Prokaryotic cells: lack membrane-bound organelles, relatively small - typically less than 10 μm in size.
Both cell types: use ribosomes to synthesize proteins, contain DNA.
Eukaryotic cells: complete copy of DNA stored in multiple chromosomes.
In particular, prokaryotic cells have no nucleus and no membrane-bound organelles, therefore their ribosomes float freely intracellularly. On the other hand, eukaryotic cells have nucleus and membrane-bound organelles. Also, their DNA is bound to proteins and stored in the form of chromosomes in the nucleus.
A. into a climax community; species replaces another
B. and replaces another; ecosystem becomes stable
C. on unoccupied ground; biological community replaces another
D. and then fails; niche changes
E. intraspecific competition; experiences interspecific competition
Answer:
C. on unoccupied ground; biological community replaces another
Explanation:
Primary succession is a gradual change that occurs on bare rocks or areas that have no life existing on it before. It could take several years to be colonized by living things.
On the other hand, secondary succession are changes that occur when one biological community replaces another as a result of factors such as wild fires, or take place in abandoned farm land. New species of organisms take over the area that has life existing on it already. Secondary succession occurs on areas or land that has been colonized initially before.
Answer:
1. Nucleotides
2. Amino acids
3. Amino acids
4. Glucose
Explanation:
All the above substance described are biomolecules. They are all polymers i.e. complex molecule bond together in a long repeating chain, made up of simpler subunits called monomers. The monomers of the different biomolecules outlined above are:
1. The nucleic acids, DNA and RNA carry genetic information and are made up of many NUCELEOTIDES. A nuceleotide is a chemical combination of a five carbon sugar (pentose), phosphate group and nitrogenous base. These nucleotides are arranged sequentially to form nucleic acids (RNA and DNA).
2. Myoglobin is a protein that binds oxygen molecules and is a polymer of AMINO ACIDS. Amino acids are the building blocks of proteins. They are arranged to form a 3D structure that determines the function of the protein.
3. Insulin is a protein hormone that regulates blood glucose levels and is a polymer of AMINO ACIDS. All proteins are made up of the amino acid but the protein's function is dependent on the 3D structure formed by the amino acid sequence.
4. Animals store energy in the form of glycogen, a carbohydrate made up of thousands of monosaccharide (GLUCOSE). Glycogen is a polysaccharide made up of many monosaccharide units. These units are glucose molecules that are multibranched to form the glycogen that stores mainly in the liver and muscles of animals.
Answer:
The miRNAs act as post-transcriptional silencers, as they are similar to specific mRNAs and regulate their stability and translation. They are small endogenous non-coding ribonucleic acid (RNA) molecules, with about 22 nucleotides, which act as regulators of gene expression in plants and animals, at the post-transcriptional level through the cleavage of a target messenger RNA (mRNA) or repression of translation.
In general, most miRNA genes are transcribed by RNA polymerase II in the nucleus in primary miRNAs (pri-miRNAs). Individually, a pri-miRNA can produce a single miRNA or contain groups of two or more miRNAs that are processed from a common primary transcript. These long pri-miRNA are cleaved by a complex comprising the double-stranded RNAse III enzyme (DROSHA) and its essential cofactor, the binding protein DGCR8 (DiGeorge Syndrome Critical Region 8 protein) in mammals. DROSHA contains two domains of RNAse III, each of which cleaves a strand of the RNA resulting in the precursor microRNA (pre-miRNA) with about 70 base pairs, which contains a double-stranded stretch and a single-stranded loop, forming a structure in clamp. The pre-miRNA is exported to the cytoplasm by the protein exportin-5 (XPO-5), where it is cleaved by DICER1, an RNAse III that assesses the 3 'and 5' ends of the pre-miRNA, generating a mature miRNA with about 22 nucleotides. The processing of pre-miRNA by Dicer promotes the unfolding of the RNA duplex in the form of a clamp. The position in the formation of the clamp can also influence the choice of tape.
Explanation:
