DNA Replication
Definition
DNA replication is the biological process by which a DNA molecule makes an identical copy of itself. This semiconservative process ensures that genetic information is accurately transmitted from parent to daughter cells during cell division. Key enzymes include DNA polymerase, helicase, and ligase.
Key Points for NEET
- 1Semiconservative: each new DNA has one old and one new strand
- 2DNA polymerase adds nucleotides only in 5' to 3' direction
- 3Leading strand is synthesized continuously
- 4Lagging strand is synthesized as Okazaki fragments
- 5Helicase unwinds the double helix
Example
DNA copying itself before a cell divides to ensure both daughter cells have complete genetic information
Asked in NEET
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More Genetics Definitions
Transcription
Transcription is the first step of gene expression, where a segment of DNA is copied into RNA (specifically mRNA) by the enzyme RNA polymerase. This process occurs in the nucleus in eukaryotes and transfers genetic information from DNA to messenger RNA, which then carries the code to ribosomes for protein synthesis.
Translation
Translation is the process by which ribosomes decode the mRNA sequence into a polypeptide chain (protein). It involves transfer RNA (tRNA) molecules that bring specific amino acids to the ribosome, where they are joined together in the order specified by the mRNA codons. This occurs in the cytoplasm.
Chromosome
A chromosome is a thread-like structure of DNA and protein found in the nucleus of cells that carries genetic information. Humans have 46 chromosomes (23 pairs). During cell division, chromosomes condense and become visible under a microscope. They contain genes that determine an organism's traits.