Download KEY TERMS FOR Characteristics of Life

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2009-2010 CP2 KEY TERMS FOR
Protein Synthesis (Transcription and Translation)
MA BIOLOGY FRAMEWORKS BEING MET:
3.2 Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic code. Explain the basic
processes of transcription and translation, and how they result in the expression of genes. Distinguish among the end products of replication,
transcription, and translation.
3.3 Explain how mutations in the DNA sequence of a gene may or may not result in phenotypic change in an organism. Explain how mutations in
gametes may result in phenotypic changes in offspring.
Exploring Life concept 11.4: A gene provides the information for
making a specific protein (overview of transcription / translation)
AND
Exploring Life concept 11.5: There are two main steps from gene to
protein (specifics of transcription / translation)
OBJECTIVES:
1. Explain the “one gene-one polypeptide” hypothesis
2. Explain the basic process of transcription (where in the cell does this process take place,
what do you start with, what do you do to it, and what do you end with?)
3. Given a DNA strand, be able to tell what the complementary mRNA strand would be
4. Compare and contrast DNA and RNA in terms of long name, type of sugar, number of
strands, what part of the cell it is found in (nucleus and / or cytoplasm) and names of bases
5. Explain what is actually happening when the DNA unzips.
6. Explain the basic process of translation (where in the cell does this process take place, what
do you start with, what do you do to it, and what do you end with?)
7. Summarize protein synthesis (tell in only a few words what is happening)
8. Distinguish between the end products of replication, transcription and translation
9. Utilize the genetic code to determine an amino acid sequence from a given strand of DNA
(transcribe DNA to mRNA, then translate mRNA to a protein).
10. List the three types of RNA and their functions
11. Label on a diagram of protein synthesis: DNA, Codon, Anticodon, tRNA, mRNA, rRNA,
Protein, Amino Acid
KEY TERMS:
TRANSCRIPTION:
Transcription: copying the DNA message into RNA language
RNA: (Ribonucleic Acid) a nucleic acid that helps make proteins
Genotype: an organism’s genetic makeup
Phenotype: an organism’s specific traits
Messenger RNA: (mRNA) carries the DNA message from the nucleus to the cytoplasm
Gene: a section of DNA that codes for a specific trait
TRANSLATION:
Translation: using mRNA instructions to make a protein
Codon: three-base code on an mRNA molecule
Amino acid: the subunit of proteins
Protein: molecule that the body uses to build and repair parts of the body with
Protein Synthesis: Making proteins
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Ribosomal RNA: (rRNA) molecule that makes up ribosomes
Ribosome: cell organelle that helps make proteins
Transfer RNA: (tRNA) molecule that carries amino acids to the ribosome
Exploring Life concept 11.6 – Mutations can change the meaning of
genes
OBJECTIVES:
12. Describe the types of mutations that can affect genes
13. Explain what can cause a mutation
14. Explain why mutations in DNA sequence may result in phenotypic changes in an organism.
KEY TERMS:
Mutagen: something that causes a mutation
Mutation: any mistake in the DNA
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Name: ___________________________________ Date: ____________ Class: ______ Page 3/19
QUESTIONS FOR: Concept 11.4:
A gene provides the information for making a specific protein
Use your textbook to find the answers to the following questions:
ONE-GENE, ONE POLYPEPTIDE
1. What is the difference between genotype and phenotype?
2. What does the “one gene-one polypeptide” hypothesis say?
INFORMATION FLOW: DNA TO RNA TO PROTEIN:
3. Fill in the following chart below. You may need to use your DNA notes to find some answers!
DNA
RNA
Long name of molecule
Type of sugar
Single or double-stranded?
Bases
4. Copying the DNA message into RNA language is called: _______________________
5. The DNA instructions remain in the nucleus. After the RNA message is copied from the DNA,
where does it move to?
6. When DNA is transcribed, what is the result?
7. Using the RNA instructions to make a protein (amino acid chain) is called: _______________
8. What is a codon?
THE TRIPLET CODE
9. Which amino acid is coded for by the RNA sequence CUA?
10. Which amino acid is coded for by the RNA sequence GAC?
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NOTES: Transcription (DNA to mRNA) Concepts 11.4 & 11.5
What is a gene?
• A gene is a unit of information in DNA (A “chunk” of instructions for how to do something)
• There are genes for…
– Hair color
– How many toes you have
– How big your eyes are
– The size of your hands
– Etc….
One Gene - One Polypeptide Hypothesis
• This hypothesis states that the function of an individual gene is to hold the instructions for
making one specific polypeptide (protein)
Information flow: DNA to RNA
• Each protein is made from the instructions in one gene
• Before a protein can be made, the DNA instructions have to be copied and moved from the
nucleus and into the cytoplasm.
• RNA is a copy of a gene (instructions) found in DNA
RNA vs. DNA
RNA
• Ribonucleic Acid
• Sugar = ribose
• Single-stranded
• Bases: AUCG
• “U” = Uracil and it is similar to T and pairs with Adenine.
DNA
• Deoxyribonucleic Acid
• Sugar = deoxyribose
• Double-stranded
• Bases: ATCG
Copying DNA’s instructions
• The DNA can’t leave the nucleus because it needs to be protected (bad if it was damaged),
and it’s too big. So, we make a copy of what we need.
• This is called “transcription”
• “transcribe” means “to copy”
• In transcription, the DNA message is just copied and brought from the nucleus to the
cytoplasm.
• The protein will be made in the cytoplasm using the copy of instructions that came from the
nucleus (RNA).
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Types of RNA Involved
• There are three types of RNA involved in making proteins:
– mRNA (messenger RNA): brings the DNA message into the cytoplasm
– tRNA (transfer RNA): transfers amino acids to the growing protein chain by reading
the mRNA instructions
– rRNA (ribosomal RNA): holds all the parts together while making a protein
Process of Transcription:
1. DNA unzips (H-bonds broken!)
2. RNA bases pair with complementary DNA bases (on only one chain of DNA)
- Remember: U instead of T!!!
1. RNA polymerase (an enzyme) links the RNA nucleotides together and an mRNA is made
2. mRNA unzips from DNA strand, DNA rejoins
3. mRNA moves to the cytoplasm
Transcription
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WS: DNA AND GENES – DNA AND RNA COMPARISON
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Questions for Concept 11.5
(Specifics of Transcription and Translation)
Use your textbook to find the answers to the following questions:
TRANSCRIPTION: DNA to RNA
1. Which of the following best describes the information flow in Transcription?
a. Use RNA to make DNA
b. Use proteins to make DNA
c. Use DNA to make RNA
d. Use RNA to make proteins
2. What are is the difference between DNA replication and transcription?
TRANSLATION: RNA to Protein
3. Which of the following best describes the information flow in Translation?
a. Use RNA to make DNA
b. Use proteins to make DNA
c. Use DNA to make RNA
d. Use RNA to make proteins
4. Translation of the mRNA message into protein language requires an interpreter. What
molecule is known as the interpreter?
5. True or False: CODONS are found on mRNA molecules
6. True or False: ANTICODONS are found on tRNA molecules
7. If a codon on an mRNA reads “CAG” what will the anticodons on the tRNA read?
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8. What is attached to the tRNA molecule on the opposite end of the anticodons?
9. The first step of translation is to bring together all of the pieces needed during translation.
These pieces are:
________________________, _______________________, _______________________
10. What is the signal for translation to begin?
11. What brings the amino acids to the ribosome?
12. There are three signals for translation to stop. What are they?
13. What is the result of translation?
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Name: ___________________________________ Date: ____________ Class: ______ Page 9/19
NOTES: Translation (mRNA to Protein)
Concepts 11.4 & 11.5
Transcription Review
• Remember, in transcription, a gene in DNA is copied into mRNA.
• The mRNA message moves from nucleus to cytoplasm. This is where the protein will be
made.
Making A Protein
• Translation is using mRNA instructions to make a protein
• When you translate, you change languages – For example, English to Russian.
• A genetic translation changes RNA language into protein language.
• Remember: DNA holds the instructions for making proteins (how to make us!)
How to Read RNA
• RNA is read in 3-letter words, called codons.
• One codon (in RNA language) = one amino acid (in protein language)
• Several codons = an amino acid “sentence”…. Or a protein!
• (Remember the protein bead necklaces we made earlier this year!!!)
The Triplet Code
• There is a code for what codons code (translate into) for which amino acids.
• You use a key to translate the mRNA into the protein language.
“Start” and “Stop Codons
• There is always a “start” codon at the beginning of the mRNA chain.
– Start codon:
• AUG (also codes for methionine)
• There is always a “stop” codon at the end of the chain.
– There are three stop codons:
• UAA
• UAG
• UGA
Practice Reading the Key:
• Translate the following mRNA into a protein using your chart!
AUG
GUC
AGA
CCC
UGA
Process of Translation
1. After mRNA moves to cytoplasm, it attaches to a ribosome
2. The ribosome (rRNA) holds onto the mRNA
3. tRNAs transfer new amino acids to the growing protein.
4. As new a.a’s add to the chain, the used tRNAs return to the cytoplasm to find another a.a.
5. When the tRNA’s reach the end of the instructions, the “stop” codon tells them to end the
protein.
6. Result of translation: string of a.a’s (protein!)
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tRNA
• tRNAs read the mRNA instructions and bring amino acids
to the rRNA / mRNA complex and join them together to
make a protein
• tRNAs have an “anticodon” that plugs into the codon on
the mRNA strand. There is one type of tRNA with an
anticodon for each codon
• Example: for the mRNA codon ACA, the tRNA will have
the anticodon UGU, which will allow the tRNA to bond to
the mRNA and transfer the amino acid to the growing
protein chain.
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Name: ___________________________________ Date: ____________ Class: ______ Page 11/19
Overview of DNA Replication,
Transcription and Translation
• Use DNA to make DNA
• DNA Replication
Happens: In Nucleus
• Use DNA to make RNA
• Transcription
Happens: In Nucleus
• Use RNA to make Protein
• Translation
Happens: In Cytoplasm
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Practice: Transcription and Translation from DNA
DNA:
RNA:
Protein:
Practice: Transcription and Translation from DNA
DNA:
RNA:
Protein:
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Practice: Transcription and Translation from DNA
DNA:
RNA:
Protein:
Practice: Transcription and Translation from DNA
DNA:
RNA:
Protein:
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FIGURE OUT THE CODONS AND AMINO ACIDS
Use what you have learned about pairing of nitrogen bases, and your codon key to fill in the missing
parts in the cart below. The first one is done for you.
Transcription
Translation
DNA codon
mRNA codon
Amino Acid coded for by
mRNA
1.
CTT
GAA
Glutamic acid
2.
GCA
3.
4.
UCA
CCT
5.
6.
ACU
GGG
7.
8.
UAA
CAT
9.
AUC
10.
CGA
11.
ATC
12.
CAA
13.
AAA
14.
ACT
15.
16.
UUG
ATG
17.
Histidine
18.
Lysine
19.
Typtophan
20.
Methionine
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Protein Synthesis Practice
1. Where does DNA replication take place? ______________________________
2. Where does transcription take place? ______________________________
3. Where does translation take place? ______________________________
4. Given the following DNA sequence, what is the amino acid chain that will be created?
TAC CCG
TGA
ATG ATT
5. The following is an amino acid sequence of a protein. What was the original DNA message?
methionine – phenylalanine – aspartic acid – lysine – stop
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Name: ___________________________________ Date: ____________ Class: ______ Page 17/19
Questions for Concept 11.6 – Mutations can change the meaning of genes
1. What is the definition of a mutation?
2. What is an example of a disease that is caused by a genetic mutation?
3. List the two types of mutations and the difference between the two.
4. Explain what a silent mutation is
5. What are three things that can cause mutations?
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NOTES: Mutations Can Change the Meaning of Genes
Concept 11.6
Mutations
• A mutation is any change in the nucleotide sequence of DNA
• Two types:
– Base substitutions – replacement of one base with another
• Can cause no change in protein, or a deformed protein
– Base insertions / deletions – inserting extra bases, or deleting some (or both)
• Causes a change in the protein
• How can some base substitutions cause no change in the protein?
•
•
•
Remember – several amino acids have more than one codon.
– Example: both GAA and GAG code for Glutamic Acid
If a mutation to DNA causes the mRNA codon to change from GAA to GAG, no change in
the protein product would result.
This is called a “silent mutation”
What causes mutations?
• Errors in DNA replication
• Errors made during the making of sex-cells (eggs and sperm)
• Mutagens: Physical or chemical agents that cause mutations
– X-rays
– UV light
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Not all mutations are bad!
• Some mutations can alter a protein in a way that may be beneficial in certain environments.
• A species of black swallowtail butterflies is poisonous and birds avoid eating these
butterflies.
• Tiger swallowtail butterflies are not poisonous but some have a mutation that makes their
wings black. Therefore, birds also avoid eating these butterflies because they look like the
poisonous ones.
Can a mutation be passed on to offspring?
• If a mutation is present in an organism’s egg or sperm DNA, it can be passed on.
•
If it is NOT in egg or sperm DNA, it can NOT be passed on.
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