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Questions and Answers
What occurs during the denaturation step of DNA extension?
What occurs during the denaturation step of DNA extension?
Which temperature range is typically used for the annealing step in PCR?
Which temperature range is typically used for the annealing step in PCR?
What is the primary role of DNA polymerase during the extension step of PCR?
What is the primary role of DNA polymerase during the extension step of PCR?
Which virus is associated with the disease known as chicken pox?
Which virus is associated with the disease known as chicken pox?
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What action does a virus take after attaching to a host cell?
What action does a virus take after attaching to a host cell?
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What type of bond joins nucleotides in the primary structure of nucleic acids?
What type of bond joins nucleotides in the primary structure of nucleic acids?
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Which component connects the nucleotide sequence in nucleic acids?
Which component connects the nucleotide sequence in nucleic acids?
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What is the primary structure of RNA defined by?
What is the primary structure of RNA defined by?
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Which of the following is NOT a component of nucleic acids?
Which of the following is NOT a component of nucleic acids?
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In the nucleotide sequence 5'-A-C-G-U-3', what does the '5'' represent?
In the nucleotide sequence 5'-A-C-G-U-3', what does the '5'' represent?
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How are the bases in nucleic acids oriented in relation to the sugar-phosphate backbone?
How are the bases in nucleic acids oriented in relation to the sugar-phosphate backbone?
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When linking nucleotides, which carbon of the sugar is bonded to the phosphate group of the next nucleotide?
When linking nucleotides, which carbon of the sugar is bonded to the phosphate group of the next nucleotide?
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What role do repressors play in gene expression?
What role do repressors play in gene expression?
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Which of the following describes the function of general transcription factors?
Which of the following describes the function of general transcription factors?
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What is the primary function of chromatin remodeling?
What is the primary function of chromatin remodeling?
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How does splicing contribute to protein diversity?
How does splicing contribute to protein diversity?
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What is the significance of the 5' cap on pre-mRNA?
What is the significance of the 5' cap on pre-mRNA?
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What happens to the pre-mRNA during the addition of the poly-A tail?
What happens to the pre-mRNA during the addition of the poly-A tail?
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What is the primary purpose of mRNA processing?
What is the primary purpose of mRNA processing?
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What is the function of specific transcription factors?
What is the function of specific transcription factors?
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What are introns in the context of pre-mRNA?
What are introns in the context of pre-mRNA?
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What is the primary role of messenger RNA (mRNA)?
What is the primary role of messenger RNA (mRNA)?
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Which type of RNA serves as a link between mRNA and amino acids during protein synthesis?
Which type of RNA serves as a link between mRNA and amino acids during protein synthesis?
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During which process is pre-messenger RNA (pre-mRNA) synthesized?
During which process is pre-messenger RNA (pre-mRNA) synthesized?
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What is the main purpose of regulating transcription?
What is the main purpose of regulating transcription?
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Which enzyme is responsible for synthesizing RNA from a DNA template?
Which enzyme is responsible for synthesizing RNA from a DNA template?
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What role do transcription factors play in transcription?
What role do transcription factors play in transcription?
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What is the role of enhancers in gene transcription?
What is the role of enhancers in gene transcription?
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What is the initial step in the production of mRNA called?
What is the initial step in the production of mRNA called?
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What does the termination region signal during transcription?
What does the termination region signal during transcription?
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Which nucleotide is found in RNA but not in DNA?
Which nucleotide is found in RNA but not in DNA?
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What bonds link adenine and thymine in the DNA double helix?
What bonds link adenine and thymine in the DNA double helix?
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Which base pairs are linked by three hydrogen bonds in DNA?
Which base pairs are linked by three hydrogen bonds in DNA?
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During DNA replication, what happens to the DNA strands?
During DNA replication, what happens to the DNA strands?
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What occurs when DNA undergoes replication?
What occurs when DNA undergoes replication?
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In DNA fingerprinting, what is used to cut DNA chains into smaller sections?
In DNA fingerprinting, what is used to cut DNA chains into smaller sections?
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What characteristic of RNA distinguishes it from DNA?
What characteristic of RNA distinguishes it from DNA?
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What is the purpose of treating DNA fragments with a radioactive isotope in fingerprinting?
What is the purpose of treating DNA fragments with a radioactive isotope in fingerprinting?
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How do the base pairs A-T and G-C contribute to the structure of DNA?
How do the base pairs A-T and G-C contribute to the structure of DNA?
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What is produced as a result of DNA replication?
What is produced as a result of DNA replication?
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Study Notes
Nucleic Acids and Proteins
- Nucleic acids are polymers of nucleotides, which have a phosphate group bonded to the -OH on C5'
- They have a unique base sequence in RNA, called the primary structure
- They carry information between cells
Primary Structure of Nucleic Acids
- Nucleotides are joined by 3'-5' phosphodiester bonds
- The 3'-OH group of one nucleotide bonds to the 5'-phosphate group of the next
- An example of sequence is 5'-A-C-G-U-3', joined by phosphodiester bonds, starting with adenine (free 5'-phosphate end)
- In nucleic acid chains, each sugar in the sugar-phosphate backbone is attached to a base
- The bases extend out from the nucleic acid backbone
- Bases are labeled from the 5' end to the 3' end
Double Helix of DNA & DNA Replication
- DNA contains complementary base pairs, with equal amounts of A and T, and equal amounts of G and C
- Adenine (A) is always linked by two hydrogen bonds with thymine (T)
- Guanine (G) is always linked by three hydrogen bonds with cytosine (C)
- Two strands of nucleotides wind together to form a double helix
- The double helix is held in place by hydrogen bonds between the base pairs A-T and G-C
- The bases along one strand complement the bases along the other
DNA Replication
- In DNA replication, genetic information is maintained during cell division
- DNA strands unwind and each parent strand bonds with a new complementary base
- Exact copies of the parent DNA are formed
- The separate strands of the parent DNA act as templates for complementary stands which produces two exact copies (daughter DNAs)
DNA Fingerprinting
- Enzymes cut DNA chains into sections
- Resulting fragments are separated by size and treated with a radioactive isotope that adheres to specific base sequences
- This creates a pattern of bands called a DNA fingerprint
- Used in forensic science to connect suspects to crimes
RNA Types
- Ribonucleic acid (RNA)
- Is a single-stranded nucleic acid similar to DNA, but with a single, helical strand of bases and role in turning DNA instructions into functional proteins
- Made up of nucleotides: ribose, phosphate group, and nitrogenous bases (adenine, uracil, guanine, cytosine)
Types of RNA
- Messenger RNA (mRNA): carries genetic information from DNA in the nucleus to the cytoplasm for protein synthesis
- Transfer RNA (tRNA): links between mRNA and growing chains of amino acids in protein synthesis
- Ribosomal RNA (rRNA): part of the ribosome which reads the order of amino acids and links them together
Protein Synthesis
- Transcription is the process of copying a segment of DNA into mRNA
- First step in gene expression that creates proteins
- In mRNA synthesis, in a eukaryotic cell, RNA polymerase binds to a promoter region
- Copying the basis on the DNA template strand to form new complementary RNA strand
- In prokaryotic cells, it's the same except the termination region signals when to stop
Nucleotides
- Nucleotides are the building blocks of nucleic acids, playing a key role in the structure and function of DNA and RNA
- Single stranded template RNA, coding strand, and template strand parts of the DNA molecule.
- The coding strand is the template strand.
- The molecules of RNA and DNA are composed of nucleotide monomers.
Maturation of Pre-mRNA
- Pre-mRNA undergoes modifications before translation (e.g., 5' capping, splicing, poly-A tail addition)
- Crucial for maturation, stability, and eventual translation of mRNA.
Regulation of Transcription
- Genes are expressed timely, in correct cells, and at appropriate levels by regulating transcription
- DNA template provides the genetic information
- RNA polymerase synthesizes RNA from the DNA template using a promoter region
- Transcription factors help initiate transcription
- Promoters are located near the start site of the gene, while enhancers and silencers increase or decrease transcription
Transcription Factors
- Activators bind to enhancer regions for increased transcription
- Repressors bind to silencer regions to decrease transcription
- General transcription factors are necessary for basic transcription
- Specific transcription factors are activated by signaling pathways
Remodeling of Chromatin
- DNA is wrapped around histones to form chromatin for gene regulation
- Splicing increases protein diversity by producing different protein isotypes from a single gene
Lac Operon
- Codes for enzymes involved in lactose catabolism
- Inducible operon; lactose presence activates it
- Operon has three enzymes (lac Z, lac Y, lac A)
Function of Lac Operon
- In absence of lactose, a repressor protein blocks transcription
- Lactose presence causes allolactose formation and repressor removal, allowing RNA polymerase to bind
- When both glucose and lactose are present, RNA polymerase is less stable during binding
Mutations
- Incorrect codons result in defective proteins and enzymes
- Causes genetic diseases (e.g., Huntington's, Cystic Fibrosis)
Translation
- Process converting genetic info (DNA/RNA's genetic code) to proteins
- Genetic code is read as triplets (codons)
- Specific amino acids correspond to specific codons
- Codons, each correspond to an amino acid or signal
2 Major Processes of Translation
- tRNA activation (aminoacylation): Charging tRNA molecules with their corresponding amino acids
- Translocation: Ribosome moves along mRNA, with dipeptide shifts to P site and empty tRNA to E site
Termination of Translation
- Polypeptide chain continues until a stop codon (e.g., UAA, UAG, UGA) appears
- Stop codons have no corresponding tRNA, causing termination
- Polypeptide is cleaved from tRNA
Viruses and Reverse Transcription
- Viruses are small particles that need a host cell to replicate
- They cause infection by releasing their DNA or RNA into the host cell
- Some viruses use reverse transcription to synthesize viral DNA in the host
HIV and AIDS Treatment
- Treatment for AIDS involves targeting HIV's life cycle
- AZT, similar to thymidine, inhibits reverse transcriptase
- Lexiva is a protease inhibitor that prevents protein synthesis
DNA Fingerprinting and Polymerase Chain Reaction (PCR)
- Technique identifies individuals by DNA characteristics
- PCR amplifies small DNA amounts for further testing
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Description
Test your knowledge on the structure and function of nucleic acids and proteins. This quiz covers topics such as nucleotides, the primary structure of RNA, and the DNA double helix. Understand the fundamentals of how information is transferred within cells.
