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.