AMOEBA SISTERS YOUTUBE VIDEOS!: https://www.youtube.com/playlist?list=PLwL0Myd7Dk1F0iQPGrjehze3eDpco1eVz Cell •Smallest structural and functional unit of an organism •Somatic cells are any cells other than germ cells - Found throughout the body - Contain 46 chromosomes in humans •Germ cells contain half the number (23) of chromosomes - Only found in the ovaries and testes (sex organs) Cell Division Two types 1.Mitosis in somatic cells results in cells exactly the same as the parent cell. Involves one “set” of division stages. 2.Meiosis in germ cells results in a variety of genetically different offspring. Involves two “sets” of division stages (Meiosis I & II). Vocabulary •Chromatin – unwound DNA •Chromosome – tightly packed DNA found only during cell division •Chromatids – each of 2 thread-like strands into which a chromosome divides during mitosis •Sister Chromatids – 2 identical copies of a chromatid •Centromere – a structure in a chromosome that holds the two chromatids together •Spindle Fibers – control the movement and separation of chromosomes during mitosis •Centriole – helps in the formation of spindle fibers •Nuclear Envelope – a membrane that separates the nucleus from the cytoplasm in eukaryotic cells Mitosis •Used for cell growth •Asexual reproduction 1.Binary Fission 2.Budding 3.Regeneration 4.Vegetative Reproduction 5.Fragmentation •Examples: some types of jellyfish, worms, and plants •Four basic phases 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase •Occurs in a strict sequential order called the cell cycle •Produces diploid cells (2) –same genetic makeup as parent cell Prophase •First phase of mitosis •Chromosomes become visible through a microscope. •Spindles begin to form. •Nuclear membrane disappears. •Centrioles begin moving toward the poles. •The chromosomes replicate and are seen as a pair of sister chromatids. Metaphase •Second phase of mitosis •The chromosomes, guided by the spindle fibers, line up in the middle of the dividing cell. •The centrosomes are at opposite ends (poles) of the cell. Centrosome - an organelle near the nucleus of a cell that contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division. Anaphase •Third phase of mitosis •The two sister chromatids of each chromosome are pulled apart by the spindle fibers. •Chromosomes move away from each other toward the poles. •The cell elongates so that the poles are farther apart. Telophase •The last stage of mitosis. •The chromosomes have reached the poles. •Two new nuclear envelopes form around each of the two separated sets of unreplicated chromosomes. •The cell has divided into two daughter cells exactly like the parent cell. Interphase •Mitosis is now over. •Chromatin is unwound •Here the cell grows in preparation for another round of cell division. •Note the position of the centrioles. •One complete cell cycle has occurred. Meiosis •This cell division occurs in two sets of stages, Meiosis I and II. •Reduces the number of chromosomes in the parent cell by half •Produces four gamete cells (sex cells) •Meiosis is required to produce egg and sperm cells for sexual reproduction. Vocabulary •Homologous Chromosomes – During meiosis, there is one paternal and one maternal chromosome pair inside a cell •Crossing Over – the process where homologous chromosomes pair up and exchange genetic material to form new chromosomes •Haploid Cells – Four cells as a result of meiosis, which are genetically different from each other and the parent cells Meiosis I – Prophase l •First phase of Meiosis l •Chromosomes become visible under a microscope. •Duplication of homologous chromosome pair and cross-over occurs. •Nuclear envelope disappears. •Spindles enter nucleus. Meiosis I – Metaphase l •Crossover is complete •Chromosomes move toward the center and line up. •Spindle fibers attach to the centromere of each chromosome. Meiosis I – Anaphase I •Cell starts to lengthen •Two of each chromosome pairs separate and are pulled by the spindle fibers toward opposite poles •In meiosis the chromatids remain together •Contrast with mitosis, where sister chromatids separate Meiosis I – Telophase I •Complete haploid (4) sets of chromosomes •A cleavage furrow appears •By the end of the stage the parent cell has divided into two daughter cells. •This separation of cytoplasm is called cytokinesis. Interkinesis in Meiosis •A period of rest called interkinesis •No replication of DNA occurs during this phase. Meiosis II – Prophase II •First step in Meiosis II •Begins with two daughter cells from Meiosis I. •Chromosomes are condensed. •Nuclear envelope begins to break down. •Centrosomes have replicated and are moving toward the poles. Meiosis ll – Metaphase Il •The second stage of Meiosis ll •The spindles draw the chromosomes to the center plate. •The centromeres are bound to the spindle fibers from opposite sides. Meiosis II – Anaphase II •The third step of Meiosis ll •Very similar to mitosis anaphase •The two sister chromatids of each chromosome are pulled apart by the spindle fibers. •Chromosomes move away from each other toward the poles. •The cell elongates so that the poles are farther apart. Meiosis II – Telophase II •Chromosomes reach opposite poles. •Cytokinesis occurs (separation of cytoplasm) and nuclear envelopes form. •Meiosis is complete with four daughter cells (haploid) each different from each other and different from the parent cell. Summary of Meiosis •Form of cell division that results in half the number of chromosomes in gametes or sex cells (sperm and ova) •Maintains the same number of chromosomes from generation to generation. •Results in an assortment of genetic material passed on to offspring. CRASH COURSE LINK: https://youtu.be/AQ5vty8f9Xc
KAHN ACADEMY LINK: https://youtu.be/ZQcf9xLABa0 LUNAR PHASE QUIZZES:
What Plants Are Legumes?
Probably the most common legumes in home gardens are peas and beans of all kinds (snap, soy, lima, broad...), but this large plant family contains upwards of 16,000 species. We generally think of legumes as foods for humans or livestock. Although not all of them are edible, many are. Besides peas and beans, there are peanuts, lentils, carob, alfalfa, and clover. But some leguminous plants are grown simply as ornamentals, like baptisia, lupins, wisteria and locust trees. What's so Great About Using Legumes in the Garden? Legumes are often used as cover crops or mixed into lawn seed mixes because of their ability to fix nitrogen. Fixing nitrogen means converting pure nitrogen (N2), which plants and animals cannot access, into its ammonia form (NH3), which we can use. Bacteria are required to make this change and the nodules on the roots of legume plants are where Rhizobium, a soil bacteria, enter the root and start to multiply. It's the bacteria that actually fix the nitrogen, which the plants then take up. The Rhizobium does not hurt the plants; it's a symbiotic relationship. You can actually see the nodules on the roots with your eyes. They are white or grey before they start fixing nitrogen, but they turn pink or red as the process gets underway. Perennial legume roots with older nodules on them can look like the fingers of a hand. On garden vegetables, they may get to the size of a pea. Some legumes fix nitrogen better than others. Green beans are on the low end, compared to peanuts, broad beans and soybeans. The nitrogen doesn't disappear immediately after the plants die. That's why it is recommended you cut pea and bean plants at their base and leave their roots in the soil. Even after the top growth is gone, the nitrogen-fixing nodules continue feeding other plants.
Nitrogen
•Makes up about 78% of the atmosphere •Nitrogen gas is colorless, odorless, and generally inert or unreactive. •Most organisms can’t use unreactive N2. •Nitrogen compounds are vital components of foods, fertilizers, and explosives. Nitrogen Compounds •Nitrogen must be converted to more chemically available forms for plants and animals to use. •N2 – atmospheric nitrogen •N2O – nitrous oxide •NH3 – ammonia •NH4 – ammonium •NO2 – nitrites •NO3 - nitrates Nitrogen Cycle •Describes how nitrogen (N2) moves between various reservoirs: •Plants •Animals •Bacteria •Atmosphere •Soil •Describes the processes by which those reservoirs exchange N2 into usable nitrogen Vocabulary •Reservoir – A place where anything is kept or stored. •Process - A series of actions that produce something or that lead to a particular result. Processes in the Nitrogen Cycle •Fixation •Nitrification •Assimilation •Ammonification •Denitrification Nitrogen Fixation •Process where N2 molecules in the air break apart and combine with other atoms to form ammonium or NH4. •Plant nutrients are the result of nitrogen fixation. •Nitrogen gets “fixed” when it combines with oxygen or hydrogen. 3 - Ways to “fix” Nitrogen 1.Atmospheric Fixation 2.Industrial Fixation 3.Biological Fixation Atmospheric Fixation •Energy from lightning breaks N2 molecules apart. •N2 atoms combine with oxygen forming nitrogen oxides (N2O). •N2O dissolves in rain, forming Nitrates (NO3). •Nitrates are carried to the ground by rain. Industrial Fixation •Under certain conditions industrial plants combine nitrogen and hydrogen to form ammonia (NH3). •Ammonia is used as a fertilizer. Biological Fixation •Free Living Bacteria – highly specialized bacteria live in soil and combines N2 with H2. •Bacteria fixes 30% of available N2. •Produces ammonium (NH4) •This is where most nitrogen fixing is completed. •Symbiotic Relationship Bacteria - bacteria live in root nodules of pulse family plants. •Provides plants with ammonia in exchange for the plant’s carbohydrates and a protected home. •Legumes fix 70% of available N2. Nitrification •Nitrifying bacteria in the ground combine ammonia with oxygen to form nitrites (NO2). •Another group of nitrifying bacteria converts nitrites to nitrates (NO3). •Green plants absorb nitrates (assimilation),which are eaten by consumers. Assimilation •NH4 Organic N2 •Organic N2 compounds –amino acids, chlorophyll, and nucleic acid •Produced when plants take up NH4 •Organisms near top of food chain eat plants taking up biologically fixed nitrogen. Ammonification •Part of the decay process •When a plant or animal dies or leaves waste products, decomposers like fungi and bacteria turn N2 back into ammonia . •Ammonia is absorbed and stored in the soil. Denitrification •Converts nitrates (NO3) in the soil to N2 •Denitrifying bacteria live deep in swampy sediments where O2 is not easily accessible. •These bacteria take O2 from nitrates leaving the byproduct nitrogen gas (N2). •Returns nitrogen to the atmosphere to begin the cycle again Lunar Cycle – the change in appearance of the Moon as it makes one full revolution around the Earth.
New Moon •The first phase of the Moon and it appears unlit from Earth. •The Moon is between the Earth and the Sun. Waxing Crescent •The lighted part of the Moon as seen from Earth is increasing. •The light on the right is new and bright. •Think about the shape of a crescent roll. First Quarter •The Moon is one quarter of the way through its cycle. •From the Earth it appears to be half lit on the right. Full Moon •From the Earth the Moon appears fully lit. •The Earth is between the Sun and the Moon. Waning Gibbous •From the Earth, the Moon appears to be more than half lit on the left. •The lighted part is now decreasing. Third or Last Quarter •The Moon is three-quarters of the way through its cycle. •From the Earth it appears to be half lit on the left. Waning Crescent •The lighted part of the Moon as seen from Earth is decreasing on the left. •The shape of the light is crescent. Can you… 1.Describe why the Moon changes shape? 2.Predict the phases of the Moon? 3.Label a blank lunar cycle diagram? |
Erik E. Mason
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