Cellular Structure and Function

Cellular Structure and Function Introduction Cells are organised together into functioning groups called tissues. These groups of cells organise together to perform a specialised task. There are four basic types of tissues found in the human body; these are epithelial, connective, muscular, and nervous. The following text aims to explain the structure and function of these tissues as well as ovum and sperm cells. Epithelial Tissue Epithelial tissues, as with all different types of tissue, can be found all over the body, they generally line the inside or outside of a body cavity. The cells are anchored down by basement membranes and form in different shapes such a flat, cuboidal, and columnar. The below text details several different types of epithelium cells that can be located around the body. . Stratified Squamous Epithelium Stratified squamous epithelium cells are present in areas of the body that are very moist and subject to abrasion, such as the mouth, esophagus and vagina. The cells are packed densely together and are very flat and irregular in shape. The tissue functions to provide a barrier to entry to inside the body and protects underlying tissues from friction and drying. Figure A. above shows a drawing of the epithelia from an overhead point of view, in shape they are very similar to that of a fried egg. Figure B. shows the cells from a side-on point of

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effect of temperature on the rate of respiration in yeast

Effect of temperature on the rate of respiration in yeast Aim: My aim is to investigate the effect of temperature on the rate of respiration in yeast by using a universal indicator. Background theory: Enzyme: Enzymes are organic catalysts that speed up the rate of a chemical reaction without being permanently altered in the process. Enzyme Characteristics * Lower the energy of activation * Form reversible complex with substrate. * Not consumed in the reaction therefore they are effect in small amounts * Very specific - (Induced fit hypothesis) react with only a single substrate. * Many need cofactors, such as certain vitamins, to be activated. * 2000+ enzymes per cell, different cells have different enzymes. * Enzymes are produced by genes. * Genetic disorders are the result of faulty enzymes. * Operate best in optimum conditions of pH, temperature, etc. * Are controlled by feedback mechanisms. Enzyme mechanism: Key and theory: The substrates (reactants) are attracted to the enzyme molecule. They join forming an enzyme-substrate complex. The reaction occurs on an area of the enzyme molecule known as the active site producing new substrates(s) or products. Induced fit hypothesis: The attraction of the substrate and enzyme form an enzyme-substrate complex. It was originally referred to as the Lock and Key Enzyme Theory. The current theory

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Effect of Anaerobic Respiration On Yeast

The Effect of Temperature on the Anaerobic Respiration of Yeast Aim: To investigate the effect of temperature on the rate of respiration in a suspension of yeast Saccharomyces cerevisiae. Background Knowledge: Yeasts are a form of eukaryotic microorganisms classified in the kingdom Fungi, with approximately 1,500 species known. They reproduce asexually by budding mainly, although some species reproduce by binary fission. They are unicellular, although some species with yeast forms may become multicellular due to way in which they normally reproduce. Typically the size of a yeast cell is approximately 3-4 µm in diameter but this can vary greatly depending on the species. The yeast species Saccharomyces cerevisiae has been used in baking and fermenting alcoholic beverages for thousands of years. It is also extremely important as a model organism in modern cell biology research, and is the most thoroughly researched eukaryotic microorganism. Researchers can use it to gather information into the biology of the eukaryotic cell and human biology. These microbes are thought to be one of the first domesticated organisms. People have used yeast for fermentation and baking throughout history. Archaeologists digging in Egyptian ruins found early grinding stones and baking chambers for yeasted bread, as well as drawings of 4,000-year-old bakeries and breweries. It has many

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Home Economics - Why is nutrition important to sports people?

In order to obtain an idea for a task I could research, I decided to do an initial brainstorm of all the areas that would be possible to complete the project on (see fig1, next page). The factors that would affect my decision of what area to choose, were how easy it would be for me to research the topic, whether I knew people I could speak to about it and whether it was something that interested me. Because of these, I decided to research into nutrition for rowing. This was because I am a rower myself which meant that it would interest me, I would already know about the topic and I knew a variety of people who would be able to provide information and help on the subject. For research: To start the project I needed to carry out some preliminary, general research into the sport and its demands. The following are some things I needed to research: o Sports nutrition o Nutritional requirements of a normal person o Nutritional requirements of a rower o What a rower should eat on the day of, and during the week before, a race. Preliminary research Sources To ensure that I could gat a balanced set of information I decided to use data from several media types. These could include magazines, people, websites, books and companies. The following are some sources I thought would be useful: o ARA (amateur rowing association) o Internet - including rowing websites, BBC website,

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An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and the Relative Duration of Each Phase of this Cellular Cycle

An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and the Relative Duration of Each Phase of this Cellular Cycle. Aim To conduct an investigation into the relative durations of the phases that occur in the mitotic nuclear division of meristematic Allium Sativum root tip cells, evaluating the validity of a hypothesis proposed that states that these mitotic phase durations will be of different. Hypothesis The Expected Results: The Relative Length of Each Stage of Mitotic Nuclear Division Through the process of conducting background research, it has been possible to suggest a theoretical ratio concerning the timing for each stage of the mitotic cycle; "Although the stages of mitosis are necessarily shown as static events, it must be emphasized that the process is a continuous one and the names "anaphase", "metaphase", etc., do not imply that the process of mitosis comes to a halt at this juncture. Moreover, the stages shown are not selected at regular intervals of time, e.g. in the embryonic cells of a particular grasshopper the timing at 38°C is as follows: prophase 100 min, metaphase 15 min, anaphase 10 min, telophase 60 min." 1 These specified times essentially form the ratio that will be used throughout the investigation (dividing each stage in the ratio by a factor of 5 provides the ratio (20:3:2:12), and allow a range of

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An Investigation into the effect of caffeine on reaction times

An investigation into the effect of caffeine on reaction times and short term memory Aim To investigate the effect of varying doses of caffeine on performance in simple reaction time and short term memory tests. Research and Rationale Having carried out the core practical on the effect of caffeine on the heart rate of Daphnia, I wanted to investigate the effect of caffeine on other functions of the body, and how this effect comes about. Caffeine is a natural pesticide, found in the leaves, beans and fruit of over 60 plants1, however in humans it acts as a central nervous system stimulant, reducing fatigue and restoring alertness2. It is said to be the most widely used drug in the world, with an average intake of 241mg per person, per day according to a Bristol survey3. I therefore decided to explore how it could affect reaction times and the extent of short term memory, as these are two factors involved in alertness. It has a similar structure to adenosine, meaning it binds to adenosine receptors in the brain. Caffeine and adenosine - http://en.wikipedia.org/wiki/Image:Caffeine_and_adenosine.svg - 22.10.08 When a nerve impulse travels through the synaptic knob, opening the Ca2+ channels, it triggers the release of adenosine, which is synthesised and stored inside the synaptic knob. Normally, the adenosine acts as a neurotransmitter when it is released into the

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Investigating the effect of enzyme concentration on the activity of cellulase.

Individual Investigation Investigating the effect of enzyme concentration on the activity of cellulase Plan Hypothesis The concentration of cellulase will affect the rate of break down of cellulose to sugar. Prediction As the concentration of cellulase increases the rate of break down of cellulose to sugar will also increase. If the cellulase concentration doubles then the rate of break down of cellulose to sugar will also double. Biological Knowledge Cellulase is an enzyme that breaks down the cellulose in the plant cell wall into soluble glucose, cellobiase and higher glucose polymers. Cellulose (insoluble in water) Glucose (soluble in water) Together with the enzyme pectinase, cellulase is involved in the ripening of fruit. It causes the degradation of plant cell walls making the fruit soft. Enzymes have the following characteristic: * They are all proteins * They are catalysts found in living tissues * Each enzyme is able to promote only one type of chemical reaction * They accelerate chemical reactions but remain unchanged at the end of a reaction * They reduce the level of activation energy needed for a reaction * They work in an optimum temperature range and pH The lock and key mechanism is the theory behind enzyme action. The enzyme has a cavity with a precise shape called the active site. The substrate (the key), the compound that the enzyme

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Sand Dune Succession Coursework

Sand Dune Succession Coursework Aim: The aim of this experiment is to discover how the pH value and the humus value of soil samples collected along a 600 metre transect change as we travel away from the shoreline. The results will indicate how succession has an affect upon the soil and the environment. Also the plant species number will be recorded and a trend will be drawn from the results of percentage cover. Background Summary: Succession is a gradual directional change in an ecosystem over time. A good example of primary succession can be seen on coastal sand dunes such as Winterton sand dunes. Here many stages of succession can be seen in one place. Primary succession is when the starting point is bare ground with no living things present. In this case the starting point is bare sand. The first species to colonise bare ground like this are called pioneer plants. These are able to survive in very difficult conditions and are more salt tolerant than other plants. The sand has very few nutrients and is also unstable. The pioneer plants, examples are sea rocket and sea holly, must be tolerant of salt pray and have xeromorphic features which aid survival in an area with a lack of fresh water in the fast-drying sand. Over many years the environmental conditions become more suitable for a wider range of plants to live. As the number of species increases, competition

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"An investigation into the Respiration of Carbohydrate Substrates by Yeast."

AS Biology Coursework 2004. Lucy Nuttney "An investigation into the Respiration of Carbohydrate Substrates by Yeast." Abstract. The investigation considered the reactivity of respiration of three different carbohydrate substrates; glucose, sucrose and starch, by two different sub-species of saccharomyces cerevisiae yeast. The rate of reaction was measured by collecting volumes of gas in a displacement reaction at standardised conditions e.g. time, temperature, pressure, volume of yeast/ sugar. Results showed that glucose produced the most carbon dioxide, followed by sucrose then starch, the biggest difference being between sucrose and starch. Baker's yeast had a slightly higher average than brewer's yeast but it was not considered to be a significant difference and therefore could have been due to chance. It was concluded that both yeasts respire glucose and sucrose at insignificantly different rates but the difference between starch is much larger and therefore much more significant. Pilot Experiment. Before we could test which carbohydrate and type of yeast produced more carbon dioxide, we had to standardise the other variables of this experiment; temperature and concentration. Therefore, in order to find the optimum conditions we carried out a pilot experiment. In this experiment we used a range of temperatures from 10° to 60°C and

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Measurement of protein solutions concentrations by biuret protein assay

Title: Measurement of protein solutions concentrations by biuret protein assay Objective: To study the principle a protein assay. To determine the absorbance rate of protein at different concentration by using spectrophotometer. To determine the concentration of unknown sample from the graph. Introduction: Protein quantitation is often necessary before processing protein samples for isolation, separation and analysis by chromatographic, electrophoresis and immunochemical techniques. Depending on the accuracy required and the amount and purity of the protein available, different methods are appropriate for determining protein concentration. Instead, several colorimetric, reagent-based protein assay techniques have been developed that are used by nearly every laboratory involved in protein research. Protein is added to the reagent, producing a colour change in proportion to the amount added. Proteins concentration is determined by reference to a standard curve consisting of known concentrations of a purified reference protein. Most pure protein solutions containing 1 mg/mL of protein have an absorbance of about 1.0 when the light path is 1 cm. This method is simple, rapid, and allows for full recovery of the protein. However, many other biochemicals absorb near this wavelength, making an accurate quantitation difficult. Furthermore, different

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