Answer:
The correct answer is ''METAPHASE I.''
Explanation:
Metaphase I is the stage in which chromosomal studies are generally performed, because its morphology is very clear. The chromosomes, moved by the mitotic spindle, are placed in the center, between the two asters and form the so-called metaphase plate, in which the chromosomes are positioned in such a way that the kinetochore of each sister chromatid are oriented towards the opposite poles. Keeping chromosomes on the cell equator implies a balance between the forces of the microtubules that tend to move the kinetochores toward opposite poles, so positioning them in the center involves a great deal of energy.In each kinetochore, between 20-30 microtubules can be anchored, which exert traction force towards the pole from which they come, so the metaphase plate is maintained by the balance between the opposite forces of the poles on the chromosomes, which hold their sister chromatids by centromeric cohesin.
Two traits that we are examining are the color (purple/white) and the smoothness.
In our sample, we have 135 individuals ( 75 +28+24+8= 135).
Since we know that expected ratio of a dihybrid cross, is <span>9:3:3:1 we can calculate what is the expected values of each phenotype is.
So, for the white wrinkled phenotype, we expect that there will be one-sixteenth of the whole sample ( there are 16 parts of the whole sample 9+3+3+1=16).
So, we multiply the whole sample- 135 with one-sixteenth (or </span>0.0625) and get 8,4375.
When you calculate the values for all phenotypes you get results shown in the attached excel table.
When you have your expected and experimental values you compare them with a chi-square test. (The test determines if the difference between the expected and experimental results is statistically significant).
Answer and Explanation:
Ribosomes are the primary structure for protein synthesis. They can be found in the rough endoplasmic reticulum or floating in the cytosol.
Free ribosomes are not attached to any cytoplasmic structure or organelle. They synthesize proteins only for internal cell use. Other ribosomes are attached to the membrane of the endoplasmic reticulum and they are in charge of synthesizing membrane proteins or exportation proteins. Free and attached ribosomes are identical and they can alternate their location. This means that although free ribosomes are floating in the cytosol, eventually, they can get attached to the endoplasmic reticulum membrane.
Synthesis of proteins that are destined to membrane or exportation starts in the cytoplasm with the production of a molecule portion known as a <u>signal aminoacidic sequence</u>. This signal sequence varies between 13 and 36 amino acids, is located in the <u>amino extreme</u> of the synthesizing protein, and when it reaches a certain length, it meets the <u>signal recognizing particle</u>. This particle joins the signal sequence of the protein and leads the synthesizing protein and associated ribosome to a specific region in the Rough endoplasmic reticulum where it continues the protein building. When they reach the membrane of the endoplasmic reticulum, the signal recognizing particle links to a receptor associated with a pore. Meanwhile, the ribosome keeps synthesizing the protein, and the enlarged polypeptidic chain goes forward the reticulum lumen through the pore. While this is happening, another enzyme cuts the signal sequence, an action that requires energy from the ATP hydrolysis. When the new protein synthesis is complete, the polypeptide is released into the reticulum lumen. Here it also happens the protein folding (which is possible by the formation of disulfide bridges of proteins are formed) and the initial stages of glycosylation (the oligosaccharide addition).
Once membrane proteins are folded in the interior of the endoplasmic reticulum, they are packaged into vesicles and sent to the Golgi complex, where it occurs the final association of carbohydrates with proteins. The Golgi complex sends proteins to their different destinies. Proteins destined to a certain place are packaged all together in the same vesicle and sent to the target organelle. In the case of membrane proteins, they are packaged in vesicles and sent to the cell membrane where they get incrusted.
There are certain signal sequences in the <u>carboxy-terminal extreme</u> of the protein that plays an important role during the transport of membrane proteins. A signal as simple as one amino acid in the c-terminal extreme is responsible for the correct transport of the molecule through the whole traject until it reaches the membrane.
