SUMMARY
Essential Cell Biology chapter 2 (p. 76-77), 5, 7, 8 (without p. 280-284)
Chapter 2 –Nucleotides (p. 76-77)
Nucleotides consist of a sugar, a phosphate and a base. They are bonded through
phospodiester bonds and are then called nucleic acids. Nucleotides are coded by their bases.
The nucleotide bases are Adenine, Guanosine, Cytidine, Thymidine and Uridine. Uridine is
used in RNA instead of thymidine.
The sugar is a five carbon sugar (pentose). Deoxyribose is found in DNA, ribose is found in
RNA.
Chapter 5 – DNA and Chromosomes
DNA: Deoxyribonucleidacid. Double stranded helix of polynucleotides.
Nucleotides: sugar, phosphate, base (A, T, C, G).
Chromosomes: one folded double stranded DNA molecule. All nucleuses of each human cell
contain 46 chromosomes, except for the gametes, they contain 23 chromosomes.
Genome: total number of chromosomes in each nucleus. Genes contain instructions to make
proteins.
Genome folding
The two helix strands are antiparallel.
The 5’ side of the DNA refers to the
fifth carbon group in the sugar of the
first nucleotide where the phosphate
binds. The 3’ side of the DNA refers to
the hydroxyl group where the
phosphate binds in the complementary
DNA strand.
DNA has a polarity, which is the
phosphate and the hydroxyl group that
attract each other because of their chemical difference.
Chromosomes are folded by histones. Histones are proteins that are positively charged (they
contain lysine, arginine) and bind to DNA, which is negatively charged. The histones form
octamers and fold around 147 base pairs.
Nucleosome = 8 histones with 147 base pairs
Chromatine = all DNA with all proteins (histones and transcription factors)
Chromosome structure
46 in a human cell.
Long (q) and short (p) arm.
Telomeres = DNA sequence that caps the ends of the DNA-molecule,
to prevent them from being mistaken for broken DNA.
Centromere = DNA sequence that allows replicated chromosomes to
separate during mitosis.
Nucleolus = part of the nucleus where ribosomal RNA’s are
synthesized and clustered.
Essential Cell Biology chapter 2 (p. 76-77), 5, 7, 8 (without p. 280-284)
Chapter 2 –Nucleotides (p. 76-77)
Nucleotides consist of a sugar, a phosphate and a base. They are bonded through
phospodiester bonds and are then called nucleic acids. Nucleotides are coded by their bases.
The nucleotide bases are Adenine, Guanosine, Cytidine, Thymidine and Uridine. Uridine is
used in RNA instead of thymidine.
The sugar is a five carbon sugar (pentose). Deoxyribose is found in DNA, ribose is found in
RNA.
Chapter 5 – DNA and Chromosomes
DNA: Deoxyribonucleidacid. Double stranded helix of polynucleotides.
Nucleotides: sugar, phosphate, base (A, T, C, G).
Chromosomes: one folded double stranded DNA molecule. All nucleuses of each human cell
contain 46 chromosomes, except for the gametes, they contain 23 chromosomes.
Genome: total number of chromosomes in each nucleus. Genes contain instructions to make
proteins.
Genome folding
The two helix strands are antiparallel.
The 5’ side of the DNA refers to the
fifth carbon group in the sugar of the
first nucleotide where the phosphate
binds. The 3’ side of the DNA refers to
the hydroxyl group where the
phosphate binds in the complementary
DNA strand.
DNA has a polarity, which is the
phosphate and the hydroxyl group that
attract each other because of their chemical difference.
Chromosomes are folded by histones. Histones are proteins that are positively charged (they
contain lysine, arginine) and bind to DNA, which is negatively charged. The histones form
octamers and fold around 147 base pairs.
Nucleosome = 8 histones with 147 base pairs
Chromatine = all DNA with all proteins (histones and transcription factors)
Chromosome structure
46 in a human cell.
Long (q) and short (p) arm.
Telomeres = DNA sequence that caps the ends of the DNA-molecule,
to prevent them from being mistaken for broken DNA.
Centromere = DNA sequence that allows replicated chromosomes to
separate during mitosis.
Nucleolus = part of the nucleus where ribosomal RNA’s are
synthesized and clustered.
