Module 6

• What does homeobox genes determine?


  They determine the anatomical development of an organism
• Mutations are changes in the sequence of nucleotides in DNA molecules.
• Insertion is a type of mutation that is when a nucleotide base pair is added onto the sequence.
• Deletion is a type of mutation when one nucleotide base pair is removed from the sequence
• Insertion and deletion mutations are known as frameshift mutations as they alter the sequence of the DNA
• Substitution mutation (point mutation) is when one nucleotide base is switched for another.
• Nonsense mutation is where translation is stopped early as the release of stop codon is released early. This makes the sequence shorter and less developed.
• Missense mutation - A change to the codon which codes for a different amino acid
• Silent mutations is a change in the codon but does not affect the amino acid sequence produced.
• Substitution mutations can either be nonsense, missense or silent
• Mutations can have a neutral effect, beneficial effect and a detrimental effect.
• Mutations that have a neutral effect is when the mutation does not affect the organism. For example, it could have occurred in a non-coding region of the DNA.
• Mutations that cause a beneficial effect to the organism can be preventing a disease.
• Mutations that can give a detrimental effect is when a protein that enhances a disease is formed by a change in the sequence of the amino acid.
• Gene expression can be controlled by the transcriptional, post-transcriptional and post-translational levels.
• Lac operon is a transcriptional control that is a section of the DNA that are composed of structural genes and control the expression of beta-galactosidase which is responsible for the hydrolysis of lactose in e.coli.
• The promoter region is the binding site for RNA polymerase to initiate transcription.
• operon is a cluster of genes under the control of the promoter
• lac operon controls lactase production by making the lactose bind to the repressor protein
• mutations can have no effect on the protein produced from that gene as they are degenerate ( some codons code for the same triplet). Therefore the sequence of the amino acids have not been altered causing no effect on the shape of the protein.
• Mutations that can alter the protein is insertion or deletion as they cause a frameshift to the sequence. This will cause the triplets to be different and can cause a change in the structure and shape of the protein.
• The three types of adaptations are: behavioural, physiological and anatomical.
• Mitosis is involved in development of body plan, production of new stem cells, proliferation of white blood cells.
• After transcription, gene expression can be regulated as the primary mRNA is modified. Once the introns are removed, the mRNA becomes mature. Splicing occurs to create the mRNA. This then produces the protein that activates CAMP. CAMP alters the shape of the protein.