Download DNA/RNA

DNA/RNA
DNA
• Deoxyribonucleic Acid
• Organic Category?
DNA Structure
• Double helix
• 1953
• Watson and Crick
• Rosalind Franklin
Nucleotides
• Made up of a sugar, a phosphate group, and a
nitrogenous base
• Deoxyribose sugar
• Nitrogenous bases
o
o
o
o
Adenine
Thymine
Cytosine
Guanine
Complementary Bases
• Nitrogenous bases pair up with each other
• Adenine with Thymine
• Cytosine with Guanine
DNA Replication
• Process by which DNA is copied in a cell before a
cell divides by mitosis, meiosis, or binary fission
• Semi-conservative replication
• Makes use of 2 enzymes
o Helicase
o DNA Polymerase
Steps of DNA
Replication
• DNA is “unzipped” by helicase; results in a
replication fork
• DNA polymerase adds new complementary bases
to the parent strand
• DNA polymerase falls off and bonds reform; results
in two daughter strands
Prokaryotic vs. Eukaryotic
DNA Replication
• Prokaryotic: replication in a circle
• Eukaryotic: replication begins at many points along
chromosome
Errors in DNA
Replication
• DNA polymerase includes enzymes which repair
errors
• Errors are mutations
• A=G
Protein Synthesis
•
•
•
•
Proteins direct most cellular processes
Transcription
Translation
Central Dogma of Biology
o DNA  RNA  Protein
RNA
• Ribonucleic acid
• Organic category?
RNA Structure
• Single helix
Nucleotides
• Made up of a sugar, a phosphate group, and a
nitrogenous base
• Ribose sugar
• Nitrogenous bases
o
o
o
o
Adenine
Uracil
Cytosine
Guanine
Complementary Bases
• Nitrogenous bases pair up with each other
• Adenine with Uracil
• Cytosine with Guanine
Types of RNA
• mRNA – messenger RNA
o Carries code from nucleus to ribosomes
• rRNA – ribosomal RNA
o Part of ribosome structure
• tRNA – transfer RNA
o Transfers amino acids to ribosome to make protein
Transcription
• DNA  RNA
• Can use either DNA strand as template
• Only certain regions of DNA are transcribed (genes)
• Makes use of 1 enzyme
o RNA polymerase
Steps of Transcription
• RNA polymerase binds to promoter region of DNA
• RNA polymerase adds new complementary bases
and joins the new bases together
• RNA polymerase reaches a termination box and
ceases activity
Gene Expression
• Introns vs. Exons
• Translate genes into proteins
• Codon – set of three nucleotides that code for an
amino acid
• 63 codons code for 20 amino acids and specific
START and STOP codons
Translation
• RNA  protein
• Forms a protein/polypeptide chain
Steps of Translation
• tRNA and rRNA join together and the ribosome
moves to the mRNA coming from the nucleus; the
tRNA carries the anticodon for the START codon
and does NOT begin until START is found on the
mRNA
• tRNA continues to bring the appropriate amino
acid with the anticodon to the mRNA
• Chain continues to grow outside of ribosome
Steps of Translation
• When the STOP codon is reached, the chain falls off
• tRNA leaves the ribosome and the ribosome moves
way from the mRNA