BAns Essays

With reference to protein structure = ALL 4 protein structure in DETAIL 

• Secondary structure: contribute to the overall folding pattern and help bring functional R groups into correct spatial orientation

• Tertiary structure: soluble in aqueous environment of the cytoplasm or extracellular fluid

How microscope can be used to study biology

• Allows for measurement of organelles 

• Study of organelles in detail (Eg. Mitochondrion and cristae)

• Study of microorganisms like bacteria / viruses

• Study of mitosis / meiosis + description of mitosis 

• Study and identification of different cell types 

• Contributes to the development of cell theory + description of cell theory 

Using named examples, relate the structure of polymers to their importance to cells

• NO lipids / phospholipids / triglycerides / collagen

• Polymers: Starch / glycogen (energy store), cellulose (structural support), Haemoglobin (oxygen transport), DNA (storage of genetic information), mRNA (carrier of genetic code), tRNA (Bringing right amino acid for translation process), rRNA (Complexes with rp to form ribosomal subunits), specific enzyme (give example), transport protein, microtubules (Movement of genetic material during cell division) 

Describe how DNA is packaged in a cell and discuss the advantages of eukaryotic chromatin being a dynamic molecule

• DNA structure + DNA packaged in BOTH eukaryotic and prokaryotic 

• Accuracy in mitosis + genetic variation in meiosis + control of gene expression (say BOTH acetylation and DNA methylation = booth sides) 

Discuss the various roles of hydrogen bonding in ensuring the continuity of life

• Maintaining protein structure (Eg. Haemoglobin, collagen) 

• ES complex 

• Carbohydrate (Eg. Cellulose -> structural support, amylose) 

• Solubility (Eg. Cell surface membrane proteins) 

• Complementary base pairing (DNA, tRNA, DNA replication) 

Discuss the advantages of having different degrees of complementarity between biomolecules in eukaryotic cellular processes

1. High complementarity

• Lock and key -> hold substrate in precise orientations 

• Transport proteins -> precise transport of substances allows maintenance of relatively constant internal concentration of ions and molecules 

• Cell-cell adhesion and recognition -> proper tissue development 

• Affinity maturation of B cells 

• Perfect complementary base pairing between doubled stranded DNA -> increase stability and structural integrity + accurate transmission of genetic information during replication and transcription 

 

2. Lower complementarity 

• Induced-fit -> enables enzyme to bind to a range of substrates with similar functional groups

• Innate immune cells recognise broad class of antigens 

• Mutations leads to variation 

• Degeneracy of genetic code minimise mutation 

Ref.sickle cell anaemia mutation, outline the MT used to determine the genotype of an unaffected individual and explain the role of “complementarity” in specific steps of MT

• Restriction enzyme’s active site is complementary in shape and charge to specific DNA sequence

• Mutation results in the loss of a restriction site in mutant allele

• When same restriction enzyme cuts both normal and recessive alleles, normal allele gives 2 smaller fragments, while mutant allele gives 1 large fragment

Explain how the community of viruses and bacteria can facilitate phenotypic alterations of a bacterium resulting in its survival in an antibiotic rich gut environment

• Transformation, transduction, conjugation 

• NOT genetic variation (NOT community) 

1. Discuss whether you agree or disagree that the impacts of human activity on climate change will lead to the greater spread of mosquitoes

• Disagree: OTHER factors cause spread of mosquito 

State importance of conformation in respiration = list function of enzymes in aerobic AND anaerobic respiration (NOT the process)

• Elaboration on conformation (define, competitive and non-competitive inhibitors)

• Can be generic if not taught: 

  • Eg. Specific enzymes act as catalysts in substrate level phosphorylation of glycolysis that produces ATP by transferring phosphate group from high-energy substrate to ADP 

  • Eg. Correct conformation of oxygen-binding site in cytochrome oxidase enables O2 reduction to water

Explain how genetic diversity within and between species is generated, maintained, and threatened

• Inheritance + Evolution + Climate Change

• Generated: mutation, meiosis, sexual reproduction

• Maintained: heterozygote advantage, neutral variation

• Threatened: natural selection, population bottlenecks, habitat fragmentation from climate change, reduced gene pool

Discuss how climate change threatens biodiversity through effects at the molecular, cellular, and ecosystem level

• Molecular: Enzyme denaturation due to higher temperatures, mutation (caused by UV light)  

• Cellular: membrane fluidity disruption due to high temperatures, membrane protein disruption

• Ecosystem: Species shift (competition with native species), changed timing of breeding, reduce biodiversity, genetic drift (bottleneck and flounder effect) 

• Eg. Coral bleaching, , change in allele frequency within gene pool of population