B5 lesson part two

B5 Growth and Development Route map Over the next 12 lessons you will study : Friday 21 October 2011 B5.1 Growing and Changing B5.2 Growth Patterns B5.3 Growing Plants B5.4 A look inside the nucleus End of module test B5.5 Making new Cells B5.6 Sexual Reproduction B5.7 The Mystery of Inheritance B5.8 Specialised cells – special protein B5.9 Switched on or off? B5.10 Stem Cells B5.11 Making Proteins B5.12 Phototropism

B5.7 The mystery of inheritance Decide whether the following statements are true or false: We will focus on. Friday 21 October 2011 First activity: DNA is a double helix made form two strands of DNA that coil around one another. DNA is found in every cell of the human body. Where did each DNA strand come from ? Literacy: DNA, double helix, genes, base pairs, Crick, Watson, base pairing, adenine, cytosine, guanine, thymine, bonds and genetic inheritance. Numeracy: Between 1860 and 1523 various scientists led the charge to discover the material of inheritance, its structure and how it passed on information form generation. In 1953, two Cambridge scientists solve the puzzle. Their name Watson and Crick. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on: Asking questions and extending our thinking about inheritance Team workers Effective participators Self managers Lesson objectives: Understand the role of DNA in the cell and its three dimensional structure Understand how DNA is copied in the cell and how DNA passes on information Understand the role of Francis Crick and James Watson in discover DNA’s strucure.

B5.7 The mystery of inheritance Extension questions: 1: Who discovered the double helix structure of DNA ? 2: Which base of the DNA molecule always pairs up with Adenine? 3: Describe what happens when a DNA molecule is copied inside the cell during mitosis (cell division) or meiosis (gamete formation) ? 4: What does base pairing mean ? 5: “Nuclein” was recognised as genetic material in what year ? 6: What is DNA short for ? Know this: a: Know the role of DNA in the human body. b: Know how DNA passes on information through each successive generation. c: Know that a single gene is 3 bases either A, T G or C. Friday 21 October 2011 Introduction: The information to determine the characteristics of your whole body is held by the nucleus in your cells and is called the genetic code . The genetic code is stored in chromosomes. A chromosome is a very long molecule of DNA . In humans there are 23 pairs of chromosomes, 23 of which are from you mother and 23 from your father. A DNA molecule contains two strands twisted together in a spiral - this is a double helix . Each strand is made of four bases: adenine (A) , thymine (T) , guanine (G) , and cytosine (C) . The order of these bases reads like a code with 3 bases making a gene which then code for an amino acid found in a protein like an enzyme.

Key concepts Look at the photograph and information and answer all the questions: Watson and Crick made cardboard models of the bases in DNA. He found that A&T base pairs were the same size as the G&C base pairs. He also discovered a spherical pattern using X-ray crystallography. He realised that there were pairs of bases between two chains (a sugar and phosphates). The shape turned out to be a double helix. Watson and Crick B5.7 a DNA, the material of inheritance X ray crystallography of DNA What are the names of the four bases and which base pairs with which base ? What is the name of the sugar backbone found in the DNA molecule ?

Key concepts Look at the photograph and information and answer all the questions: During cell division DNA is replicated. The double helix structure allows for this replication. In the diagram opposite left, the two strands separate (blue). Free bases then form two new strands (orange). You are then left with two identical double helix molecules. Each DNA molecule is made from half old DNA (shown in blue) and half new DNA (shown in orange.) During normal cell division when does DNA replicates itself ? Who discovered the double helical structure of the DNA molecule ? If you examine the DNA found in sperm or egg gametes would it look the same as the picture opposite left ? B5.7 b Replicating DNA inside the cell maternal strand paternal strand Old DNA New DNA

B5.7 Plenary Lesson summary: amino triplet nucleus genetic Friday 21 October 2011 In 1953, Crick and Watson published their now famous paper, “a structure for Deoxyribose Nucleic Acid” in the scientific journal Nature. This paper brought together all their work on DNA and they used it to work out the structure of the double helix structure of DNA. How Science Works: Research how proteins are made inside the cell from the information found in DNA and what are the role of proteins inside the cell and human body. Preparing for the next lesson: Cells make proteins from about 20 _______ acids. There are thousands of different proteins. Each protein has a certain combination of amino acids joined together in a particular order. Each amino acid has a three-base code (a _______ code). The ________ code for making proteins is held on DNA in the cell ________. Decide whether the following statements are true or false : False True 3: You share 50% of your DNA with your mum and dad ? False True 2: Abbot and Costello discovered the structure of DNA ? False True 1: Adenine and guanine pair together in the DNA strand ?

B5.8 Specialised cells – special proteins Decide whether the following statements are true or false: Lesson objectives: Understand the role of proteins as structural molecules and enzymes in the human body Understand how proteins are made inside the cell Understand why cells become specialised inside the human body We will focus on. Friday 21 October 2011 First activity: List as many different proteins in the body and describe their role, for example collagen is important in holding skin cells together ? Literacy: Genes, DNA, proteins, keratin, elastin, collagen, structural proteins, enzymes, Antibodies, genetic switches, cells, skin, bone, nails, tendons, and ligaments Numeracy: All cells contain the same genetic information yet cell are different they are specialised. A skin cell is very different to a muscle or nerve cell. How this happens is by gene switching on or off PLTS Independent enquirers Creative thinkers Reflective learners We will focus on: Identify questions to answer about the different proteins within the body. Team workers Effective participators Self managers

B5.8 Specialised Cells Extension questions: 1: Name three types of protein in your body ? 2: Name one structural protein and say how it is suited to do its job ? 3: DNA is a cell’s genetic code. What does it do in a cell ? 4: How do genes control how a cell develops ? 5: Name a cell which would make these proteins: a) collagen, b) amylase and c) haemoglobin ? 6: Enzymes are proteins what role do they play in the body ? Know this: a: Know the role of proteins inside the cell and human body B: Know that humans have over 300 types of specialised cells. b: Know how cell become specialised by gene switching. Friday 21 October 2011 Introduction: Some proteins make up the framework of cells and tissues. These are structural proteins. If you were to remove all the water from an animal cell, 90% of what is left is proteins. Different specialised cells will contain different structural proteins needed to allow them to do their job inside the human body (both structural and enzymes) Other proteins that are also made using fragment of your DNA are also essential to life, for example all enzymes are proteins that speed up chemical reactions in a cell and during the digestion of food from your diet.

Key concepts Look at the photograph and information and answer all the questions: Explain why mammals like humans have more specialised cells when compared to plants like trees ? Give the name of the specialised cell that a) produces glucose b) carries oxygen c carries electrical impulses d) fertilises an egg e) detects light and colour ? In organisms which are multi cellular (made up of many cells), they cells are often specialised so they can perform a particular job better. They often have special shapes or structures in order to do their job better. This often results in the specialised cells being dependant upon other cells in the organism to perform the living processes it cannot. B5.8 a Specialised cells in plants and humans Plants typical have between 25 to 30 specialised cells for example, root hair cells, palisade cells, and stomata cells. Humans typically have between about 300 specialised cells for example, skin cells, red blood cells, nerve cells and muscle cells

Key concepts Look at the photograph and information and answer all the questions: Cardiac cells are unique in that they ‘twitch’ or contract naturally. Why does this feature make them good at their job in the heart ? Give two other specialised cells and explain how they are adapted to do their job in the human body ? Cells are designed for the specific functions they play in the human body as part of the billions of cells that work together to support life. A nerve cell for example is long and thin and conducts electrical impulses. A red blood cell has a large surface area and no nucleus, so it can transport the maximum amount of oxygen from the lungs to the rest of the body. B5.8 a Specialised cells in plants and humans Plants cells Human cells

B5.8 Plenary Lesson summary: tissues reactions antibodies proteins Friday 21 October 2011 Proteins are essential structural molecules found in cell membranes and provide the framework to make tissues like skin boner and muscle. Enzymes are proteins which speed up the chemical reactions that keep our bodies working. For example, digestive enzymes (amylases, proteases and lipases) speed up the chemical reactions the digestive system. How Science Works: Research into how proteins are made and how one gene codes for protein which have specific role in the human body. Preparing for the next lesson: Structural ________ are the framework which make up cells and ___________. There are other proteins which are essential for the chemical _________ that keep our bodies working. Other proteins called __________ are the proteins that help to defend our bodies against disease. Decide whether the following statements are true or false : False True 3: All cells in your body came from just one original cell, the zygote ? False True 2: Plants have less specialised cells when compared to humans ? False True 1: Human hair and fingernails are both made from proteins ?

B5.9 Switched on or off ? Decide whether the following statements are true or false: Lesson objectives: Understand how proteins are made inside the cell and how one gene codes for one amino acid the building blocks of proteins. Understand how and when gene switching occurs in different specialised cells. We will focus on. Friday 21 October 2011 First activity: All cells contain exactly the same genetic information and yet a skin cell is very different from a nerve cell or a red blood cell. Specific genes are switched on or off to make cell different and specialised. List the feature of each cell type and say how it help each cell do its job in the human body ? Literacy: DNA, genes, base pairs, thymine, guanine, cytosine and adenine, amino acids, proteins, cells, specialised cells, genetic switching, one gene theory, organism, chromosomes and DNA. Numeracy: Humans have about 25,000 to 30,000 genes. Each gene ode for a unique protein. Each proteins (structural or a proteins that folds to create an enzyme) will do a specific job. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on: Communicating your learning and understanding in relevant ways for different audiences Team workers Effective participators Self managers

B5.9 Switched on or off ? Extension questions: 1: Suggest a function, other than respiration, that all cells carry out ? 2: At the 8-cell stage of any embryo, how may genes are switched on ? 3: Draw a diagram which shows the genes which are switched on in an unspecialised cell ? 4: Write a definition for the one-gene-one-protein theory ? 5: Where would you find unspecialised stem cells in an adult ? Know this: a: Know how proteins are made inside cells from the information contain in our DNA. b: Know how gene switching causes cells to become specialised in the human body. Friday 21 October 2011 Introduction: One-gene-one-protein theory says that each gene controls the manufacture of one type of protein. In humans there are 20000 to 25000 genes. Not all genes are active and as cells grow some genes switch ‘off’ or ‘on’. In a hair cell, the genes for the enzyme that make keratin will be switched on, but the genes for those that make enzyme amylase (found in salvia and the small intestine) will be switched off. Some proteins are found common to every cell ,f or example all cells need to respire so genes that make enzymes that allow respiration to occur will be switched on in all cells.

Key concepts Look at the photograph and information and answer all the questions: Why could stem cells be used as therapies of the future to treat disease organs including the brain ? What causes genes to become switched on or off ? All cells contain the same DNA code. When a cell has to become specialized, it has to switch on certain genes and switch off the transcription of others. This mechanism of keeping a check on the genes being expressed at any point of time is referred to as gene regulation. A neuron, for example, will have a certain set of genes switched on, which is different from the genes switched on in a muscle cell. B5.9 a Gene switching making specialised cells stem cell blood cells muscle cells nerve cells (gene switching) unspecialised stem cell gene ‘on’ gene ‘off’

Key concepts Look at the photograph and information and answer all the questions: You identify a cell which makes an amylase enzyme and an antiseptic protein where would you fins these cells ? You identify a cell that makes a tough water membrane resistant to UV light where would you find these cells ? Cells are specialised doing very different jobs in the human body. You would expect a red blood cell which carries oxygen around the body in blood to be the same as a nerve cell which carry electrical impulses to and from the brain to all areas of the body. Different gene which make different proteins are either switched ‘on’ or ‘off’ to make he cell adapted for their function. B5.9 b Gene switching making specialised cells Genes used to make haemoglobin protein which traps iron which then binds oxygen. Blood cells Nerve cells Heart cells Genes used to produce a insulating myelin sheath so nerve cells can conduct impulses. Gene sues to produce structural proteins which are able to ‘twitch’ on their own.

B5.9 Plenary Lesson summary: genetic protein cell hair Friday 21 October 2011 In a developing embryo, the cells near the end of a limb will make fingers. Cells nearer the body will make an arm. This happens because of the difference in the concentration of chemical signals in each region of the embryo. Quite how the embryo manages to control all the cells is still a miracle and mystery of life of the developing foetus ! How Science Works: Research into what are stem cells and how might stem cell therapy be used to treat medical conditions like disease of the brain (Parkinson's disease, Alzheimer's) or damaged organs (Heart lung or liver) Preparing for the next lesson: DNA is a cell’s ________ code. Each gene is the instruction for a cell to make a particular ________. By controlling what proteins a cell makes, genes control how a _____ develops. We are still unsure what makes some cells turn into nerve cells or ________ cells. We think there must be some sort of gene switching in every cell. Decide whether the following statements are true or false : False True 3: DNA is not a cell’s genetic code ? False True 2: All genes in every cell of your body are active ? False True 1: In a salivary gland cell, the genes to produce amylase are switched on ?

B5.10 Stem cells Decide whether the following statements are true or false: Friday 21 October 2011 First activity: Imagine you have been diagnosed with life changing or threatening Parkinson's disease, dementia, Alzheimers or even liver cancer, why could doctors and laboratories who offer stem cell therapy potential take advantage of you PLTS Independent enquirers Creative thinkers Reflective learners We will focus on Team workers Effective participators Self managers Lesson objectives: Understand that cloned stem cell may offer therapeutic treatments in the future for disease or damaged organs Understand the ethical questions that may arise when using stem cell technology to treat patients with life changing o threatening diseases. Literacy: Asexual reproduction, clones, cloning, identical, twins, fertilisation, sperm, egg, molly, dolly, stem cells, undifferentiated, differentiated, Parkinson's disease, dementia and Alzheimer's. Numeracy: Currently stem cell therapy where stem cells are injected into a target organ like the liver or brain to form new brain or liver cells is banned in this country. In Switzerland, certain doctors now offer stem cell therapy at a cost of £20,000.

Stem cells Extension questions: 1: How are stem cells different from other cells ? 2: Why would scientists think stem cells would be useful in treating Parkinson’s disease ? 3: Explain how stem cell technology/treatment is different from cloning an adult ? 4: For each of these cells, say whether or not your body would reject it: bone marrow from a) your twin b) your sister and c) from stem cells with some of your own genes ? Know this: a: Know that cloned stem cells may offer therapeutic treatments in the future for disease or damaged organs. b: Know that stem cell scan be sources form bone marrow although only 1 in 10,000 bone marrow cells are stem cells. Friday 21 October 2011 Introduction: Scientists are try to improve methods for cloning animals. So in the future it may be possible to clone humans. But most scientists don’t want to clone adult human beings. However, some scientists do want to clone human embryos. They think that some cells from cloned embryos could be used to treat diseases. Stem cells which are unspecialised are found in embryos (left over form fertility treatment) and are unspecialised cells, which could be given to patients to repair damaged or diseased organs. To avoid rejection of the stem cells, they would need to have the same genes as the person getting them as a treatment. B5.10

Key concepts B5.10 a Look at the photograph and information and answer all the questions: Stem cells can now be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture. It is hoped that stem cells source form either embryos or umbilical cord tissue will be used to treat, replace and repair damages, disease or ageing organs including the heart, brain, liver and skeletal muscle. In the future disease like dementia, may be cured by injecting stem cells into the brain. Would you take this treatment if you suffered from one of these diseases ? State the ethical issues of using stem cells from a) embryos and b) umbilical cord ? Using stem cell technology Brain Other Stem cells could treat diseases like Parkinson disease where neurons cease to produce dopamine Stem cells could treat damaged organs like the heart of skeletal muscle. They could also treat organs identified with tumour for example liver cancer

B5.10 b Look at the photograph and information and answer all the questions: Occasionally a vital organ like a heart may fail even when we’re young. Scientists are now researching how to repair these organs using ‘stem cells.’ Unlike transplants, where you require a donor organ, stem cells once injected into a damaged organ can turn into new cells that can repair that organ. Stem cells unlike transplanted organs are not rejected by the body’s immune system. Explain why there is a real need to research the use of ‘stem cells’ as a source of cells that could produce any type of new cell as our own population ages ? Most stem cells used in scientific research are taken from embryos that are unwanted...what are the ethical issues of using cells taken from embryos ? If stem cell technology worked and was simple to administer we could all live to about 140...discuss the consequences of this on society ? Harvested stem cells Stem cell Blood cells Nerve cells Heart cells Stem cell technology Key concepts

B5.10 c Look at the photograph and information and answer all the questions: Give two ethical reasons for and against why we should all have access to stem cell therapy/treatment ? If stem cell technology could improve life expectancy should we use it ? Stem cell technology is yet proven may never work Stem cell technology would only be available to those patients who could afford to pay ? Human embryos should not be used as a source of stem cells ? The money could be better spent on preventing people form smoking or drinking and leading an unhealthy life Medical researchers believe that stem cell therapy has the potential to dramatically change the treatment of human disease. In the future, medical researchers anticipate being able to use technologies derived from stem cell research to treat a wider variety of diseases including cancer, Parkinson's disease, spinal cord injuries, multiple sclerosis, and muscle damage, However, there still exists a great deal of social and scientific uncertainty surrounding stem cell research, which could possibly be overcome through public debate and future research. Is using stem cell technology ethical Stem cell technology could help people live longer free of disease The cost of treating an elderly person with dementia using stem cell technology would be cheaper than having to provide long term care Scientists will be able to use embryos as a source for stem cells that would normally be destroyed Arguments for ? Arguments against ? If the technology works then we have the duty to make sure that we all benefit from it Key concepts

B5.10 Plenary Lesson summary: unspecialized cloned treat different Friday 21 October 2011 How Science Works: Research into how the body makes proteins using genes located in the DNA double helix. Preparing for the next lesson: Stem cells are ___________ animal cells which can develop into _________ types of cells. This is advantageous for scientists who want to use some cells from _______ human embryos to _______ diseases. Scientists at the University of Freiberg in Germany treated 60 patients who had heart disease. Some of the patients were treated using stem cells. The scientists think that the stem cells turned into new blood vessels or heart muscle cells or made the heart tissue secrete chemicals that encouraged growth of the patient’s own heart cells. Decide whether the following statements are true or false : False True 3: Using stem cells could help cure diseases like the common cold and flu ? False True 2: Bone marrow is the source of our own stem cells ? False True 1: We now clone humans all the time ?

B5.11 Making Proteins Decide whether the following statements are true or false: Lesson objectives: Understand how the genes contained in DNA are used to manufacture proteins inside the cell cytoplasm. Understand how proteins are made and their role in cells. We will focus on. Friday 21 October 2011 First activity: Name the four base pairs that make the unique code of life DNA. How are they pair and how is DNA replicated during normal cell division ? Literacy: Amino acids, triplet code, mRNA, DNA, Arginine, Lysine, Tyrosine, Ribosome, cytoplasm, nuclear membrane, proteins, genes. Numeracy: There are just 20 different amino acids which are used to make long chain proteins. Some proteins can be up to 2000 amino acids long meaning that 6000 base pair were required to manufacture that protein found along part of your DNA. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on: Questioning your own and other’s assumptions about how proteins are made Team workers Effective participators Self managers

B5.11 Making Proteins Extension questions: 1: Why are instructions for making proteins copied onto mRNA instead of using DNA itself ? 2: How many DNA bases code for a single amino acid? 3: What is the triplet code for tyrosine ? 4: Which amino acid has the code GCC ? 5: What are the differences between DNA and mRNA ? 6: What controls the sequence of amino acids in a protein chain ? Know this: a: Know how proteins are made inside the cell and how the sequence of amino acids is controlled the genes found in DNA. b: Know that the three dimensional shape of a proteins controls its properties. Friday 21 October 2011 Introduction: The great number of jobs carried out by proteins means that the are different from one another. The exact shape of a protein can be very important to how it works. Cells make proteins from 20 different amino acids and many proteins can be chains of 1000 to 2000 amino acids. The sequence of these amino acids is determined by your DNA. The sequence of the amino acids fixes the way the chains of amino acids fold to form the three-dimensional shape of the protein either as a structural protein like collagen or keratin or an enzyme like amylase or protease.

Key concepts Look at the photograph and information and answer all the questions: The amino acids used to build proteins chains are sources from where ? Why is DNA copied forming RNA which is then used outside the cell nucleus to code for the new protein chain made from amino acids ? Protein synthesis is the process in which cells build proteins. Making proteins is a multi-step process, beginning with amino acid synthesis and transcription of nuclear DNA into messenger RNA, which is then used to determine which amino acids go where. Short fragments call tRNA pick up the right amino acid and start building the protein chain. B5.11 a How are proteins synthesised

Key concepts Look at the photograph and information and answer all the questions: What role do antibodies play on our body are where would d you find these proteins ? Enzymes work by locking onto one substrate…explain why the folding of a enzyme is important to its function ? Proteins are like long necklaces with differently shaped beads. Each "bead" is a small molecule called an amino acid. There are 20 standard amino acids, each with its own shape, size, and properties. Proteins typically contain from 50 to 2,000 amino acids hooked end-to-end in many combinations. To become active, proteins must twist and fold into their final, shape. which enables proteins to accomplish their function. B5.11 b Three dimensional shapes of proteins Collagen in our cartilage and tendons gains its strength from its three-stranded, rope-like structure. It provide a matrix for skin and other cells. Antibodies are immune system proteins. The two arms of the Y-shaped antibody bind to a foreign molecule and help white blood cell trap bacteria/viruses. Enzymes, which are proteins that speed reactions, often contain a groove or pocket to hold the molecule they act upon. Collagen Antibody Different enzymes

Key concepts Look at the photograph and information and answer all the questions: Explain why beta sheets proteins are used to make small tube like structures inside the cell ? The proteins containing alpha and beta sheets what does this resemble ? When proteins fold, they don't randomly fold into twisted masses. They form set three dimensional shapes. Often, short sections of proteins form recognizable shapes. Where a protein chain curves into a corkscrew, that section is called an alpha helix . Where it forms a flattened strip, it is a beta sheet . Some proteins can contain or a mix of alpha helices and beta sheets . B5.11 c Three dimensional shapes of proteins The three dimensional image above shows a protein with a mix of alpha helices and beta sheets . The three dimensional image above shows a protein with mostly beta sheets The three dimensional image above show a protein with mostly alpha helices .

Key concepts Look at the photograph and information and answer all the questions: Explain why the shape of a red blood cell in very important so it can do its job ? Explain why there is no know cure form sickle cell at the current time ? Small errors in proteins can cause disease like sickle cell anaemia. Sickle cell disease, which most often affects those of African descent, is caused by a single error in the gene for haemoglobin, the oxygen-carrying protein in red blood cells. This error, results in an single incorrect amino acid. Hemoglobin molecules with this incorrect amino acid stick together and distort the normally smooth, lozenge-shaped red blood cells into jagged sickle shapes. B5.11 d Three dimensional shapes of proteins The most common symptom of the disease is unpredictable pain in any body organ or joint, caused when the distorted blood cells jam together, unable to pass through small blood vessels. These blockages prevent oxygen-carrying blood from getting to organs and tissues . Normal red blood cells Sickle cell

B5.11 Plenary Lesson summary: protein cells chains function Friday 21 October 2011 In 1961, Crick worked out that a three-base code for each amino acid would work. Different combinations of the four bases produce 64 triplet codes. So there is more than one code for each amino acid. There are also codes that signal the starting and stopping of the protein chain. These start and stop triplets mark the beginning and end of a gene. How Science Works: Research into how plants grow and how they can respond to stimuli such as light, moisture and gravity. Preparing for the next lesson: Each ________ is very different from each other due to the different type of job they have. _________ make proteins from about 20 different amino acids. They can join in __________ from 50 to many thousands. The order of the amino acids determines the shape and _________ of the protein. Decide whether the following statements are true or false : False True 3: Genes found in the DNA can leave the cell nucleus ? False True 2: Four bases on DNA codes for an amino acid, the building blocks of proteins ? False True 1: In mRNA the uracil base (U) takes the place of the thyamine base (T) on DNA ?

B5.12 Phototropism Decide whether the following statements are true or false: Lesson objectives: Understand that plant growth can respond to stimuli like light, moisture and gravity. Understand how plants grow towards the light displaying photropism. We will focus on. Friday 21 October 2011 First activity: What is mRNA? How is it different from DNA ? Why are instructions for making proteins copied onto mRNA ? How many DNA base code for an amino acid? Literacy: Plants, growth, phototropism, stimuli, moisture, light, gravity, auxin, roots, shoots, bending, development, hormones, roots, shade and sunshine. Numeracy: How plants shoots bend towards the light or how plant roots bend towards the ground is cause by the plant cells growing at different rates on one side of a growing shoot or root. PLTS Independent enquirers Creative thinkers Reflective learners We will focus on: Generate ideas and explore possibilities Team workers Effective participators Self managers

B5.12 Phototropism Extension questions: 1: How does the walking palm tree grow towards the light ? 2: Explain why a plant benefits from bending towards the light ? 3: Write a definition for phototropism ? 4: Where does a shoot detect light ? 5: When a shoot bends towards the light which cells in the shoot grow the quickest ? 6: How would a seed grow in zero gravity and light (sketch) ? Know this: a: Know how plants respond to stimuli like light by auxin controlled growth b: Know that the palm tree, Socratea durissima , grows new roots towards a sunny patch which pulls the stem and leaves towards the light. Friday 21 October 2011 Introduction: Plants rooted in soil can’t move from place to place. You may have noticed that plants on windowsills seem to be bending towards the light. They are not moving, but growing. When the direction the light comes from affects the direction of plant growth, it is called phototropism . The only part of the plant that grows in the opposite way are the roots. They grow down into the ground away from the light. This is negative phototropism. Plants can also respond to gravity and moisture.

Key concepts Look at the photograph and information and answer all the questions: Using your knowledge of auxin in response to light and the direction of light why do we germinate seeds in the dark ? Why is it beneficial for plants to bed towards the light ? B5.12 a Plant’s response to light The three dimensional image above shows a protein with mostly beta sheets Light energy from sunlight Auxin accumulates on the dark side of the shoot causing cell elongation and the subsequent bending of the shoot towards the light source Auxin accumulation Plants can respond to environmental stimuli like light, gravity and water. Unlike humans and other animals, plants cannot move themselves because they lack a skeletal muscle system. Plants can, however grow towards or away from a light source. Plant shoots grow towards the light, whereas plant roots grow towards gravity and moisture.

Key concepts Look at the photograph and information and answer all the questions: B5.12 b Plant’s response to light The three dimensional image above shows a protein with mostly beta sheets Plants must grow in one direction or another to respond to stimuli like light, moisture or even gravity. They can’t simply move because thy don’t have a nervous or muscle system. The following experiments help us understand the role auxin plays in controlling a plant’s response. Look at the three different scenarios and predict where auxin is found and how this affects plant growth ? Light energy from sunlight Expt. one Expt. two Expt. three Three different experiment were set up as shown above: In experiment one: the shoot is untouched. In experiment two: foil covers the tip of the shoot. In experiment three: foil covers the base of the tip. Look at the result sand what do these results tell us ? results results results

B5.12 Plenary Lesson summary: clone organ roots auxins Friday 21 October 2011 Charles Darwin experimented with phototropism. He showed that the young shoots of grasses normally grew towards light and remained straight when he covered their tips. When he covered the lower parts of the shoot it didn’t stop them from bending towards the light. This proved that only the tip of the plant was sensitive to light. How Science Works: Revise for an end of module test on all the work you have covered on B5 Growth and Development. Preparing for the next lesson: Unspecialised plant cells can make any type of _______ the plant needs. Rooting powder can be used to encourage cut shoots to form _______. Rooting powder contains plant hormones. The _______ cause the new cells produced by the new cells in the shoot to develop into roots. The cutting then grows into a complete plant which is a _____ of the parent. Decide whether the following statements are true or false : False True 3: Low concentrations of auxins cause shoot cells to expand ? False True 2: Light is an essential requirement for plants ? False True 1: Phototropism is when shoots grow in the direction of light ?

B5 lesson part two

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B5 lesson part two