DNA, RNA, Protein Synthesis
• DNA Structure• DNA Replication : DNA DNA• RNA Structure• Protein Synthesis• Transcription : DNA RNA• Translation : mRNA amino acid
Human Genotype
• The human genotype contains 46 chromosomes
• Each chromosome has 2 chromatid legs• Each chromatid leg has thousands of
genes• Each gene has thousands of DNA
nucleotides in loose strands called chromatin
Role of DNA
• 1) DNA stores the genetic information in the nucleus until is time to pass the genetic information on to progeny
• 2) DNA is the blueprint for the cell to make proteins
DNA Structure
• DNA is a double helix = twisted ladder• DNA is a polymer of DNA monomers• Eg. DNA nucleotides in a DNA strand are
like beads in a necklace
DNA Nucleotide
• Each nucleotide has 3 sub-components• 1) 5 carbon sugar called deoxyribose• 2) phosphate group• 3) nitrogen-containing base
DNA Nucleotide Base
• There are four bases: adenine (A), thymine (T), guanine (G) and cytosine (C)
• The name of the DNA nucleotide is the name of the base
• The DNA nucleotides undergo “complementary” base-pairing: A=T , T=A, G=C, C=G
DNA Nucleotides
• Hydrogen bonding between complementary bases :
• A=T T=A G=C C=G• Keeps the two DNA strands together in the
double helix shape
DNA Replication
• DNA Replication = 1 “Parent” Double Strand DNA 2 “Progeny” Double Strand DNA
• DNA Replication is called “Semi-conservative” because each progeny double strand DNA has one original parent DNA strand and one new DNA strand
DNA Replication
DNA replication requires 3 enzymes:
1) DNA helicase : “unzips” the double helix by breaking hydrogen bonds between bases
2) DNA polymerase : attaches new DNA nucleotide to complementary DNA nucleotide in parent DNA strand
3) DNA ligase: ties the strands back together
RNA Structure• DNA• Double helix• Deoxyribose sugar
• A=T, T=A, G=C, C=G• DNA remains in
nucleus
• RNA• Single strand• Ribose sugar• Uracil base replaces
Thymine base• A=U, T=A, G=C,
C=G• RNA is made in
nucleus and moved to cytoplasm
Role of RNA
• Messenger RNA : carries protein synthesis information stored in DNA in the nucleus to the ribosome in the cytoplasm
• Transfer RNA: brings amino acids to the ribosome for protein synthesis
• Ribosomal RNA: combines with proteins to make the ribosomes
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