Organizational Hierarchy, Nucleus

disease

loss of normal function

Scurvy

Nutritional deficiency

• Most animals make vitamin C - not primates and guinea pigs

• Vit C is required for collagen synthesis

• Collagen is a major component of connective tissue

causes increased hemorrhaging - BV rely on collagen/connective tissue for structure

lots of abrasion on gums causing more visible signs and lots of BVs close to the surface

Nieman-Pick Type C disease (NPC)

cholesterol storage disorder

• cholesterol is an important lipid for membrane function and a precursor to steroid hormones and bile acids

• cells can acquire cholesterol by endocytosis of circulating LDL’s

• cholesterol is water insoluble and requires a specialized protein machine for transport out of the lysosome

caused by mutations in the cholesterol transport machine

NPC disease pathology

occurs in humans and siamese cats

neurological defects present in juveniles

• CNS is particulary susceptible to toxic cholesterol accumulation

  • results in neuron loss in the brain (Purkinje cells - coordinate motor function)

• clumsiness, learning disabilities, and loss of body control (ataxia)

• premature death

hierarchical organization - where things happen and are seen

nucleus

compartment for storing and managing genetic information

DNA

sugar-phosphate backbone

directionality (5’ → 3’)

nitrogen-containing base

• Adenine - Thymine

• Guanin - Cytosine

chromatin compaction

chromatin is DNA + histones

Heterochromatin is more tightly packed, less actively expressed than Euchromatin

nuclear structure

nuclear membrane (envelope) - inner and outer membrane

nuclear pores - small molecules can freely diffuse (RNA nucleotides), larger molecules (protein, RNA) are regulated

lamina - cytoskeleton of nucleus, gives spherical shape (WBC exception)

mitotic figures

used to assess cell division in tissue

nucleolus (pl. nucleoli)

one or more dense compartments within nucleus

provides a gauge of cellular activity

site of ribosomal RNA transcription and assembly with ribosomal proteins

DNA replication

unwrap DNA from histones → DNA remodeling

open the helix to separate the DNA strands → helicase

unwind/rewind the DNA → topoisomerase

copy the DNA → DNA polymerase

semi-conservative process

synthesized 5’ to 3’

transcription

gene expression

a means to protein translation

RNA

Bases

• Uracil - Adenine

• Guanine Cytosine

types: mRNA, rRNA, tRNA, snRNA (small nuclear)

Single-stranded - can fold into diverse forms with carious functions (structural and catalytic)

some viruses genomes are RNA

structure of a gene

coding region

• exons - expressed

• introns - intervening sequences

promoter (influences transcription, when and where)

• recruit transcription factors that enable RNA polymerase binding