras, and Periods.
An Eon is a billion years. An example is the Neoproterozoid Eon. Eons are made up of several Eras and Eras are made up of periods. An example of an era is the Mesozoic era. Whilst periods are smaller units of an era, eg. Triassic era.
As scientists deduced the causes for the formation of fossils and topographical remains/patterns, they collected events that occurred within the same time period and group them together.
This range of events became known as the geological time scale.
The age of fossils and rocks is also used to map out the calibrations on the scale.
The age of fossils and rocks is determined using the process of radioactive dating.
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Which location would have the LEAST variation in air temperature during a 24-hour period?
A)
A
B)
B
o
D)
D
Answer:
b
Explanation:
Structure that display characteristic of living organisms only within living cells
this is the answer I hope it helps u
What type of material did the water most likely encounter when it stopped?
Answer:
Rocks
Explanation:
Rocks normally stop streams
Select the item(s) that describe a producer.
1.takes energy from the sun
2.helps rot dead organisms
3.fungus
4.tall grass
5.food is mostly animal
6.plant eater
multiple choice
Answer:
3. fungus
4. tall grass
5. food is mostly animal
What is the strengths and weaknesses of the various developments in science and technology
Answer:
Strengths, Weaknesses, Opportunities and Challenges ... Some have “ centres for research and development” while others ...
Please help!
..........
Answer:
我期望1个是正确的答案 并问老师好
Explanation:
你可以在书中找到
How do specialized cells within an organism help the organism perform the essential functions of life?
Answer:
Systems of specialized cells within organisms help them perform the essential functions of life, which involve chemical reactions that take place between different types of molecules, such as water, proteins, carbohydrates, lipids, and nucleic acids. All cells contain genetic information in the form of DNA molecules.
A class is debating the advantages and disadvantages of different types of reproduction. One student argues that organisms that reproduce asexually, like bacteria, have no advantage over organisms that reproduce sexually.
Which of the following choices below represents an argument for the advantages of asexual reproduction?
A. Organisms that reproduce asexually are likely to find a mate at a faster rate than sexually reproducing organisms, which allows them to reproduce faster.
B. Organisms that reproduce asexually are more diverse and are more likely to pass on key genes for survival to future generations, which aids in maintaining beneficial genes for survival in the gene pool
C. Organisms that reproduce asexually gain variation through processes like crossing over, which allows survival in instances of ecological change
D. Organisms that reproduce asexually create a large amount of offspring in a short period of time in order to maintain their population
Answer: D. Organisms that reproduce asexually create a large amount of offspring in a short period of time in order to maintain their population.
Explanation:
When an organism is able to reproduce asexually as opposed to sexually, it means that they do not require a mate to make offspring. Offspring of such organisms will therefore receive all their genes from one source.
Such organisms are able to reproduce very fast when they are presented with adequate conditions especially because they do not need another organism to do so. They will neither have to waste much energy nor have to go through the whole sexual process so they will be able to produce lots of offspring.
Animals are known to have offspring through asexual and/or sexual reproduction. The choices that has an argument for the advantages of asexual reproduction is that Organisms that reproduce asexually create a large amount of offspring in a short period of time in order to maintain their population.
Asexual reproduction is simply known as a type of reproduction where offspring are genetically identical to the parent.The offspring are regarded as clones that derives its root from the original parent.
A single individual can have offspring asexually and also in large numbers quickly.
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what is a tumor and what does it have to do with mitosis
ASAP
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Answer:
Tumors constantly undergo mitosis.
Explanation:
Tumors are (generally) considered to be cancerous; therefore, they divide uncontrollably. Tumors undergo mitosis just like any other cell in your body but can be dangerous over time if not dealt with.
Answer:
What is cancer and what does it have to do with mitosis?
Cancer: mitosis out of control
Mitosis is closely controlled by the genes inside every cell. Sometimes this control can go wrong. If that happens in just a single cell, it can replicate itself to make new cells that are also out of control. These are cancer cells.
Explanation:
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What are molecules?
The smallest unit into which a substance can be divided without changing its chemical nature
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Answer:
a group of atoms that form the smallest identifiable unit
Explanation:
explain how the cells, tissue, and organs within the circulatory system work together to enable it to perform its function of pumping materials around the body and removing waste products such as carbon dioxide.
Answer:
the body has levels of organization that build on each other.Cells make up tissues,tissues make up organs,and organs make up organs system.
The total number of cells in an organism increases as a result of which process?
A respiration
B. photosynthesis
C cell division
D fermentation
Answer:
I am pretty sure that the answer is C.
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Which feature is forming?
Oceanic crust
Continental
crust
Lithosphere
Lithosphere
Asthenosphere
Answer:
An island
Explanation:
for me i got it right
What does the term Pangaea mean?
Answer:
Pangea refers to the one, large, solid land mass that is believed to have existed before the continents divided.
Explanation:
Pangea is often the explanation for tectonic plates, as they are believed to have been a by-product of the split of Pangea well over a million years ago.
Type Newton's Second Law of Motion as it is written.
Answer:
I hope you understand please give brainliest
Explanation:
Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
Answer:
Yes it is written that second law of Newton is motion of an object
what are the factors affecting brilliance of stars
the age of the star because just like people as they grow older they become weak and so arr the stars their brilliance fade when they become older.
When you by strawberry is "TEXTURE " matters? and why is that?
Answer:
Yes, it does.
Explanation:
If the strawberry you buy is all soggy and way too soft, it is likely rotten, while the normal texture we are used to shows that it is edible.
Answer:
Frozen strawberries were characterized organoleptically by a moist, soft and limp appearance, and poor shape retention. They felt very soft, moist, limp and slightly slimy in the mouth. Interior fibers had a tough texture.
Give three reason why specialized systems are necessary in large multicellular organisms
Answer:
Specialized systems are necessary in large multicellular organisms since 1. there is a division of labor between cells, 2. many individual cells cannot work together without coordination, and 3. most of the cells are not in direct contact with the outside environment
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Specialized systems are necessary in large multicellular organisms since 1. there is a division of labor between cells, 2. many individual cells cannot work together without coordination, and 3. most of the cells are not in direct contact with the outside environment.
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Describe the relationship between the sickle cell phenotype and hemoglobin’s structure and function
Answer: Explanation:
Sickle hemoglobin differs from normal hemoglobin by a single amino acid: valine replaces glutamate at position 6 on the surface of the beta chain. Therefore the red blood cell bends differently giving it a sickle shape
Answer:
Explanation:
Sickle cell disease is a group of disorders that affects hemoglobin, the molecule in red blood cells that delivers oxygen to cells throughout the body. People with this disease have atypical hemoglobin molecules called hemoglobin S, which can distort red blood cells into a sickle, or crescent, shape.
Signs and symptoms of sickle cell disease usually begin in early childhood. Characteristic features of this disorder include a low number of red blood cells (anemia), repeated infections, and periodic episodes of pain. The severity of symptoms varies from person to person. Some people have mild symptoms, while others are frequently hospitalized for more serious complications.
The signs and symptoms of sickle cell disease are caused by the sickling of red blood cells. When red blood cells sickle, they break down prematurely, which can lead to anemia. Anemia can cause shortness of breath, fatigue, and delayed growth and development in children. The rapid breakdown of red blood cells may also cause yellowing of the eyes and skin, which are signs of jaundice. Painful episodes can occur when sickled red blood cells, which are stiff and inflexible, get stuck in small blood vessels. These episodes deprive tissues and organs, such as the lungs, kidneys, spleen, and brain, of oxygen-rich blood and can lead to organ damage. A particularly serious complication of sickle cell disease is high blood pressure in the blood vessels that supply the lungs (pulmonary hypertension), which can lead to heart failure. Pulmonary hypertension occurs in about 10 percent of adults with sickle cell disease.
With respect to normal base pairing, when a molecule of DNA replicates, thymine will most likely pair with 2 points
Answer: Adenine
Explanation:
The structure of the DNA double helix is complex in nature. There are two strands of DNA that are wound around each other. The nitrogenous bases are bonded with hydrogen bonding and base complementarity. According to the Chargaff's rule of base complementarity adenine always pairs with the thymine and guanine with cytosine. These nitrogenous bases are paired on the basis of hydrogen bonding. Adenine bonded with thymine through two hydrogen bonds whereas the cytosine pairs with guanine via three hydrogen bonds. During DNA denaturation these hydrogen bonds are broken whereas during DNA replication these hydrogen bonds are formed between the nitrogenous bases.
which of the following are not considered as examples of asexual reproduction of plants?
a. ginger, onion, garlic
b. camote, carrot,potatoes
c. banana,bamboo,turmeric
d. avocado, papaya,mango tree
Super easy. Please help
Answer:
Identical twins tend to be more similar to each other than fraternal twins do.
Explanation:
The term population dynamics would not be used to describe which of the following examples?
Α.
birth rates
B.
changes in population size
death rates
success of offspring reaching reproductive age
Answer:
Population size is influenced by the per capita population growth rate, which is the rate at which the population size changes per individual in the population. This growth rate is determined by the birth, death, emigration, and migration. Pretty much Birth rate or Death rate.
Explanation:
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what are some products that come from plants?
Answer:
Aspirin tablets. Sponges. ...
Sponges made from trees. Chewing Gum. ...
Sapodilla tree. Carnauba Wax. ...
Copernicia prunifera. Henna Dye. ...
Henna tattoo. Rubber. ...
Tapping into trees for rubber.
Answer:
Rubber, sponges
Explanation:
these are Frome trees
Pick three correct statements about enzymes.
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What are 2 facts about energy?
Answer: Only 10 percent of energy in a light bulb is used to create light. ...
The amount of energy Americans use doubles every 20 years. ...
Explanation: