DNA and Meiosis Flashcards

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1
Q

Explain how a change in sequence of DNA bases could result in a non-functioning enzyme

A
  • Change in primary structure
  • Change in hydrogen/ionic/disulfide bonds
  • Alters tertiary structure/active site (of enzyme)
  • No enzyme-substrate complexes form
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2
Q

Define “allele”

A

(different) form/type/version of a gene/different base sequence of a gene

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3
Q

Explain the ‘X’ shape of a chromosome

A
  • Two/sister chromatids
  • Due to DNA replication
  • Joined by a centromere
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4
Q

Give reasons why there are more genes than the minimum amount of genes that code for set amounts of amino acids

A
  • Start/stop codons
  • Non coding DNA/introns/multiple repeats/junk DNA
  • Two chains/a non-coding strand/complementary base pairs
  • Addition of bases by mutation
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5
Q

Why might homologous chromosomes not be genetically identical despite carrying the same genes

A

They carry different alleles

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6
Q

Describe the role of independent segregation in meiosis

A
  • To provide genetic variation
  • Allows different combinations of maternal and paternal chromosomes/alleles
  • To produce haploid cells/half the chromosome number
  • Allows homologous chromosomes/pairs to arrange randomly at the equator of the cell
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7
Q

How is the structure of DNA related to its function?

A
  • sugar-phosphate (backbone)/double stranded/helix provides strength
  • Long molecule so can store lots of information
  • Helix/coiled so compact
  • Base sequence codes for amino acids/proteins
  • Double stranded so strands can act as templates for replication
  • Complementary base pairing so accurate replication
  • (weak) hydrogen bonds for unzipping/strand separation
  • many hydrogen bonds so stable/strong
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