Answer:
Carbohydrates, particularly glycoproteins act as ligands for cell surface receptors.
Explanation:
Glycoproteins
- Glyproteins are conjugate molecules comprising of carbohydrates conjugated with proteins.
- Glycoproteins play a vital role in cell-cell recognition, pathogen recognition and and cell adhesion.
- Glycoproteins on the surface of pathogens act as prominent antigens for the immune system.
Glycoproteins in Fertilization:
Several glycoproteins are attached to the surface of the zona pellucida, the envelope of the oocyte. In humans, these have been termed as ZP1-4.
Glycoprotein-sperm interaction is one of the most crucial steps in fertilization. This receptor-ligand interaction ensures the entry of the sperm into the zona pellucida, the extracellular coat, covered in glycoproteins that surrounds the oocyte or egg.
Carbohydrate binding proteins present on the surface of the sperm recognize the glycoproteins on the zona pellucida (ZP). This enables them to adhere to the surface of the ZP and also to gain access to the oocyte.
C. consumers depends upon producers for food
Answer:
Ecologists
Explanation
often estimate the size and density of populations using quadrats and the mark-recapture method. A population can also be described in terms of the distribution, or dispersion, of the individuals that make it up. Individuals may be distributed in a uniform, random, or clumped pattern.
Answer:
A lethal mutation, thereby the resulting phenotype is not observed
.
Explanation:
Lethal mutations are the result of genomic changes that may be lethal in certain conditions. In genetic research, this type of mutation has shown to be very useful in analyzing gene function (i.e., genes whose protein products are key for the survival of the organism in question), and they are perfect gene markers. In bacteriophages, for example, temperature-sensitive mutants of phage T4 that can not grow at temperatures higher 42°C have been identified (Edgar & Lielausis 1964).
Citation:
R. S. Edgar, & I. Lielausis (1964). Temperature-sensitive mutants of bacteriophage T4D: their isolation and genetic characterization. Genetics, 49(4), 649.
