Transcript Slide 1

FROM GENE TO PROTEIN!
Gene Expression and Gene Regualtion
DNA

A gene is a segment of DNA that
codes for a protein.

Let the BioRap explain!

Every protein in a living organism
is unique and is encoded by a
different sequence of DNA
nucleotides.

Typical proteins have 200-300
amino acids, but some are much
longer and some are much
shorter.
FROM DNA TO PROTEIN…

There are two steps to make protein from DNA: Transcription
& Translation.

In transcription, one mRNA (messenger RNA) is made from
one gene using the DNA template.

In translation, the mRNA is used to make a protein from
amino acids.
RNA IS SLIGHTLY DIFFERENT THAN DNA

RNA differs from DNA in
three ways:
1. Single strand instead
of double strand.
1.
Ribose instead of
deoxyribose (sugar).
Phosphate
Group
5
CH2
O
C4
Sugar
(ribose)
C3
1.
Uracil (U) instead of
Thymine (T).
Nitrogenous
base
(A, U , G, C )
C1
C2
N
1. MESSENGER RNA (MRNA) – CHECK OUT THIS VIDEO!

mRNA copies information
from DNA for protein
synthesis.

DNA can not leave the
nucleus so mRNA is the
messenger.

mRNA is made up of RNA
nucleotides.

Each set of three nucleotides
codes for a single amino acid
and are called “codons”.
2. TRANSFER RNA (TRNA)

tRNA is made of RNA nucleotides and each tRNA is attached to
one specific amino acid.

The three-nucleotide sequence that determines what amino acid is
attached to it is called the “anticodon”.
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At least one kind of tRNA is present for each of the 20 amino acids
used in protein synthesis.
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tRNA anticodons are complimentary to mRNA codons.
AMINO ACIDS
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Amino acids are the building
blocks of protein.

Amino acids bind together to
form long chains.

The chains fold into specific
structure to dictate a specific
function for each protein.
(next week)
TRANSCRIPTION

In order for cells to make proteins, the DNA code must be
transcribed (copied) to mRNA.

Transcription occurs in the nucleus.
TRANSLATION

Once the mRNA reaches the ribosome, the codons are
“read” and paired with the complimentary anticodons of
the tRNA.

The amino acids are released from the tRNA and added one
at a time to the growing amino acid chain.
MAKE AN MRNA STRAND
DNA sequence
TAC TTT TTG TTC CAT ATC
What is the mRNA sequence?
AUG AAA AAC AAG GUA UAG
DETERMINE THE AMINO ACID SEQUENCE.
mRNA sequence
AUG AAA AAC AAG GUA UAG
What is the amino acid sequence (protein)?
DETERMINE THE AMINO ACIDS
mRNA sequence
AAA AUG AAA AAC AAG GUA UAG
What is the protein sequence?
met lys asn
lys val stop