Biology High School

n
Which statement best describes the step in muscle contraction when the sarcomere is the shortest?
A The sarcomere is contracted, and the actin and myosin filaments are partially overlapped.
B The sarcomere is relaxed, and the actin and myosin filaments are partially overlapped.
C The sarcomere is contracted, and the actin and myosin filaments are completely overlapped.
D The sarcomere is relaxed, and the actin and myosin filaments are completely overlapped.

Answers

Answer 1

Answer:

C The sarcomere is contracted, and the actin and myosin filaments are completely overlapped.

Explanation:

In rest, the tropomyosin inhibits the attraction strengths between myosin and actin filaments. Contraction initiates when an action potential depolarizes the inner portion of the muscle fiber. Calcium channels activate in the T tubules membrane, releasing calcium into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to troponin C, troponin T alters the tropomyosin position by moving it and unblocking the binding sites. Myosin heads join the uncovered actin-binding points forming cross-bridges, and while doing so, ATP turns into ADP and inorganic phosphate, which is released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament.  Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Finally, Z-bands are pulled toward each other, shortening the sarcomere and the I-band, producing muscle fiber contraction.

In the sarcomere, which is the contractile unit of skeletal muscles, there are

Thick myosin myofilaments in the central region belonging to the A band.  Thin filaments united to the Z lines, extending in the interior of the A band until they reach the border of the H band.  Thin actin filaments composing the I band, which belong to two sarcomeres adjacent to a Z line.

When the muscle contracts, the muscular fiber gets shorter and thicker due to the reduction in the length of the sarcomere. The H line and the I band get shorter. The Z lines get closer to the A band, meaning that they get closer to each other. A band keeps constant in length. This change is produced by movement mechanisms that involve a change in the relative position of actin and myosin filaments.

Answer 2

Answer:

C

Explanation:

edge 2021

Related Questions

Cationic detergents are surface active agents, also known as ______, which damage bacteria by binding bacterial surface proteins and disrupting ______.

Answers

Surfactants; cell membrane

In 1980, scientists suggested that the great mass extinction of 65 million years ago (which ended the reign of dinosaurs) may have been caused by a large impact from space. What discovery gives a big boost to this idea

Answers

Answer: the discovery of a buried crater (about 200 km across) near Chicxulub, Mexico

The discovery of a buried crater (about 200 km across) near Chicxulub, Mexico.

What is extinction?

Extinction is defined as the disappearance of an organism or a group of organisms as a result of environmental factors or changes in the members' evolutionary processes.

It can also be defined as an evolutionary process that causes a species or population to go extinct.

When there are no longer any living members of a certain animal or plant species anywhere in the globe, the species has become extinct.

Generally speaking, species disappear for the following reasons:

Genetic and demographic phenomena.Habitat destruction in the wild.Species introduction that are invasive.Global warmingHunting and illicit trade.

Thus the discovery of a buried crater (about 200 km across) near Chicxulub, Mexico.

To learn more about extinction, refer to the link below:

https://brainly.com/question/14480057

#SPJ2

why is DNA a useful form of evidence for developing a phylogenetic tree?

a) DNA never changes
b) DNA is the newest thing in science
c) DNA is passed from generation to generation ​

Answers

Answer:

DNA is useful for a phylogenetic tree because DNA is passed from generation to generation.

the answer;

should be C

HAVE A NİCE DAY

Explanation:

greeetings from Turkey ツ

C , dna is passed generation to generation!

In 40 words or fewer, why do you think a 0.1% difference in DNA can
be useful to society?

(The answer is this ⬇️)


The 0.1% difference in DNA
can be used to identify
someone who has
committed a crime or free
someone who hasn't, to determine someone's family
heritage, and to help give a
person more precise
medical treatments.

To anyone who needs it

Answers

Answer:

The 0.1% difference in DNA

can be used to identify

someone who has

committed a crime or free

someone who hasn't, to determine someone's family

heritage, and to help give a

person more precise

medical treatments.

Explanation:

Easy points thxx

Other Questions
I will mark you brainlist if you helppp me pls and thankyouuu Where should the author of a case study introduce the central question of the text?at the conclusionat the beginningafter the evidencealong with the supplemental facts elige la opcin correcta:(choose the correct option)1)when was the last time you____ someone's birthday?a)forgotb)forgottenc)forgetted2)when was the last time you_____a museum?a)sawb)watchedc)visitedd)went3)when was the last time you______your email?a)checked b)logged onc)receivedd)watched4)when was the last time you_____to your grandparents?a)met b)sawc)visited5)when was the last time you_____an argument with your parentsa)disagreedb)shoutedc)had help pls and explain!!!If x^2 + kx + 6 = (x+n)(x + 3) for all values of x, where k and n are constants, what is the value of k?A) 5B) 3C) 2D) 1 The combination of ions most likely to produce a precipitate is Group of answer choices Mg2 and C2H3O2-. Fe3 and OH-. Li and PO43-. Pb2 and NO3-. NH4 and SO42-. In spite of the impact of Chinese influence, a. Korea never came under Chinese political control. b. Japan never adopted either Chinese characters for writing or any of its governmental system. c. Vietnam developed chu nom, which was a writing system for spoken Vietnamese. d. Korea never accepted tributary status under Chinese overlordship. e. Confucianism itself had little influence anywhere outside of China proper. Dark skin ( a result of increased melanin production in equatorial populations), is likely a response to ultraviolet radiation because UV radiation causes: 1 ________ does Polly doin the evening?___________________2 ________ phone isringing now?___________________really fast5 ________ does thepostman bring you theletter?___________________6 ________ does Danielride his scooter?___________________9 ________ does Monawork?___________________10 ________ does Tomcan see fish?___________________ Cotton plant is mainly harvested at flowering stage true false A large container holds 4 gallons of chocolate milk that has to be poured into bottles. Each bottle holds 2 pints.If the ratio of gallons to pints is 1: 8, bottles are required to hold the 4 gallons of milk. On January 1, 2017, ARC Inc. issued 100 5-year bonds, with a face value of $1,000 each and a coupon rate of 10%, payable semiannually. The interest is paid on June 30 and December 31 of each year. The market rate of interest at the time that the bonds were issued was 13%, so that the bonds were sold for $892 each.1. Interest expense for the January 1June 30 period was $_____.2. Interest expense for the July1December 31 period was $_____.3. Book value of Bonds on June 30 was $_____.4. Book value of Bonds on December 31 was $_____.5. Interest payment on June 30 was $_____. The Aqua Liquid Assets Money Market Mutual Fund has a NAV of $1 per share. During the year, the assets held by this fund appreciated by 1.4 percent. If you had invested $50,000 in this fund at the start of the year, how many shares would you own at the end of the year Read this passage I am mindful that only yesterday in Birmingham, Alabama, our children, crying out for brotherhood, were answered with fire hoses, snarling dogs and even death. I am mindful that only yesterday in Philadelphia, Mississippi, young people seeking to secure the right to vote were brutalized and murdered. And only yesterday more than 40 houses of worship in the State of Mississippi alone were bombed or burned because they offered a sanctuary to those who would not accept segregation. I am mindful that debilitating and grinding poverty afflicts my people and chains them to the lowest rung of the economic ladder. -Martin Luther King Jr., Nobel Prize acceptance speech, 1964 How does King show that the struggle for freedom and equality is not over? A. By asking the committee to help thestop the violence B. By refusing the award because peace has not been achieved C. By giving examples of violent events that recently took place D. By explaining that he is not an expert in the field of civil rights A town recently dismissed 5 employees in order to meet their new budget reductions. The town had 4 employees over 50 years of age and 16 under 50. If the dismissed employees were selected at random, what is the probability that no more than 1 employee was over 50 Help please I dont understand MC Qu. 114 Lowden Company has an overhead application... Lowden Company has an overhead application rate of 155% and allocates overhead based on direct material cost. During the current period, direct labor cost is $60,000 and direct materials used cost $90,000. Determine the amount of overhead Lowden Company should record in the current period. If the balance of the cash account is $80,800 at the end of the month, what was the cash balance at the beginning of the month You are analyzing ABC Company, a computer manufacturer. You notice that inventory turnover this year is significantly lower than in prior years. You also notice that accounts receivable turnover is significantly lower this year when compared to previous years. Provide three explanations that would be consistent with your observation for inventory turnover and include an explanation of whether these would be of concern to you, as well as what the effect might be on the next period's financial results. In addition, provide three explanations that would be consistent with your observation of the accounts receivable turnover, and explain whether these would be of concern to you. When people are asked to recall a list of words they had earlier memorized, they often substitute common synonyms for some of the words on the original list. This best illustrates the effects of Computer data that is suitable for text