SCI MT 3

• Protein synthesis is the process of making proteins from amino acids.
• Transcription is the first stage of protein synthesis where DNA is copied into mRNA by RNA polymerase.
• DNA stands for deoxyribonucleic acid
• Genes are made up of DNA which has proteins
• DNA is a molecule that carries genetic information inside the nucleus
• DNA is double stranded helix containing 2 meters of DNA
• Nucleotide is the basic unit / backbone of DNA
• Nucleotide consists of five-carbon sugar, phosphate group, and nitrogenous base
• Guanine always pairs with Cytosine
• Adenine always pairs with Thymine
• The two types of bases found in DNA are purines (adenine and guanine) and pyrimidines (cytosine and thymine)
• The sequence of bases on one strand determines the sequence of bases on the other complementary strand.
• Ribonucleic acid (RNA) is single strand helical structure
• RNA has uracil instead of thymine
• RNA contains ribose instead of deoxyribose
• Genes are a sequence of DNA nucleotides that control the formation of a single polypeptide, which is used to make proteins
• Genetic code contains the message used to make proteins
• For every 3 bases = one codon = one amino acid
• 50 amino acids to make one protein
• The phases of protein synthesis are transcription and translation
• Transcription: problem: DNA is too big that it cannot exit the nucleus
• Three major differences between DNA and RNA

  1. DNA double stranded, RNA single stranded
  2. DNA 1 type, RNA 3 types
  3. DNA has thymine, RNA no thymine (instead, uracil)
• Explain role of DNA in determining what an organism is to be and in producing variations in organisms

  DNA makes up genes. These code for different proteins and information of a person. The DNA in genes is responsible for unique features and characteristics.
• Explain why thymine and cytosine nucleotides cannot pair with one another

  C&T cannot pair with each other because of their structure
• Transcription occurs in the nucleus and is the process of copying the DNA into mRNA. (reducing the DNA to 1 strand)
• types of RNA: mRNA, tRNA, rRNA
• Transcription begins when the RNA polymerase binds to the promoter region of the gene. The promoter acts like a signal telling the polymerase where to start copying. Once the RNA polymerase is bound, the DNA molecule begins to unwind.
• Transcription Elongation: As the DNA unwinds, the RNA polymerase starts moving along the DNA strand. It reads the sequence of nucleotides in the DNA and builds a complementary RNA molecule. The RNA polymerase adds nucleotides one by one, following the base-pairing rules
• Transcription Termination: When the RNA polymerase reaches the end of the gene, it stops adding nucleotides to the growing RNA chain. This happens at a terminator sequence on the DNA. The newly formed RNA molecule detaches from the DNA and leaves the cell's nucleus through a nuclear pore.
• Transcription Processing: The RNA molecule produced during transcription is called pre-mRNA. Before it can be used to make proteins, it undergoes processing. After, the modified mRNA molecule is then ready to leave the nucleus and enter the cytoplasm, where protein synthesis will occur.
• Once transcription is complete, the RNA molecule undergoes processing to become mature mRNA, which carries the genetic information from the DNA to the ribosomes for protein synthesis.
• Translation: where the information in mRNA (which was copied from DNA during transcription) is used to build a protein
• Translation Initiation - mRNA molecule reaches a ribosome (protein-making factory). The ribosome attaches to the mRNA near its starting point, known as the start codon (AUG).
• Translation Elongation - the ribosome starts reading the mRNA, three nucleotides at a time. each set of three nucleotides, called a codon, codes for a specific amino acid. tRNA molecules bring the corresponding amino acids to the ribosome. the ribosome then links the amino acids together in the order dictated by the mRNA sequence.
• Translation Termination: Translation continues until the ribosome reaches a stop codon (UAA, UAG, or UGA) on the mRNA. When the ribosome encounters a stop codon, it releases the newly formed protein, and the whole translation process ends.
• Amino acids come from mRNA
• Population is the amount of same species in an area at a given time.
• Population is affected by mortality, natality, emigration, and immigration.
• Ideal environment has rapid increase in population and unlimited resources
• Realistic environment: S shape, slowly increases and becomes stagnant due to the limited resources