DNA+and+RNA
DNA: The Blueprint of Life
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DNA stands for Deoxyribonucleic Acid
DNA is the molecule of life found in cells
It consists of chromosomes and genes
The DNA sequence includes nucleotides like T, A, G, and C
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DNA was established by James Watson and Francis Crick
Hershey and Chase confirmed DNA as genetic material
Watson and Crick discovered the double helix structure of DNA encoding genetic information
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DNA is made of nucleotide pairs with hydrogen bonds
Nucleotides are the repeating subunits of DNA
Nucleotides include Adenine, Thymine, Cytosine, and Guanine
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A nucleotide consists of a phosphate, a nitrogenous base, and a pentose sugar
Nitrogenous bases can be A, T, C, or G
The structure of a nucleotide includes a phosphate, deoxyribose sugar, and a nitrogenous base
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Base-Pair Rule: Adenine pairs with Thymine, Guanine pairs with Cytosine
DNA ladder sides are phosphate and sugar linked by hydrogen bonds
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Base Pair Rule shows complementary base pairs on DNA strands
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Deoxyribonucleic Acid (DNA) structure includes sugar-phosphate backbone and base pairs
DNA is composed of nucleotides forming the genetic code
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A combination of A, T, G, C in DNA determines traits like hair color
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Semiconservative Replication produces two copies of DNA with conserved information
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DNA replication occurs in the nucleus of eukaryotic cells
Replication also happens in prokaryotic cells
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Key players in DNA replication are Polymerase, Helicase, Primase, and Ligase
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Helicase breaks hydrogen bonds in DNA strands during replication
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DNA Polymerase replicates and proofreads DNA during replication
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DNA Primase creates RNA primers to start DNA replication
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DNA Ligase helps in joining DNA fragments during replication
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Multiple choice questions on DNA base pairing and structure
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Matching enzymes involved in DNA replication with their functions
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Step by step process of DNA replication
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DNA Polymerase builds new strands in a specific direction during replication
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Lagging strand in DNA replication involves Okazaki fragments and DNA Ligase
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Illustration of leading and lagging strands in DNA replication
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Explanation of the 5' and 3' directions in DNA structure
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Introduction to DNA transcription process
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Transcription is the first step in gene expression
RNA polymerases are enzymes involved in transcription
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Illustration of DNA transcription and translation processes
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RNA polymerase synthesizes RNA from DNA template
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Stages of transcription: Initiation, Elongation, Termination
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Initiation stage of transcription involves RNA polymerase binding to the promoter region
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Recognition sites
Transcribed region 5' 3' DNA 3' 5'
Promoter 11 RNA polymerase 5' 3 DNA 3' 5'
Single-stranded template
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Elongation
Template strand of DNA guides RNA polymerase
RNA molecule built from complementary nucleotides
RNA transcript carries information like non-template DNA strand
Thymine in DNA replaced by Uracil in RNA
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RNA polymerase
Reads coding strand of DNA
Builds RNA from template strand
Complementary base pairing
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Termination
Terminator sequences signal RNA transcript completion
Release of transcript from RNA polymerase
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Rewound DNA
RNA transcript termination
Polyadenylation signal
Completed RNA transcript
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Journey to the protein maker
mRNA from transcription delivered to ribosome
Ribosome made of rRNA
rRNA builds proteins in translation
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mRNA Translation
mRNA transcribed from DNA
mRNA translated into amino acids
Codons correspond to amino acids
Amino acids form polypeptide chains
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Translation Process
tRNA carries amino acids
Amino acids group to build proteins
mRNA guides tRNA to transfer amino acids
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Translation Continued
tRNA binds with complementary base pairs
Codons and anticodons
Amino acid determination using codon chart
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Codon Chart
Codon rules for mRNA
Different codes for the same amino acid
Example with Leucine
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Codon Chart Usage
Identifying codons
Complementary anticodon determination
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Amino Acid Formation
tRNA leaves, amino acids form peptide bonds
Chain formation until stop codon
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Stop Codons
Stop codons signal end of protein building
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Summary
Amino acid chain built from mRNA
DNA directs protein building
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Gene Expression and Regulation
Prokaryotic and eukaryotic gene regulation
Environmental factors influence gene expression
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Prokaryotic Gene Regulation
Regulation for response and energy conservation
Transcription and translation simultaneous
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Promoter and Operon
Promoter for gene transcription
Operon includes promoter and operator
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lac Operon
Gene regulation example in bacteria
3 genes controlled by one promoter/operator
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lac Operon Function
Switch on/off based on lactose presence
Resource conservation mechanism
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Operon Mechanism
Repressor protein binds to operator
Lactose presence affects transcription
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lac Operon Illustration
Repressor and RNA polymerase interaction
Lactose influence on operon transcription
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Eukaryotic Regulation
Introns and exons in DNA
Introns removed from mRNA before leaving nucleus
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Intron Purpose
Protection and break for RNA polymerase
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Gene Expression
Internal and external factors influence
Uneven distribution of molecules in cells
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External Factors
Oxygen, temperature, light influence gene expression
Example with caterpillars and butterfly wing colors
Note
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Example of Temperature Influencing Genes
The C gene in Himalayan rabbits determines black/white coloration on body parts.
Black body parts develop at 30 degrees C or higher.
White body parts develop at 20 degrees C or lower.
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Gene Mutations
Permanent alterations in DNA sequence can lead to changes in protein production.
Mutations can affect the amount or type of protein produced.
Example: Normal Hemoglobin vs. Mutated Hemoglobin.
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Understanding Mutations
Mutations involve changes in nucleic acids like DNA and RNA.
Many mutations are "silent" and do not impact the host.
Mutations can be neutral, harmful, or helpful, and are random occurrences.
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Factors Influencing Mutations
Both internal and external factors can increase mutation chances.
External factors include sunlight, smoking, and radiation.
Internal factors include frameshift mutation, point mutation, and somatic mutations.
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Types of Gene Mutations
Substitution: Incorrect bases matched together.
Insertion: Extra base added to the DNA strand.
Deletion: Base deleted that should not have been.
Insertion and deletion mutations can be dangerous.
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Frameshift Mutations
Insertion or deletion mutations can change the reading frame of tRNA.
Altered reading frame can lead to major protein mix-ups.
Frameshift mutations occur when bases are read in 3's by tRNA.
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Chromosome Mutations
Duplication: Extra gene copies are created.
Deletion: Loss of genetic material.
Inversion: Broken chromosome segment reattaches in reverse.
Translocation: Fragment from one chromosome attaches to another.
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Occurrence of Mutations
Mutations are more likely during DNA Replication and Meiosis.
Nondisjunction can lead to cells with abnormal chromosome numbers.
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Inheritance of Mutations
Sickle cell is an autosomal recessive disorder.
Mutant DNA can result in different amino acids being produced.
Example: Thymine replaced with adenine leading to Uracil on the RNA