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35 Cards in this Set
- Front
- Back
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Outline the Cell Theory
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1. All living organisms are made up of cells: multicellular/unicellular 2. Cells are the smallest unit of life; smallest structures capable of living on their own 3. All cells must come from pre-existing cells; cannot be created from non-living material. Must happen through cell division and a zygote (first cell formed when organism produced) that arises from the fusion of a sperm and egg cell. |
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Discuss the evidence for the cell theory
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Looked through microscopes and identified that all living organisms are made up of small units named cells. When cells were taken from the tissues, they were able to live for a period of time, nothing smaller was able to live independently. Supports that cells are the smallest unit of life. Pasteur's experiment supports that all cells must come from pre-existing cells. If flask is closed off and there is no interaction with the external environment, mold cannot grow as there are no cells to begin the cell division. If flask is open, cells can enter and start to divide and grow to form mold. |
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What are the functions of life?
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Reproduction Homeostasis Nutrition Excretion Response Growth Metabolism (Movement) |
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List with proper SI unit in decreasing order of size of cells and components.
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Eukaryotic cell - upto 100 micro m Organelles - upto 10 micro m Bacteria - upto 1 micro m Virus - 100 nano metres Cell membrane - 10 nano metres Molecules - 1 nanometre |
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Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification.
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1. Measure the width or length of drawing. 2. Measure the width or length of specimen, convert to the same SI units if necessary. 3. Use formula: length of drawing/length of specimen |
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State the Metric prefix chart
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G - Giga 10+9 M - Mega 10+6 k - kilo 10+3 h - hecto10+2 da- deca 10+1 - 1 d- deci10-1 c- centi 10-2 m- milli 10-3 u- micro 10-6 n- nano 10-9 |
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Explain the importance of the SA to volume ration as a factor limiting cell size.
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Many reactions occur within the cell and substances are needed to be taken in to fuel these reactions and the waste products of the reactions need to be removed. When the cell increases in size, so does its chemical activity which means the more substances needed, the more that needs to be removed. SA affects the rate at which the particles enter and exit while the volume affects the rate at which materials are produced and used in the cell (chemical activity per unit of time). As the volume of the cell increases, the SA does not increase as quickly so as the cell gets bigger the SA to volume ration gets smaller. For example, compare a cube with a side of 1cm to a cube with a side of 4 cm. Cube 1 SA: 6 * 1^2 = 6cm^2 Volume: 1^3=1cm^3 Ratio: 6:1 Cube 2: SA: 6 * 4^2 = 96cm^2 Volume: 4^3 = 64cm^3 Ratio: 1.5:1 The cube with the larger SA and volume has the smallest ratio. If the ratio get too small than substances will not be able to enter fast enough to fuel the reactions and waste products will start to accumulate as production will be faster than elimination. Cells will also not lose heat fast enough and may overheat. Large cells with have less SA to carry out these functions of life, therefore large animals have more cells and nt large cells. Larger cells are either long and thin rather than spherical and have infoldings and outfoldings to increase ratio. |
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State that multicellular organisms show emergent properties.
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Multicellular organisms show emergent properties. Cells form tissues, tissues for organs, organs form organ systems and organ systems form multicellular organisms. The whole is greater than the composition of its parts. Our lungs are made up of many cells, but the cells themselves are not much use but need to work together to carry out their function.
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Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.
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Every cell in a multicellular organism contains all the genes of that organism, however only certain genes are activated from cell to cell. This is called gene expression. The cells in our eyes are not the same as the cells in our hair because different genes are expressed such as the gene that codes for proteins in the production of keratin in hair and nail cells. The proteins regulate the function and structure of the cell which means that cells develop in different ways which is called differentiation. Differentiation depends on gene expression which is regulated mostly during transcription. It is advantageous for multicellular organisms to have cells differentiate and specialize to be more efficient unlike unicellular organisms who carry out all the functions within that one cell.
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State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways.
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Adults have stem cells in the tissues in their bodies that need to be frequently replaced such as the skin. Stem cells have the ability to produce a wide range of cells which means that they are pluripotent, They retain their ability to divide and produce many different cells by cell division and the process of differentiation. For example, one type of stem cells in the bone marrow produce a wide variety of red and white blood cells.
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Outline one therapeutic use of stem cells.
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Bone marrow transplants is a therapeutic use of stem cells. Stem cells found in the bone marrow give rise to the red blood cells, white blood cells and platelets in the body, These stem cells can be used in bone marrow transplants to treat people who have certain types of cancer.
When a patient have cancer and is given high does of chemotherapy, the chemotherapy kills the cancer cells and the normal cells in the bone marrow. This means the patient cannot produce blood cells. Before the patient is treated with chemotheraphy, they must undergo a bone marrow harvest in which stem cells are removed fro the bone marrowby using a needle which is inserted into the pelvis (hip bone). Atlernatively, if stem cells cannot be used from the patient then they mustbe harvested from a matching donor. After the chemo treatment, the patient will have a bone marrow transplant in which the stem cells are transplanted back in to the patient through a drip. These transplanted stem cells go back to the bone marrow and produce healthy blood cells for the patient. This therapeutic use enables some cancer patients to undergo high chemotherapy, without it, only low doses of chemo would be allowed and would lower their chances of curing the disease. |
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Draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote.
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Annotate the diagram from 2.2.1 with the functions of each named structure.
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Cell wall: Protects the cell from the outside environment and maintains the shape of the cell. It also prevents the cell from bursting if internal pressure rises. Plasma membrane: Semi-permeable membrane that controls the substances moving into and out of the cell. It contains integral and peripheral proteins. Substances pass through by either active or passive transport. Cytoplasm: Contains many enzymes used to catalyze chemical reactions of metabolism and it also contains the DNA in a region called the nucleoid. Ribosomes are also found in the cytoplasm. Pili: Help bacteria adhere to each other for the exchange of genetic material. Flagella (singular flagellum): Made of a protein called flagellin. Helps bacteria move around by the use of a motor protein that spins the flagellum like a propeller. Ribosomes: They are the site of protein synthesis. Contributes to protein synthesis by translating messenger RNA. Nucleoid: Region containing naked DNA which stores the hereditary material (genetic information) that controls the cell and will be passed on to daughter cells. |
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Identify structures from 2.2.1 in electron micrographs of E. coli.
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State that prokaryotic cells divide by binary fission.
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Prokaryotic cells divide by binary fission. Binary fission is a method of asexual reproduction involving the splitting of the parent organism into two separate organisms.« PreviousNext »
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Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell.
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Annotate the diagram from 2.3.1 with the functions of each named structure.
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Ribosomes: Found either floating free in the cytoplasm or attached to the surface of the rough endoplasmic reticulum and in mitochondria and chloroplast. Ribosomes are the site of protein synthesis as they translate messenger RNA to produce proteins. Rough endoplasmic reticulum: Can modify proteins to alter their function and/or destination. Synthesizes proteins to be excreted from the cell. Lysosome: Contains many digestive enzymes to hydrolyze macromolecules such as proteins and lipids into their monomers. Golgi apparatus: Receives proteins from the rough endoplasmic reticulum and may further modify them. It also packages proteins before the protein is sent to it’s final destination which may be intracellular or extracellular. Mitochondrion: Is responsible for aerobic respiration. Converts chemical energy into ATP using oxygen. Nucleus: Contains the chromosomes and therefore the hereditary material. It is responsible for controlling the cell. |
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Identify structures from 2.3.1 in electron micrographs of liver cells.
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Compare prokaryotic and eukaryotic cells
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Prokaryotic cells have naked DNA which is found in the cytoplasm in a region named the nucleoid. On the other hand, eukaryotes have chromosomes that are made up of DNA and protein. These chromosomes are found in the nucleus enclosed in a nuclear envelope.2.Prokaryotes do not have any mitochondria whereas eukaryotes do. 3.Prokaryotes have small ribosomes (70S) compared to eukaryotes which have large ribosomes (80S).4.In prokaryotes there are either no or very few organelles bounded by a single membrane in comparison to eukaryotes which have many of them including the Golgi apparatus and the endoplasmic reticulum.
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State three differences between plant and animal cells.
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- Animal cells only have a plasma membrane and no cell wall. Whereas plant cells have a plasma membrane and a cell wall. - Animal cells do not have chloroplasts whereas plant cells do for the process of photosynthesis. - Animal cells store glycogen as their carbohydrate resource whereas plants store starch. - Animal cells do not usually contain any vacuoles and if present they are small or temporary. On the other hand plants have a large vacuole that is always present. - Animal cells can change shape due to the lack of a cell wall and are usually rounded whereas plant cells have a fixed shape kept by the presence of the cell wall. |
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Outline two roles of extracellular components.
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The plant cell wall gives the cell a lot of strength and prevents it from bursting under high pressure as it is made up of cellulose arranged in groups called microfibrils. It gives the cell its shape, prevents excessive water up take by osmosis and is the reason why the whole plant can hold itself up against gravity.The animal cell contains glycoproteins in their extracellular matrix which are involved in the support, movement and adhesion of the cell.
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Draw and label a diagram to show the structure of membranes.
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Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes.
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Phospholipid molecules make up the cell membrane and are hydrophilic (attracted to water) as well as hydrophobic (not attracted to water but are attracted to other hydrophobic tails). They have a hydrophilic phosphate head and two hydrophobic hydrocarbon tails. Cell membranes are made up of a double layer of these phospholipid molecules. This is because in water the hydrophilic heads will face the water while the hydrophobic tails will be in the center because they face away from the water. The phospholipid bilayer makes the membrane very stable but also allows flexibility. The phospholipid in the membrane are in a fluid state which allows the cell to change it’s shape easily.
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List the functions of membrane proteins.
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Membrane proteins can act as hormone binding sites, electron carriers, pumps for active transport, channels for passive transport and also enzymes. In addition they can be used for cell to cell communication as well as cell adhesion.
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Define diffusion and osmosis.
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Diffusion is the passive movement of particles from a region of high concentration to a region of low concentration.Osmosis is the passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.
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Explain passive transport across membranes by simple diffusion and facilitated diffusion.
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Membranes are semi-permeable which means that they allow certain molecules through but not others. The molecules can move in and out through passive transport which is a method that does not require any input of outside energy. It can either be done by simple diffusion or facilitated diffusion. Molecules will go from a region of high concentration to a region of low concentration as they move randomly and eventually become evenly distributed within the system if they are permeable to the membrane. Simple diffusion involves the diffusion of molecules through the phospholipid bilayer while facilitated diffusion involves the use of channel proteins embedded in the membrane. The cell membrane is hydrophobic inside so hydrophobic (lipid soluble) molecules will pass through by simple diffusion whereas hydrophilic molecules and charged particles will use facilitated diffusion. Water moves through by osmosis which is also by passive transport. Osmosis involves the movement of water molecules from a region of low solute concentration, to a region of high solute concentration. So if the solute concentration is higher inside the cell than outside the cell, water will move in and vice versa.
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Explain the role of protein pumps and ATP in active transport across membranes.
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Active transport involves the movement of substances through the membrane using energy from ATP. The advantage of active transport is that substances can be moved against the concentration gradient, meaning from a region of low concentration to a region of high concentration. This is possible because the cell membrane has protein pumps embedded it which are used in active transport to move substances across by using ATP. Each protein pump only transports certain substances so the cell can control what comes in and what goes out.
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Explain how vesicles are used to transport materials within a cell between the rough endoplasmic reticulum, Golgi apparatus and plasma membrane.
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After proteins have been synthesized by ribosomes they are transported to the rough endoplasmic reticulum where they can be modified. Vesicles carrying the protein then bud off the rough endoplasmic reticulum and are transported to the Golgi apparatus to be further modified. After this the vesicles carrying the protein bud off the Golgi apparatus and carry the protein to the plasma membrane. Here the vesicles fuse with the membrane expelling their content (the modified proteins) outside the cell. The membrane then goes back to its original state. This is a process called exocytosis. Endocytosis is a similar process which involves the pulling of the plasma membrane inwards so that the pinching off of a vesicle from the plasma membrane occurs and then this vesicle can carry its content anywhere in the cell.
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Describe how the fluidity of the membrane allows it to change shape, break and re-form during endocytosis and exocytosis.
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The phospholipids in the cell membrane are not solid but are in a fluid state allowing the membrane to change its shape and also vesicles to fuse with it. This means substances can enter the cell via endocytosis and exit the cell via exocytosis. The membrane then returns to its original state. In exocytosis the vesicles fuse with the membrane expelling their content outside the cell. The membrane then goes back to its original state. Endocytosis is a similar process which involves the pulling of the plasma membrane inwards so that a vesicle is pinched off it and then this vesicle can carry its content anywhere in the cell.
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Outline the stages in the cell cycle, including interphase (G1, S, G2), mitosis and cytokinesis.
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The first stage of cell division is interphase which is divided into 3 phases; G1, S and G2. The cell cycle starts with G1 (Gap phase 1) during which the cell grows larger. This is followed by phase S (synthesis) during which the genome is replicated. Finally, G2 (gap phase 2) is the second growth phase which separates the newly replicated genome and marks the end of interphase. The fourth stage is mitosis which is divided into prophase, metaphase, anaphase and telophase. During mitosis the spindle fibers attach to the chromosomes and pull sister chromatids apart. This stage separates the two daughter genomes. Finally, cytokinesis is the last stage during which the cytoplasm divides to create two daughter cells. In animal cells the cell is pinched in two while plant cells form a plate between the dividing cells.
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State that tumours (cancers) are the result of uncontrolled cell division and that these can occur in any organ or tissue.
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Tumors are formed when cell division goes wrong and is no longer controlled. This can happen in any organ or tissue.
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State that interphase is an active period in the life of a cell when many metabolic reactions occur, including protein synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplasts
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Interphase is an active period in the life of a cell during which many metabolic reactions occur such as protein synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplast.
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Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase and telophase).
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During prophase the spindle microtubules grow and extend from each pole to the equator. Also chromosomes super coil and become short and bulky and the nuclear envelope breaks down.During metaphase the chromatids move to the equator and the spindle microtubules from each pole attach to each centromere on opposite sides.During anaphase the spindle microtubules pull the sister chromatids apart splitting the centromeres. This splits the sister chromatids into chromosomes. Each identical chromosome is pulled to opposite poles.During telophase the spindle microtubules break down and the chromosomes uncoil and so are no longer individually visible. Also the nuclear membrane reforms. The cell then divides by cytokinesis to form two daughter cells with identical genetic nuclei.
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Explain how mitosis produces two genetically identical nuclei.
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Mitosis is divided into four stages; prophase, metaphase, anaphase and telophase. During prophase, the chromosomes become visible under a light microscope as they super coil and therefore they get shorter and more bulky. The nuclear envelope disintegrates and the spindle microtubules grow and extend from each pole to the equator. At metaphase the chromatids move to the equator. The sister chromatids are two DNA molecules formed by DNA replication and are therefore identical. These sister chromatids are then separated in anaphase as the spindle microtubules attaches to centromere and pulls the sister chromatids to opposite poles. As the sister chromatids separate they are called chromosomes. This means that each pole has the same chromosomes (same genetic material). Finally the microtubules break down, the chromosomes uncoil and the nuclear membrane reforms. The cell then divides into two daughter cells with genetically identical nuclei.
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State that growth, embryonic development, tissue repair and asexual reproduction involve mitosis
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Growth, embryonic development, tissue repair and asexual reproduction involve mitosis
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