Transcription vs Translation
The process by which DNA is copied to RNA
vs
RNA is used to produce proteins
What are the differences between RNA and DNA?
RNA has uracil, DNA has thymine
RNA has a ribose (sugar), DNA has deoxyribose
DNA is a double helix, RNA is a single helix
What are the main enzymes involved in DNA replication & transcription?
DNA polymerase (DNA replication)
RNA polymerase (transcription)
What are genes made of?
DNA
How is cell differentiation related to genes?
cell differentiation is how unspecialized cells become specialized
gene expression is the combination of genes turned on or off
gene expression dictates how a cell functions
What is the central dogma of molecular biology?
DNA → RNA → Proteins
Which nitrogenous base is present in RNA and not in DNA?
Uracil
The three types of RNA
mRNA - carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell
tRNA - carries each amino acid to a ribosome during protein synthesis
rRna - combines with proteins to form ribosomes
How many nucleotides make up a codon?
3
The products and the locations of transcription
RNA
nucleus
The products and the locations of translation
protein
ribosomes
What are the two ways mRNA is edited before leaving the nucleus?
5’ cap & poly-A tail: 5’ cap is added to the beginning of RNA transcript and a 3’ poly-A tail is added to the end
Splicing: intron section of the RNA transcript are removed to join the exons back together
What is the purpose of the 5’ cap and poly-A tail?
5’ cap is added to protect RNA from degradation
adenine nucleotides (where poly-A tail comes from) is added to the 3’ end to stabilize the molecule and allow it to leave the nucleus
Introns vs Exons
Introns are noncoding sections of RNA transcript
Exons code for proteins
What is the monomer for a protein?
amino acid
The importance of proteins
Help determine all our physical traits
Speed up the rate of reactions
Reduce the amount of energy needed for reactions in cell
The start codons
AUG ( codes for Methionine)
The steps of transcription
DNA is split apart
RNA polymerase binds to the template side with a promoter sequence
mRNA is transcribed from DNA template
pre-mRNA steps are take (5’cap, poly-A tail, splicing)
mRNA leaves the nucleus
The steps of translation
mRNA moves into the ribosome, the first tRNA meets the mRNA at the start codon
Amino acids are brought to the mRNA by the tRNA based off the mRNA codon
After the stop codon is read the final protein (polypeptide) is released in the cell
What is a mutation?
Any change in the sequence of nucleotides of DNA or RNA
What causes mutation?
errors in DNA replications
exposure to mutagens or viral infections
What a mutagen is
any chemical or physical agent that can change a sequence in DNA or RNA
usually are harmful but sometimes can be beneficial
Protein structure order
Primary - order of amino acids
Secondary - sheets or helices formed by hydrogen bonding
Tertiary - 3D structure of one polypeptide
Quaternary - multiple tertiary structures linked together
The different type of mutations
Frameshift
Point
Missense
Nonsense
Silent
Deletion
removal of one or more bases to the sequence
Insertion
insertion of one or more bases to the sequence
Frameshift mutation
a mutation that completely shifts the reading frame for the rest of the sequence
Point mutation
the changing/substitution of one single nucleotide
Silent Mutation
No change to the resulting amino acid
Nonsense Mutation
Change to one amino acid
Missense Mutation
A premature stop codon is created, making a shortened protein
Substitution
type of mutation in which one nucleotide is replaced by a different nucleotide
Enzymes
increases the rate of reactions
proteins that help speed up metabolism or chemical reactions in the body
How enzymes work?
they bind to reactant molecules and hold them in a way that the chemical-bond breaking and bond forming process takes place more easily
Their structure allows only certain reactants to bind to them
Epigenetics
the study of how your behaviors and environment can cause changes that affect the way your genes work
CRISPR
Clustered Regularly Interspaced Short Palindromic Repeats
Repetitive DNA sequences called CRISP
bacterial defense system that forms the basis for CRISPR-Cas9 genome editing technology
Gel electrophoresis
method used to separate mixtures of DNA, RNA, or proteins
How mutations affect organisms (how mutations affect proteins)?
prevent one or more proteins from working properly
What the wobble hypothesis states?
some tRNAs can pair with more than one mRNA codon
Importance of the wobble hypothesis?
states that normal base pairing can occur between nitrogen bases in positions 1 and 2 of the codon and the corresponding bases 3 and 2 in the anticodon
Translation
mRNA is read
a protein is made from the genetic info read from the mRNA
occurs in the ribosome
Transcription
copies strand of DNA to produce a strand of mRNA
product of RNA
occurs in the nucleus
requires RNA polymerese
Stop codons
UGA, UAA, UAG
reading frame
the order in which you read the codons on a DNA or RNA sequence