2/6/15 objective: how does dna build proteins (transcription)?

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