Unit 4 Biology – AoS 1: Heredity

 

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This Area of Study includes key knowledge about genetics and heredity:

Cell reproduction:

  • binary fission in prokaryotes
  • the phases of the cell cycle in eukaryotes including DNA replication, the division of the nucleus (mitosis), and cytokinesis
  • the key events that result in the production of haploid sex cells from a diploid cell (meiosis), including recombination

Molecular genetics:

  • the nature of genomes, genes and the genetic code
  • gene expression: the genetic code and roles of RNA in transcription, RNA processing in eukaryotes, and translation
  • the concept of gene regulation (the switching on and off of genes by factors expressed by regulator genes and environmental factors)

DNA tools and techniques:

  • gel electrophoresis;
  • DNA amplification;
  • DNA sequencing;
  • making a recombinant plasmid;
  • bacterial transformations;
  • DNA profiling;
  • gene cloning;
  • and using plasmids as gene delivery systems

Inheritance:

  • the nature of chromosomes, alleles, genotype and phenotype
  • the causes of phenotypic variation: mutations; recombination of parental alleles in sexual reproduction; polygenes; and interactions of environmental factors with genes
  • continuous and discontinuous variation
  • patterns of inheritance involving the monohybrid cross: dominance; recessiveness; co-dominance; multiple alleles
  • dihybrid crosses as independent or linked
  • pedigree analysis: autosomal and sex-linked inheritance; use of the test cross.

Some resources to assist your revision of this topic:

DNA tools and techniques

Gel Electrophoresis: This technique is used to separate fragments of DNA according to their size – longer fragments with a large number of base pairs travel more slowly through the substrate (agarose gel), while shorter fragments with a smaller number of base pairs travel a greater distance. A buffer solution is added to the apparatus and DNA fragments are ‘cut’ at specific sites using restriction enzymes and loaded, together with a fluorescent dye, in ‘wells’ at the negative end of the apparatus.  An electric charge is applied and the negatively charged DNA fragments are attracted to the positive end of the gel matrix. Gel Electrophoresis on YouTube. 

DNA amplification: Using a Polymerase Chain Reaction (PCR) researchers can create many copies of DNA in a test tube.

DNA profiling: Also called DNA fingerprinting, this technique compares DNA from victims, suspects and crime scenes to determine which samples have the most in common. How does DNA fingerprinting work from the Naked Science Scrapbook (YouTube). 

DNA recombination: Scientists are able to insert fragments of DNA from one organism into another organism, bringing together genetic material from various sources. Recombinant DNA produces genetically modified organisms, that may add desirable characteristics to food crops, for example.

DNA sequencing: DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule. DNA Sequencing on YouTube.

Gene cloning: Molecular cloning is a set of experimental methods in molecular biology that are used to assemble recombinant DNA molecules and to direct their replication within host organisms. Gene cloning in plain English on YouTube. 

Gene transformation: “In molecular biology, transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material (exogenous DNA) from its surrounding and taken up through the cell membrane.” Bacterial transformation by zabaaz on YouTube.

Animal Behaviour

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Animal behaviour (ethology) is an interesting field of study that has fascinated biologists for hundreds of years. From Jean-Baptiste Lamarck and Charles Darwin to Konrad Lorenz, Ivan Pavlov and Skinner, scientists have studied animals and wondered how their behaviour relates to humans.

  • Innate Behaviour – Reflexes, Kineses and Taxes (7.15 minute video)
  • Learned Behaviour – Imprinting, Habituation and Conditioning (6.24 minute video)
  • Animal behaviour (23.40 minute YouTube video) – What can we learn by using video cameras attached to animals or in their burrows to see the world from an animal’s perspective? Cameras were attached to reptiles, mammals and even insects to observe animal behaviour in their natural environment. These are animals from North America (wild turkeys, armadillo, moles and chickadees).
  • Produce a slideshow showing the structural, functional and behavioural adaptations of some Australian native animals. For example, koala, kangaroo, emu, echidna, crocodile, tiger snake, thorny devil, platypus or kookaburra.

 

Welcome Back – Term 3!

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Year 12 students will be counting down the next 14 weeks until their VCE Biology exam on the morning of Friday 30th October. We will start this term with a review of the structure of DNA, using the GTAC resources, “Exploring the structure of DNA“.

On Wednesday 22nd July we will be heading to the University of Melbourne Genetics Department to complete three practical activities that will contribute to your school-based assessment:

  1. An investigation using a DNA tool and a manipulation technique
  2. An investigation of inheritance in Drosophila melanogaster including a review of meiosis in gamete formation
  3. Meiosis in Drosophila

On Friday 4th September you will have the opportunity to travel to Brauer College and participate in GTAC outreach program, “From Hominoids to Hominins”.

On Tuesday 13th October you will be able to attend a “Get into Genes” program as revision prior to your exam.

Structural, Functional and Behavioural Adaptations

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Image Source – 20 Amazing Animal Adaptations for Living in the Desert

Living organisms are spread across the planet in a wide variety of different habitats and environments. Various adaptations assist organisms to survive in the hottest and driest deserts, coldest arctic tundra and wettest rainforests. Structural adaptations are how an organism is built, such as the wings, feathers and hollow bones of birds that assist them to escape from predators and find their food. Functional or physiological adaptations are how an organism works, which you may not necessarily be able to see from the outside, such as the ability of desert dwellers to survive without drinking water by re-absorbing much of the water from their faeces and producing small amounts of very concentrated urine. Behavioural adaptations are the actions that an animal takes – what it does – to survive, such as migration, resting in the heat of the day or huddling with other individuals to conserve body heat and moisture.

 

Semester 2 Biology – Adaptations (Y11) and Heredity (Y12)

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This semester we will be starting Unit 2 (Organisms in their Environment) Area of Study 1: Adaptations of Organisms and Unit 4 (Continuity and Change) Area of Study 1: Heredity. We have created Quizlet Sets for each of these topics:

 

Unit 1 and Unit 3 Biology Exam Revision

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There are several strategies you can use to revise for mid-year exams – here are just a few:

  • Use the Hawkesdale Biology Quizlet Class to revise terms and definitions for each chapter
  • Copy and revise the Slideshows I have saved in the Year 11 and Year 12 Biology class folders (Student Public Drive)
  • Create a set of study notes with the Chapter headings, diagrams and key concepts. These will be very useful at the end of the year for revision too.
  • Create mind maps that link each of the main concepts – use colour to help you remember.
  • Use the posts in this blog to review YouTube videos and other resources for each chapter.
  • Past exams are a good indication of the standard of questions you will be asked – do as many as you can reasonably cope with! Use questions you find difficult as a guide to what you need to study more of.
  • Create flow charts and posters for the wall at home of concepts that can be represented diagrammatically.

Chapter 8 – Immunology

Immunity

Biological Classification

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Classification of living organisms has been a human pastime throughout history – it is important that we can name and identify organisms, especially if they are harmful (venomous snakes and spiders for example) or beneficial (organisms that provide food, fibre, medicine or services). It also helps us to group and organize the huge variety of living organisms on our planet. The science of identifying and naming organisms is referred to as ‘taxonomy’. Carl Linnaeus, a Swedish scientist, is often referred to as the ‘father of taxonomy’ because he developed the naming system that we still use today, called binomial nomenclature, which literally means “two-name naming-system”. Every organism belongs to a particular species and is identified by two latin words – the Genus and species. So, Homo sapiens (modern humans) belong to the genus Homo and species sapiens. Note that the genus name is capitalized, but the species name is not.

Two organisms that belong to the same genus (Eg. Eucalyptus citriodora and Eucalyptus camaldulensis) are more closely related than two organisms with the same species name (Eg. Eucalyptus citiodora and Backhousia citriodora). This is because the species name (citriodora) is a descriptive name that can refer to a characteristic of different groups, in this case, Lemon-scented Gum and Lemon-scented Myrtle.

Within the Five Kingdoms of Living organisms (Protists, Prokaryotes, Fungi, Animals and Plants) are the Phyla, Classes, Orders, Genera and species. It helps to remember this sequence of groups:

  • Kingdom
  • Phylum (and sub-phyla)
  • Class (and sub-class)
  • Order (and sub-order)
  • Genus
  • Species

Some more resources to learn about classification:

Fern Reproduction – Alternation of Generations

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1. Watch the Secret Life of Ferns; the Fern Life Cycle and the Fern sporangium catapult on YouTube.

2. Go to The Fern Life Cycle – Student Tutorial and label the Fern Life Cycle diagram as you work through the tutorial.

3. Use this worksheet to create a new task for next year’s Biology class to learn about the Alternation of Generations in ferns.

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This image is a screenshot from the YouTube video “The fern sporangium catapult” showing spores being released from a sporangium and the annulus colored blue, representing the water that is critical to the process of ejecting the spores. Due to the cohesive properties of water molecules and the structure of the annulus, as water evaporates, the sporangium ruptures as the annulus curls back. At a critical point, when water continues to evaporate, there are not enough water molecules to hold the annulus open and the ‘head’ of the sporangium springs back, ejecting the spores.