dna structure & replication

    Cards (15)

    • draw the structure of a nucleotide?
      nucleotide
    • name the pentose sugar in dna?
      deoxyribose
    • when does dna replication occur?
      before mitosis
    • what is dna?
      • contains genetic info of all living organisms
      • its used to instruct organism function,development & reproduction
    • dna nitrogenous bases?
      • adnenine & thymine - 2H
      • cytosine & guanine - 3H
    • dna structure?
      • monomer nucleotide
      • complimentary base pairs
      • double stranded - anti parallel
      • sugar phosphate backbone
      • adjacent deoxyribose sugars linked by phosphodiester bonds
      • 5' & 3' ends give dna strands directionality
      • dna tightly coiled by proteins to fit into nucleus
      • dna & histone protein - chromatin
    • purines?
      • adenine & gunanine
      • 2 carbon nitrogen ring bases
    • pyrimidine?
      • cytosine & thymine
      • 1 carbon nitrogen ring base
    • why is dna replication important?
      • before mitosis & meiosis dna replication must occur - basis for biological inheritance
      • certain somatic cells divide by mitosis so body can develop & grow tissues/organs
      • maintained & repaired in response to injury
      • meiosis occurs in specialised germ cells to produce sperm & oocytes
    • dna replication process?
      1. double helix separates into 2 strands - helicase breaks h bonds holding 2 strands together - each strand acts as template
      2. dna polymerase makes dna in 5' to 3' direction - adds nucleotides to template strand
      3. dna primase binds to 3' end of strand - always binds at starting point
      4. leading strand is template - replicated in same direction as movement of repli fork
      5. repli of lagging strand discontinuous - movement of dna polymerase in opp direction of repli fork requires multiple rna primers
      6. dna polymerase synthesise short fragments of dna - okazaki fragment
    • 4 types of mutation?
      1. base substitution
      2. deletion
      3. insertion
      4. rearrangement
    • mutations?
      • arise spontaneously due to errors
      • induced by dna damage
      • radiation can damage dna
      • mutagens - carcinogens
    • mutations in somatic cell?
      • not inherited
      • may lead to cancer
    • mutations in germ cell?
      • inherited in offspring
      • new genetic disease
    • what is dna replication
      • biological process of producing 2 identical replicas of dna from 1 original dna molecule
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