Week 7

Note: most of the latter part of this week's notes were taken down verbatim from Dr Paul Matewele's onscreen notes, with a little contraction in places.

Today's Topics:
○ eukarya

Lecture Topic:
○ Differences:
§ Eukarya
□ "True nut"
□ Organelles
□ Golgi
□ Mitochondria
□ Endoplasmic Reticula
□ Nuclear membrane
□ Nucleus
□ Histones
□ Non histones
□ Multiple chromosomes (mainly)
□ Use mitosis & meiosis
□ 80s ribosomes
§ Prokarya
□ "Before nut"
□ Single chromosome (mainly)
□ 70s ribosomes
○ In meiosis, progeny is haploid, and diploid status is restored by sexual reproduction. Prokarya do not use sexual reproduction.
○ Mitosis - non sexual reproduction. Diploid parent produces two diploid offspring. Mitosis (genetic reproduction) is followed by cytokinesis (cell division). Mitosis --> Cytokinesis --> G1 phase (growth) --> S phase (DNA synthesis) --> G2 phase (more growth) --> Mitosis.
○ Meiosis - sexual reproduction. Gametes fuse (cytoplasm only) - plasmogamy - forms dikaryon (two nuclei) --> Nuclei fuse - karyogamy - forms diploid zygote --> meiosis - forms four haploid gametes --> gametes fuse.
○ Plasmogamy and karyogamy may be referred to collectively as syngamy.

○ Different types of eukaryotes:
○ Fungi, protozoans, algae.
○ Fungi and algae have cell walls. Fungi generally have chitin, whilst algae have cellulose or cellulose and pectin. Protozoans have no cell wall. The morphology of protozoa is maintained by an ectoplasm - gelatinous material the cell membrane - this is inside cell membrane, unlike the slime capsule that bacteria use.
○ Fungi
§ Can be divided into two classes - fungi perfecti and fungi imperfecti.
§ Fungi perfecti have a sexual stage, aka the perfect stage, whereas fungi imperfecti have no sexual reproduction.
§ The species or genus names are also associated with the type of spores produced during sexual reproduction, e.g. Bacidiomycetes produce basidiospores. An example is Agaricus bisporus, the common mushroom. Ascomycetes produce ascospores; examples include Penicillium notatum and Aspergillus niger. Oomycetes produce oospores; examples include Lagenidium callinectes and Phytophthora infestans.
§ An example of fungi imperfecti is the class of dermatophytes, which cause skin infections such as Trichophyton rubrum, which causes athletes foot.
§ Characterisation of fungi is generally based on the types of spores produced and the spore bearing structures.
§ Spore grows into a germ tube, which then becomes a hypha. Mycelia branch off of the hyphae, and spore bearing structures grow on the mycelia.
§ Example: P. infestans, an oomycete. (see diagram in lecture notes book, page 21).
○ Algae
§ These can carry out photosynthesis.
§ The type of chlorophyl - a / b / c / c1 / c2 / d - can be used in their classification.
§ Algae in deep oceans cannot absorb light directly; they have pigments called phycobilins. Some are red - phycoerythrins, and others are blue - phycocyanins.
§ The storage products can also be used in classification, e.g. starch, lipids, and glycogen.
§ The cell wall is predominately cellulose.
§ Some algae are flagellated, and have various habitats. This is another source of classification.
§ Example: Ulva spp. (see diagram in lecture notes book, page 22)