BIOLOGY 152 1st Edition Lecture 9Outline of Last LectureVasculature Xylem Phloem Angiosperm Reproduction Outline of Current LectureAngiosperm Reproduction contd. & Plant Growth Alternation of Generations Angiosperm Lifestyle Double Fertilization IV. Introduction to Animal PhysiologyThree Trends in the Animal Body Plan a. SymmetryCurrent LectureAngiosperm Reproduction & Plant Growth**Clicker Question**In some taxa of plant there are two different free living organisms as part of this life cycle (alternation of generation) Which of these is 1n?Gametophyte (G) Sporophyte (S) • A is 1n (sperm and egg), sporophytes are 2nAlternation of GenerationsThere is a sporophyte generation (2n) there is a gametophyte generation (1n) These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.each can function as different organisms, one makes sperm and egg cells, one makes spores in angiosperms and conifers, the gamteophytes are very reduced (still multicellular) in most animals, the sperm and egg are one cell Angiosperm Lifestyle• In the flowering plants the gametophyte is not free-living 1. Mesioiss in the flower creates pollen and ovule 2n —>1nlittle dots inside are the pollen (or male G)Pollen released & must be transfered to female G ( pollen lands on stigma and grows down) — to fertilize ovule Double fertilization — the sperm nuclei fuzes with the egg nuclei (1n from sperm, 1n from egg makes embryo a 2n organism) Embryo plus endosperm become a seed — becomes a plant the embryo in the seed is 2nthe G doesn’t come from a seed, it comes from a spore, so why it’s 1n 1. a fern doesn’t have seeds it has spores **Clicker Question**Almost any cell in a plant is totipotent, but there are notable exceptions. Which of the following is not totipotent? Leaf cell root cell embryo cell pollen Answer = D (pollen) because it is 1n the point of this question was to make you think about which cells were 1n and which were 2n a leaf cell is 2n, it can become anything because it has 2 copies of the genome all the plant species that are 2n have this capacity (to be grown from leaf cells, root cells, etc)embryo could because it is egg + sperm the seed is not just the embryo, there is more to a seed than that though (see further down) Double Fertilizationthe seed is a product of double fertilization there are 2 sperm nuclei in the pollen (two 1n nuclei) one of those nuclei fuses with the egg cell to become an embryo (which is 2n) the other nuclei fuses with two other cells (2 nuclei) — this makes a triploid nucleus (3n nuclei) it has 3 copies of the genome this creates the endosperm so double fertilization leads to the creation of the embryo and endospermThe seed is made up of the:seed coat (maternally derived, not coming from fertilization) — at the “top” of the seed and is 2n it is the brown covering that cracks and goes away as the plant grows in the middle is the endosperm (3n) at the bottom is the embryo (2n) the embryo is the part that becomes the plant, and the endosperm is then used up by the plant (consumed) by the time the seed is germinated, the endosperm is gone Endosperm :Starch, rice/wheat protein like beans sometimes very fatty (canola)the reason it is 3n is so that it can produce many of these biological molecules (carbs, proteins, fats), which can then feed the embryo endosperm = little packet of food for embryo advantage to being 3n is that it provides more copies of each gene **ClickerQuestion** Should the endosperm be totipotent? NO Think about: how many copies of each chromosome does the plant have? 2 copies (embryo turns into the plant and is 2n) The endosperm has too many copies to easily turn into any part of the plant— if the endosperm was 2n, then it would be totipotent Being 3n causes it to be infertile, because it arises from the nuclei making proteins, starches and fats What is a seed and what is a fruit?A seed is the embryo a fruit is maternally derived, it is the swollen ovary around the seed **Clicker Question**Where does meiosis occur? — Use the diagram from the lecture slides Think about where fertilization happens — have an embryo at D (2n) but meiosis is before that, or where the 1n’s are being made/split so where is that on the diagram?Answer = A**Clicker Question**The female gametophyte in maize is what?2n The green organism at right the silk the pollen the un-polinated kernels on the cob the gametophyte needs to be where the seed is/going to be, so when you plant the corn, what do you plant? the kernel Answer = E. The pollen lands on the silks and the pollen tube will grow the full length of that silk and every single kernel must be pollinated in order to get a nice corn on the cob. It grows extraordinarily fast (pollen tubes are the fastestgrowingcells)Introduction to Animal Physiology DefineWhat are animals?multicellular sexually reproductive (with some notable exceptions) complex organ systems eukaryotic heterotrophs mobile (common, not in all) no cell wall Generalized characteristics of animals (there are 2 major exceptions)Heterotrophic euk multicelllack cell wall- development is governed by a unique conserved genetic network (hox genes) *see the rest on slides*exceptions = the sea slug, which eats algae then digests the cell wall and brings the chloroplasts into its body so it can photosynthesize-sponges (porifera) who have no true muscles, nerves or box genesThree Trends in the Animal “Body Plan”Symmetry:radial symmetry: can split it laterally and has symmetrical sections bilateral symmetry: they must have a clearly defined front, back, top and bottom only animals that lack this are the cnidaria and upwards ancestral traits one that is shared by the taxa (groups of organisms) and includes ancestorsfor example, in the group mammals, giving birth to live young is an ancestral trait (going back in time all mammals have this)derived traits one not shared by ancestors but present in decedents - walking around on two feet is a derived trait for humans **Clicker Question**Does a starfish have radial or bilateral symmetry?Radial.Is radial symmetry a derived or an ancestral trait?Derived.The ancestral trait would be bilateral ism (although it does not have that trait, so it has a derived trait making it different from it’s ancestors. So most likely they lostthe trait because they didn’t select for it in their niche. Bilateral symmetry