Biogeochemical Cycles; True ECOSYSTEM Processes (Week 8) c) How and why are the C and N biogeochemical cycles so tightly linked? How can understanding these linkages help us to understand nutrient limitation of ecosystem productivity? (30m) 2018 Link between C and N Cycles Fixed C is: 1. Respired by living organisms directly 2. Ends up in soil (Plant litter,…… Continue reading Ecology of Ecosystems #2
Modes of Predation & Herbivory (Week 3) a) Outline the hypotheses that have been proposed to explain how the importance of predation might change within and between food webs. Briefly evaluate the evidence for and against these hypotheses. (15m) 2017 Importance of predation can be evaluated by their direct effects, indirect effects, facilitation and inhibition.…… Continue reading Ecology of Ecosystems #1
Explain how red blood cells from an individual with sickle cell anemia “sickle” and why they can cause painful “crises” in nerves and bones. Why is avoidance of dehydration and physical exertion important to avoid these crises? Sickle cell anemia is resultant of a polymorphism, where there is a Glu6Val mutation in the beta-globins of…… Continue reading Inherited Diseases & Disorders
What are the major roles of the following, in collagen structure and/or function? Glycine at every 3rd amino acid position Vitamin C N-terminal signal peptide sequence Glycine is the smallest amino acid and provides flexibility, enabling it to fit into restricted spaces between polypeptide chains of collagen fibrils. Having it at every 3rd amino acid…… Continue reading Types of Proteins
Outline how a newly translated polypeptide folds correctly, including in your answer the role of chaperone (Hsp70) and chaperonin (Hsp60). Some polypeptides fold spontaneously once released from the ribosome, but most proteins require assistance to fold correctly. Molecular chaperones assist in the folding of newly synthesised proteins and refolding of misfolded proteins, and exist in…… Continue reading Protein Folding, Trafficking & Degradation
Explain how tumour suppressor genes differ from oncogenes. (4m) Oncogenes are linked to cancer via gain-of-function gene mutations that only require 1 of the 2 alleles to be mutated, while tumour suppressor genes are linked to cancer via loss-of-function mutations that require both alleles in a cell to be mutated. Mutations of proto-oncogenes into oncogenes…… Continue reading Cancer Stuff
Embryonic stem (ES) cells exhibit the quality of pluripotency. Define pluripotency. Describe 2 assays that are used to demonstrate the pluripotency of mouse ES cells. Pluripotent cells will give rise to cells under all three germ layers of the embryo proper, which are the endoderm, mesoderm and ectoderm, but not the placental tissue. Pluripotency of…… Continue reading Cell Differentiation & Stem Cells
Microevolution vs Macroevolution: Micro; Changes in gene frequencies within species, due to natural selection by mutation, gene flow and genetic drifts. When continued over long periods of time, these microevolutions lead to macroevolution. Macro; Evolution of major alterations that distinguish higher taxa, including the studies of diversification, extinction, success and failure of major lineages. …… Continue reading #1; Behavioural & Evolutionary Ecology
SEXUAL SELECTION Trait that increase reproductive success can be selected for, even if it decreases survival. Sexual selection acts in same way as natural selection: Variation in sexual trait Trait has to be heritable Variation in reproductive success Correlation between trait and reproductive success Sexual selection requires: Sexual reproASEXUAL REPRO Haploid Pathenogenesis (unfertilised egg…… Continue reading #5; Behavioural & Evolutionary Ecology
DISPERSAL Dispersal benefits to individual often appear in conflict to population demographic benefits. Source-Sink Source population (fecundity > mortality) Sink population (fecundity < mortality) So why would individuals move from source to sink populations? Spatial heterogeneity can vary through time – Source habitat quality may decrease, while sink habitat quality becomes better Ideal Free…… Continue reading #2; Behavioural & Evolutionary Ecology
"Open your eyes and see what you can with them before they close forever." 