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Questions and Answers
What is the central dogma of molecular biology?
Where is DNA found in prokaryotes?
What is the structure of DNA proposed by Francis Crick and James Watson?
What is the composition of a nucleotide?
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What is the characteristic of purines?
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What replaces thymine in RNA?
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What is the primary function of mRNA?
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What is the sugar backbone of RNA composed of?
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What is the role of tRNA in protein synthesis?
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Where is rRNA primarily found in a cell?
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What determines the properties of proteins?
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What is the result of certain RNA defects?
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What is the function of codon charts?
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What is the relationship between DNA and RNA?
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How do cells decode mRNAs?
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What is the function of the 'start' codon AUG?
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What type of amino acids are essential for our daily diet?
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How many amino acids are there?
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Study Notes
Central Dogma of Molecular Biology
- The central dogma is the process of genetic information flowing from DNA to RNA to make a functional protein.
Components of the Central Dogma
- Deoxyribonucleic Acid (DNA)
- Genetic material passed from parents to offspring
- Found in nucleoid region in prokaryotes and nucleus in eukaryotes
- Proposed by Francis Crick and James Watson in 1953
- Double helix structure with nucleotide building blocks
- Nucleotide composed of phosphate group, sugar, and nitrogenous bases
Nitrogenous Bases
- Purines have a double ringed structure
- Pyrimidines have a single ring structure
- Complementary base pairing: each pair has one purine and one pyrimidine
- Uracil replaces thymine in RNA
Importance of Nitrogenous Base Pairing
- Genetic information is stored in these base pairs
- Biological processes depend on the sequence of nitrogenous base pairs
Ribonucleic Acid (RNA)
- Single-stranded molecule composed of nucleotides
- Sugar backbone is ribose
- DNA serves as the manual, and RNA serves as its "photocopy"
- Three types of RNA: mRNA, tRNA, and rRNA
Types of RNA
- mRNA (messenger RNA)
- Made from DNA in nucleus
- Travels out of nucleus and finds a ribosome
- Carries genetic information from nucleus to cytoplasm
- tRNA (transfer RNA)
- Brings amino acids to the ribosome
- Found in cytoplasm
- rRNA (ribosomal RNA)
- Part of the ribosome
- Directs the translation of mRNA into proteins
Importance of RNA
- Acts as enzymes that speed up chemical reactions
- Regulates various cell processes, including cell division, growth, and cell aging and death
- RNA defects can result in human diseases
Proteins
- Composed of polymers of numerous amino acids known as polypeptides
- 20 amino acids
- Amino acids can be configured into unique information-carrying structures
- Properties of proteins are determined by the order of amino acids in a polypeptide
Amino Acids
- Essential amino acids: cannot be produced by our bodies
- Nonessential amino acids: can be produced by our bodies
- Conditionally nonessential amino acids: not vital but may become urgent during health crisis or stress
Genetic Code and Codon
- The language of instruction in the mRNA is called genetic code
- The 3-letter combination in the mRNA is known as a codon
- Codon charts are used to find the amino acid that corresponds to DNA and RNA
- Features of codons:
- Most codons specify an amino acid
- Three "stop" codons (UAG, UGA, UAA) mark the end of a protein
- One "start" codon (AUG) marks the beginning of a protein and encodes the amino acid methionine
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Description
Test your understanding of the central dogma, a fundamental principle in genetics that explains how genetic information flows from DNA to proteins. Covers DNA replication, transcription, and translation.