The hydrogen bonding of nucleotides into a new DNA molecule is facilitated by enzymes. Hydrogen bonding is the electromagnetic attraction between polar molecules in which hydrogen is bound to a larger atom, such as oxygen or nitrogen. The nucleotides in a base pair are complementary which means their shape allows them to bond together with hydrogen bonds. The A-T pairs forms two hydrogen bonds while the C-G pair forms three. The enzymes called DNA polymerases join the nucleotides by way of phosphodiester bonds.
Answer:
All of these choices are correct.
Explanation:
Cell cycle is the process of growth and division of cell. It comprises of interphase and mitosis. In interphase the cell grows, replicates its genomic content and prepares itself for division. In mitosis the division occurs.
Cell cycle is controlled by a group of kinases called as Cyclin dependent Kinases (CDKs). They act by phosphorylating their substrates. They are of various types like Cdk1, Cdk2, Cdk4 etc. They become active when they bind to a regulatory protein called cyclin. They are also of various types like Cyclin A, Cyclin B, Cyclin C etc. Level of cyclin and corresponding CDK increases and decreases according to the stage of cell cycle. For example in S phase of cell cycle concentration of cyclin A and E shoots up. CDK2 is able to bind to these cyclin molecules and hence it becomes active.
Cell cycle has major checkpoints where the condition of cell is analysed before it proceeds to the next stage of cycle. If any abnormality is detected, repair mechanism is activated or the cell is killed. Checkpoints do not allow cell cycle to proceed in damaged cells.
p53 is a tumor suppressor protein which can halt cell cycle when it detects some abnormality in cell. It usually acts in G1/S checkpoint (before the DNA replication starts in cell) and G2/M checkpoint (before the cell division begins). Hence, all of the above statements are true.
Answer:
The correct answer to the following question will be Option B and C.
Explanation:
- Monsoon seems to be a change throughout the course including its predominant hot air flowing from either the south-western oceans of India towards India.
- The summer monsoon gives a luxurious atmosphere as well as heavy rains to something like the coastline of Asia (south-east), where many monsoon showers of rain undergo their rainy season throughout the winter.
The other choices are not related to the given circumstances. So that Option B & C would be the appropriate choice.
Earth Axial tilt
The answer is
23.44
