Feedback Systems. Feedback Loop Video Fig. 1-13 Negative feedback Excess D blocks a step D D D A B...
-
Upload
kaylyn-bevington -
Category
Documents
-
view
252 -
download
0
Transcript of Feedback Systems. Feedback Loop Video Fig. 1-13 Negative feedback Excess D blocks a step D D D A B...
Feedback Systems
Feedback Loop Video
Fig. 1-13
Negativefeedback
Excess Dblocks a step
D
D D
A
B
C
Enzyme 1
Enzyme 2
Enzyme 3
D
(a) Negative feedback
W
Enzyme 4
XPositivefeedback
Enzyme 5
Y
+
Enzyme 6
Excess Zstimulates astep
Z
Z
Z
Z
(b) Positive feedback
Negative Feedback• Most common form of
regulation• Accumulation of end product
slows the process
Positive Feedback• End product SPEEDS UP
production of that product• Blood clotting• Childbirth
• The idea is for the process to go to completion
Fig. 8-22
Intermediate C
Feedbackinhibition
Isoleucineused up bycell
Enzyme 1(threoninedeaminase)
End product(isoleucine)
Enzyme 5
Intermediate D
Intermediate B
Intermediate A
Enzyme 4
Enzyme 2
Enzyme 3
Initial substrate(threonine)
Threoninein active site
Active siteavailable
Active site ofenzyme 1 nolonger bindsthreonine;pathway isswitched off.
Isoleucinebinds toallostericsite
Feedback Inhibition• Metabolic pathway• Switched off by inhibitory
binding of end product to an enzyme earlier in the pathway of production
Fig. 40-8Response:Heater turnedoff
Stimulus:Control center(thermostat)reads too hot
Roomtemperaturedecreases
Setpoint:20ºC
Roomtemperature
increases
Stimulus:Control center(thermostat)
reads too cold
Response:Heater turnedon
Nonliving Example of What type of Feedback to maintain homeostasis
Fig. 40-16Sweat glands secrete sweat, which evaporates, cooling the body.
Thermostat in hypothalamus activates cooling mechanisms.
Blood vessels in skin dilate: capillaries fill; heat radiates from skin.
Increased body temperature
Decreased body temperature
Thermostat in hypothalamus activates warming mechanisms.
Blood vessels in skin constrict, reducing heat loss.
Skeletal muscles contract; shivering generates heat.
Body temperature increases; thermostat
shuts off warming mechanisms.
Homeostasis: Internal temperature of 36–
38°C
Body temperature decreases; thermostat
shuts off cooling mechanisms.
How is this an example of feedback?
Is it positive or negative feedbac
Fig. 40-17
Organic moleculesin foodExternal
environment
Animalbody Digestion and
absorption
Nutrient moleculesin body cells
Carbonskeletons
Cellularrespiration
ATP
Heat
Energy lostin feces
Energy lost innitrogenouswaste
Heat
Biosynthesis
Heat
Heat
Cellularwork
Blood Sugar Levels
Example of Hormonal Feedback System
Test Review Info
Every Pyruvate produces
• 3 NADH• 1 ATP• 1 FADH2
• HOW MANY PYRUVATES DO YOU GET FROM 1 SUGAR MOLECULE?
Fig. 10-9
Wavelength of light (nm)
(b) Action spectrum
(a) Absorption spectra
(c) Engelmann’s experiment
Aerobic bacteria
RESULTS
Rate
of p
hoto
synt
hesi
s(m
easu
red
by O
2 rel
ease
)Ab
sorp
tion
of li
ght b
ych
loro
plas
t pig
men
ts
Filamentof alga
Chloro- phyll a Chlorophyll b
Carotenoids
500400 600 700
700600500400
Can you fill this out?
Photosynthesis Cellular Respiration
Organelle for Process
Reactants (needed material)
Cycle of Chemical Reactions
Electron Transport Chain
Products (what is made)
What is the structure of a Mitochondria?
What is the structure of a Chloroplast?
Comparison of Photosynthesis & Cellular Respiration
Photosynthesis Cellular Respiration
Organelle for process
Chloroplast Mitochondrion
Reactants CO2 and H2O Sugars (C6H12O6) and O2
Cycle of chemical reactions
Calvin cycle in stroma of chloroplasts builds sugar molecules
Krebs cycle in matrix of mitochondria breaks down carbon-based molecules
Electron Transport Chain
Proteins within thylakoid membrane
Proteins within inner mitochondrial membrane
Products Sugars (C6H12O6) and O2
CO2 and H2O