FOI.6 Nucleus: Understand the storage of genetic information and how it is passed down to successive generations and the principles of basic techniques in Molecular Biology
nuclear genome
- 23 pairs chromosomes (22 pairs autosome + X/Y sex) - protein-coding DNA (~2-5% of the genome!!!)
constitutive heterochromatin
- Always condensed (inactive)
Euchromatin
- Dispersed chromatin - Transcriptionally active genes
facultative heterochromatin
- Either condensed or dispersed (permanent or temporarily inactive genes)
centromere
- Noncoding DNA - Binds to mitotic spindle during mitosis - Has satellite DNA sequences - arrays of short repeats of DNA - satellites, mini- and micro-satellites
Bacteria genome
- circular in bacteria cells - attached to the plasma membrane - can include a separate DNA fragment - plasmid DNA
mitochondria genome
- code for genes for the electron transport chain - generation of ATP
plasmids
- small circular DNA - can carry antibiotic resistance genes - can be transferred between bacteria
Prokaryote genome
single circular chromosome
chromatin
string of nucleosomes connected by the linker DNA into a "beads on a string" arrangement DNA + Histones + Non-Histones - linker H1 - core H2A, H2B, H3, H4 Non-histone proteins: - HMGs, transcription factors, etc.
nucleosome
Basic unit of organization of DNA around a histone octamer (two each of the core histones H2A,H2B,H3 and H4).
Mitotic chromosome
Chromatin folded into highly condensed metaphase chromosomes for cell division
Heterochromatin
Condensed chromatin Transcriptionally inactive Eg: Barr body in female cells represents inactive X chromosome, centromere, telomere
Mitotic chromosome
The chromatin fibers are further folded into the highly condensed mitotic chromosome for cell division
Telomere
a region of repetitive DNA at the end of a chromosomes - Protects the end of the chromosome from deterioration - Repeated sequence in humans (TTAGGG repeats)
histone H1 binding
coils the nucleosomes into higher order required for higher order folding of chromatin (as seen in heterochromatin)
human chromosome
consists of a single DNA molecule of about 6 cm
nuclear proteins
Histone and non-histone proteins
Interphase chromosome
Nucleosomes arranged into chromatin: for transcription, replication, repair,
human chromosome
humans have 23 different types of chromosomes with a total of 46 since there are 2 each.