Mr. Gibson Biochemistry I Class

Lecture Hall - 213/Laboratory -214

Week of April 16, 2012

The "Redundancy " & "Junk" for

Codons

Notice the amino

acid. Leucine (L)?

The "Redundancy " & "Junk" for

CodonsLeu uses the (not only)

one set of codons within

one of our 16 code boxes

that have the same 1st

two letters, (but also)

another box of codons

with another pair of

different 1st two letters –

although they are the

same within the that

box, they are different

when compared to the

other box.

The "Redundancy " & "Junk" for

Codons

Recent lab analysis

has shown there are

purposes for both

[the] “redundancy”

& “junk”.

GCUGCCGCAGCG

A

The "Redundancy " & "Junk" for

Codons

Regarding [the]

“redundancy”….

Let’s say the cell calls for the

amino acid shown here –

alanine; to be inserted at

multiple points on the

polypeptide (multiple amino-

acids) chain in a particular

protein …

GCUGCCGCAGCG

A

The "Redundancy " & "Junk" for

Codons

Regarding [the]

“redundancy”….

The 1st two letters

(nitrogenous bases) guanine

& cytosine – will deliver a

tRNA molecule with the

amino acid alanine

covalently bonded to its

acceptor arm.

GCUGCCGCAGCG

A

The "Redundancy " & "Junk" for

Codons

Regarding [the] “junk”….

The 3rd letter (nitrogenous

base) of the codon makes no

difference in terms of

delivering the correct tRNA

molecule with the alanine

amino acid covalently

bonded to its acceptor arm.

GCUGCCGCAGCG

A

The "Redundancy " & "Junk" for

Codons

Although the cell

needs (proteins) to

(operate) and

(maintain) itself;

GCUGCCGCAGCG

A

The "Redundancy " & "Junk" for

Codons

The cell does not want

proteins to be… too many or

too few for its needed

processes

OR

to hang around for too long

or too short of a time as it

is being used.

GCUGCCGCAGCG

A

The "Redundancy " & "Junk" for

Codons

At a level of study that would be

too complex and take up too much

time for our understanding -- we

can say this:

Muliple codons with different 3rd

letters… do tell the proteins that

come out of the ribosome

translation process how long they

are to hang out in a cell once

delivered…

The "Redundancy " & "Junk" for

Codons

AND;

also tells the proteins how

many or few of them are to

show up at the cell (correct

amounts) to meet the cell’s

needs.

The "Redundancy " & "Junk" for

Codons

In fact…

If there are too many or too few

proteins –or-

if they don’t break down

(denature) and go away thus hang

around for too short or long of a

time;

a third type of disease occurs in all

living cells.

The "Redundancy " & "Junk" for

Codons

As you may recall from your

biology class studies; there

are two types of diseases that

destroy cells (a) bacteria

and (b) viruses.

The "Redundancy " & "Junk" for

Codons

A third type of disease prion

disease all centers around the

tRNA bringing the correct

amino acid along with its

correct directions in terms of

amount (expression) & longevity

(dwell time)for the ribosome to

make the protein possessing the

correct structure/information-

function [as] dictated by the

“redundant” & “junk” codons/3rd

letter.

The "Redundancy " & "Junk" for

Codons

Prion diseases are always

debilitating and often fatal.

Many, many times it doesn’t

even show up in a living

organism until much later in

its life cycle – and then, with

devastating results.

The "Redundancy " & "Junk" for

Codons

A vivisection (cross-section) of

a human brain with areas that

are degenerating (breaking

down… getting soft or mushy);

A cow that is loosing the

motor function in its legs due

to nerve degradation

(breaking down, no longer

able to carry electrical

impulses).

The "Redundancy " & "Junk" for

Codons

We now have a glimpse into

understanding the nature,

importance and complicated

directions that are delivered by the

codons as they relate to amino acids

and protein amounts/life

expectancy;

We will next look at the make up of

the “manufacturing site” – the

ribosome – in terms of its parts &

functions of those parts.