Super Yeast
Why did we do the lab?
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Apply steps of scientific method
Apply key terminology of scientific method
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variables, controls, constants, hypotheses
Data collection, data graphing and data analysis
Hands-on scientific techniques and proper use of
scientific equipment – proper measuring
Error analysis
Introduction into biochemistry and cellular
respiration
What we did well during the lab and not so well?
(error analysis)
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Correct procedures were followed
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Could go smoother if read ahead as instructed
Excellent behavior in the lab setting – on task
Team work was great – lots of helping one
another
Measurements – pretty good, although some
initial errors but corrections were made
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Ex. not adding any drops of sucrose at first and
wondering why it wasn’t changing color – opps!
What we did well AFTER the lab and not so
well? (post lab write-ups need some work)
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First – hypotheses need to be done before the
experiment is performed. This WILL be
checked next time.
Graphing data – titles, labels and units!
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Maximize graph space for best analysis of data
Compare graphs
Post lab reflection continued
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Analyzing data
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Does it support or not support your hypotheses?
Your lab results do NOT prove anything –
just support or not support your prediction
Part 1 - reviewed
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Recap: What were we trying to find out in
part 1 of the Super Yeast lab?
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Which type of sugar will cause the yeast to have
the fastest rate of cellular respiration?
How did we measure cellular respiration?
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CO2 bubble produced
Biggest CO2 bubble = fastest rate of cellular
respiration
Review data for part 1
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Rate of cellular respiration was measured by?
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CO2 produced (mL)/ the time (min) = __mL/min
Do the calculations: the solutions below stayed in the
incubator for 10 mins.
Yeast and sugar
solution
Volume of solution
remaining (mL)
Volume of CO2
produced (mL)
Rate of cellular
respiration (mL/min
of CO2)
Sample 1 with
glucose
7.1 mL
2.9 mL
.29 mL/min
Sample 2 with
fructose
8.5 mL
1.5 mL
.15 mL/min
So what does the rate mean?
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Which yeast sample had the faster rate of cellular respiration
according to the data?
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Sample 1 because it produced .29 mL of CO2 every minute
Sample 2 only produced .15 mL of CO2 every minute
Yeast and sugar
solution
Volume of solution
remaining (mL)
Volume of CO2
produced (mL)
Rate of cellular
respiration
(mL/min of CO2)
Sample 1 with
glucose
7.1 mL
2.9 mL
.29 mL/min
Sample 2 with
fructose
8.5 mL
1.5 mL
.15 mL/min
Why would Sample 1 yeast be faster
than Sample 2 yeast?
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Glucose was the better sugar for the yeast to
use for cellular respiration when compared to
the fructose
Ok – so now what question(s) should you be
asking and answering?
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Why does glucose increase rate of cellular
respiration for yeast?
What is the difference between glucose and
fructose?
What is the difference between all of
the sugars in part 1 of Super Yeast lab?
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Such an important question – we asked you
twice!
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Glucose, fructose = monosaccharides
Sucrose = disaccharides
Starch = polysaccharide
Different structures = different functions
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Glucose= smaller, faster energy source, main
energy molecule for all cells to break down
Know and love glucose – the sooner
the better!
Part 2 - reviewed
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Recap: what were we trying to find out in part
2 of the Super Yeast lab?
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Does the concentration of sucrose cause a faster
rate of cellular respiration?
How did we measure cellular respiration?
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Increase in CO2 causes increase in acid
Measure how fast it turns acidic (blue to green
using Bromothymol blue indicator)
Review data for part 2
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Rate of cellular respiration was measured by?
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time for color change to occur
Faster color change = faster production of CO2
How would you graph the following
data?
# of drops of
sucrose added to
TT
Time in mins/secs for Time in mins/secs for
color change
color change
TEAM
CLASS AVERAGE
0
-
-
2
5 mins 20 sec
7 mins 30 sec
4
4 mins 15 sec
6 mins 20 sec
6
4 mins 1 sec
4 min 52 sec
8
3 mins 40 sec
3 min 58 sec
10
3 mins 5 sec
2 min 49 sec
Variables
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Independent (x-axis)
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Dependent (y-axis)
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# of drops of sucrose
Time for color change
Type of graph to make
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Line = relationship between sucrose
concentration and rate of cellular respiration (as
measured by color change)
Various amounts of sucrose drops added to
yeast solution and the time in minutes for the
color change
10
8
Red = class average
Time
Blue =team results
6
In
Minutes
for color 4
change
2
0
2
4
6
8
10
Drops of 2% sucrose added to the
yeast solution
Was there a relationship between sucrose
concentration and rate of cellular respiration?
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Yes – how did you know?
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More sucrose drops = faster color change
meaning CO2 was being produced at a faster rate.
Cellular respiration: two types
presented in the introduction of lab
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Aerobic- with oxygen
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C6H12O6 + 6O2 ---- 6CO2 + 6 H2O + 36
ATP
Anaerobic (aka fermentation) – without
oxygen
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C6H12O6 ---- 2CO2 + 2C2H5OH + 2 ATP
YEAST CELLS DO BOTH TYPES
OF CELLULAR RESPIRATION!!!!!!
What do they produce in each?
Controls vs constants
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Control for part 1?
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Control for part 2?
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Distilled water added to yeast solution
Zero drops of sucrose added to yeast solution
Purpose of having a control?
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Needed as a base or standard to compare the
experimental groups
Controls vs constants
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Constants for part 1?
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Constants for part 2?
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Amount of yeast, amount of sugar, time in
incubator, temperature
Amount of yeast, amount of indicator, start time,
temperature
What is the purpose of constants?
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To ensure that you are only testing one
experimental variable
How would you test the effect of
temperature on cellular respiration in yeast?
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Question
Background research on the effects of
temperature on…
Hypothesis
Materials
Procedure
Data to be collected (tables and calculations)
Review your lab
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What did you do well?
What do you need to improve upon next time?
Did you procrastinate?