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Study Guide

[BIO315H5] - Midterm Exam Guide - Everything you need to know! (15 pages long)


Department
Biology
Course Code
BIO315H5
Professor
Hai- Ying Mary Cheng
Study Guide
Midterm

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UTM
BIO315H5
MIDTERM EXAM
STUDY GUIDE

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Lecture 1 pages 813-819
Quorum sensing: a system of stimuli and response correlated to population density. Many species of
bacteria use quorum sensing to coordinate gene expression according to the density of their local
population.
‘many bacteria respond to chemical signals that are secreted by their neighbors and accumulate
at higher population density allows bacteria to coordinate their behaviour, including their
motility, antibiotic production, spore formation, and sexual conjugation
Communication between cells in MULTICELLULAR organisms is mediated mainly by extracellular signal
molecules
Four Forms of Intercellular Signalling
A) Contact-dependent signalling requires cells to be in direct membrane-membrane contact
B) Paracrine signalling depends on local mediators that are released into the extracellular space
and act on neighboring cells (Autocrine cells produce signals that they themselves respond to)
C) Synaptic signalling performed by neurons that transmit signal electrically along their axons
and release neurotransmitters at synapses, which are often located far away from the neuronal
cell body
D) Endocrine signalling depends on endocrine cells, which secrete hormones into the
bloodstream for distribution throughout the body. Many of the same types of signalling
olecules are used i paracrie, syaptic, ad edocrie sigallig’ the crucial differeces lie i
the speed and selectivity with which the signals are delivered to their targets
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Long distance signalling: synaptic and endocrine signalling
Signal molecule often has different effects on different types of target cells.
Ach decreases the rate of action potential firing in heart pacemaker cells, and
stimulates production of saliva by salivary gland cells (even though receptors are same
on both cell types)
In skeletal muscle, Ach causes cells to contract by binding to a different receptor
protein.
Different effects in these cell types result from differences in intracellular signalling
proteins, effector proteins, and genes that are activated
Most extracellular signal molecules bind to specific receptor proteins on surface of target cells and do
not enter cytosol or nucleus. The cell-surface receptors act as signal transducers by converting an
extracellular ligand-binding event into intracellular signals that alter the behavior of the target cell
G-Protein-coupled receptors: act by indirectly regulating activity of separate plasma-membrane-bound
target protein enzyme or ion channel
A G-protein mediates interaction between activated receptor and this target protein
This activation of target protein can change the concentration of one or more small intracellular
signalling molecules (is target protein is enzyme), or it can change the ion permeability of
plasma membrane (if target protein is ion channel)
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