HEREDITY: INHERITANCE and VARIATION

• DNA is the genetic material, or instructions, that makes us who we are. It determines certain traits, such as our height and eye color, as well as how our bodies function.
• The long molecules of DNA in your cells are organized into 23 pairs of chromosomes that you inherit from your parents (half from your mother, the other half from your father.)
• There are four types of nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
• From Nucleus to Cytoplasm:

  DNA (transcription)-> mRNA (translation) -> Protein
• Proteins - are made in the ribosome and contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur
• Proteins are made up of organic compound called amino acids.
• Different proteins are made by forming combinations from any of the 20 amino acids.
• A chain of amino acids is linked together by peptide bonds (chemical bonds between two molecules) and is called polypeptide.
• Proteins are made in the ribosomes in a process called protein synthesis.
• The process of converting the information in messenger RNA into a sequence of amino acids that make a protein is known as translation
• The role of transfer RNA (tRNA) is to bring amino acids in the cytoplasm to the ribosomes to make proteins
• Protein synthesis has two steps:

  Transcription & Translation
• Deoxyribonucleic acid -DNA
• Deoxyribonucleic acid - contains the hereditary information and directs reproduction of itself and

  the synthesis of RNA.
• Ribonucleic acid - RNA
• Ribonucleic acid - diffuse out of the cell nucleus and carry out the critical task of protein synthesis in ribosomes located in the cytoplasm
• The DNA and RNA are made up of three components: namely:

  • Sugar
  • Phosphate group
  • Nitrogenous base
• DNA is double stranded while RNA is single- stranded.
• The sugar in DNA is deoxyribose while that in RNA is ribose.
• TRANSCRIPTION The process in which the genetic information in DNA is transmitted or copied into the RNA.
• The process of making copies of DNA is called replication
• Messenger RNA - mRNA
• Transfer RNA - tRNA
• Ribosomal RNA - rRNA
• mRNA - carries the genetic information for a protein from the DNA in the nucleus to the ribosomes.
• The message is in the form of TRIPLETS OF BASES specifying AMINO ACIDS or PUNCTUATIONS called CODONS.
• mRNA - It is a complementary RNA copy of a gene on the DNA.
• rRNA - is a structural and functional component of the ribosomes.
• rRNA - This serves as the site of attachment for protein synthesis
• tRNA - This translates the genetic message through protein synthesis.
• mRNA - This carries the information from the DNA to the Ribosomes.