Lecture 8c: Molecular Biology- Gene Expression Flashcards
Gene expression
the flows of genetic information from the genotype to the phenotype
DNA—>RNA—>Protein
transcription
is the process by which the information encoded in DNA is made into a complementary RNA.
the Central Dogma is
DNA –(Transcription)-> RNA–(Translation)-> Protein
Gene
an organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a function of a functional product
what is a gene composed of?
the promoter, the regulatory sequence, the transcribed region and the terminator
promoter
the site in the DNA where RNA polymerase binds to begin transcription
regulatory sequences
the sites binding to regulatory proteins control whether a gene is turned on or off
Transcribed region
a region of a DNA that is transcribed into an RNA molecule
terminator
a sequence that causes the RNA strand to be released from the transcription complex
Transcription molecular processes
transcription initiation
transcription elongation
transcription termination
exon
a coding portion of the gene
intron
a non-coding portion of a gene that is excised from the RNA transcript
RNA splicing
the removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence
Capping
a 7-methylguanosine attached to the mature eukaryotic mRNAs at the 5’ end
tailing
a poly A tail is added to the most mature eukaryotic mRNAs at the 3’ end
the genetic code (simple def)
Genetic code refers to the instructions contained in a gene that tell a cell how to make a specific protein.
mutation
a mutation is the permanent alteration of the nucleotide sequence of the genome of an organism (2 common forms)
common gene mutations occur in which 2 ways
- a base substitution
- an insertion or deletion
Common forms of mutations
- Base-pair substitution
- Missense mutation
- Silent mutation
- Nonsense mutation
- Frameshift mutation
Base-pair Substitution:
Also called point mutation- the replacement of one nucleotide and its partner in the complementary DNA strand with another pair of nucleotides
Missense mutation
A point mutation in which single nucleotide change results in a codon that codes for a different amino acid
Silent Mutation
A mutation where a change in a DNA codon does not result in a change in amino acid specified by the gene
Nonsense mutation
a mutation in which a sense codon that corresponds to one of the 20 amino acids specified by the genetic code is changed to a chain-terminating codon
Frameshift mutation
a mutation caused by insertions or deletions of a number of nucleotides in a DNA sequence that is not divisible by 3
The translation process requires
-Amino acids (20AA)
- ATP and GTP
- Enzymes and proteins
- RNAs (mRNA, tRNA, rRNA)
- Ribosomes (small and large subunits)
Anticodon
the 3-nucleotide segment that base-pairs with a codon in mRNA
