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.

Heterochromatin

Condensed chromatin Transcriptionally inactive Eg: Barr body in female cells represents inactive X chromosome, centromere, telomere

human chromosome

consists of a single DNA molecule of about 6 cm

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

nuclear proteins

Histone and non-histone proteins

Interphase chromosome

Nucleosomes arranged into chromatin: for transcription, replication, repair,

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

humans have 23 different types of chromosomes with a total of 46 since there are 2 each.