Transcript TRANSCRIPTION & TRANSLATION: From DNA to Protein

Take out your HW: Transcription wkst
Homework due tomorrow:
Protein Synthesis wkst
Somewhere on a sheet of scratch paper or in
your notes, TRANSCRIBE the following DNA
sequence into mRNA:
TAC AGT CCA GCG ATA ATT
AUG UCA GGU CGC UAU UAA
TRANSCRIPTION & TRANSLATION: From
Chapter 11, Section 2
DNA to Protein
Think back to the information contained in your
homework assignment:
1. What is produced when the process of
transcription is complete?
2. What are 2 differences that were listed/shown
between DNA and RNA?
Genes & Proteins
• What is the function of a gene?
– codes for traits, inherited from parents
• Genes code for specific proteins
– Proteins make up muscles, hair, tissues,
enzymes, & pigments
• Protein Synthesis = reading the DNA,
forming RNA, using RNA to make the
protein (DNA  RNA  Protein)
– Occurs through the processes of
transcription and translation
RNA
• RNA is a nucleic acid (like DNA)
• Differs in structure from DNA:
DNA
RNA
Number of Strands
2
1
Nucleotide Sugar
Deoxyribose
Ribose
Nitrogenous Base
Pairs
Thymine(T),
Adenine(A),
Guanine (G),
Cytosine (C)
Uracil (U),
Adenine(A),
Guanine (G),
Cytosine (C)
Focusing on RNA
• There are 3 different types of RNA that you will
need to know:
– mRNA
– rRNA
– tRNA
Types of RNA
• 1. Messenger RNA
(mRNA)
– Carries genetic
“message” from
DNA to the
ribosomes in the
cytosol
– “Read” by
ribosomes to make
proteins
– Contain codons
• 2. Ribosomal RNA (rRNA)
– Part of the structure of ribosomes
– Ribosome = protein and rRNA
• 3. Transfer RNA
• Transfers amino acids to the ribosome to make
protein
Transcription: Getting the
message out of the nucleus
• Transcription = enzymes make RNA by copying
a portion of DNA in the nucleus
• If a DNA sequence is AATCCGGA, what is the
complimentary RNA sequence?
• UUAGGCCU
• The mRNA that gets sequenced is sent out of the
nucleus to help make protein
Genetic Code
• Sequence of Nitrogenous Bases codes for a
specific Amino Acid that is connected to other
amino acids to make a Protein
• Codon = the nitrogenous bases of 3 adjacent
nucleotides in mRNA that code for
– Start Signal (starts the protein making process)
– 1 of 20 different amino acids (parts of a protein)
– Stop Signal (stops the protein making process)
• Codons are like 3-letter words
– Words contain meaning to us: CAT =
– Codons contain meaning in the form of an amino acid
CAU = Histidine
•An amino acid can be coded for by more than one codon
•20 amino acids combine in different combinations to make
various proteins
Translation: Going from the language
of bases (AUGC) to proteins
• Translation = using the mRNA to make protein,
reading the codons
– Takes place at the ribosomes
• The mRNA is “read” in between the 2 sub-units of
the ribosome
• tRNA carries the amino acid coded for by the
mRNA codons and has an anticodon that pairs up
with the mRNA codon
– Codon (mRNA) and anticodon (tRNA) follow RNA
base-pairing rules
• Amino acids form peptide bonds between each
other to create a long chain of amino acids
Transcription
Amino acids to protein
• Amino acid chains
start to fold
creating 3dimensional
structures
• Several of these 3D structures
combine to form a
functional protein
• These proteins
then carry out
cellular functions