important stuff on the final com

explain how serial endosymbiosis could have resulted in mitochondria and chloroplasts. be sure to explain what kind of cells were engulfed by the larger cell, what advantages the symbiotic relationship provided, and the significance of the sequence of events during symbiosis

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compare and contrast cellular respiration vs photosynthesis in regards to oxidation, phosphorylation and chemiosmosis

All living organisms must find a way to harvest energy in order to maintain life. Animals use cellular respiration in order to convert food into chemical energy. Plants release chemical energy through photosynthesis. Oxidation-reduction in cellular respiration differs from photosynthesis in the direction of the electron transfer. In respiration, electrons are transferred from glucose molecules to oxygen. Therefore, glucose is oxidized, while oxygen is reduced in cellular respiration. However, in photosynthesis, electrons travel from water to CO2. In cellular respiration electrons travel from organic molecules to oxygen, while in photosynthesis electrons travel from oxygen in water to a carbon-based molecule. Both cellular respiration and photosynthesis use chemiosmosis to create ATP. Chemiosmosis refers to specific steps within the electron transport chain utilized to create ATP. In this particular part of the electron transport chain some molecules also accept and release protons, pumping them into the intermembrane space creating a proton gradient. Potential energy, also known as the proton-motive force, is stored in the gradient. This energy is then used to drive ATP synthesis. In cellular respiration, food is converted into ATP, while photosynthesis uses light energy to release ATP.

discuss darwin experiment with plant hormones

Charles Darwin and his son Francis were one of the earliest scientists who studied phototropism (the growth of stems and leaves toward light). The Darwins studied coleoptiles (the protective sheath around the embryonic shoot in grass seeds) of canary grass and oats. They discovered that both plants grow toward the light source. The Darwins followed up this discovery with these experiments: (i) The tips of coleoptiles were covered with a metal foil. This blocked the incoming light and the coleoptiles did not grow toward light. When the foil was removed they grew toward the light. (ii) The growing region of the coleoptiles rather than their tips were covered and they discovered that the coleoptiles grew toward the light. The conclusion was made that the growth of coleoptiles toward light was controlled by the tip of the coleoptile. The Darwins suggested that, "phototropism was due to an 'influence' produced in the tip of a coleoptile that moved to the growing region, where it caused the coleoptile to grow toward light." Their discovery helped later scientists discover plant hormones.

compare non competitive vs competitive inhibition

Competitive inhibitors are molecules or compounds that blocks the active site of an enzyme. By blocking the active site, no substance can binds at the active site, results in stopping the catalytic action of an enzyme. However, it can be overcome by increasing the amount of substrate near the enzyme. Non-competitive inhibitors are molecules or compounds that bind to the allosteric site of an enzyme, leading to distortion in shape or size of the active site, causing substrate inability to attach to the active site. Unlike competitive inhibitors, these inhibitors will remain attach regardless of the amount of substrate present or period of time. Most poison are non-competitive inhibitors as antidotes are required to reverse the inhibition.

discuss went's experiment with agar block

He cut off the tips and placed the cut surfaces onto agar. The tips were removed after an hour and the agar was placed on the cut tips of the coleoptiles grown in the dark. Went's different experiments and results: (i) Cut off coleoptiles & without agar blocks, did not grow. This confirmed that the tips produced something essential for growth. (ii) Agar blocks that contacted cut tips were placed on the center of the cut off coleoptiles and they grew straight up. Therefore, the chemical diffused into the agar from the coleoptile tips, and stimulated their growth. (iii) Agar blocks that did not contact the cut tips of coleoptiles did not show any response. Therefore, nothing in the agar caused growth of the coleoptile. (iv) Agar blocks that had contacted the cut tips when placed on one side of the cut off coleoptiles, curved away from the agar blocks. This confirmed that the agar blocks had a chemical that stimulated growth of coleoptiles. Went came to the conclusion that the phototrophic response was due to a chemical coming from the coleoptile's tip. He named this chemical auxin which comes from a Greek word meaning "to grow."

glycolysis: starting product, ending product, and transistor product

Overall, glycolysis converts one six-carbon molecule of glucose into two three-carbon molecules of pyruvate. The net products of this process are two molecules of ATP ( 4 ATP produced − 2 ATP used up) and two molecules of NADHN, A, D, H.

describe the reproductive cycle of fern

The diploid sporophyte produces haploid spores by meiosis, the same process that produces eggs and sperm in animals and flowering plants. Each spore grows into a photosynthetic prothallus (gametophyte) via mitosis. Because mitosis maintains the number of chromosomes, each cell in the prothallus is haploid. This plantlet is much smaller than sporophyte fern. Each prothallus produces gametes via mitosis. Meiosis is not needed because the cells are already haploid. Often, a prothallus produces both sperm and eggs on the same plantlet. While the sporophyte consisted of fronds and rhizomes, the gametophyte has leaflets and rhizoids. Within the gametophyte, sperm is produced within a structure called an antheridium. The egg is produced within a similar structure called an archegonium. When water is present, sperm use their flagella to swim to an egg and ​fertilize it. The fertilized egg remains attached to the prothallus. The egg is a diploid zygote formed by the combination of DNA from the egg and sperm. The zygote grows via mitosis into the diploid sporophyte, completing the life cycle.

mechanism of gibberellin acid and cell elongation

The gibberellins are an ubiquitous class of growth regulators in higher plants. They control various aspects of plant development and are known to be involved in all phases of the developmental cycle of angiosperms. These growth regulators were discovered because of the dramatic effect they exert on stem growth via effects on cell elongation. Gibberellins stimulate cell elongation by altering the rheological properties of the cell wall; as a consequence, the water potential of the cell is lowered allowing for water uptake and therefore an increase in cell volume. The precise mechanism for the change in cell wall properties brought about by the gibberellins is not known; however, we do know that the mechanism is not based on the secretion of protons as it is in the case of auxin‐stimulated growth.

describe the reproductive cycle of moss

The life cycle of most mosses begins with the release of spores from a capsule, which opens when a small, lidlike structure, called the operculum, degenerates. A single spore germinates to form a branched, filamentous protonema, from which a leafy gametophyte develops. The gametophyte bears organs for sexual reproduction. Sperm, which are released by the mature antheridium (the male reproductive organ), are attracted into the neck of an archegonium (the female reproductive organ). Here, one sperm fuses with the egg to produce the zygote. After cell division, the zygote becomes the sporophyte, and, at the same time, the archegonium divides to form the protective calyptra. The sporophyte usually consists of a capsule and a seta. Asexual reproduction occurs within the capsule and the whole process may begin again.

alternation of generation model

The sexual phase, called the gametophyte generation, produces gametes, or sex cells, and the asexual phase, or sporophyte generation, produces spores asexually. In terms of chromosomes, the gametophyte is haploid (has a single set of chromosomes), and the sporophyte is diploid (has a double set). In bryophytes, such as mosses and liverworts, the gametophyte is the dominant life phase, whereas in angiosperms and gymnosperms the sporophyte is dominant. The haploid phase is also dominant among fungi. Although some algae have determinate life cycle stages, many species alternate between the sexual and asexual phases in response to environmental conditions.

transcription and translocation

Transcription is the process of making an RNA copy of a gene sequence. This copy, called a messenger RNA (mRNA) molecule, leaves the cell nucleus and enters the cytoplasm, where it directs the synthesis of the protein, which it encodes. Translation is the process of translating the sequence of a messenger RNA (mRNA) molecule to a sequence of amino acids during protein synthesis. The genetic code describes the relationship between the sequence of base pairs in a gene and the corresponding amino acid sequence that it encodes. In the cell cytoplasm, the ribosome reads the sequence of the mRNA in groups of three bases to assemble the protein

compare linear vs non linear electron flow

Under certain conditions, the photoexcited electrons take an alternative path called cyclic electron flow, which uses photosystem I (P700) but not photosystem II (P680). This process produces no NADPH and no O2, but it does make ATP. This is called cyclic photophosphorylation. The chloroplast shifts to this process when the ATP supply drops and the level of NADPH rises. Often the amount of ATP needed to drive the Calvin cycle exceeds what is produced in non-cyclic photophosphorylation. Without sufficient ATP, the Calvin cycle will slow or even stop. The chloroplast will continue cyclic photophosphorylation until the ATP supply has been replenished. ATP is produced through chemiosmosis in both cyclic and non-cyclic photophosphorylation.

define duplication, inversion, translocation, missense, non disjunction and frameshift mutations

duplication: a DNA segment in a chromosome which is a copy of another segment. inversion: An inversion is a chromosome rearrangement in which a segment of a chromosome is reversed end to end translocation: Translocations are chromosome mutations in which chromosome segments, and the genes they contain, change positions. missense: a missense mutation is a point mutation in which a single nucleotide change results in a codon that codes for a different amino acid. It is a type of non synonymous substitution non disjunction: Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division. frameshift mutation: A frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (insertions or deletions) of a number of nucleotides in a DNA sequence that is not divisible by three

compare chemiosmosis in chloroplasts and in mitochondria

he ATP synthase complexes of the two organelles are also very much alike. But there are noteworthy differences between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. In mitochondria, the high-energy electrons dropped down the transport chain are extracted from food molecules (which are thus oxidized). Chloroplasts do not need food to make ATP; their photosystems capture light energy and use it to drive electrons to the top of the transport chain. In other words, mitochondria transfer chemical energy from food molecules to ATP, whereas chloroplasts transform light energy into chemical energy. The spatial organization of chemiosmosis also differs in chloroplasts and mitochondria (FIGURE 10.15). The inner membrane of the mitochondrion pumps protons from the mitochondrial matrix out to the intermembrane space, which then serves as a reservoir of hydrogen ions that powers the ATP synthase. The thylakoid membrane of the chloroplast pumps protons from the stroma into the thylakoid space, which functions as the H+reservoir. The thylakoid membrane makes ATP as the hydrogen ions diffuse from the thylakoid space back to the stroma through ATP synthase complexes, whose catalytic knobs are on the stroma side of the membrane. Thus, ATP forms in the stroma, where it is used to help drive sugar synthesis during the Calvin cycle. Comparison of chemiosmosis in mitochondria and chloroplasts.In both kinds of organelles, electron transport chains pump protons(H+) across a membrane from a region of low H+concentration (light brown in this diagram) to one of high H+concentration (darker brown). The protons then diffuse back across the membrane through ATP synthase, driving the synthesis of ATP. The diagram identifies the regions of high and low H+concentration in the two organelles.The proton gradient, or pH gradient, across the thylakoid membrane is substantial. When chloroplasts are illuminated, the pH in the thylakoid space drops to about 5, and the pH in the stroma increases to about 8. This gradient of three pH units corresponds to a thousandfold difference in H+concentration. If in the laboratory the lights are turned off, the pH gradient is abolished, but it can quickly be restored by turning the lights back on. Such experiments add to the evidence described in Chapter 9 in support of the chemiosmotic model.