Answer:
Molecules which move against the concentration gradient across the cell membrane employ the mechanism of active transportation.
Explanation:
Normally, permitted molecules moves across the cell membrane of the cell by the process of diffusion and osmosis. This is used when molecules move from hypertonic region to hypotonic region (if ions) and hypotonic to hypertonic (if water). This is a passive transportation which do not require the expense of energy from the cell.
In contrast, when molecules move in or out of the cell against their concentration gradient, that is ions moving from hypotonic region to hypertonic region, they implore the expense of energy in form of adenosine triphosphate (ATP), and the involvement of the membrane carrier proteins. This is called active transport.
Answer:
The troposphere is the lowest layer
Explanation:
hope this helps!! there could be more that are right I'm just not sure so
Answer:
1 . The stage on the first meiotic division when the homologous chromosomes move to opposite poles but the sister chromatids remain together
: b. Anaphase I
2 . The stage in the second meiotic division where sister chromatids migrate to opposite poles
: c. Anaphase II
3 . A structure on the chromosome that holds a pair of chromatids together during replication
: f. centromere
4 . A double-stranded chromosome following replication attached by a centromere
: d. chromatid
5 . A condition where non-sister chromatid of homologous chromosomes exchange genes
: e. crossing over
6 . The stage in the first meiotic division where the homologous chromosomes line up as a pair
: a. Metaphase I
7 . The stage in the second meiotic division where the chromatid pair lines up at the equator of the cell: g. Metaphase II
Explanation:
DNA replication occurs during the S phase of the interphase of the cell cycle. The replicated DNA molecules are accommodated in two sister chromatids of a chromosome that are held together by a centromere.
During prophase I, the chromatids of a homologous chromosome pair exchange a genetic segment. This process is called crossing over. It generates recombinant chromatids with new combinations of genes.
Metaphase I of meiosis I includes the alignment of homologous pairs of chromosomes at the cell's equator. This is followed by separation and movement of homologous chromosomes to the opposite poles of the cell during anaphase I.
Metaphase II of meiosis II includes the alignment of individual chromosomes, each with two sister chromatids, on the cell's equator. During anaphase II, splitting centromere separates the sister chromatids which then move to the opposite poles of the cell.
Quick Answer. Collagen is the protein that all animals have in common, even single-celled animals and creatures such as sponges that lack differentiated bodies. Collagen is a cable-like protein that can calcify into bone, shell or other hard structures.
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MARK BRAINLIEST PLZ!!!!!!!!
Answer:
la vida no podría continuar sin los procesos de división celular
Explanation:
La mitosis es el proceso de división celular mediante el cual se producen dos células idénticas a partir de una sola célula. Durante la mitosis la célula crece y duplica la cantidad de ADN, con lo cual exactamente el mismo contenido de información genética es trasmitido a las sucesivas células que el proceso de mitosis va a dar origen. Por otra parte, la meiosis es un proceso celular en el cual se producen dos divisiones nucleares y citoplasmáticas (meiosis I y meiosis II) las cuales son precedidas por una fase de replicación del ADN. En la especie humana, la mitosis da lugar a células diploides (2n) con dos set completos de cromosomas homólogos, mientras que la meiosis da lugar a cuatro células haploides (n) llamadas gametos (el gameto masculino es el espermatozoide y el gameto femenino es el óvulo) las cuales contienen la mitad del número cromosómico al de la célula de origen. En organismos eucariotas pluricelulares tales como la especie humana, la función de la mitosis es producir más células somáticas (soma: cuerpo) con idéntico material genético, mientras que la función de la meiosis es producir células aptas para el proceso de reproducción, es decir, células con la mitad del material genético que se fusionarán para generar una célula diploide o zigoto a partir del cual y mediante sucesivas mitosis se desarrollará un organismo adulto.
