DNA and Proteins - Language of Life

DNA replication is called semi-conservative because each newly formed DNA molecule contains one original (parental) strand and one newly synthesized strand. This means that half of the original DNA molecule is conserved in each new molecule.

DNA polymerase is the primary enzyme responsible for synthesizing new DNA strands during replication. It adds nucleotides to the growing DNA strand according to the base pairing rules (A with T and C with G). DNA polymerase ensures accurate replication by proofreading and correcting errors, preventing mutations.

Having two copies of every gene (one from each parent) provides genetic redundancy. If one copy of a gene is damaged or mutated, the other copy can still provide the necessary instructions for protein synthesis. DNA replication ensures that both copies of each gene are faithfully replicated and passed on to daughter cells, preserving genetic integrity.

<p>Helicase is responsible for unwinding the DNA double helix, separating the two strands to expose the bases. DNA polymerase then uses these exposed bases as templates to synthesize new complementary strands. Without Helicase, DNA replication could not begin, as the strands would remain intertwined and inaccessible. Without DNA polymerase, new strands couldn't be synthesized, leading to incomplete or defective DNA molecules.</p> Signup and view all the answers

<p>The base-pairing rules (A with T and C with G) are universal across all life forms on Earth. This universality suggests that all life shares a common ancestor, as these rules are fundamental to the process of DNA replication. A common ancestor would have possessed this genetic code, which has been passed down through generations, leading to the same base pairing rules in diverse organisms.</p> Signup and view all the answers

<p>DNA replication is essential for cell division because it ensures that each daughter cell receives a complete copy of the genetic material. Before cell division, the entire DNA molecule is duplicated, creating two identical copies called sister chromatids. These sister chromatids are attached to each other and remain together until cell division, when they are separated and distributed to the daughter cells. This ensures genetic continuity between generations of cells.</p> Signup and view all the answers

<p>Exons are coding segments of DNA that contain the genetic information for building proteins. These segments are transcribed into messenger RNA (mRNA) and then translated into amino acid sequences that form proteins. Introns, on the other hand, are non-coding segments that are transcribed but not translated. They are spliced out of the mRNA molecule before it is translated. While exons directly contribute to protein synthesis, introns play a regulatory role and can influence gene expression by affecting mRNA stability, splicing efficiency, and protein function.</p> Signup and view all the answers

<p>RNA polymerase is an enzyme that plays a central role in transcription, the process of copying DNA into RNA. It binds to a specific region of DNA known as the promoter and unwinds the DNA double helix. RNA polymerase then uses one strand of DNA as a template to synthesize a complementary RNA molecule, known as messenger RNA (mRNA). This mRNA molecule carries the genetic code from the DNA to the ribosomes, where it is translated into a protein. Thus, RNA polymerase initiates the flow of genetic information from DNA to RNA, a crucial step in protein biosynthesis.</p> Signup and view all the answers

<p>DNA strands have a directionality, with one end designated as 5' and the other as 3', based on the location of the phosphate group on the sugar molecule. During transcription, RNA polymerase reads the template strand of DNA in the 3' to 5' direction. The template strand is the one that RNA polymerase uses as a guide to synthesize the complementary mRNA strand. It works like a chain letter. The template strand acts like the 'chain', and RNA polymerase adds the new 'link' to the RNA chain as it copies the sequence from the template in the reverse direction.</p> Signup and view all the answers

<p>Codons are three-nucleotide sequences in mRNA that specify a particular amino acid. Anticodons are complementary three-nucleotide sequences found on transfer RNA (tRNA) molecules. Each tRNA molecule carries a specific amino acid. When an mRNA codon interacts with a tRNA anticodon, it brings the corresponding amino acid to the ribosome for protein synthesis. This precise pairing of codons and anticodons ensures the accurate translation of the genetic code into an amino acid sequence. The amino acid sequence, in turn, determines the protein's structure and function, making it the fundamental building block of life. This relationship is known as the genetic code, the universal language that allows all living organisms to translate their genetic information into proteins.</p> Signup and view all the answers

A unique sequence of nucleotides that codes for a protein or RNA.

The process by which DNA makes a copy of itself.

Exons are coding segments, introns are non-coding in genes.

Each new DNA molecule contains one old strand and one new strand.

Process of converting DNA into messenger RNA (mRNA) in the nucleus.

An enzyme that unwinds and splits the DNA double helix.

The process of interpreting mRNA to form an amino acid sequence at the ribosomes.

An enzyme that synthesizes new complementary DNA strands.

DNA consists of two strands forming a double helix with a sugar-phosphate backbone and four bases (A, T, G, C).

Rules determining how nucleotides pair in DNA (A-T, G-C).