DNA, RNA, Protein Flashcards
DNA location
nucleus - main
Mitochondria - some
Heritable material
DNA
Code of trait
Gene
Houses Genes
DNA
Rosalind Franklin
Used X-rays to image DNA with a coil pattern (Watson/Crick used her work to discover double helix structure)
DNA Structure
Sugar, Phosphate, nitrogenous base
(four bases: adenine, guanine, thymine, and cytosine)
In a double helix
DNA replication
Each existing strand becomes a template strand for replication as DNA unwinds
New strand is made as a complement of template strand
Semiconservative replication
two daughter strands produced
4 requirements for DNA to be genetic material
1) Must carry genetic information
2) Must replicate
3) Must allow for information to change
4) Must govern the expression of the phenotype
DNA polymerase III
Produces new strand of complimentary DNA
DNA polymerase I
Fills in gaps between newly synthesized Okazaki fragments
DNA helicase
unwinds double helix
Single-stranded binding proteins
keeps helix open for replication
Primase
Creates RNA primers to initiate synthesis
Ligase
Welds Okazaki fragments together
Redundancy
Basis for repair of errors that occur during replication
Enzymes repair chemical damage to DNA
Errors during replication are rare (but can occur)
RNA structure
“Ribose nucleic acid”
Ribose sugar and uracil (different from DNA)
Single stranded
Doesn’t last as long as DNA
Central Dogma
DNA -> RNA -> Protein
(DNA->RNA = transcription)
(RNA->Protein = translation)
Three different RNA molecules
Messenger (mRNA)
Ribosomal (rRNA)
Transfer (tRNA)
Transcription
Occurs in nucleus
mRNA carries info for what protein to make from the DNA in nucleus to ribosome
DNA unwinds for RNA to be synthesized
Creates one strand of complementary mRNA from the DNA molecule
RNA polyermase
attaches to promotor sequence in DNA and unzips the strand (for one mRNA to be formed)
Introns
noncoding sequences that are removed from the mRNA
Exons
Coding sequences that are left after the introns are removed to create the mRNA strand
Modifications of RNA
1) 7-methyl guanosine cap (G-cap)
2) Polyadenalation (Poly-A tail)
3) Intron Splicing
7-methyl guanosine cap
At the 5 prime end of RNA
Roles:
-Stability of mRNA
-Helps with attachment to ribosome
-Prevents degradation of mRNA
Polyadenylation
“Poly-A tail”
Addition of adenosine to the 3 prime end of mRNA
Role:
-Stability of mRNA
-Helps with attachment to ribosome
Intron Splicing
Removal of introns from mRNA
Role:
-Helps with nuclear export
-Helps mRNA to form different proteins by its removal
-Stability of mRNA
Genetic Code
3 nucleotide bases form a codon which codes for an amino acid
Start codon- AUG (Met)
Stop codons - UAA, UGA, UAG
20 amino acids
Are the building blocks that make up proteins
Translation
synthesizing a protein from animo acids by reading nucleotide sequence on mRNA
Occurs in ribosome
Ribosomal RNA (rRNA)
needed for protein synthesis
helps mRNA bind to small subunit
Transfer RNA (tRNA)
Brings specific codon to ribosome to code for a specific amino acid
recognizes the correct codon on mRNA molecule
Ribosome
Site of protein synthesis
Consist of a large and small subunit
(mRNA binds to small subunit)
Mutations
Changes in the DNA sequence that may be passed along to future generations
Point mutations
A single base unit substitution
EX: ATTCG (normal)
AATCG (mutation)
Deletion
a small DNA segment is lost
Insertion
a segment of DNA is added
Frame-shift mutation
Modification of the reading frame after a deletion or insertion, resulting in all codons downstream to be different
