Welcome to the Molecular Genetics page!
Section One: Cellular Division (Mitosis/Meiosis)
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The picture on the right is of a garlic root tip cell in metaphase was taken by an MHS student using a digital light microscope at 400x. The chromosomal squash procedure used aceto-orcein stain. Note, the image is so clear, it is even possible to make out the individual chromosomes.
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The key concepts here are that there are two kinds of cellular division:
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Asexual (mitosis) which involves no change in chromosome count.
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Sexual (meiosis) which involves a chromosome reduction by half.
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The goal of the two processes is very different.
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Mitosis allows for growth, repair and differentiation.
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Meiosis sets the stage for the recombination of two genomes.
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The rest of the focus for this section will be on terminology, events and processes.
Section Two: The Chemistry of Life
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This section is placed here as a primer to the molecules, terminology and bond processes necessary to understand molecular genetics.
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It is easy to get overwhelmed with this section if you haven't had a lot of chemistry (at least grade 11) so review each night, ask questions and come in for help when you need it.
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Our curriculum adds photosynthesis and cellular respiration in this section as these two energy systems are best understood with a little chemistry behind you.
Section Three: DNA is The Molecule of Life
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DNA is considered the molecule of life because in its vast code, it allows for both biological complexity and continuity.
It always helps when we take a little tour through history...
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Key figures from your notes are Meisher, Levine, Griffith (and Avery), Chargaff, Franklin, Watson and Crick.
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The continuity of life relates to the structure of DNA and its mechanism of semi-conservative replication.
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The complexity of life generally refers to DNA's ability to create mirror copies of itself in small enough pieces (genes transcribing RNA) that are capable of coding for all of life's functions.
Section Four: DNA in Action is Gene Expression
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It's very size and fragility limits DNA's ability to make anything in the cytoplasm take place directly. It is locked into the protective envelope of the nucleus.
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As a result, DNA makes discrete copies of a mirror image of itself in the form of RNA using units called genes in a two-step process called transcription and translation.
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RNA, in one of three forms, makes possible the conversion of the genetic code into protein polymers.
Section Five: Looking at the heredity of traits (Mendelian Genetics)
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Once again, it is important to travel back in time to glimpse some of the early beliefs in human heredity. We'll even see how dating practices of Victorian England were influenced by misguided science.
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The 'Father' of genetics, Gregor Mendel, worked wonders with no formal understanding of chromosomes or DNA. His laws of heredity are still applicable today (with slight modifications for terminology).
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One of your largest projects will be in this section with the completion of your family tree.