Author Archives: brittgow

About brittgow

Science and maths teacher at a small, rural school in Victoria, Australia. One husband, two children and three dogs on a sheep and cattle farm. Interests are: Education for Sustainability, web 2.0, beautiful gardens and good food.

Week 6: Energy transformations in cells – photosynthesis

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Learning intention: Students will understand the energy transformations from sunlight to chemical energy in the process of photosynthesis.

Watch the following videos and take Cornell notes. Especially pay attention to the products and reactants of the light-dependent and light-independent (Calvin cycle) parts of the reaction.

Week 5: Enzyme regulation in biochemical pathways

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Image result for effect of pH on enzyme activity

Learning Intention: Students will better understand the use of mass spectroscopy in the diagnosis of a medical condition and explore the implications of enzyme deficiencies in protein metabolism. They will also understand the effect of pH on enzyme activity and apply their knowledge of scientific method to writing the procedure for a practical experiment.

Success criteria: Students will complete the practical activity “Absent enzymes – phenyketonuria and albinism”.

  • Liver contains an enzyme that catalyses the reaction to breakdown hydrogen peroxide (H2O2)
  • Enzyme activity in this case  is indicated by the production of oxygen – a splint re-ignites in the presence of oxygen.
  • High temperatures denature proteins and prevent enzyme activity.
  • Diastase in an enzyme in plants that converts starch into glucose at an optimum temperature of 20 degrees Celcius.
  • The presence of starch in solution is indicated by iodine turning blue-black.

Your task is to devise an experiment that demonstrates the effect of pH on enzyme activity. Remember that pH is a logarithmic scale – a pH of 4 is ten times more H+ ions than a pH of 5.
pH and Enzymes
Effect of pH on enzyme activity

Second-hand data activity: PKU Genetics (YouTube, 5.00min)

Week 4: Gene structure and regulation

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Learning Intention: Students will understand the genetic code as a degenerate triplet code and the steps in gene expression including transcription, RNA processing in eukaryotic cells and translation. Students will also understand gene structure and regulation, especially start/stop, promoter regions, exons/introns and the lac operon.

Transcription – the process by which the DNA code is transcribed into messenger RNA in the nucleus of a cell. (DNA to mRNA)
RNA processing – the process by which introns are removed and the exons are spliced together, leaving a single-stranded mRNA molecule which travels through the nuclear pores into the cytoplasm.
Translation – the process by which the mRNA code is converted to a protein code by ribosomes adding amino acids that are attached to an anticodon that pairs with codons on the mRNA strand.
Gene structure and regulation
• the functional distinction between structural genes and regulatory genes
• the structure of genes in eukaryotic cells including stop and start instructions, promoter regions, exons and introns
• use of the lac operon as a simple prokaryotic model that illustrates the switching off and on of genes by proteins (transcriptional factors) expressed by regulatory genes.

Non-coding DNA explained
DNA transcription promoter
Gene expression and order of the operon
Lac operon from Virtual Cell

Week 3: Structure and function of nucleic acids and proteins

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Image result for transcription and translation diagram

Learning Intention: To understand nucleic acids as information molecules that encode instructions for the synthesis of proteins in cells and the processes of transcription and translation in cells. Students will also understand protein functional diversity and the nature of the proteome as well as the functional importance of the four hierarchal levels of protein structure. They will perform experiments that demonstrate the effect of temperature and pH on enzymes.

  • Catalase is an enzyme found in liver extract that breaks down hydrogen peroxide (H2O2) into water and oxygen.
  • Hydrogen peroxide is a toxic product of digestion that needs to be eliminated from the body. Water and oxygen are the safe products of hydrogen peroxide breakdown.
  • Primary structure of protein – order of amino acids
  • Secondary structure – alpha helix, beta pleated sheets or random coils
  • Tertiary structure – folding of the polypeptide chain due to disulphide bridges and other attractions or repulsions between molecules.
  • Quarternary structure – two or more polypeptide chains folded together to form a complex protein.

Week 2: Transport across the plasma membrane

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Image result for phagocytosis and pinocytosis

Learning Intention:
“Students will understand the role of different organelles including ribosomes, endoplasmic, reticulum, Golgi apparatus and associated vesicles in the export of a protein product from the cell through exocytosis and cellular engulfment of material by endocytosis.”

Ribosomes translate the messenger RNA into a protein by matching the 3-base pair codon with an anticodon on the transport RNA, allowing the production of a polypeptide. The endoplasmic reticulum allows the transport of polypeptides (protein chains) to the Golgi aparatus, where proteins are collected, packaged and distributed throughout the cell and exported through the cell membrane (exocytosis).

Osmosis is the passive movement of water across a semi-permeable membrane
Diffusion is the natural tendency of particles to move from a higher concentration to a lower concentration. It is a passive process – does not require energy to be expended.
Facilitated diffusion is when a protein channel is required to allow the passive movement of larger molecules through the cell membrane.
Active transport (as opposed to passive transport) means that energy is required for the cell to all transport of substances against the concentration gradient.
Phagocytosis is the movement of solids across a membrane, usually when the cell creates a pocket and engulfs the nutrient.
Pinocytosis is the movement of liquids across a membrane, for example, when a Paramecium expels liquid waste water.
Endocytosis is when substances move into the cell.
Exocytosis is when substances move out of the cell.

Week 1: Fluid mosaic model of the cell membrane

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Which molecules can move through the cell membrane passively (by diffusion)?

Which molecules can move through the cell membrane by active transport (requiring energy)?

Which molecules cannot pass through the cell membrane?

Step Up to 2017!

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sparkling trails of light drawing out the numbers 2017 in glowing light to welcome in the new year

Welcome to the step up week for Year 12 Biology in 2017. This post is to let you know about some of the resources that are available for your studies. It is a new course for Unit 3 and 4 next year and we will be using the Heinemann textbook (3rd edition). You will also need a copy of the Heinemann Student Workbook for practical activities and revision questions.

The Hawkesdale Biology Quizlet page is where you can access learning activities for each Chapter to assist you with key terms and definitions. Please sign up to Quizlet and join the class.

Andrew Douch is a very experienced VCE Biology teacher who produces free weekly podcasts (Douchy’s Biology Podcasts) that are worth listening to. He also has a popular Facebook page where you can ask questions.

Mr Barlow has produced four apps, one for each Biology unit, which are available on iTunes. You may find these useful for revision.

Unit 3 – Area of Study 1 – How do cellular processes work? 

Outcome 1: On completion of this unit the student should be able to explain the dynamic nature of the cell in terms of key cellular processes including regulation, photosynthesis and cellular respiration, and analyse factors that affect the rate of biochemical reactions.

Unit 3 – Area of Study 2 – How do cells communicate?

Outcome 2: On completion of this unit the student should be able to apply a stimulus-response model to explain how cells communicate with each other, outline human responses to invading pathogens, distinguish between the different ways that immunity may be acquired, and explain how malfunctions of the immune system cause disease.

Unit 4 – Area of Study 1 – How are species related?

Outcome 1: On completion of this unit the student should be able to analyse evidence for evolutionary change, explain how relatedness between species is determined, and elaborate on the consequences of biological change in human evolution.

Unit 4 – Area of Study 2 – How do humans impact on biological processes?

Outcome 2: On completion of this unit the student should be able to describe how tools and techniques can be used to manipulate DNA, explain how biological knowledge is applied to biotechnical applications, and analyse the interrelationship between scientific knowledge and its applications in society.

Unit 4 – Area of Study 3 – Practical Investigation

Outcome 3: On the completion of this unit the student should be able to design and undertake an investigation related to cellular processes and/or biological change and continuity over time, and present methodologies, findings and conclusions in a scientific poster.

Term 4 Exam Revision

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My class have identified three areas in each of Unit 3 and Unit 4 that they would like to do more work on before the exams:

Unit 3: Signatures of Life

Unit 4: Continuity and Change

Human Evolution

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evolution_silohettesImage source

One of the earliest defining human traits, bipedalism — the ability to walk on two legs — evolved over 4 million years ago. Other important human characteristics — such as a large and complex brain, the ability to make and use tools, and the capacity for language — developed more recently. Many advanced traits — including complex symbolic expression, art, and elaborate cultural diversity — emerged mainly during the past 100,000 years.

Since Darwin first proposed that humans and apes had a common ancestor, our understanding of human evolution has improved due to fossil finds, analysis of our closest living and extinct relatives, studies of geographic distribution and DNA analysis. Although the image above is often used to represent human evolution, the process is not the simple linear procession that is shown. Your task is to write an essay of at least eight paragraphs that explains why this image is suitable, but also why it is an inaccurate representation of human evolution.

  • Introduction – what will the following paragraphs explain?
  • Outline primate family tree, including lemurs, monkeys, apes, hominins and Homo sapiens.
  • Where do Australopithecus sp., Homo erectus, Homo habilis, Homo neanderthalensis and Homo heidelbergensis fit in?
  • Discuss bipedalism – location of foramen magnum, shape of spine  and ratio of arm to body length.
  • Discuss skull shape, brow ridges, sagittal and nuchal crests, prognathous jaw and facial sloping.
  • Discuss cranial capacity and relationship to body mass and intelligence.
  • What is the evidence that human evolution is not a linear progression, but a many-branched family tree?
  • Conclusion – what are the main characteristics that can be identified in the image and why is the image an inaccurate representation of human evolution.

Introduction to Human Evolution from the Smithsonian 

7 Strange and Surprising ways that humans have evolved recently

Human intervention in evolution

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GMO_Papaya_sunset

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This fruit is from a genetically modified papaya plant, bred to reduce the risk of disease. How are genetically modified organisms created? (YouTube video, 5.31min)

Quizlet – Flashcards for Chapter 16

While genetic techniques have certainly provided health benefits to our society (disease diagnosis and therapies, production of insulin and increased production of more nutritious and disease resistant foods), there are also community concerns about the ways that these technologies are being used and the future consequences. ABC Splash have some short videos that outline some of the issues of genetic technologies: