University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

280

Pages:

3
Author:

Mariam A. A.

DNA Structure GCAT Write the complement of GCCCATGCTGCATGCAT CGGGTACGACGTACGTA What the model contains: The above Watson and Crick model is, ✓ Composed of nucleotides.(GCAT and they are held together by hydrogen bonds) ✓ Double stranded. ✓ Twisted into helix shape (spiral). ✓ Composed of a sugar-phosphate backbone. ✓ Composed of bases attached to backbone: adenine, guanine, cytosine and thymine. (hydrogen bases) Bonding and pairing of nucleotides: ✓ Nucleotides are joined by phosphodiester bonds. ✓ Complementary nitrogenous bases are joined by hydrogen bonds. ✓ Adenine always pairs with thymine held by 2 weak hydrogen bonds. ✓ Guanine always pairs with cytosine held by 3 weak hydrogen bonds. DNA Replication 1. DNA replication starts with a double-stranded DNA helix molecule. 2. The enzyme, helicase, attaches to and unwinds the double-stranded DNA helix. Helicase also facilitates the breaking of hydrogen bonds between the nitrogenous bases (Adenine, Thymine, Guanine and Cytosine). This would lead to the separation of the two DNA strands. 3. Each of the two now separated DNA single strands act as templates for free (available) nucleotides from the nucleoplasm (inside nuclear membrane) to join via complementary base pairing, i.e. Adenine bonds with Thymine and Guanine bonds with Cytosine. The enzyme, DNA polymerase, moves along the DNA strands during this process to catalyse the reaction, allowing complementary base pairing to occur. 4. The enzyme, DNA ligase, secures each of the new DNA strands formed with free nucleotides (monomers) with complementary base pairing. 5. Each DNA double strands return to their chemical stable state by winding up spontaneously to form a two double-stranded DNA helix. Assess the effect of the cell replication processes on the continuity of species PDEEL P= point D= definition E= example E=elaborate L = linking statement Cell replication is an essential process that living organisms use to produce daughter cells that are able to carry the same function as the parent. This process is required for living organisms to continue functioning and to reproduce. Cell replication is the process of a parent cell producing identical daughter cells through meiosis or mitosis. For example, meiosis is responsible for reproducing gametes. Gametes are essential for reproduction as without them, species would become extinct due to their inability to produce offspring. On the other hand, mitosis is responsible for the production of somatic cells such as muscle and neuron cells. Without the replication of these cells, species would not be able to function in a way that enables them to survive. For example, a bird who lacks muscle cells, would be unable to fly properly and thus would become vulnerable to predator and would not be able to withstand competition for prey. During cell replication, the DNA is replicated, this is required as the DNA carries the genetic information that coordinates proper functioning. Moreover, in cell replication the genes are transferred from the parent to the daughter cell. This occurs as a result of the DNA that has been replicated, because it transfers all the important information to the daughter cell, which enable it to carry out function. Hence, without cell replication species would not be able to survive due to their inability to perform essential functions, and could possibly become extinct.