dna, rna and protein synthesis how proteins are made and how are your traits determined through gene...
TRANSCRIPT
DNA, RNA and Protein Synthesis
How Proteins Are Made and How Are Your Traits Determined through Gene Expression?
What are Proteins?
• Organic compounds contain C, H, O, N
• Made of small units called amino acids-
building blocks of proteins
What are Proteins continued?
• Proteins are made at the ribosomes• Ribosomes read the DNA message on the mRNA and join amino acids to make proteins• Your body can make 12 of the 20 amino acids, but the other 8 essential amino acids must
come from your diet• Name food items that are good source of these
essential amino acids? (Hint: must come from protein source).
Marcia S. Brose, M.D., Ph.D., Assistant Professor, Hematology/Oncology, The University of Pennsylvania Cancer Center, Philadelphia, PA. Review provided
http://training.seer.cancer.gov/module_anatomy/unit4_1_muscle_functions.html
Functions of Proteins• Enzymes-catalyst proteins used to control the rate of chemical reactions (lower amount of energy needed to start a reaction)
• Structural component of body: skin, hair, muscles, bone
http://www.accs.net/users/kriel/chapter%20seven
Functions of Proteins continued
• Some proteins are hormones and carry chemical messages; for example insulin, regulates blood sugar
• Transport substances such as hemoglobin in RBC that
carries O2
• Protect body against disease; antibodies of immune system
SO…how does a cell make proteins anyway? And what does
this have to do with DNA and RNA?
DNA• Contains deoxyribose
sugar• Is double stranded• Bonds A-T and C-G• Never leaves the nucleus
• Contains ribose sugar• Is single stranded• Bonds A-U and C-G• Can leave the nucleus
vs. RNA
Let’s Review…
Remember there are three types of RNA
• mRNA: messenger RNA; carries DNA message to ribosomes
mRNA
tRNA towingAmino acid
• rRNA: ribosomal RNA; makes up ribosome-protein factories of the cell
• tRNA: transfer RNA; transfers amino acids to ribosomes
Proteinfactory
Role of RNA
• While DNA contains the instructions for making proteins in the form of genes…
• RNA is the molecule that actually does all the work of putting the protein together
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Overall Process of Protein Synthesis (Gene Expression)
DNA
Transcription Translation
Transcription •Information in DNA is “transcribed” (rewritten) as a molecule of mRNA
mRNA
Protein
Translation•DNA information on mRNA is “translated” into protein language
Enzymes
• What organic compound group do enzymes belong to?
• There are two different enzymes necessary in making a protein.
• Helicase – breaks hydrogen bonds between nitrogen bases
• Polymerase – brings new nucleotides and bonds them to existing strands
TRANSCRIPTION- First Process of Protein Synthesis
• Occurs in the nucleus
• Initiator (start) Codon: AUG
• 60 nucleotides are copied per second
• Makes mRNA from DNA template
• Uses RNA Polymerase
TRANSCRIPTION Steps
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
1. Helicase breaks the hydrogen bonds between the nitrogen bases
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TRANSCRIPTION
2. The DNA strands break apart A
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TRANSCRIPTION
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3. RNA Polymerase brings in mRNA nucleotides and matches them with their DNA complement.
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mRNADNA
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U 4. mRNA breaks away from the DNA strand and goes to the ribosome
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To Ribosome
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5. The DNA strand is put back together
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SUMMARYTranscription
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CG
DNA mRNA
Translation
A U U
Amino Acid
tRNA Protein
Some additional notes about making
mRNA… • DNA contains many non-coding regions, also
known as “junk DNA” • RNA is not made from the junk DNA• Only 1 of the 2 DNA strands is used to make the
mRNA; this strand is called the DNA template• DNA code on the mRNA is read three bases at
once, and these three letter base combinations on the mRNA are called codons
• Codons determine your genetic code and the traits expressed from protein synthesis