- Today, we'll discuss strategies
for tackling the MCAT Biology
and Biochemistry section.
The MCAT Biology/Biochemistry
section often includes
the most experiment-based
passages on the exam,
so it is important to be able
to interpret figures, graphs, and tables.
I'm Vikram Shaw, MCAT
expert and 528 MCAT scorer.
In this video, I'll share
the exact strategies I used
to ace the MCAT Biology
and Biochemistry section.
I'll tell you what topics are on the exam,
a formula for how to read
figures, graphs, and tables,
and some helpful study tips you can use
to improve your MCAT score.
So, let's get started.
What's actually on the
Biology/Biochemistry
section of the MCAT?
The MCAT Biology/Biochemistry section
will test your knowledge of key concepts
in the fields of Biology and Biochemistry
as they relate to the human body.
Like the Chemistry/Physics
and Psychology/Sociology
sections of the exam,
the Biology/Biochemistry
section contains 59 questions
that you must answer in 95 minutes.
44 of these questions
are based on 10 passages
while 15 questions are standalone.
The American Association of
Medical Colleges, or AAMC,
writes the MCAT and they break down
what's actually going to be on your exam.
According to the AAMC,
the Biology/Biochemistry
section of the MCAT
is composed of 25% first
semester Biochemistry,
65% introductory Biology,
5% General Chemistry,
and 5% Organic Chemistry.
You might be wondering,
"What exact topics are covered
in each of these categories?"
Topic number one is amino acids
and the structure and
function of proteins.
For example, do you
know what a ligase does?
Topic number two is the
central dogma of Biology
in which DNA is replicated to DNA,
transcribed to RNA, and
translated into protein.
Topic number three covers Genetics,
such as mitosis, meiosis,
and Mendelian inheritance.
A question may ask about the difference
between mitosis and meiosis.
Topic number four covers metabolism,
which includes topics such
as glycolysis, gluconeogenesis,
the Krebs cycle,
and the electron transport
chain, among others.
Topic number six covers the
nervous and endocrine systems,
and topic number seven covers
the structure and function
of main organ systems such
as the kidney or liver.
Many students worry that they
have not yet taken Physiology,
and if that is the
case, you are not alone.
Using the building blocks from your
introductory undergraduate Biology class,
you will be able to learn the level
of detail tested on organ
systems for the MCAT.
Now that you know what
you're gonna be tested on,
let's go over tips and
study strategies you can use
to score a 132 on the Biology
and Biochemistry section.
MCAT Biology/Biochemistry Tip number one,
practice interpreting
graphs, figures, and tables
using the TAID P method.
TAID P stands for title,
axes, independent variable,
dependent variable, and patterns.
If you can identify these elements
in a graph, figure, or table,
you'll be able to understand
what the data is telling you.
Let's look at this example
using the TAID P method.
The title, T, states, "Effect
of Drug on Cell Survival."
So, we can determine that the researchers
are treating cells with a drug
and measuring cell survival.
Now, let's look at the axes, or A.
The x-axis shows increasing concentrations
of drug in micromolar,
while the y-axis measures
the percentage response,
which we know from the title
has something to do with survival.
When we look at the graphs,
the axes make it easy to determine
the independent and dependent variables,
which are I and D in the TAID P method.
First, what do the independent
and dependent variables measure?
The independent variable is something
that you change on purpose
while the dependent
variable is the response.
The independent variable is
also shown on the x-axis,
so we know here that drug concentration
is our independent variable.
The dependent variable, on the other hand,
is shown on the y-axis,
so we know that drug response
is our dependent variable.
Finally, let's look at the patterns, or P,
Are there any patterns in this curve?
At what drug concentration
do we see the greatest
percentage response?
There seems to be a sharp transition
between seven and eight micromolar
in that drug concentrations
above eight micromolar lead to
a favorable percent response.
Now that we have completed this exercise,
we are ready to approach any questions.
You should aim to identify
the TAID P elements
for any given figure
within 15 to 20 seconds.
The goal is to understand the big picture
without getting lost in any small details.
The reason you should not spend
too much time on any given figure
during your first reading of the passage
is that there may not even
be a question on that figure.
For example, if an MCAT
Biology/Biochemistry
passage has three figures,
they may only ask a
question about two of them,
so you don't want to waste a minute
understanding the figure in great detail
if they're not even gonna
ask a question about it.
So, how do you get faster at
applying the TAID P method?
MCAT Biology/Biochemistry Tip number two,
when you review a Bio/Biochem figure
while going over your mistakes,
study every small detail
of each figure carefully.
Anytime you take an MCAT
Biology/Biochemistry passage
that has a figure,
you should come back after
you have submitted the answers
and thoroughly review it
during your test review.
Why should you do this?
By practicing applying the TAID P method
under no time constraints,
you will get better at being able
to quickly and accurately
interpret figures.
By the time you have completed
several full-length practice exams,
you will have taken almost a hundred
MCAT Biology/Biochemistry
practice passages.
If you spend the time
to review the figures on each of those,
there are very few figures
that you will encounter on your MCAT
that you would not have seen
at least some variation of before.
MCAT Biology/Biochemistry
Tip number three.
Know the one-letter code,
three-letter code, structures,
and chemical properties
of all 20 amino acids.
This tip is one of the most
important tips you will receive
as it is virtually guaranteed
that you will see amino
acid questions on both
the MCAT Biology/Biochemistry
and Chemistry/Physics sections.
It is not enough to
memorize the structures,
but you should know what properties
different structures
provide the amino acids.
For example, would you be more
likely to see an arginine,
which carries a positive charge,
or a valine, which is hydrophobic,
on the exterior of a protein.
The exterior of a protein
is usually composed of
hydrophilic residues
since it interacts with water,
so we would be much more likely
to see the charged arginine,
which can interact with water.
Let's go through an example
of an MCAT-style Biology
and Biochemistry question.
Which of the following amino
acids is most likely located
at the junction of two alpha
helices in a protein domain?
A, proline, b, tryptophan,
c, serine, and d, glutamine.
There are two amino acids that are known
to introduce flexibility and
kinks into peptide chains.
These are proline and glycine.
We are likely to see an amino acid
that changes the direction of the chain
by introducing flexibility
at the junction of two alpha helices,
so answer choice a is correct.
Notice that the question did not ask us
what the structure of proline is,
but rather it asked us to identify
which amino acid side chain
has the necessary properties
to be located at the junction
of two alpha helices.
Let's now look at MCAT
Biology/Biochemistry Tip number four.
Understand the integration of metabolism
by focusing on rate limiting
steps and big picture ideas.
Many students often
assume that they will need
to memorize every enzyme,
reactant, product,
and how to draw the reactants or products
in metabolic pathways such as glycolysis.
Your time and effort,
however, is very valuable
while studying for the MCAT
and is probably better spent elsewhere
on high-yield material.
What is high yield from glycolysis?
Instead of memorizing every
reactant, product, and enzyme,
memorize the rate limiting enzymes
that control movement through the pathway.
What are the non-reversible
enzymes in glycolysis,
and how does the body
regulate these enzymes
in order to control our metabolism?
Let's look at an example.
Phosphofructokinase-1, or PFK-1,
is the rate limiting step of glycolysis.
This means that the
entire glycolysis pathway
can only move as quickly as PFK-1.
Why does the body do this?
Rate limiting steps are often
very important regulatory
points within metabolism
and biological pathways in general.
Let's say we eat a large meal
and have a lot of glucose
in our bloodstream.
We want to process this glucose
and either use it as immediate energy
or store it for future use.
In order to do this, we need
to carry out glycolysis.
After we eat the large meal,
insulin is also released
in our bloodstream.
Insulin, through a series of steps,
upregulates PFK-1 so that
it works more quickly,
allowing glycolysis to
also occur more quickly.
This is an example of the level
at which you should understand
a given metabolic pathway.
The metabolic pathways you should know are
glycolysis, gluconeogenesis,
glycogenesis, glycogenolysis,
Krebs cycle, electron transport
chain and ATP synthesis,
fermentation, the pentose
phosphate pathway,
fatty acid synthesis,
and fatty acid oxidation
also known as beta-oxidation.
Finally, MCAT Biology/Biochemistry
Tip number five.
Be familiar with experimental techniques.
Experimental techniques
on the MCAT Biology/Biochemistry
section include PCR,
Western blot, Southern
blot, Northern blot,
gel electrophoresis, SDS-PAGE
and reducing gels versus
native gels, molecular cloning,
and transformation,
conjugation, and transduction.
You will encounter these techniques
in Biology/Biochemistry passages
and by applying strategies one and two,
you will be able to work
your way through them.
Here, we'll go over
what each technique does at a high-level.
So let's start with PCR.
This technique can amplify
small amounts of DNA
and is useful in modern
applications such as sequencing
or determining cellular mRNA levels.
Western blot, this technique
measures protein levels
in a sample using antibodies.
Southern blot, this
technique detects DNA levels.
Northern blot, this
technique detects RNA levels.
Gel electrophoresis, this
technique separates molecules
on the basis of size and charge.
SDS-PAGE/reducing gels,
this technique separates
denatured proteins
on the basis of size.
Native gels, this technique
separates proteins
in their native conformation
that allows subunits to remain intact.
Molecular cloning, this technique is used
to introduce genetic
information into a plasmid
for protein expression
or genetic manipulation.
Transformation, conjugation,
and transduction.
These techniques are used
to transfer genetic information
into bacterial species.
And that's how to master
the MCAT Biology and Biochemistry section.
Now, you have a toolbox
of study strategies
to attack your practice problems,
so you can achieve your highest score
on the MCAT Biology/Biochemistry section.
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