Enzyme Regulation and Microbiomes

Question 1

Simple Feedback Inhibition

Answer 1

-regulatory enzyme is inhibited by the end product of the pathway

Question 2

Positive Regulation

Answer 2

• the product of an enzyme can stimulate the activity of enzymes downstream in the pathway
• precursor activation

Question 3

Cumulative Feedback Inhibition

Answer 3

• in a branched pathway that results in more than 1 product, multiple products can inhibit the activity of an enzyme
• end products may inhibit the enzyme in different ways and their effects may be additive

Question 4

Concerted Feedback Inhibition

Answer 4

• in pathways where isoenzymes catalyze a rxn
• end products may act only on one isoenzyme
• an end product from another branch of the pathway may inhibit the other isoenzyme and act in concert

Question 5

Allosteric Modification

Answer 5

• a product may bind an enzyme that may increase/decrease its activity
• binding of the product induces a conformational change in the enzyme that changes its activity
• altered confirmation may make enzyme bind substrate better or worse or alter its catalytic activity

Question 6

Covalent Modification

Answer 6

• reversible attachment of a chemical group
• acetylation, phosphorylation, adenylation
• addition of chemical group alters confirmation of the protein
• may make enzyme bind substrate better or worse, or alter catalytic activity

Question 7

Forward Genetics

Answer 7

• look for a phenotype and try to identify mutation linked to phenotype
• not possible until next gen synthesis became available-to find mutations you have to sequence genomes

Question 8

Reverse Genetics

Answer 8

• make mutation w/ precision

- look for phenotypes to determine what gene does

Question 9

Loss of gene function

Answer 9

• results in phenotype
• put gene back in and restore the phenotype-complementation
• use extrachromosomal DNA, a plasmid-trans complementation
• put back in chromosome at right place-cis complementation

Question 10

Using mutations to assign gene function

Answer 10

• replace wild type gene w/ mutant versions
• truncations-map functional domains of protein (e.g. remove part of 3’ end)
• use site directed mutagenesis to identify residues critical for gene function

Question 11

Redundancy

Answer 11

• genomes are buffered against mutation
• 2 genes encode for proteins of overlapping fxn
• loss of either gene on their own may have mild phenotype
• loss of both genes results in severe phenotype
• identification of these genetic relationships can be used to assign gene fxn

Question 12

What is a micro biome?

Answer 12

• populations of cohabiting and interacting microbes
• populations can have defined functions
• next gen sequencing makes it possible to study unculturable organisms-cant recreate exact environment in lab, some organisms need specific metabolic products from other organisms

Question 13

Gut Microbiome

Answer 13

• healthy gut has a micro biome that is stable and diverse

- antibiotics can alter micro biome by killing off pop., can deplete or shift the pop.

Question 14

How do we study micro biomes?

Answer 14

• 16s ribosomal rRNA: analyze 16s to determine the identity of the microbes that are present
• OTU=operational taxonomic unit, a unit of microbial diversity
• metagenomic analysis-sequence everything

Question 15

Do microbial communities have core functions?

Answer 15

• carb metabolism
• energy metabolism
• aa metabolism
• xenobiotic metabolism