May I please get help with checking my answers for these questions please tell m
ID: 73274 • Letter: M
Question
May I please get help with checking my answers for these questions please tell me if they are right, if there is a shorter summary of some of these answers that would be easy to remeber please tell me I also am not sure about number 6 I'm having trouble saying why each statement is incorrect on that. there are a few I don't have answers for I could you help with. thank you for any and all help!
1.Cystic fibrosis results from a non-functioning CFTR (cystic fibrosis transmembrane conductance receptor). Loss of function of the receptor results in altered epithelial salt and water transport due to an inability of CFTR to transport Chloride ion (CL-). The loss of transport function has multi-system impacts, leading to a variety of pathologies associated with CF.
A)One of the most common genetic mutation responsible for a defective CFTR is a 3 base pair deletion which results in the in-frame deletion of phenylalanine residue. Apply your knowledge of central dogma (from transcription to protein synthesis) and protein structure and function to explain how this deletion can result in a fully0synthesized CFTR which is inserted correctly into the epithelial membrane yet remains non-functional.
amino acids are coded for by codons and codons consist of three base pairs. The in-frame deletion means that 3 of the base pairs from the codons that are being transcribed have been deleted changing a single amino acid. This single change will mean that a protein is still made because an entire codon was deleted meaning that the codons will still be able to be read but there will be missing information. The missing information creates an incomplete protein and defective CFTR.
B)Loss of CFTR function in the lungs leads to production of extremely thick mucus. Based on your knowledge of transepithelial transport, do you think that CFTR is no longer able to import or export CL- ? Provide a rationale for your answer
In the case of malfunction CFTR, the channel is unable to move ions in and out freely, and thus Cl- and Na+ ions remain in the cell. Due to the lack of negative ions outside the cell, extracellular environment becomes hypotonic and water does not move outside the cell to dissolve mucus.
C)Patients typically have difficulty performing moderate to heavy aerobic activities. Using your knowledge of cellular respiration and respiration (breathing) explain why this occurs.
For cellular respiration to occur at its most effective level there needs to be O2 as the final electron acceptor. This allows for a larger number of ATP to be produced and helps fuel the body during aerobic activities and in everyday life. If O2 is not present, then only the first step in cellular respiration can occur. This process does not produce as many ATP and also produces lactic acid causing a decrease in ATP available to muscles. CF patients are incapable of getting enough O2 because of the defective CFTR and therefore cannot get O2 to the electron transport chain.
Mutation of CFTR also has implications for the gastrointestinal and endocrine systems. Pancreatic Function can be impaired in patients, leading to various pathologies. A thickening of pancreatic secretions is associated with poor growth and development while structural damage to the pancreas is related to development of cystic fibrosis-related diabetes (CFRD).
D)Apply your knowledge of the gastrointestinal system to explain the connection between decreased, thickened secretions and poor growth & development.
The lack of digestive enzymes leads to difficulty absorbing nutrients with their subsequent excretion in the feces, a disorder known as malabsorption. Malabsorption leads to malnutrition and poor growth and development because of calorie loss. Resultant hypoproteinemia may be severe enough to cause generalized edema. Individuals with CF also have difficulties absorbing the fat-soluble vitamins A, D, E, and K.
Thickened secretions also may cause liver problems in patients with CF. Bile secreted by the liver to aid in digestion may block the bile ducts, leading to liver damage. Over time, this can lead to scarring and nodularity (cirrhosis). The liver fails to rid the blood of toxins and does not make important proteins, such as those responsible for blood clotting. Liver disease is the third most common cause of death associated with CF.
E)Apply your knowledge of the endocrine functions of the pancreas to explain why CFRD develops and possible consequences of developing CFRD.
In people with CF, the thick sticky mucus that is characteristic of the disease causes scarring of the pancreas. This scarring prevents the pancreas from producing enough insulin, which is why people with CFRD experience a feature of type 1 diabetes when they become insulin deficient. They will develop resistant to insulin and will not be able to regulate blood glucose without medical help
2) in your study of plants and animals throughout the semester, you have come to appreciate that there are not only many differences, but also many similarities between these organisms.
The antagonistic action of hormones is essential to many processes in plants and animals
a)Discuss how the processes of cell growth and elongation and seed dormancy and germination are controlled by antagonistic hormones in plants
The hormones, which act against functions of each other, are called antagonistic hormones. In plants the cell division is controlled by the two main hormones, auxin and cytokinins. The auxins, like indole acetic acid (IAA) and cytokinins both promote the cell division, but the variation in the concentration results changes in cell division. For example, if auxin levels are more than cytokinins the cell parenchymal cells become expand, but cannot divided. If both of them are present in equal concentration, then cell division and cell expansion takes place and results formation of an undifferentiated tissue called callus. The auxins promote the growth of roots, whereas cytokinins promote the growth of shoots.
b)Discuss how the antagonistic actions of hormones is responsible for maintaining blood glucose levels in animals. The antagonistic hormones responsible for blood glucose regulation are Insulin and Glucagon. Insulin is a metabolic hormone released from the beta cells of pancreas. The “Islets of Pancreas” contain four types of cells namely “alpha, beta, delta and F cells.” Alpha cells secrete glucagon and beta cells secrete insulin. Insulin converts glucose into glycogen (lowers blood glucose levels), and glucagon converts glycogen into glucose molecules (raises blood glucose levels), thus helps to regulate the circulating glucose levels.
Plants and animals both must acquire nutrients from their environment
c)Where and how do plants and animals obtain their required nutrients? Your answer should include a brief description of the systems involved in both the acquisition of nutrients and transport of nutrients throughout the organism.
The plants obtain nutrients from the soil, whereas animals obtain them by ingestion. The roots of plants absorb minerals from soil and water to maintain proper metabolism. The plants are usually autotrophs, therefore they can synthesize other material, like carbohydrate by a process called photosynthesis. The animals cannot synthesize their own food material; hence they depend on either plants or other animals for food source.
d)How do plants and animals convert the carbon they obtain into the cellular energy of ATP? (should include how photosynthesis and cellular respiration are involved in this process)
Plants conduct a mechanism called photosynthesis. Plants utilize carbon atom especially in the form of carbon dioxide, plants take in Co2 through stomata, which is essential for photosynthesis and though which they produce sugar molecules and other complex materials for use the plant growth and metabolism.
Plants are the major source of food for humans and many other organisms. They are the dominant terrestrial organisms and about 300,000 species are now in existence.
Animals eat plants of other animals and digest them into simple molecules called sugars and fatty acids. Now they enter into glycolysis of beta-oxidation and oxidized into carbon-dioxide and produce ATP. This process is called catabolism.
Both plants and animals reproduce sexually
F)Identify and discuss 2 similarities and 2 differences in the sexual life styles of plants and animals. (your answer should focus on the processes of gametogenesis, fertilization, and development)
Both plants and animals reproduce sexually. However, most of the animals can reproduce sexually alone, whereas plants can reproduce both sexually and asexually too.
* Both plants and animals have male and female sex organs. Both of these kingdoms produce male and female gametes. The fusion of these gametes gives rise to a zygote.
* After fertilization of gametes, the zygotes produced by plants are called a seed. The seed remains viable for comparatively longer time period. It germinates and gives rise to offspring when favorable conditions are provided. However, animals are not gifted with this, the zygote produced by most of the animals immediately develop into the offspring
* The male gametes of plants, the pollen contains pollen sacs. Each sac contains 4 microspores. They give rise to a gametophyte, each gametophyte has a generative cell and a tube cell. The tube cell produces pollen tube that delivers sperm to the female gametophyte. Such an arrangement is not seen in animals.
Differences between plants and animals in terms of gametogenesis:
* Plants produce female gametophytes which are surrounded by two integuments and one micropyle. Only one gamete produced from megasporocyte (the precursor cell for female gamete) during meoisis surives, and the remaining three disintegrate. The one that survived undergo meiosis thrice, without cytokinesis, and result in a cell with eight haploid nuclei. The cell then divides into a multicellular gametophyte. This is called the embryo sac. One of them becomes ovule.
As described, the male gamete produces pollen tubes.
This type of arrangement and division is not seen in animals. Animal gametes are produced by meoitic division.
* Most of the plants produce both male and female gametes, whereas most animals produce gametes of either sex only.
* Though plants produce gametes of both sex, they do not pollinate (fertilize) themselves. They take help of things like air, insects, or other VECTORS for transmission of pollen and fertilization. Plants do not require intimate contact to fertilize.
Animals (or most of the animals) require physical contact for the gametes to be fertilized.
* Plants are not parented, they grow individually. Animals show parenting of their offspring. Plants show little differentiation of their tissue. Animals show extensive differentiation of tissues, and their growth is extremely complex.
Plants develop from seed; animals develop from zygote, either in mother womb or in an egg.
3) Suppose a steroid animal hormone acts at the gene level to alter the behavior of a target cell; assume the alteration in cell behavior requires a cytoplasmic protein that was not present prior to interaction of the hormone with the target cell. Beginning with binding of the hormone to it to its receptor, summarize the steps leading to appearance of the final functional gene product. For each step, be sure to include the cellular compartment in which the step occurs and cellular components involved in each step.
1) After ligand binding to the cytoplasmic receptor, the receptor's chaperone is released
2) The steroid hormone receptor and its ligand are transported into the nucleus
3) Changes in gene expression/activity occur
Steroid hormone binds to receptor in cytoplasm-----> After binding, the hormone-receptor complex moves into the nucleus-----> here it can bind with HRE (hormone response elements) in DNA----->This causes transcription at this site------->mRNA is produced-----> this mRNA moves into the cytoplasm------> causes protein synthesis and as a result, the required cytoplasmic protein (mentioned in the question) is produced ----->behavior of target cell changed.
4) Eukaryotic cells make ATP by substrate level phosphorylation, oxidative phosphorylation, and photophosphorylation. Even though the general outcome is the same in each case –i.e., ADP is phosphorylated to become ATP-various distinctions can be made among three processes briefly address each of the following:
a) what enzyme activity is required for both oxidative phosphorylation and photophosphorylation, but not for substrate level phosphorylation?
Both oxidative phosphorylation and photophosphorylation occur in specialized membrane systems called mitochondria and chloroplast respectively. The matrix of these membrane systems contains cytochromes. However, the main enzyme that synthesizes ATP is ATP synthase during chemiosmosis,
b) In terms of phosphate source how does substrate level phosphorylation differ from both oxidative phosphorylation and photophosphorylation? Substrate level phosphorylation directly couples an inorganic phosphate to an ADP, whereas oxidative phosphorylation couples high energy phosphate ion to ADP
c) what cellular compartments are associated with each of the three processes? Be as specific as possible. Substrate level phosphorylation occurs in cytoplasm. Oxidative phosphorylation occurs in the inner mitochondrial matrix. Photophosphorylation occurs in the thylakoid membrane (matrix)of chloroplasts
E) what condition is required for oxidative phosphorylation but not for either substrate level phosphorylation or photophosphorylation? Why is the condition required?
Oxidative phosphorylation occurs only in the presence of oxygen. Oxygen is required as terminal electron acceptor during the electron transport. The protons pumped during the electron transport generate a proton gradient, which is used to synthesize ATP
G)what condition is required for photophosphorylation but not for either substrate level phosphorylation or oxidative phosphorylation? Why is this a condition required?
Photophosphorylation requires photolysis of water as a source of electrons. This is not required in oxidative phosphorylation since electrons are derived from oxidation of highly reduced metabolic compounds. Substrate level phosphorylation does not require any electrons
5) mitosis and meiosis are types of cell division characteristic of eukaryotic cells. This does not mean that all eukaryotic cells have the ability to undergo both mitosis and meiosis.
During early development of an animal or plant, all of the cells may undergo mitosis. In a mature animal or plant, most of the cells no longer divide, through new cells are constantly required.
A)What is the general source of new somatic cells for an animal? The general source of new somatic cells for an animal are somatic stem cells.
B)What is the source of new cells required for continuing elongation of plant shoots? The source of new cells required for continuing elongation of a plant shoot apical meristem and lateral meristem, which contains plant stem cells.
C)In animals, what cells undergo the first meiotic division he germ line stem cells (diploid) undergo meiosis to produce gametes (haploid) in animals.
D)Where are these cells found in male and female humans? testes and ovaries
E)Haploid cells cannot undergo meiosis, but they can undergo mitosis. Explain why haploid cells cannot undergo meiosis, and give a specific example of haploid cell undergoing mitosis. This example must be for an organism having a life cycle featuring alternation of generations ( haplo-diploid life cycle) . Haploid cells cannot undergo meiosis because they contain only "n" number of chromosomes, as meiosis is reduction division, it cannot again undergo meiosis, if so the cells produced will not be viable. The green algae which were the ancestors of today’s plants are aquatic organisms. For the establishment of plants on land and to overcome the environmental challenges, they had adopted some key innovations which led to their terrestrial development. Plants have an “alteration of generations,” the haploid gamete producing plant (gametophyte) alternates with the diploid spore producing plant (sporophyte).
F)In what way is metaphase to anaphase transition in mitosis fundamentally different from metaphase to anaphase transition during meiosis I? During mitosis, the cohesion between the sister chromatids is completely dissolved in mitosis and the chromatids are pulled towards the opposite sides. in case of meiosis, the cohesion is only removed from the chromosomal arms, whereas the cohesion at the centromeres is not removed and is maintained till the metaphase II of meiosis.
6)Neurons are able to generate action potentials, propagate signals along axons, and communicate with other neurons or effector cells at chemical synapses. Explain why each of the following statements regarding nerve cells function is incorrect. In each case, and adequate explanation requires a correct statement regarding the aspect of neuron behavior being addressed.
a) an action potential is a rapid change in membrane potential depolarization followed by repolarization) that occurs over the surface of the entire neuron. This is wrong because
B) when an action potential has been generated, propagation of the signal entails diffusion of the action potential along the axon.
C) Arrival of the signal at the end of axon results in release of vesicles containing neurotransmitter molecules; the vesicles diffuse across the synaptic cleft and fuse with the post synaptic membrane.
7) Macromolecules- polypeptides, polysaccharides, nucleic acids- are important components of living systems. Members of each class of macromolecules are composed of monomers joined by dehydration reactions to form polymers.
A) what is a dehydration reaction? Dehydration reaction involves the loss of water. When two monomers come closer to connect, a hydrogen atom from one monomer and -OH from second molecule combine to form water molecule which releases as substrate along with polymers.
B) what monomers are used to construct each of the three classes of macromolecules? ( in each case, indicate the functional groups that interact to allow successive monomers to be linked together.
There are three major types of macromolecules present in mammals
1. Carbohydrates where monomer unit is monosaccharides.
2. Nucleic acids where monomer unit is nucleotides.
3. Proteins where monomer unit is amino acids.
Monosaccharides possess two functional groups, one carboxyl group and other hydroxyl group. On polymerization, hydroxyl group of one monosaccharide react with hydroxyl group of other monosaccharide and combined with glyosidic linkage.
Nucleotides comprise of three parts, Phosphate, Monosaccharide (Ribose in ribonucleotides & Deoxyribose in DNA, which lacks a 2' -OH) and a base. Nucleotides polymerizes to form esteric linkage between the 5'-phosphate of one nucleotide and the 3' -OH of other nucleotide along with release of one molecule of water.
Amino acids contain a carboxylic acid (-COOH) group and an amino (-NH2) group. Amino acid polymerizes to form an amide linkage (peptide bond) between the amino and carboxyl groups of two different amino acids. A molecule of water is also released with polymerization of amino acids.
C) Only one of the three classes of macromolecules includes representatives that are branched? Glycoprotein, a type of protein having a carbohydrate as prosthetic group, represents the branched macromolecules.
d)without referring to electrical charge, what do we mean when we say that both polypeptides and nucleic acids display polarity? Polypetides and nucletides shows polarity because of their peculiar structures. Polypeptides possess COO- at one end and NH3+ at other end which causes polarity of molecule. on the other hand, base pairing in nucleic acids form complimentary sequences which create double helix of opposite polarity.
Example :
5' ...ATCCGAGTG... 3' 3' ...TAGGCTCAC... 5'
8) the term metabolism refers to the collection of chemical reactions carried out by the cells of an organism-typically thousands of reactions. Each reaction is catalyzed by a specific enzyme, and the reactants for an enzyme-mediated reaction are called substrates.
a) In general, enzymes are proteins. Including the terms substrate, active site, and induced fit in your answer, explain the importance of stabilization of enzyme structure by weak interactions, such as hydrogen bonds.
Weak Interactions like hydrogen bonds provide accurate working conditions of optimum temperature to the enzyme for successful reaction. Above the optimum temperature, the hydrogen bonds of enzyme break up and enzyme changes its shape to a coiled structure. And the substrate cannot fit into the active site. At normal optimum temperature, the substrate binds to the active site of enzyme, and being attached together in the complex the substrate converts into product. The product is released and enzyme is left for a new reaction. The manner in which substrate binds to active site, is Induced fit manner
b) with respect to non-competitive inhibitors of enzyme function, what is the significance of stabilization of enzyme structure by weak interactions?
Inhibitors inhibit the enzyme function and reduce the rate of reaction. As described earlier, one of the key inhibitor of enzyme function is the temperature. Each enzyme has an optimum temperature at which it works fastest. Above the optimum temperature, the enzyme cannot work. Other inhibitors like pH, substrate concentration and enzyme concentration also affect the active site and structure of enzyme stability. Non competitive inhibitor molecules do not fit into the active site of enzyme. It attaches to another part of enzyme thus change the shape of enzyme, so that the enzyme cannot bind to substrate molecule. In this way they reduce the efficiency of working enzymes.
C) how did you use your quantitative assays to determine optimal temperature and pH for cellobiase?
9) in general, eukaryotic cells are larger than prokaryotic cells. The two cell types also differ in degree of compartmentalization, with eukaryotic cells displaying many different compartments.
a) indicate three features common to both prokaryotic cells and eukaryotic cells?
Both have cell membrane and chromosomes, cytosol. both are microscopic, both have DNA for their genetic material and both have ribosome 3. Having similar basic metabolism and require similar reaction for storing energy and metabolism metabolic activity eg. building proteins
b) different compartments in eukaryotic cells typically have different internal conditions; presumably this allows optimization of functions associated with the compartment. The individual compartments could be described as semi-autonomous: they are not totally isolated from the rest of the cell. Excluding the nucleus, give two examples of functional interaction between the two compartments, or between a compartment and cytosol.
1.The nuclear membranes are linked to another membrane-defined structure, the endoplasmic reticulum, which plays a host of cellular roles, including drug detoxification and the modification of proteins for secretion
2.Transcription and translation take place in different cellular compartments: transcription takes place in the membrane-bounded nucleus, whereas translation takes place outside the nucleus in the cytoplasm
c) How does the lack of compartmentalization in prokaryotic cells relate to temporal and spatial aspects of transcription and translation in prokaryotic cells in comparison with two processes in eukaryotic cells?
Compartmentalization plays role in to generate a specific micro-environment to spatially or temporally regulate a biological process. As an example, a yeast vacuole is normally acidified by proton transporters on the membrane. In eukaryotes, transcription and translation take place in different cellular compartments: transcription takes place in the membrane-bounded nucleus, whereas translation takes place outside the nucleus in the cytoplasm. In prokaryotes, the two processes are closely coupled, the translation of bacterial mRNA begins while the transcript is still being synthesized, because there is no nucleus to separate the processes of transcription and translation, when bacterial genes are transcribed, their transcripts can immediately be translated. The spatial and temporal separation of transcription and translation enables eukaryotes to regulate gene expression in much more intricate ways, contributing to the richness of eukaryotic form and function.
Transcription and translation are spatially and temporally separated in eukaryotic cells; that is, transcription occurs in the nucleus to produce a pre-mRNA molecule. The pre-mRNA is typically processed to produce the mature mRNA, which exits the nucleus and is translated in the cytoplasm.
10) throughout the semester, we have discussed transport of solutes across membranes. Briefly describe each of the following with regards to solute transport and energy:
a) diffusion
Spontaneous movement of particles from an area of high concentration to an area of low concentration. Diffusion process not require energy .it is occurring via random kinetic movement. Diffusion stops when concentration on both sides equal (if crossing a membrane) or when there is a uniform distribution of particles. Diffusion of one compound is independent to diffusion of other compounds
b) passive transport It is a movement of biochemical and other atomic or molecular substances across cell membranes. p passive transport not requires energy. It does not require an input of cellular energy because it is instead driven by the growth of entropy of the system.
The rate of passive transport depends on the permeability of the cell membrane. The four main kinds of passive transport are
1 - Diffusion
2 -facilitated diffusion,
3 - Filtration
4 - Osmosis
c)active transport is the movement of molecules across a cell membrane in the direction against some gradient or other obstructing factor (often a concentration gradient.
Active transport uses cellular energy to move them against a gradient, polar repulsion, or other resistance. Active transport is usually associated with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acid. If the process uses chemical energy, such ATP. It is termed primary active transport. Secondary active transport involves the use of an electrochemical gradient Examples of active transport:
Uptake of glucose in the intestines in humans and the uptake of mineral ions into root hair cells of plants.
Explain thoroughly solute transport and its importance in the following
e)A bacterium adapted to living in a high-salt environment
f)How plant sugars are transferred from source to sink
Source-to-sink transport of sugar is one of the major determinants of plant growth and relies on the efficient and controlled distribution of sucrose (and some other sugars such as Raffi nose and polyols) across plant organs through the phloem.
g)How neurons conduct action potentials:
Propagation of an action potential down a single neuron axon and movement of the action potential between neurons: In neurons, action potential play a central role. In other types of cells, their main function is to activate intracellular processes. Action potentials in neurons are also known as "nerve impulses” and the temporal sequence of action potentials generated by a neuron are called its "spike train". A neuron that emits an action potential is often said to "fire"
Explanation / Answer
** I would write a better answer for you.
B. Normally, the CFTR is responsible for movement of chloride and thiocyanate ions actively out of the cells of lung epithelium. Sideways, sodium ions also move out of the channel passively. This causes solute concentration to increase outside the cell. So, exosmosis occurs and water moves out of the cell. This dissolves mucus.
Now, when CFTR is defected ions do not move out of the cell due to blockage in the channel. So, exosmosis does not occur and lack of water causes accumulation of thick mucus.