Chapter 11.2

Chapter 11.2: From DNA to Protein

I CAN...
-Relate the concept of the gene to the sequence of nucleotides in DNA
-Sequence the steps involved in protein synthesis

Section 11.2

Vocab:
mRNA
rRNA
tRNA
transcription
codon
translation

​Genes and Proteins

• Nucleotide sequence in DNA = information for protein production

• Some proteins become structures, others become enzymes

  • Enzymes control all chemical reactions within an organism

• Proteins are polymers made up of AMINO ACIDS

  • Nucleotides in a gene contains info for assembling the string of amino acids that make up a single protein.
    

Multiple Choice

How does DNA control the activities of cell?

• By containing instructions for making proteins
• By providing energy for cellular activities
• By regulating the cell's shape and size
• By controlling the movement of organelles within the cell

• Both are NUCLEIC ACIDS

  • 3 Key Differences:

    1. Single Stranded

    2. Sugar = Ribose

    3. U (uracil)

​RNA vs DNA

​Role of RNA in a Cell

• Protein Production => Assembly Line

  • Workers for protein synthesis are RNA molecules

  • RNA take DNA instructions on how the protein should be assembled

  • Amino Acid by amino acid - they assemble the protein

Types of RNA

mRNA
(messenger RNA)

-Brings instructions from DNA in the nucleus to the factory floor (cytoplasm).
-mRNA moves to the assembly line, a ribosome.

rRNA
(ribosomal RNA)

-The ribosome binds to mRNA and uses the instructions to assemble the amino acids in the correct order.

tRNA
(transfer RNA)

-The supplier
-Delivers amino acids to the ribosome to be assembled into a protein.

Multiple Select

What are the 3 key differences between DNA and RNA?

(select 3)

• Sugar: Deoxyribose vs Ribose

• Phosphate Group vs Hydrogen Group

• Base Thymine vs Base Uracil

• Double Strand vs Single Strand

• Base Adenine vs Base Uracil

Multiple Choice

What are the 3 types of RNA?

• mRNA, rRNA, tRNA

• ATP, ADP, AMP
• Protein, Lipid, Carbohydrate
• DNA, RNA, mRNA

Transcription

• RNA is made from a part of a DNA strand.

  • Gets information to cytoplasm from DNA through mRNA.

• Transcription is similar to replication with 1 IMPORTANT DIFFERENCE - a single strand RNA is created rather than a double strand DNA molecule, and uracil pairs with adenine.

​transcription

1. Portion of DNA unzips, free RNA nucleotides pair with the DNA nucleotides on the strand.

2. mRNA is completed when the RNA nucleotides form a strand by bonding together.

3. mRNA strand breaks away and the DNA strands rejoin.

4. mRNA leaves nucleus & enters cytoplasm.

Multiple Choice

How is transcription different from replication?

• Transcription produces RNA, while replication produces DNA.
• Transcription produces DNA, while replication produces RNA.
• Transcription and replication both produce DNA.
• Transcription and replication both produce RNA.

​RNA Processing

• Not all of a DNA strand carries info to make proteins, so enzymes cut out any noncoding nucleotides of the DNA strand.

• This is so that mRNA only carries info it needs to make a protein.

The Genetic Code

• The nucleotide sequence transcribed from DNA to a strand of mRNA is a genetic message that has all the info needed to build a protein.

• Proteins are made up of amino acid (20) chains that are created from 4 nitrogenous bases.

• Requires a group of 3 nitrogenous bases in mRNA to code for 1 amino acid (CODON)

• Every amino acid has a 3-letter codon

  • EX: alanine = G-C-U and lysine = A-A-A

• Codon for start & stop

Translation

• Process of changing the information in mRNA into an amino acid chain in protein .

  • Require all 3 types of RNA

Translation

1. mRNA moves to cytoplasm

2. A ribosomes (rRNA) attaches itself to the start codon, A-U-G, on the mRNA.

3. Transfer (tRNA) molecules, carrying amino acids approach the ribosome. The complementary base to the mRNA is the anticodon. If the mRNA codon is G-C-C, the tRNA anticodon is C-G-G. For every codon on mRNA there is an anticodon on tRNA.

4. The ribosome attaches the anticodon to the codon and amino acids bond. The ribosome then slides to the next codon.

5. Repeats step 4, and continues this translation process until the stop codon is reached. At this point the amino acids have formed a chain and when the stop codon is reached, the chain is released.

Multiple Choice

What is the anticodon of A-C-G?

• U-G-C
• T-A-C
• C-G-A
• A-C-G