Here are definitions and examples for each of the given terms:
1. Chromosome: A chromosome is a long, coiled-up structure made of DNA and proteins that carries genetic information in cells. Chromosomes are found in the nucleus of eukaryotic cells, and they come in pairs, with one chromosome inherited from each parent. Humans have 23 pairs of chromosomes, for a total of 46 chromosomes. Example: The 23rd pair of human chromosomes determines the individual's sex, with two X chromosomes resulting in a female and an X and a Y chromosome resulting in a male.
2. DNA: DNA, or deoxyribonucleic acid, is a molecule that carries genetic information in cells. It is a long, double-stranded molecule made up of nucleotides, and it is found in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. Example: DNA is responsible for carrying and transmitting genetic information from parents to offspring.
3. Double helix: The double helix is the structure of DNA, consisting of two strands of nucleotides twisted around each other in a spiral shape. The two strands are held together by hydrogen bonds between complementary base pairs. Example: The double helix structure of DNA was first discovered by James Watson and Francis Crick in 1953.
4. Messenger RNA (mRNA): Messenger RNA is a type of RNA that carries the genetic information from DNA to ribosomes, where it is used to make proteins. mRNA is made during the process of transcription, in which a section of DNA is copied into a complementary sequence of mRNA. Example: In the process of protein synthesis, a mRNA strand is used as a template to direct the assembly of amino acids into a protein.
5. Nucleotide: A nucleotide is the basic building block of nucleic acids, such as DNA and RNA. It is made up of a sugar molecule, a phosphate group, and a nitrogenous base. Example: Adenine, guanine, cytosine, and thymine are the four types of nucleotides found in DNA.
6. RNA: RNA, or ribonucleic acid, is a molecule that plays a key role in the expression of genetic information. There are several types of RNA, including messenger RNA, ribosomal RNA, and transfer RNA. Example: RNA is involved in the process of protein synthesis, in which the genetic information carried by DNA is used to create proteins.
7. Transcription: Transcription is the process by which a section of DNA is copied into a complementary sequence of RNA. RNA polymerase is the enzyme responsible for carrying out transcription. Example: During transcription, a section of DNA is copied into a complementary sequence of mRNA, which is used to direct the assembly of amino acids into a protein.
8. Translation: Translation is the process by which the genetic information carried by mRNA is used to create proteins. Translation occurs on ribosomes, and involves the assembly of amino acids into a protein based on the sequence of codons in the mRNA. Example: In the process of protein synthesis, translation follows transcription, in which a section of DNA is copied into a complementary sequence of mRNA.