Genetics and Metabolism Flashcards
What is anabolism?
uses energy stored in ATP to synthesise the building block of macromolecules that make up the cell
- requires energy
biosynthesis of amino acids and nucleotides
- amino acids are derived from inorganic nitrogen source
- purines are constructed from inosinic acid
- pyrimidines are constructed from uridylate
biosynthesis of sugars and polysaccharides
- polysaccaharides synthesized from either uridine diphosphoglucose or adenosine diphosphoglucose
What is catabolism?
energy released from the breakdown of organic compounds can be used to synthesise ATP
- releases energy
How are sugars metabolised?
respiration
- aerobic/catabolism = glycolysis and Krebs cycle
- anaerobic = glycolysis and fermentation
What are glycolysis and the Krebs cycle?
glycolysis
- metabolic pathway that converts glucose into pyruvate
- occurs in the cytoplasm
- generates energy (ATP)
krebs cycle = tricarboxylic acid cycle = citric acid cycle
- series of biochemical reactions that releases large amounts of potential chemical energy
- series of oxidations and reductions transfer the potential energy to electron carrier coenzymes
How are fatty acids metabolised?
fatty acids are broken down into acetic acid
- triglycerides undergo lipolysis to form fatty acid + glycerol
fatty acids undergo beta oxidation (catabolic process)
- break down fatty acids into acetate
- acetate combine with coenzyme A to form acetyl CoA
- acetyl CoA joins the Krebs cycle
What happens if fatty acids are the sole source of carbon for organisms?
organisms will undergo a modified Krebs cycle
- glyoxylate cycle = not generally found in animal cells as they do not have the required enzymes
What is genetic material? How is it expressed?
Genetic material is DNA
DNA is expressed by synthesis of specific RNAs and proteins
- via transcription and translation
bacterial genomes vary in size
genome = complete set of genetic information
What is a plasmid?
DNA molecules
they code for traits that are not essential for bacterial viability
- code for genetic advantages
- resistance, production of toxins, synthesis of cell surface structures
greater in number than chromosome and are smaller = makes them easier to locate
What are the types of plasmid?
stringent
- replicate only when the chromosome replicates
- less than 100 copies per cell
relaxed
- replicate on their own
- more than 100 copies per cell
How is gene expression regulated?
gene expression is regulated by induction and repression of genes
What are operons? What do operons consist of?
operon are a group of contiguous (adjacent) genes that are transcribed as a single unit and are translated to produce the corresponding gene products
- codes for a series of functionally related genes
- are under the control of one promoter
operon consist of
- regulatory gene = upstream of the promoter
- promoter
- operon gene
- structural genes = are transcribed and translated
What is a regulon? What is the difference between an operon and a regulon?
regulon
- alters the expression of genes and operons
operons and regulons are both clusters of genes and both produce functionally related gene products
operons
- are functionally related genes
- appear contiguously in the genome
- located in a specific part of the genome
- co-regulated
regulon
- consist of several operons or genes
- located in different regions within the genome
- regulated by a single regulatory protein simultaneously (same for all) = transcription factor is the regulator
What is the function of regulatory genes, the promotor, operator gene and the structural genes?
regulatory gene
- codes for repressor protein
- binds to the operator when glucose is present
operator gene
- on/off switch
- short sequence of DNA
- repressor binds to it, surpressing transcription = stops RNA binding and transcription
structural genes
- area which is transcribed and translated to produce proteins
What is the difference between inducible and repressible genes?
inducible genes
- genes whose expression are turned on by the presence of a specific substance = inducer
- binding of the inducer to the repressor gene bound to the operon turns the gene on = repressor gene is released as inducer causes a conformational change
repressible genes
- genes whose expression are turned off by the presence of a specific substance = co-repressor
- substance binds to the repressor = forms co-repressor
- binding of the co-repressor to the operon turns the gene off
What is catabolite repression? What are the factors affecting catabolite repression?
catabolite repression - controls inducible operons
- inhibition of the catalysis of enzymes involved in the catabolism of carbon sources other than the preferred me.
- means glucose should be used when in high levels so catabolism (breakdown) of other carbon sources (lactose) are prevented
factors affecting
- inducers and regulatory genes
- level of glucose in the environment = when in high levels, repressor protein binds to the operator gene
