DNA Flashcards
State the difference between heterochromatin and euchromatin
HETEROCHROMATIN
Solenoid fibre
Genes not expressed
EUCHROMATIN
Beads on a string
Genes expressed
Describe structural components of nucleic acids.
Compare DNA and RNA
Nucleic acids formed of chains of repeating units.
Nucleotides: (DNA) Pentose sugar (-H) + Nitrogenous base + phosphate
Nucleosides: (RNA) Pentose sugar(-OH) + Nitrogenous base
Describe the relationship between DNA, chromosomes and genes.
One DNA molecule formed from sugar group, phosphate group + base (1 of 4 - ATCG).
Genes = segment of DNA
Chromosome = Tightly packaged DNA around histones (chromatin) > coils to solenoid structure of chromosome.
Describe DNA replication
- Catalysed by DNA polymerase
- DNA strands separate
- Stepwise reaction (pyrophosphate hydrolysis)
- Direction chain growth 5’ to 3’
Describe the types of DNA mutations at the nucleotide level.
- Substitution (change of a single letter) Sickle Cell
- Deletion (DNA section deleted)
- Insertion (extra base pairs inserted into DNA section) Huntington’s
Describe the types of DNA mutations at the chromosomal level.
- Duplication
(Sister chromatids don’t split equally) - Deletion
(Part of chromosome breaks off in meiosis) - Translocation
(Broken part attaches to non-homologous chromosome) - Inversion
(Broken part flips and reattaches)
What are telomeres?
Repeated sequences (TTAGGG) at the end of each chromosome / chromatid
Which enzymes are involved in DNA replication?
HELICASE
- Separates strands
DNA PRIMASE
- Lays primers for DNA Polymerase
DNA POLYMERASE
- Builds complimentary strands
LIGASE
- Fills in gaps (Okazaki fragments)
Compare DNA and RNA
5 Differences
- DNA double stranded, RNA single strand
- DNA deoxyribose sugar, RNA ribose sugar
- DNA Nucleus, RNA Cytoplasm
- DNA Thymine, RNA Uracil
- DNA stable (histones), RNA free / degradable
