Genes to ecosystems tri 1 lect 4

  • Created by: Loz1669
  • Created on: 31-12-19 13:08
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  • Genes to Ecosystems
    • Flow of information through the cell
      • Gene: hereditary unit of function
        • Types of genes:
          • Structural: produce proteins that are involved in the structure and architecture of cells and organisms
            • Example: collagen which is a component of hair and skin
            • Example: tubulin which is a part of the cytoskeleton that maintains the shape and structure of cells.
          • Housekeeping: these genes encode proteins that function as enzymes and catalyse metabolic reactions within the cell. The proteins produced by these genes are crucial to the function of the cells and the overall organism.
            • Example: The breakdown of ATP to produce energy for the cell.
          • Regulatory: these genes encode proteins that function to regulate other genes. These are often responsible for the overall architecture of an organism
            • Example: the gene for polydactyl (extra finger) or other regulators such as hormones or growth factors.
        • Structure of a gene
          • Mode of DNA and arranged along a single strand of DNA which is wrapped in a protein package as a chromosome
          • Genes are arranged along the DNA strand.
          • Each gene has a start of the gene and an end.
          • They often have a regulatory region called a promoter.
          • A gene is made of DNA - a string nucleotides.
            • Proteins are made of a string of amino acids
            • Structure of DNA
              • Double Helix
                • Two strands of the backbone are compromised of sugars linked by phosphate groups. The two strands are antiparallel.
                  • The direction of the backbone is described and 3' and 5' based on the chemical structures of sugars.
                  • Strong covalent bonds link the sugars with the phosphate groups and the bases.
                    • These 3 components form a nucleotide
              • Four bases adenine, guanine, cytosine and thymine
                • Weak chemical bonds called hydrogen bonds are responsible for base pairing and are easily broken.
              • DNA is a string of nucleotides and is sometimes called a polynucleotide.
              • Properties of DNA
                • Double stranded DNA can be easily denatured into Z single stranded molecules. This can occur by heating the DNA to a temp greater than 63. This is due to weak hydrogen bonds between bases. The two strands can reform into the double helix if the DNA is cooled, returned to neutral pH or by enzymes.
            • DNA replication
              • 1. Complex of enzymes unwinds the DNA and separates the two strands
                • 2. The enzyme DNA polymerase then copies each strand running in 3' or 5'
                  • 3. It copies each of the two strands to produce a new strand that is complementary to the existing strand.
            • Flow of info from DNA to a protein
              • DNA is transcribed into messenger RNA (transcription) occurs in cell nucleus
                • Once mRNA is produced it crosses the nuclear membrane into the cytoplasm where it is translated into a protein. (translation)
                  • Translation
                    • Converting info from mRNA into proteins
                      • mRNA is translated into 3 groups known as a codon with a starting codon being AUG
                        • How does translation work?
                          • mRNA and tRNA and the ribosome (made of proteins and rRNA are required.
                • Structure of mRNA
                  • Single sugar phosphate backbone with A&T and C&U
                  • Runs from 5' to 3' which is the opposite to a DNA strand.
                  • Start codon is AUG
                  • Stop codons are UAA/UAG/UGA
                • Transcription
                  • 1. Proteins unwind DNA to produce single stranded DNA
                    • 2. RNA polymerase copies 3' to 5' strand of the DNA producing a 5' to 3' RNA molecule that has a complimentary base sequence.
                      • 3. mRNA is release and the double helix reforms.
                        • 4. mRNA processing
                          • on its own mRNA is fairly unstable and can be easily broken down
                            • processing prevents this from happening.
                              • 1. 5' cap is added to 5' end of the mrna
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