Gene Regulations and Mutations
Gene Regulation Genes are regulated differently in prokaryotic cells vs. eukaryotic cells 21,000 genes in the human genome Expressed genes= genes that are turned into RNA
Prokaryotic Gene Regulation Operon/Operator- a functioning unit of DNA containing a multiple genes under the control of a single promoter Usually only found in prokaryotes turns the genes “on” or “off”
Prokaryotic Gene Regulation Repressor proteins stop the transcription process RNA polymerase is blocked by the protein and therefore cannot transcribe the gene.
Eukaryotic Gene Regulation Genes are controlled individually Regulatory sequences are much more complex then in prokaryotes Genes are regulated by enhancer sequences Enhancer region
Cell specialization Cell specialization requires genetic specialization Specific cells must express specific proteins Pancreas= insulin protein Skin cells= keratin protein Blood cells= hemoglobin protein Only a small fraction of genes need to be expressed in any given cell Prokaryotes are single celled and so they have to express ALL genes
Development and Differentiation Cells don’t just grow and divide during development they also differentiate specialized in structure and function
Hox Genes Cells become specialized based on location in the body and hox genes Hox genes- control the body plan of cells in the embryo
Mutations Mutation= changes in the DNA code during the replication process DNA polymerase adds the wrong nucleotides Changes in the gametes effect the entire organism Changes in the body cells effect only that cell
Chromosomal Mutations Chromosomal mutations- changes to the whole chromosome Changes in the number or structure of chromosomes
Changes in Chromosome Number What is the normal number of chromosome in a human cell? 46 (23 pairs)
Chromosomal mutations Deletion Duplication Inversion Translocation
Gene Mutations Gene mutations- changes to a single gene
Types of Gene Mutations Point mutation one base pair is replaced by another Changes in one or a few nucleotides
Types of Gene Mutations Frameshift mutations Codon pairing changes, changing the whole sequence of amino acids Insertions: one or more base pairs are added to the sequence Deletions: one or more base pairs are deleted from the sequence
Effect of Mutations Silent Mutation- have not effect Even though the RNA strand is effected the same amino acid sequence is made How is this possible? 1 amino acid is created by more than 1 codon
Effects of Mutations Substitution: base pair is substituted and the new codon codes for a different amino acid There are still the same number of bases in the RNA strand
Effects of Mutations Premature Stop: substitution results in the formation of a STOP codon before all codons have been translated UAA UAG UGA
Effects of Mutations Codon Deletion or Insertion: A whole new amino acid is added, or one is missing from the protein Caused by the addition or removal of bases in the DNA strand
Practice Evaluating Mutations Original DNA Strand: TACGGGTACGGCGGCATT Original mRNA strand: Original amino acid Sequence: Mutated DNA Strand: TACGAUTACGGCGGCAUU Original mRNA strand: Original amino acid Sequence: Kind of Mutation: What is the Effect:
Significance of Mutations No impact Most mutations are neutral Positive impact Mutations provide genetic variability in organisms Plant and animal breeders use beneficial mutations to better crops and livestock Negative tioimpact Harmful mutans cause genetic disorders