Download
1 / 102
1.04k likes | 1.3k Views
Biology 1112. Lecture Three. Slide 2 – Common terms and definitions - sporangium. Sporangium (sporangia) – is an organ containing and/or producing spores. It is also defined as a protective layer of sterile cells surrounding haploid spores in a sporophyte
E N D
Biology 1112 Lecture Three
Slide 2 – Common terms and definitions - sporangium Sporangium (sporangia) – is an organ containing and/or producing spores. It is also defined as a protective layer of sterile cells surrounding haploid spores in a sporophyte (defined as a spore-case or a receptacle for spores).
Slide 3 – Common terms and definitions – Sporophyte and gametophyte • Spore (zoospore) – an asexual reproductive cell that can develop into a free living organism • Sporophyte – Diploid structure and is a spore producing stage of protests and/or some plant life cycle with each cell containing two complete sets of chromosomes • It is also defined as the spore-producing individual or phase in the life cycle of a plant having alternation of generations • The sporophyte develops from the union of two gametes, such as an egg fertilized by a sperm; in turn, the sporophyte forms spores that develop into gametophytes. • Gametophyte – haploid, multicelled, gamete producing phase in life cycle of most plants. • Gametophyte is a phase of an organism’s life cycles in which the gametes (e.g. egg and sperm) are produced. • The gametophyte is haploid, that is, each cell contains a single complete set of chromosomes, and arises from the germination of a haploid spore.
Slide 4 – Common terms and definitions – hyphae and mycelium Hypha (hyphae) – is composed of fine microfilaments usually consists of chitin. These structures are usually involved in absorption structure component of the mycelium Mycelium – A multicellular structure that is formed by a mesh of branching hyphae
Slide 6 – General characteristics of protists • Most organisms that belong to the Kingdom of Protista (or protests) are generally unicellular organism. • Protists are eukaryotes and have a nuclear envelope encircling their genetic materials. • These eukaryotes have membrane bounded organelles within their cytoplasm. • Protists have plant-like, fungal-like, and at times animal-like characteristics • Some scientists believe they are the protists evolved into higher organisms. Paramecium
Slide 7 – Protists’ characteristics (movement) Mobility – most protists utilizes either flagella, cilia, amoeboid-like (using pseudopods) for movement
Slide 8 – Protist characteristics (energy production/consumption) • Food or energy production – protists could either utilize chloroplasts (autotrophic) for energy production, taking in (ingesting) organic substance via food vacuoles (heterotrophic), or possesses both the combined ability
Slide 9 – Protist characteristics (reproduction) • Reproduction – they could reproduce either asexually or sexually. Sexual reproduction generally occurs when conditions are harsh and that genetic diversity may aid in the organism’s ability to survive • Survival – when faced with harsh conditions, the protists develops many sporangia where spores are produced and released to propagate in many different locations where one of these locations may allow the ‘offspring’ of the protist to survive • Furthermore, protists may also survive the onset of harsh environments by forming cysts • A cyst is a dormant cell with a resistant outer covering, which allows it to survive harsh droughts, temperature changes and even digestive juices of the animal digestive tracts.
Slide10 – Importance of protists • Some protists belong to a group of free-floating organisms know as planktons are photosynthesizes and they gives off oxygen • These planktons provide food for other heterotrophic protists and animals • Protists also form symbiotic relationships with corals and allow the corals to become photosynthetic • A type of protists known as algae can provide valuable materials (e.g. agar) for medical or scientific research. Algae can processed to form fertilizers and can be harvested for algin – a pectin like substance that is added to ice cream, cheese to give it stable consistency • Diatoms – a type of protist with its silicate based outer shell will accumulate on the bottom of the ocean. These diatoms are harvested and used as filtering agents, sound proofing materials and gentle abrasives
Slide 11 – Chytridiomycota Chytrids (chytridiomycota) – chytrids are molds that predominantly exists in both marine and fresh water environments Most of these organisms are saprobes – a type of heterotrophs that secrete digestive enzymes to break down organic substances in its immediate surroundings. Once the organic substance is broken down, chytrids than absorb the nutrients Some Chytrids are parasites on living plants and animals (e.g. mosquito larvae, nematodes and liver flukes) Most of the chytrids are also known as decomposers which are responsible (generally) for breaking down dead materials Chytrids have chitin strengthening their cell walls, and one subgroup (Hyphochytrids) have cellulose as well
Slide 12 – Chytridiomycota lifecycle of Allomyces – alternation of isomorphic generations
Slide 13 – Water molds (Oomycota) Oomycota are saprobic decomposers that reside mostly in moist and/or aquatic habitats Oomycota are previously grouped into Kingdom Fungi but now are placed in protests There are about 475 species of Oomycota Oomycota are commonly referred to as Oomycetes Some oomycota are parasitic (e.g. blight of potatoes – Irish potato famine in 1845-1847) They produce extensive mycelium and contain cellulose in their cell wall rather than chitin They can reproduce sexually and asexually
Slide 14 – Lifecycle of Oomycota (Saprolegnia ) - alternation of heteromorphic generations
Slide 15 – Cellular slime molds (Acrasiomycota) Cellular slime molds (Acasiomycota) - spend most of their lives as separate single-celled amoeboid protests Cellular slime molds consists about 65 species These free living amoeba like cells are phagocytic predators and feed off bacteria or decomposers who feeds off decaying leaves or bark These amoeba like cells are haploid (n) containing a single nucleus These organisms are similar to plants where they are rich in cellulose
Slide 16 – Reproductive cycle of cellular Slime Mold (Dictyostelium discoideum)
Slide 17 – Plasmodial slime molds Plasmodial slime molds (Myxomycota) are composed of many single celled slime molds with no cellular boundaries which gives it the appearance of having thousands of nuclei Plamsmodial slime molds consist of 450 species They are formed when individual amoeboid like cells swarm together and fuse There are no boundaries between the individual amoeboid-like cells therefore they are referred to as multinucleate plasmodium The result is one large bag of cytoplasm with many nuclei with free floating cytoplasm also known as cytoplasmic streaming These plasmodial slime molds are both predatory as well as decomposers where they ingest bacteria, fungal spores and dead leaves etc. The plasmodial slime molds reproduce both sexually and asexually
Slide 20 - Protozoan cysts (Entamoeba histolytica - amebic dysentery)
Slide 32 – General symptoms of Malaria Matured trophozoite and ruptured schizont in red blood cells
Alternation of generation – the life cycle of the organism is alternating between haploid (1N) and diploid (2N). There are two types of alternation of generations: Slide 38 – Alternation of generation
Haplontic reproductive cycle – the adult is haploid (1N) Slide 39 – Haplontic and Diplontic reproductive cycle Diplontic reproductive cycle – the adult is diploid (2N)
Slide 42 - Diatoms • They are important part of the food source for both fresh water and marine organisms • The diatom is composed of a box like structure where it is arranged in a two half structural system – a larger top half and a smaller lower half • Outside of the cell wall of the diatom is a silicate compound similar to glass and are used for protection • Diatoms lack flagella and are free-floating organisms • Asexual reproduction – where the asexually reproduced half receives the top half of the “box” while the new “box” grows inside of the old one - Because of the box within a box system of asexual reproduction, the new organisms are 30% smaller on average than the original. • Sexual reproduction – (haplontic) diatoms produces oogamy (sperm and egg) while the sperm are flagellated - The zygote (2n) grows and divides mitotically and produces diatoms of normal size • Commercial benefits – The remains of diatoms with its silicate based outer shell will accumulate on the bottom of the ocean. • This is harvested and is used as filtering agents, sound proofing materials and gentle abrasives
Slide 44 - Dinoflagellates • If the cell wall is present, they are mostly composed of cellulose plates • This type of organism possesses two flagella for mobility • They contain both chlorophyll a and c and are also a part of the phytoplankton population within earth’s oceans • Reproduction – Dinoflagellates proceed through mitosis (asexual reproduction a form of binary fission) nevertheless they have some significant differences in their process of mitosis • The nuclei of the dinoflagellates are unlike those of any other organisms – the chromosomes lack any centromere and are permanently in condensed formation • Even when the organism is proceeding through mitosis, the nucleolus and nucleus persist throughout cellular division • Benefits – some dinoflagellates forms symbiotic relationships with corals and allow corals to become photosynthetic • Commercial significance – Some dinoflagellates when their population increases may cause “red tide” • These dinoflagellate produces a type of neurotoxin that causes paralysis in fish and could be accumulated in shellfish • These shellfish, if consumed by humans, will cause paralysis of the respiratory tract and eventually death
Slide 46 - Euglenoids • One-third of this group is photosynthetic (photoautotrophs) while the remaining are heterotrophs (ingesting or absorb organic materials for food). • They contain two flagella where one is longer than the other • They have a pyrenoid – which is centers of carbon dioxide fixation • Through carbon dioxide fixation they produces a type of carbohydrate known as paramylon for storage and utilization • They have chloroplasts containing chlorophylls a and b and various carotinoids • Euglenoids also have an eyespot, which contains photoreceptors for detecting light. • Reproduction – mitosis (asexual) in a form called longitudinal cell division
Slide 48 - Chlorophyta • This unicellular organism and/or multicellular organism comprise of 8000 different species • They live in oceans, fresh water or even on land where abundance of moisture is available. • Green algae form symbiotic relationship with fungi, plants and even animals. • They are believed to be closely related to plants since they possess cell walls that contain cellulose and have chlorophyll a and b and stores starch inside the chloroplast, which is similar to that of plants. • These organisms release oxygen as a by-product just like plants • Sexual reproduction – Haplontic cycle
Slide 49 – Flagellated green algae • This type of protist has a definite cell wall and a large cup-shaped chloroplast that contain a pyrenoid (where starch is synthesized) • This algae also contain a stigma or eye spot to identify where the light source are located and direct the two whip-like flagella towards the light source • Sexual reproduction – Haplontic cycle Pyrenoid
