2/6/15
Objective: How does DNA build proteins (Transcription)?
What happens at the….
Protein• Protein
- Made at the ribosomes
- Made of sequences of amino acids (there are 20)
- Examples:
- Enzymes, hormones, receptors, antibodies
- Function of a protein is determined by its structure
Importance of DNA in building a protein
• Has the code to determine the amino acid sequence
• It first has to be copied to RNA because it is too big to leave the nucleus
RNA
• Ribonucleic Acid
Comparing DNA and RNA
DNA
# of strands: double strandedSugar: deoxyriboseBases Used: A, T, C, G
RNA
# of strands: single strandedSugar: riboseBases Used: A, U, C, G
Transcription
• Transcribe = to copy
- Helicase unwinds DNA
- RNA polymerase adds RNA nucleotides
- Template strand of DNA is written into
RNA
Each circle in the protein represents one amino acid
mRNA
- mRNA(messenger RNA): a molecule of RNA that will be sent to the ribosome to build a protein
Each circle in the protein represents one amino acid
• Exons: coding sequences
• Introns: noncoding sequences (junk DNA)
• RNA splicing: coding sequences are cut out and put together forming RNA strand
Transcribe this sequence of DNA into RNA
A
T
T
C
G
G
A
A
C http://www.youtube.com/watch?v=ztPkv7wc3yU&feature=related
DNA- AAGCCTCCA
Practice more:
RNA:
CCGGUUAAG
UGACCGAUU
AGUAGACCC
RNA- UUCAGAGGU
Amino acid sequence=
Phe-Arg-Gly
Practice more:
RNA:
CCGGUUAAG
UGACCGAUU
AGUAGACCC
Activity-Amino Acid Bingo
Separate a piece of paper into a 4 X 4 grid- 4 boxes across and 4 boxes down.
Write the name of one amino acid in each box.
Listen to the RNA codon. Look at the chart and cross off the
corresponding amino acid. Four across, down or diagonal is amino acid
bingo.
Phenylalanine HistidineLeucine GlutamineIsoleucine AsparagineMethionine StopValine LysineSerine Aspartic acidProline Glutamic acidThreonine CysteineAlanine TryptophanTyrosine ArginineGlycine**You will have 1 free space and 3 repeats
DNA and proteins• Every three bases (codon) in a DNA molecule, corresponds to
one amino acid.
• First DNA must be transcribed into RNA using the following rules:
• C=G• G=C• T=A• A=U**********
Practice:• DNA: ATCGGTAGC DNA: TGCCAGTAG• RNA: UAGCCAUCG RNA: ACGGUCAUC