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DNA & RNA – Day 1
DNA
= Deoxyribonucleic acid
- Helix shaped
- Made up of nucleotides
- Each nucleotide made up of 3 basic components:
1) 5-Carbon sugar called Deoxyribose
2) Phosphate group
3) Nitrogenous base (4 different ones)
- 4 Nitrogenous Bases
1) Adenine (A)
2) Guanine (G)
3) Cytosine (C)
4) Thymine (T)
- Chargaff’s Rules:
- Pairing of Bases:
- A and T always go together
- G and C always go together
History of DNA
1) Rosalind Franklin (1950’s)
- 1st to find helix structure DNA
- Used X-ray evidence
2) Francis Crick & James Watson (1953)
- Discovered Franklin’s picture
- Came up with double helix model
Double Helix
= Looks like a twisted ladder or a spiral staircase
- hydrogen bonds were between the nitrogenous bases
(ATCG)
DNA in Cells
1) Prokaryotic Cells
- Single, circular DNA
- DNA found in cytoplasm (no nucleus)
2) Eukaryotic Cells
- Lots more DNA
- DNA located in nucleus
- DNA found in Chromosomes
Chromosomes
= DNA that is supercoiled
- Humans have 23 pairs
DNA & RNA – Day 2
DNA Replication
= DNA makes a copy of itself.
- Occurs in the cell’s nucleus
- Complementary= each strand can be used to make a copy
-
How does replication occur?
1) Helix unzipped by enzyme Helicase
2) Replications from 5” to 3” end
3) Nucleotides pair up
4) Combine to pair with Hydrogen bond
2 types of strands from unzipped DNA
1) Leading strand- DNA polymerase
2) Lagging strand- form Okazaki fragments; RNA polymerase
Genes
= working subunits of DNA within chromosomes
- Only copy what is needed to make protein
- Encodes for specific enzymes or proteins
RNA
= ribonucleic acid
- Single stranded
- Made up of: 5- carbon sugar ( Ribose ), phosphate, and
nitrogenous base
- Contains Uracil ( U) instead of Thymine ( T)
- A=U and G=C
Similarities & Differences between DNA & RNA
3 types of RNA
1) Messenger RNA: AKA mRNA; carries copies of DNA out to
rough ER.
2) Ribosomal RNA: AKA rRNA; proteins assembled on ribosomes
3) Transfer RNA: AKA tRNA; transfers amino acids to the
ribosome
DNA & RNA – Day 3
Transcription
= process of creating a complementary RNA copy of a
sequence of DNA
- Requires the enzyme RNA polymerase
- Copies sections of DNA
Translation
= process of decoding of instructions for making proteins
- Sequence of nucleotides serve as instructions for the amino
acids
- Read 3 letters at a time
Translation process
1) mRNA is transcribed from DNA in the nucleus
2) the amino acid is brought in by tRNA
3) peptide bond is formed
4) continues to grow until reaches a stop codon
DNA & RNA – Day 4
Mutations
= mistakes in the DNA copying
Types of Gene Mutations
1) Point mutations = causes replacement of a single base
nucleotide with another nucleotide
Example: Sickle Cell Anemia
2) Frameshift mutation= caused by a deletion or insertion
Example: Tay-Sachs Disorder
Chromosomal mutation
= changes in the number of chromosomes
Examples: Wolf-Hirschorn Syndrome/ Carcot-Marie-Tooth
disease
Types of chromosomal mutations
1) Inversion= insertion of a chromosome in reverse
2) Translocation= attachment of chromosome fragments
3) Deletion= lose of a portion of chromosome
4) Duplication= portion of the chromosome is duplicated (extra
genetic material)
REVIEW: DNA & RNA
DNA
RNA
Sugar: Deoxyribose
Sugar: Ribose
Bases: A to T, C to G
Bases: A to U, C to G
Double Stranded
Single Stranded
Located in Nucleus
Copies DNA in nucleus
(mRNA) & leaves to make
amino acids in cytoplasm
REVIEW: DNA/RAN Processes
Process
DNA Replication
Transcription
Translation
Location
Inside nucleus
What Happens
Makes
complimentary
strand of DNA (DNA
copies itself)
Nucleus & Cytoplasm mRNA copies DNA in
nucleus, then brings
info into cytoplasm
Cytoplasm
mRNA is read in
codons (3 base pairs
at a time), amino
acids are put in a
sequence to form a
protein