Proteins Structure 4a'
Summary
TLDRThis lecture explores the intricate relationship between genes and proteins, focusing on the translation process and the genetic code. It delves into the composition of RNA, the structure of proteins, and the significance of amino acids. The lecture also discusses the concept of colinearity between genes and proteins, demonstrating how the sequence of a gene directly corresponds to the sequence of a protein. Additionally, it covers the historical experiments that led to the understanding of the genetic code as a triplet code, highlighting the pivotal role of in vitro translation and RNA synthesis in decoding how specific nucleotide sequences dictate amino acid formation.
Takeaways
- 🧬 The lecture introduces the concept of translation in genetics, focusing on the synthesis of proteins from mRNA by ribosomes and other cellular components.
- 📚 mRNA and tRNA constitute over 95% of RNA in a cell, with mRNA making up only 1-2%, indicating their stability and importance in cellular transcription.
- 🔑 The genetic code is the link between the nucleotide sequence of a gene and the amino acid sequence of the protein it encodes.
- 🌟 Proteins are crucial for an organism's phenotype, acting as enzymes to catalyze chemical reactions and forming structural components of cells.
- 🔍 Understanding protein structure is essential for comprehending genes, as proteins are encoded by genes and reflect the information they contain.
- 📝 Amino acids, the monomer subunits of proteins, are polymerized into polypeptides through peptide bonds, forming the primary structure of proteins.
- 🌀 The secondary structure of proteins, such as alpha-helices and beta-sheets, arises from hydrogen bonding between amino acids, contributing to the protein's overall shape.
- 🧬 Tertiary structure refers to the three-dimensional conformation of a single polypeptide chain, influenced by its secondary structures and amino acid interactions.
- 🤝 Quinary structure describes the arrangement of multiple polypeptide chains in a protein complex, held together by various weak bonds.
- 🔄 The concept of colinearity between genes and proteins was demonstrated by Charles Yanofsky, showing that the sequence of a gene directly corresponds to the sequence of its protein product.
- 🧬 The genetic code is a triplet code, with three nucleotides specifying a single amino acid, and is non-overlapping, meaning each codon is read individually.
Q & A
What are the main components involved in protein synthesis?
-Protein synthesis involves messenger RNA (mRNA), transfer RNA (tRNA), and ribosomes. mRNA is read by ribosomes, and tRNA brings the appropriate amino acids to the ribosome to generate proteins.
What percentage of RNA in a cell is made up of rRNA and tRNA?
-rRNA and tRNA make up over 95% of RNA in a cell.
How does the stability of rRNA and tRNA compare to mRNA?
-rRNA and tRNA are more stable than mRNA and do not get degraded and turned over as fast.
What is the relationship between the nucleotide sequence of a gene and the amino acid sequence of a protein?
-The genetic code describes the relationship, where the nucleotide sequence of the gene specifies the amino acid sequence of the protein.
What are the 20 different subunits that make up proteins called?
-The 20 different subunits that make up proteins are called amino acids.
What is a polypeptide and how is it formed?
-A polypeptide is a polymer composed of amino acids, also known as peptides. It is formed by peptide bonds created through condensation reactions between the amino group of one amino acid and the carboxy group of another.
What are the four levels of protein structure?
-The four levels of protein structure are primary (linear sequence of amino acids), secondary (regular repeated structures like alpha helix and beta pleated sheets), tertiary (three-dimensional structure of a single polypeptide chain), and quinary (structure of multiple subunit proteins).
What is the significance of the directionality of polypeptides and mRNA?
-The amino terminus of a polypeptide is lined up with the five prime end of the mRNA, and the carboxy terminus with the three prime end, indicating the direction of translation from the mRNA to the protein.
How was the colinearity of genes and proteins first demonstrated?
-Colinearity was first demonstrated by Charles Yanofsky in 1963 through his work with the trpA gene in E. coli. He induced mutations and showed that each mutation created an amino acid substitution in the same order as the mutations in the gene.
What does the genetic code being non-overlapping mean?
-The genetic code being non-overlapping means that each triplet of bases (codon) is read individually without overlapping into the next triplet, ensuring a specific and consistent translation of the mRNA sequence into amino acids.
How did experiments with T4 phage contribute to understanding the genetic code?
-Experiments with T4 phage showed that mutations causing an addition or deletion of one or two bases resulted in nonfunctional proteins, while three base additions or deletions close together resulted in functional proteins with only small changes, indicating that the genetic code is read in triplets.
Outlines
🧬 Introduction to Translation and Genetic Code
This lecture introduces the topic of translation, which is the process of converting the genetic code into proteins. It emphasizes the importance of mRNA and tRNA, which together make up over 95% of cellular RNA and are more stable than mRNA. The genetic code is described as the relationship between the nucleotide sequence of a gene and the amino acid sequence of the protein it encodes. Proteins, which are crucial for an organism's phenotype, are composed of amino acids and are encoded by genes. The lecture promises to delve into the structure of proteins, the genetic code, and the molecular details of translation.
🌀 Protein Structure and Amino Acids
The paragraph discusses the structure of proteins, which are polymers made up of amino acids. There are 20 different amino acids that form the building blocks of proteins. Each amino acid has an amino group, a carboxy group, and a unique side chain (R group) that gives it distinct properties. The amino acids are linked together by peptide bonds, which are formed through a condensation reaction. The paragraph also explains the directionality of polypeptides and mRNA, noting that the amino terminus of a protein aligns with the 5' end of mRNA, and the carboxy terminus aligns with the 3' end.
🔍 Levels of Protein Structure
This section explains the four levels of protein structure: primary, secondary, tertiary, and quinary. The primary structure refers to the sequence of amino acids. Secondary structures, such as alpha-helices and beta-sheets, are formed through hydrogen bonding. Tertiary structure is the three-dimensional shape of a single polypeptide chain, influenced by secondary structures and R group interactions. Quinary structure pertains to multi-subunit proteins, where multiple polypeptides come together to form a complex. The paragraph also touches on the general shapes of proteins, such as globular and fibrous, and the concept of domains within proteins that have specific functions.
🧵 Colinearity of Genes and Proteins
The concept of colinearity between genes and proteins is introduced, which means that the linear sequence of bases in a gene corresponds to the linear sequence of amino acids in the protein. This was first demonstrated by Charles Yanofsky in 1963 through his work with the trpA gene in E. coli. He induced mutations and showed that each mutation corresponded to an amino acid substitution in the same order along the protein. The paragraph also discusses the non-overlapping nature of the genetic code, where each set of three nucleotides (codon) codes for a single amino acid.
🧪 Decoding the Genetic Code
The paragraph describes how the genetic code was deciphered in the 1960s. Scientists used cell-free translation systems to isolate cellular components capable of protein synthesis. They could control the mRNA sequence to observe which proteins were produced. Additionally, in vitro synthesis of RNA allowed scientists to create specific mRNA sequences to test. Through experiments with base additions and deletions, they discovered that one or two base changes could disrupt protein function, while three closely placed base changes could result in a functional protein with minor amino acid sequence alterations. This led to the understanding that the genetic code is read in non-overlapping triplets, each coding for a specific amino acid.
Mindmap
Keywords
💡mRNA
💡tRNA
💡Ribosomes
💡Genetic Code
💡Amino Acids
💡Peptide Bonds
💡Primary Structure
💡Secondary Structure
💡Tertiary Structure
💡Quaternary Structure
Highlights
Introduction to the lecture series on translation, the genetic code, and proteins.
Messenger RNAs (mRNAs) are read during protein synthesis by ribosomes, tRNAs, and other components.
rRNA and tRNA make up over 95% of RNA in a cell, with mRNA constituting 5% or less.
The genetic code describes the relationship between the nucleotide sequence of a gene and the amino acid sequence of the protein it specifies.
Proteins are essential for the phenotype of an organism, acting as enzymes and structural components of the cell.
Proteins are polymers composed of 20 different amino acids, which are the monomer subunits.
Amino acids are distinguished by their unique R groups, which give them their chemical properties.
Peptide bonds, formed by a condensation reaction, link amino acids together in a polypeptide chain.
Polypeptides have directionality, with the N-terminus aligning with the 5' end of mRNA and the C-terminus with the 3' end.
Proteins form complex structures with four levels of organization: primary, secondary, tertiary, and quaternary.
The primary structure of a protein is the specific order of amino acids in the polypeptide chain.
Secondary structures, such as alpha-helices and beta-sheets, arise from hydrogen bonding between amino acids.
Tertiary structure refers to the three-dimensional structure of a single polypeptide chain.
Quaternary structure is the three-dimensional structure formed by multiple polypeptide chains.
Proteins can be globular or fibrous, with globular proteins being compact and fibrous proteins having a linear shape.
Colinearity between genes and proteins was demonstrated by Charles Yanofsky in 1963, showing a direct correspondence between gene sequence and protein sequence.
The genetic code is a triplet code, with three nucleotides coding for a single amino acid.
The genetic code is non-overlapping, meaning each codon is read individually without overlap.
Experiments with T4 phage by Francis Crick and Sydney Brenner helped determine the nature of the genetic code.
In vitro translation and RNA synthesis techniques in the 1960s allowed scientists to determine which codons coded for which amino acids.
Transcripts
all right welcome back this is a new
lecture set where we will talk about
translation and the genetic code and a
little bit about proteins right at the
beginning here so this is the first um
recorded lecture for this lecture
set okay so as an introduction messenger
mrnas okay or messenger rnas or mrnas as
we just talked about are read during
protein synthesis the translation by
ribosomes TRNA is and other components
to generate proteins okay R RNA and TRNA
make up over 95% of RNA in a Cell
remember I said in the last lecture said
that rrna makes up 50% rrna plus TRNA
make up 95% of all the RNA in a Cell
they are more stable than mRNA so they
don't get degraded and turned over as
fast and their genes represent over 50%
of the transcription that takes place in
a Cell mRNA makes up 5% or less all the
RNA in a Cell often times only making up
between 1 and 2% of the RNA in a Cell
the genetic code describes the
relationship between the nucleotide
sequence of the Gene and the amino acid
sequence of the protein it specifies so
in this lecture set we'll start by
talking about proteins a little bit then
we'll get into um the genetic code and
we'll get into the molecular details of
translation all right Pro proteins are
the structures that determine much of
the phenotype of an organism they are
responsible as enzymes to catalyze
chemical reactions and also form
structural components of the cell genes
encode proteins so understanding
proteins helps in the understanding of
genes so in case you're asking the
question why are we talking about
proteins um because they're sort of
linked to the information contained
within the genes so before talking about
how proteins are made we'll briefly talk
about protein structure a protein is a
polymer composed of monomer subunits the
protein subunits are called amino acids
and there are 20 different amino acids
that make up proteins amino acids were
once called peptides and so polymer of
amino acids or peptides is called a
polypeptide it makes more sense to call
it a poly amino acid but it's always
called the poly peptid you can think of
a peptide as pretty much equivalent to
an amino acid each amino acid has an
amino group a carboxy group and a side R
Group which is different for each amino
acid and gives each amino acid their
distinctive
properties so here's amino acid
structure you have a central Alpha
carbon you have a carboxy group um
normally there' be an H here but under
physiological conditions in our cells um
it gives up that H have the negative
charge that H ends up on the amino group
so instead of being nh2 it's NH3 and it
has a positive charge here it's aoxy
group amino group Alpha carbon there's
always a hydrogen here and then every
one of those 20 different amino acids
has a different R Group and again the
different R groups then give different
characteristics chemical characteristics
to these different amino acids and so
different books um classify them
differently but a lot of times see the
non-polar ones so in Orange here are the
r groups and you can see that they're
nonpolar there's no charges there's no
unequal distribution of charge you see a
lot of hydrocarbons there um aromatic
amino acids okay so you have the groups
here polar um but neutral okay so they
don't have charges but they have
polarity to them hydroxy group here
hydroxy group there amino group there
carox carox amine there polar AIC amino
acids all right so they have a negative
charge they've given up a hydrogen or
proton a polar Amino or basic amino
acids so they're going to have a
positive charge on these and then
non-standard so non-standard sort of
different um
cysteine here pyly here um you get some
different types of amino acids um they
are non-standard ones so just one way to
look at it we're not going to get into
um in of course such as biochemistry or
something that would be really important
when you're talking about protein
biochemistry to sort of know the
chemistry of all these we're not going
to get into that a lot just be aware of
the different amino acids and they have
to come together then to um form a
polypeptide so amino acids then are
joined together by something called
peptide bonds these are calent bonds
formed by condensation reaction between
the amino group of one amino acid and
the carboxy group of another amino acid
this is a condensation or dehydration
reaction as a molecule of water is
removed every polypeptide has a free
amino group at the N Terminus and a free
carboxy group at the C Terminus so just
like how a polymer of nucleotides DNA
RNA has a five Prime n with a free five
Prime phosphate or a three prime n with
a free thre Prime hydroxy proteins have
a free ENT Terminus or have a free amino
group creating the ENT Terminus on one
end and a free carboxy group but the
other end um which is then the C
Terminus so here's this dehydration
reaction so here's one amino acid there
second amino acid so here's carboxy
group amino group they join together and
this Bond here then is a peptide bond so
it's a dehydration reaction because it
gives up a molecule of water then when
forming this peptide
bond so here's another figure showing
this so this is already a polypeptide
and the next one coming in there's a
carox group there's amino group come
together a molecule water and that
peptide bond forms there and then
directionality of polypeptide and mRNA
we'll talk a little bit more about this
in a bit there's the amino Terminus it's
actually lined up with the five Prim
five Prime end of the MRNA carboxy
Terminus lines up with three prime end
of an mRNA and we'll talk briefly about
this in a little
bit here then again showing um peptide
bond um joining together the point of
this slide here is um these peptide
bonds actually have a partial double
bond character so all that means is um
at the peptide bond they're not allowed
to rotate freely they can't just circle
around um they're restricted in their
movement it's it's more like um if you
think of a chain the different lengths
of a chain together rather than um sort
of beads um on a string you know beads
on a string you can take that string and
you can twirl it around tie it up do all
of things it's sort of free rotation do
whatever you want but with a chain you
can twist a chain around but there's
kinks in the chain and so sort of like a
partial double bond between every link
of a chain and that's sort of how these
peptide bonds um act or behave um yeah
another side forgot about this one so
again amino acid amino acid coming
together forming peptide bond
dehydration uh reaction all right so
most polypeptides in our cells are
polypeptides average about 200 to 300
amino acids all right so 200 to 300
amino acids linked together is the
average size of most polypeptides and by
convention um I showed you that how the
N Terminus and C Terminus match the five
Prime and three prime NS of DNA and
since DNA is written five Prime to three
prime by convention um proteins if you
were to write out the number of amino
acids in a protein it would be written
from the N Terminus to the C Terminus
from left to right um so proteins form
complex structures um and can classify
those structures into four levels of
organization so uh the first level is
called the primary structure and primary
structure is the specific order of amino
of amino acids or the linear sequence um
it's usually written out in a
three-letter code or a one letter code
again those letter codes are something
you might memorize or look at if you
take a course such as biochemistry so
here's primary structure and again
primary structure they draw it out here
but it's really all it is is the order
of the amino acids and again by
convention you start at the amino end
when listing those amino acids
um here again order of amino acids on
the left that's just the primary
structure uh secondary structure is a
regular repeated structure or pattern in
a polypeptide chain um only parts of the
entire polypeptide form this so um
sometimes it's easier to talk about
tertiary structure first
so tertiary structure okay is the
three-dimensional structure of a
complete polypeptide chain it's also
referred to as its confirmation so this
complete three-dimensional shape of a
polypeptide chain of a single
polypeptide chain secondary structure
then is part of the overall tertiary
structure so there are multiple
secondary
structures within the full tertiary
structure the full of the secondary
structure and the rest of the
polypeptide chain creates the
three-dimensional tertiary structure um
what plays a role in the shape this
tertiary structure takes is of course
the secondary structure within it and
the interaction between the r groups so
we'll get back to secondary structure in
a second so tertiary structure is just
here so it's a
complete threedimensional
structure there's another image here so
it's a full polypeptide chain and it's
three-dimensional structure that it
takes on
all right so getting back to secondary
structure then again a regular repeated
structure regularly repeated not
confirmation regularly repeated
structure in a polypeptide chain only
parts of the polypeptide form this um
the shape of the secondary structure
arises primarily from the hydrogen
bonding between amino acids okay the
most common the most common examples of
secondary structure are the alpha Helix
and the beta pleed sheet all right so
let's take a look here so here's primary
structure secondary structure then is an
alpha Helix okay it's a right-handed
Helix and again the hydrogen bonding is
what determines the structure so you can
see hydrogen bonding here the dotted
lines here dotted lines here dotted
lines here so in general if the r groups
line up just right you'll get hydrogen
bonding between these different amino
acids and it'll take a regular repeated
pattern um which then make up part of
the entire tertiary structure so here's
the whole tertiary structure you can see
here it has one prominent Alpha Helix
and that's it so it's a part of the full
tertiary structure the other secondary
structure common one is a beta pleted
sheet so instead of weaving around each
other it sort of goes back and forth it
turns somewhere and then another run of
amino acids interact with the amino
acids next to it so again these dotted
lines hydrogen bonding is what is
holding it together so again going to
this tertiary structure here so there's
two turquoise ones and there's two um
beta pleated sheets behind it um making
up part of the whole and this next image
here same thing you see the red one two
three Alpha helices start of alpha Helix
there 1 2 3 four five six beta pleted
sheets okay with these two likely
interacting strongly and these two
interacting strongly and but then a lot
of
non identifiable green here so it bends
and it turns and it twist T but it's not
an identifiable secondary structure um
but it still is responsible for making
up the large um or the overall
three-dimensional
shape all right so the last type of
structure is quinary structure so
quinary structure is the confirmation of
a multiple subunit protein okay so it
has to have more than one polypeptide
that interacts and then it's that
three-dimensional shape of multiple
polypeptides coming together it's
composed of two or more folded
polypeptides or subunits joined together
by weak bonds joined together by
hydrogen electrostatic so polar calent
bonds Vander wals forces different
things that are holding it together if
two different polypeptides come together
they form a hetero dimer heterol for
different dimer for two die for two if
two of the same polypeptides come
together they form a homo dier and so
we've looked at this figure before so
here's one subunit here's another
subunit looks like they just STI this
one turn it upside down and put it
together so that's a homo dier it looks
like two identical subunits there this
is not this is a different
example um myoglobin well here's an
example so the green the red and the
other color green um three different
proteins um coming together interacting
so that would then be an example of
quinary structure all right proteins are
also sometimes identified by their
General overall shape um they can be
called globular proteins or fibrous
proteins so proteins that have compact
shapes so proteins like enzymes or
antibodies are called globular proteins
these proteins can form Pockets when
folded especially enzymes or protruding
parts that interact with other proteins
or other molecules uh parts or sequences
of a protein that have a particular
function are called domains okay so you
can have an entire protein and you can
have a certain part of the protein that
does a certain job and that is called a
domain for example um A protein that
interacts with DNA can have a DNA
binding domain so you can have part of
the protein that binds the DNA and it
still has a whole other part of it that
does some other job um so globular
proteins
example an example here of an enzyme so
it sort of rolls up on itself Compact
and since it's enzyme has an active
sight or a little CFT or an opening
where things take place um examples here
myoglobin is a globular protein it's
compact where collagen is a fibrous
protein okay proteins that are fibrous
can take on a linear shape um they're
longer they're not Co globbed up if you
will and so they're called fibrous
protein so collagen is one keratin that
makes up hair it's fibrous um collagen
is found mainly in the extracellular
Matrix outside of our
cells is is where you find things like
that all right now we're going to talk
about colinearity of a gene and protein
so what is the relationship between
genes and proteins I sort of already
given this away right talking about the
five Prime end of the MRNA corresponds
to the amino Terminus and the three
Prime with the carboxy Terminus well how
do we know this so colinearity of genes
and proteins is the idea that the linear
sequence of the gene corresponds with
the linear sequence of the poly peptide
in other words one end of the gene
corresponds to one end of the protein
that genes and proteins are colinear was
first demonstrated by Charles yanowski
in
1963 he was looking at a
polypeptide um was called trip a that
was part of tryptophan synthesis enzyme
and
ecoli he induced 16 different mutations
in this trip a gene all of which produce
an inactive enzyme he mapped these sites
by recombination analysis
we'll talk later in the course about uh
recombination and it what it is and how
it's a tool to figure out where things
are to put it shortly it was a lot of
work uh he then analyzed the trpe mutant
proteins and discovered that each
mutation created an amino acid
substitution each of these amino acid
substitution was in the same order as
the mutations in the gene in other words
if an amino acid at the beginning of the
polypeptide was mutated this correspond
responded to a mutation at the beginning
of the Gene and amino acid mutation at
the end of the protein corresponded to a
mutation towards the end of the gene
therefore the Gene and protein are
collinear all right so um this is just
showing collinearity here's the DNA
here's the RNA and start codon here so
at the five Prime end of the MRNA you
have the beginning of the polypeptide
which would be the N Terminus and at the
three prime end of the MRNA you have the
end of the protein which would be the
carboxy end so
here's the different types of mutation
inasi looked at in the in what he saw in
the amino acid so normal amino acid had
this particular sequence he made a bunch
of mutations and then he went and
checked where those mutations were so he
knew a446 was the first one or closest
to the five primen and he knew a169 was
closest to three Prim you do the order
of all of them in between you then could
then um uh figure out the amino acid
sequence of the protein and see where
changes were made and when you saw that
the change made closest to the amino
Terminus was closest to the five Prime
and and so on and so forth so that's how
he determined the colinearity uh between
the Gene and
proteins all right we know that DNA
contains the information to code for
proteins how does the information
molecule how or how does in information
molecule with only four different bases
code for 20 different amino acids IDs
two bases could code for 16 different
amino acids and three bases together
could code for
64 okay so the question is are only some
of the 64 three base triplets or codons
used to code for 20 amino acids or are
some of the 20 amino acids coded for by
multiple Triplets of
nucleotides so the genetic code is a
triple code so three nucleotides in row
will code for a single amino acid so we
can see this here Aug codes for
methionine AGC codes for serine okay and
so on and so
forth and so but there's still lots of
questions like how do we figure this out
or how did science figure out well first
the genetic code is non-overlapping in
other words each triplet of bases is
read individually and then the next full
triplet of bases all right so figure
here what that means so one here could
be 1 2 3 and you can imagine then two
could be the second third and fourth
three could be the third fourth and
fifth that would be an overlapping code
it turns out that's not how it works
it's nonoverlapping so one two three
nucleotides code for amino acid then
it's a shift to four oops four five6
code for the second 7 8 n that trip
closer to the third so it's a
nonoverlapping
code all right so how was it
demonstrated that the genetic code was a
tripli code well Francis Crick Sydney
brener and colleagues did experiments
with a T4 virulent bacteria phage trying
to determine the nature of the genetic
code so again now they're working with
bacteria phages or viruses that infect
bacterial cells because you can grow
lots of them up and you can do really
fine tuning of uh the genetics in these
types of experiments so they discovered
while isolating mutants of this phage
and the particular types of mutants they
are looking for were that preferentially
added or deleted a base so while
isolating mutants for this phage they
discovered that mutations which cause an
addition or a deletion of one or two
bases resulted in a nonfunctional
protein while an addition or deltion of
three bases relatively close to one
another resulted in a functional protein
with only small changes in the amino
acid sequence so one or two base
additions deletions completely stop
translation three base additions delions
close to one another did
not um result in the stopping of the
protein they resulted in A protein that
was pretty similar so what does this
look like then so here's wild type
protein mutagenesis by base addition all
right so you're can add one base here
and it will mess up all the rest so
after three in here messes up all the
rest of the amino acids all right same
thing if you added two
but if three were added I think this
next slide shows that so here you DNA
and if you get 1 2 three mutations close
together you'll the MRNA still translat
or transcribes fine and you get
relatively the same amino acid sequence
so this is altered so a couple of amino
acids are different than what would be
in the wild type Gene before it was
mutated um but then Downstream of that
again Downstream of that um you get all
the same amino acids so the protein
slightly altered but still usually in
these cases still works so that's how
they discovered one or two base
additions cause problems three that are
close together then usually return the
protein to
um functionality um they also discovered
revertant right so if they had one base
addition or deletion they could get the
opposite happening and they could revert
back to normal and that's what this
slide also had here so Genesis here
mutation changes everything another
mutation just a little bit down the way
returns you got Arginine Serene Serene
Argin returns or reverts the protein
back to near Wild type function okay so
again apart from those two amino acids
here um all the others are the same so
that's what a revertant is it's a
mutation that has been reverted back to
Wild type function you can tell it's not
exactly the same but the functionality
of the protein um is close enough to
what the wild type
go all right so how was it figured out
which codons which three nucleotides
together coded for which amino acids
there are two techniques in the 1960s
that made this possible one was cell
free or in vitro
translation okay in vitro in a test tube
or without
cells and in in vitro
translation the scientists had the
ability to make cell-free extracts all
right so they are able to extract or
take apart cells and use the components
within within a um test tube and all
those components then when they isolated
them were able to carry out protein
synthesis all right so they're able to
take apart a cell isolate the parts that
could make um a protein or could
translate and then they could control
what mRNA was used to make the protein
so they could put in a very specific
sequence and see what protein got made
in that
process and they able to control what
mRNA was in because the other um
technique they had was invitro synthesis
of RNA they could specifically
synthesize RNA of the nucleotides they
wanted to within limits it started where
it was a probability thing um and then
they got better and better at it so they
could put together exact
um sequences of um mRNA so they would do
things like put together all A's or all
C's or all G's that would be how they
would start and then they would do
things I think slide here shows this
they would do things where they would
put a a two a d nucleotide together a u
and a c and allow the U and C to go
together um randomly so sometimes you'd
get
ucu sometimes you'd get CU c um you get
these two possibilities and then you'd
get a protein that came out of that inal
translation of serene and Lucine so you
knew Serene had to be either ucu or CU
and Lucine had to be the other one so
they did a lot of these um
two nucleotides together and they always
got two different options of codons and
they would always get two different
amino acids that were made then they
went to triplets and then you get lots
of different options here and then they
went to putting together single
nucleotides in different um percentages
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