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Genes & the Genetic Basis of Metabolism & Development - Coggle…
Genes & the Genetic Basis of Metabolism & Development
Storing genetic information
Protecting the genes
It is critically important that DNA is stored accurately, if storage is not safe the information produced by the DNA will be inaccurate, useless & even harmful
There are many ways where DNA is kept safely, most DNA is stored in the nucleus protected from the cytoplasm by the nuclear envelope
The genetic code
Is the set of nucleotide triples in DNA that code for amino acids to be inserted during protein synthesis
Genetic code is almost universal, all organisms & genetic systems all share one genetic code
The genetic code is the sequence of base triplets (codons) in mRNA that code for a specific amino acid. The genetic code is non-overlapping because, each codon is read in a sequence, separate from the codon before it and after it. Codons do not share their bases, therefore the code is non-overlapping.
The structure of genes
Most genes are quiescent most of the time and are activated and read only when the cell needs the particular enzymes they code for
Genes are made up of a structural region that codes for amino acid sequence and a promoter, controlling region involved in regulating the synthesis of mRNA
Transcription of genes
After RNA polymerase binds and encounters the start signal, it begins creating RNA in a process called transcription
Then, the two strands of DNA separate from each other over a short distance, and then free ribonucleotides diffuse to the region
Alternative splicing
Different forms of mature mRNAs (messengers RNAs) are generated from the same gene. Alternative splicing is a regulatory mechanism by which variations in the incorporation of the exons, or coding regions, into mRNA leads to the production of more than one related protein, or isoform.
Protein Synthesis
Ribosomes
Are small particles that read the genetic message in mRNA and construct proteins guided by that information
tRNA
Are necessary because a codon cannot interact directly with an amino acid the genetic code can be red only by a ribonucleic acid that has a three-nucleotide sequence called anticodon
An anticodon is needed in the transfer of RNA, the nucleotide triplet complementary to the codon of mRNA
mRNA Translation
The synthesis of a protein molecule by ribosomes under the guidance of mRNA is called translation
In protein synthesis the utilization of mRNa to guide the incorporation of amino acids into protein
mRNA mediates the transfer of genetic information from the cell nucleus to ribosomes in the cytoplasm, where it serves as a template for protein synthesis. Once mRNAs enter the cytoplasm, they are translated, stored for later translation, or degraded.
Ribosomes bind to mRNA and read its codons, guided by the information in the nucleotide sequence of the mRNA the ribosomes catalyze the polymerization of amino acids in the order specified by the gene from the mRNA was transcribed
Analysis of Genes & Recombinant DNA Techniques
Nucleic acid hybridization
Single-stranded nucleic acids DNA or RNA are allowed to interact so that complexes called hybrids are formed by molecules with similar, complementary sequences.
is a process used to identify specific DNA sequences. Specific DNA probes are denatured and annealed to sample DNA that has also been denatured.
Reannealing is used to determine the relatedness of two types of DNA
Restriction endonucleases
Protein produced by bacteria that cleaves DNA at specific sites along the molecule. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms.
Enzymes that recognize specific sites in DNA double helices then cut the two strands in complementary sites
Identifying DNA fragments
After restriction endonucleases have acted the DNA fragments can be identified and used.
Fragments are used directly to study the evolution of DNA
DNA cloning
Producing large numbers of identical copies of DNA, usually by inserting it into bacteria and allowing the bacteria to multiply
The colony that contains the important fragment can be subcultured and grown easily and each time a bacterium divides, a new copy of the experimental DNA fragment is made
DNA sequencing
Is used to determine the exact sequence of bases (A, C, G, and T) in a DNA molecule. The DNA base sequence carries the information a cell needs to assemble protein and RNA molecules. DNA sequence information is important to scientists investigating the functions of genes.
The steps to DNA sequencing
Sequencing entire genomes
ostensibly the process of determining the complete DNA sequence of an organism's genome at a single time. This entails sequencing all of an organism's chromosomal DNA as well as DNA contained in the mitochondria and, for plants, in the chloroplast.
