Answer:
Base
Explanation:
Deoxyribonucleic acid, DNA, is one of the four major biomolecules in living organisms. It is a polymer made up of monomers called NUCLEOTIDES. The nucleotides that make up a DNA molecule is composed of three substances namely: Sugar (deoxyribose), nitrogenous base, and a phosphate group.
However, among these three components of the nucleotide monomer, NITROGENOUS BASE is the only portion that is not the same in every DNA molecule. There are four nitrogenous bases in nature viz: Adenine, Guanine, Cytosine and Thymine. These four bases can be alternated in a DNA molecule.
Note that, phosphate group and deoxyribose sugar are constant in every DNA.
Answer;
-Zygote
When sperm and ovum unite at conception, a zygote results.
Explanation;
-Conception occurs when a sperm cell from a fertile man swims up through the vagina and into the uterus of a woman and joins with the woman's egg cell (ovum) as it travels down one of the Fallopian tubes from the ovary to the uterus.
-A zygote is the union of the sperm cell and the ovum. Also known as a fertilized ovum, the zygote begins as a single cell but divides rapidly in the days following fertilization. After this two-week period of cell division, the zygote eventually becomes an embryo.
I hate to ask and sound stupid, but the drug or the basic chemical?
<u>Answer</u>:- <em>Option 3 </em>(desert), <em>Option 4</em> (tundra) and <em>Option 5</em> (grassland).
<u>Explanation</u>:-
The amount of rainfall varies in different biomes:-
1. Tropical rain forests - The annual rainfall in these forests falls in the range of <em>125 to 660 cm</em> which varies according to the seasons.
2. Temperate rain forest - The annual rainfall in these forests can range from <em>200 cm to 350 cm</em> depending on the region where they are found. The annual rainfall is higher in warmer regions .
3. Desert - As the name suggests, the desert areas do not get enough rainfall. The annual rainfall in a desert is less than <em>25 cm</em>.
4. Tundra - It is a biome which is found in relatively cooler climates and the amount of rainfall is very less these regions. The annual rainfall in tundra biomes is less than <em>20 cm</em>.
5. Grassland - in these biomes, the rainfall is higher than the tundra and desert but is not as high as the rain forests and thus, grass is the dominant vegetation. The annual rainfall ranges from <em>60-90 cm</em>.
Answer: The DNA on the paternal copy of the chromosome will be methylated at the imprinting center, while the DNA on the maternal copy of the chromosome will not be methylated in this region.
Explanation:
Chromosomes are DNA structures associated with proteins such as histones. They are found in the nucleus of cells and contain genetic information for the development and functioning of an organism. Human beings are diploid, meaning that they possess two copies of each of the 23 chromosomes (a total of 46).
Gametes, which are sex cells such as the sperm (produced by the male) and the egg (produced by the female) that are haploid. This means that they possess only one chromosome of each pair. During fertilization, a male gamete fuses with a female gamete to generate a zygote, which will give rise to a new human being. <u>This new individual will possess half of the genetic material from its father and half from its mother. Thus having a total of 46 chromosomes, 23 from each parent</u>.
Genetic imprinting modulates gene expression by chemical modification of DNA and/or modification of chromatin structure. Often, genetic imprinting causes a gene to be expressed only on the chromosome inherited from one of the parents. One example of imprinting is DNA methylation, which is a process by which methyl groups are added to DNA. <u>Methylation modifies DNA function when found in the promoter gene, repressing gene transcription. This means that a methylated gene will not be expressed</u>, that is, it will not produce a protein encoded by that gene. So, if a region of DNA is imprinted in the sperm cell, the paternal chromosome inherited from this sperm will be methylated in the genes of the offspring. And the offspring will only express the maternal copy inherited, which will not be methylated.
