diversity

• What is one type of DNA and where is it located?

  DNA in eukaryote nucleus (nucleated organisms: all organisms apart from all bacteria, all viruses and some algae).
• What is a second type of DNA and where is it found?

  DNA in prokaryotes: in cytoplasm (no nucleus).
• What is a third type of DNA and where is it found?

  DNA in mitochondria and chloroplasts, only found in eukaryotes.
• Where is the fourth place where DNA can be found?

  In viruses.
• What is DNA stored as in eukaryotes?

  Chromosomes
• What shape are chromosomes in eukaryotes?

  Linear
• What tightly wrap around DNA in the nucleus and condense DNA?

  Histones
• What is the complex on DNA wrapped around a histone called?

  Nucleosome
• Is DNA double stranded in eukaryotes?

  Yes
• What does DNA contain in eukaryotes?

  Introns
• What are introns?

  Non-coding regions of DNA.
• What size are DNA molecules in prokaryotes and shape?

  Small and are circular loops of genomic DNA.
• Is the DNA wound around histones in prokaryotes?

  No
• Does DNA in prokaryotes contain introns and why?

  No, as there is not enough space.
• What does the DNA do to fit into the prokaryotic cell?

  Supercoils
• Is DNA double stranded in prokaryotes?

  Yes.
• What is DNA in the mitochondria and chloroplasts similar to?

  To prokaryotic DNA
• So what size and shape is DNA in mitochondria and chloroplasts?

  Short and circular.
• Is DNA in mitochondria and chloroplasts wound around histones?

  No
• Why do mitochondria and chloroplasts have their own DNA?

  As essential reactions occur within them: aerobic respiration and photosynthesis. So the DNA codes for enzymes essential for those reactions.
• What is the shape of DNA in viruses usually?

  Linear
• Viruses may have what as their genetic material?

  DNA or RNA
• Can viral DNA be double stranded or single?

  Both.
• Does DNA in viruses have introns or any associated proteins?

  No.
• what's a gene?

  A specific sequence of nucleotides that codes for a specific sequence of amino acids in a polypeptide.
• What's the locus?


  The location of a particular gene on a chromosome.
• What's an allele?

  Alternative form of a gene.
• What's a chromosome?

  In a eukaryotic cell, DNA is tightly coiled. Forming chromosomes, which is stored in the nucleus.
• How many pairs of chromosomes do humans have?

  Humans have 23 pairs of chromosomes, for a total of 46 chromosomes.
• What is the start codon?


  On the start on every gene, codes for the amino acid methionine- which is later removed from the protein if it is not needed for the structure.
• What's the end codon?


  On the end of every gene, 3 bases that don't for an amino acid. Marking the end of a polypeptide chain. Causes ribosomes to detach and so translation stops.
• How many amino acids is there for the genetic code to code for?

  20
• What are the four DNA bases?

  Adenine, Thymine, Guanine, Cytosine
• What does a triplet consist of?

  Three bases.
• How can you prove that 3 bases are needed to make enough combinations to code for at least 20 amino acids?

  Mathematically by $4^n$
• What does 4 and n stand for in $4^n$


  4- is that there are 4 options of possible bases. n- is the number of bases that make up the genetic code.
• How many bases needed to code for at least 20 amino acids?

  3
• What does degenerate mean?

  More than 1 triplet of bases code for the same amino acid.
• How is degenerate code an advantage?

  Because if a mutation happened, the triplet of bases would be different, but it would still code for the same amino acid and therefore have no effect- silent mutation.
• What does universal genetic code mean?

  The same triplet of bases codes for the same amino acid in all organisms.