Chromosome
Definition
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.
Key Points for NEET
- 1Made of DNA wrapped around histone proteins
- 2Humans have 46 chromosomes (23 pairs)
- 3Autosomes (44) and sex chromosomes (2)
- 4Each chromosome has a centromere
- 5Homologous chromosomes carry alleles for same genes
Example
Human sex chromosomes: XX in females, XY in males
Asked in NEET
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More Genetics Definitions
DNA Replication
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.
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.