Category Archives: Unit 3 Biology

The Immune System – Like fighting invaders on the Great Wall

Image source

First line of defence (innate immunity): This is like a moat and castle walls, preventing invasion by foreigners. There are physical and chemical barriers to infection.

Second line of defence (innate immunity): If the foreign materials breach the first line of defence, an infection forms. This is the inflammation (heated battle) where invaders are being killed indiscriminately.

Third line of defence (active immunmity) : The last line of defence is the active, specific response by trained killer cells (ninjas!) that recognise their targets and actively seek them out and destroy them. They may be proteins or pathogens that have taken over the reproductive capacity of the cell (prions and viruses, for example), so the infected cell must be destroyed.

Gene Technology Access Centre’s Online courses – Active immunity

At the Gene Technology Access Centre for the “Body at War – Day of Immunology” seminar and workshops, you learned about pathogens, the human body’s response to antigens and how vaccines have been developed to reduce the spread of disease.  You conducted ELISA tests to identify infected individuals and observed diseased tissues through microscopy. A valuable activity was the Immunology Game, which demonstrated the response to antigens at a cellular level and gave you the experience of controlling the movement of white blood cells (dendrites, plasma cells, macrophages and B and T cells) around the body.

GTAC also have several online courses that I would like you to complete this week.

Signalling molecules, antigens and the immune system

How do cells communicate? In this area of study students focus on how cells receive specific signals that elicit a particular response. Students apply the stimulus-response model to the cell in terms of the types of signals, the position of receptors, and the transduction of the information across the cell to an effector that then initiates a response. Students examine unique molecules called antigens and how they elicit an immune response, the nature of immunity and the role of vaccinations in providing immunity. They explain how malfunctions in signalling pathways cause various disorders in the human population and how new technologies assist in managing such disorders.

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 immune responses to invading pathogens, distinguish between the different ways that immunity may be acquired, and explain how malfunctions of the immune system cause disease.

In Area of Study 2: How do cells communicate? we study cellular signals (signalling molecules, signal transduction and apoptosis); responding to antigens (including antigens, innate and adaptive immunity and the lymphatic system) and the immune system (including diseases of the immune system and cancer immunotherapy). The following links are some resources for study in these topics.

Chapter 6: Cellular Signals

Chapter 7: Responding to antigens

Chapter 8: Immunity, immune malfunctions and immunotherapy

Signal Transduction and Apoptosis

Last lesson we learned about the different types of signalling molecules (plant and animal hormones, neurotransmitters, cytokines and phermones). Today we will learn what happens when these signalling molecules reach their target cells, causing a response in the cell. Lipophobic (hydrophilic) signalling molecules cannot pass through the cell membrane, so they rely on complementary protein receptors that are embedded in the cell membrane. Once the signalling molecule – or ligand – binds to the receptor protein, secondary messenger molecules are released inside the target cell. Learn more about the specifics of signal transduction here:

Signal transduction from the Penguin Prof Channel

Signal transduction from Mr Bozeman (simple animated diagrams with commentary)

In the video above, observe one of the consequences of signal transduction – apoptosis or programmed cell death.

Week 6: Energy transformations in cells – photosynthesis

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

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

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

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.

Step Up to 2017!

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

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