<span>There are numerous proteins in muscle. The main two are thin actin filaments and thick myosin filaments. Thin filaments form a scaffold that thick filaments crawl up. There are many regulatory proteins such as troponin I, troponin C, and tropomyosin. There are also proteins that stabilize the cells and anchor the filaments to other cellular structures. A prime example of this is dystrophin. This protein is thought to stabilize the cell membrane during contraction and prevent it from breaking. Those who lack completely lack dystrophin have a disorder known as Duchene muscular dystrophy. This disease is characterized by muscle wasting begininng in at a young age and usually results in death by the mid 20s. The sarcomere is the repeating unit of skeletal muscle.
Muscle cells contract by interactions of myosin heads on thick filament with actin monomers on thin filament. The myosin heads bind tightly to actin monomers until ATP binds to the myosin. This causes the release of the myosin head, which subsequently swings foward and associates with an actin monomer further up the thin filament. Hydrolysis and of ATP and the release of ADP and a phosphate allows the mysosin head to pull the thick filament up the thin filament. There are roughly 500 myosin heads on each thick filament and when they repeatedly move up the thin filament, the muscle contracts. There are many regulatory proteins of this contraction. For example, troponin I, troponin C, and tropomyosin form a regulatory switch that blocks myosin heads from binding to actin monomers until a nerve impulse stimulates an influx of calcium. This causes the switch to allow the myosin to bind to the actin and allows the muscle to contract. </span><span>
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<u> Allele frequencies to change from one generation to the next.-</u>
<u>B. </u><u>Mutation</u><u>; C. Random genetic drift; D. </u><u>Migration</u><u>; F. Natural selection</u>
- Selection, mutation, migration, and genetic drift are the mechanisms that effect changes in allele frequencies.
- When one or more of these forces are acting, the population violates Hardy-Weinberg assumptions, and evolution occurs.
Why do allele frequencies change from one generation to the next?
Random selection: Allele frequencies may fluctuate from one generation to the next when people with particular genotypes outlive those with different genotypes.
No mutation: Allele frequencies may fluctuate from one generation to the next if new alleles are produced via mutation or if alleles mutate at different rates.
What are 5 factors that cause changes in allele frequency?
- A population, a collection of interacting individuals of a single species, exhibits a change in allele frequency from one generation to the next due to five main processes.
- These include natural selection, gene flow, genetic drift, and mutation.
Learn more about allele frequency
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<u>The complete question is -</u>
Identify the evolutionary forces that can cause allele frequencies to change from one generation to the next. Check all that apply
A. Inbreeding
B. Mutation,
C. random genetic drift
D. migration
E. extinction
F. natural selection
Answer:
I believe it's the <em>collecting</em><em> </em><em>duct</em>
The main reason that most farmers use stem cuttings rather than just planting a seed is that a tree's genetic variation will occur. The seeds of many fruit trees tend to vary differently from the parent, because seeds themselves are produced by sexual reproduction (i.e they receive genes from a male and female to form). As they are a cross from two sets of genes, many fruit trees are not “true to seed”. Their seeds will produce a generally different variety of tree from the parent. When using stem cuttings, it's almost like a cloning process.