Biology Chapter on Transcription and Translation

Transcription

• DNA contains the information for protein synthesis.
• Messenger RNA (mRNA) is produced based on the sequence of nucleotides in DNA.
• Only one strand of DNA is used in this process.
• The sequence of nucleotides in mRNA is complementary to the DNA strand.
• Uracil replaces thymine in RNA.
• The process of RNA synthesis is called transcription.

Translation

• mRNA, produced in the nucleus, moves into the cytoplasm.
• mRNA carries the coded message from DNA.
• This message contains the codes for amino acids.
• Each amino acid is encoded by a triplet codon, which consists of three nucleotides.
• Dr. Har Govind Khorana, an Indian scientist, contributed to the discovery of triplet codons for 20 amino acids.
• He received the Nobel Prize in 1968 for his work.
• Each mRNA is made up of thousands of triplet codons.
• tRNA supplies amino acids based on the message on mRNA.

Genetic Disorders

• Genetic disorders are caused by abnormalities in genes or chromosomes.
• These disorders can be inherited from parents or occur spontaneously.
• Examples of genetic disorders:
  • Sickle cell anemia
  • Cystic fibrosis
  • Down syndrome
  • Hemophilia

Embryological Evidences

• Comparative study of embryonic development in vertebrates shows similarities during the initial stages.
• These similarities indicate a common origin of all vertebrates.
• The similarities decrease gradually as development progresses.

Darwin's Theory of Natural Selection

• All organisms reproduce prolifically.
• Organisms compete for resources and survival.
• Organisms with favorable adaptations are more likely to survive and reproduce.
• Natural selection is the process of organisms that are best suited to their environment surviving and reproducing.
• Darwin proposed that all species have evolved from a common ancestor over thousands of years.
• Darwin's theory was widely accepted but faced some objections including the lack of explanations for abrupt changes and the role of factors besides natural selection in evolution.

Human Evolution

• Primitive apes started living on land as forests declined due to dry environments.
• Their pelvic girdles adapted to an erect posture.
• They began using their hands for various tasks.
• These first human-like animals with erect posture emerged around 20 million years ago.

ATP: Energy Currency

• Adenosine triphosphate (ATP) is a high-energy molecule.
• Energy is stored in the phosphate bonds of ATP.
• ATP is composed of adenine, ribose sugar, and three phosphate groups.
• Energy is released by breaking a phosphate bond in ATP.
• This process converts ATP to ADP (adenosine diphosphate).
• ATP is considered the "energy currency of the cell."

Cellular Respiration

• Lipids and proteins can be used for energy production if carbohydrates are insufficient.
• Lipids are converted into fatty acids and proteins are converted into amino acids in these conditions.

Mitosis

• Before cell division, the cell duplicates its chromosomes (2n to 4n).
• Somatic cells and stem cells divide by mitosis.
• Mitosis consists of two main steps: karyokinesis (nuclear division) and cytokinesis (cytoplasmic division).
• Karyokinesis occurs in four stages:
  • Prophase: Chromosomes condense and become visible.
  • Metaphase: Chromosomes align at the center of the cell. Centromeres of each chromosome attach to spindle fibers.
  • Anaphase: Sister chromatids separate and move to opposite poles of the cell.
  • Telophase: Chromosomes reach the poles and the nuclear membrane reforms.

Mitochondria & Tri-carboxylic Acid Cycle

• The tri-carboxylic acid cycle (Krebs cycle) occurs in the mitochondrial matrix.
• Each NADH2 molecule yields 3 ATP molecules, and each FADH2 molecule yields 2 ATP molecules.
• Water is also produced in this reaction.
• The electron transport chain, crucial for ATP production, occurs in the mitochondria.

Energy Co-enzymes

• NAD (Nicotinamide Adenine dinucleotide) and FAD (Flavin Adenine dinucleotide) function as coenzymes in cellular respiration.
• They are produced and used in cells.

This quiz covers the crucial biological processes of transcription and translation, detailing how mRNA is synthesized from DNA and how it carries genetic information for protein synthesis. Additionally, it touches upon the significance of triplet codons and the role of tRNA in the process. Test your understanding of these fundamental concepts in genetics.