Theme 2A Flashcards
Overview of Central Dogma of Molecular Biology
Central Dogma
universal information flow from DNA to protein in order to convert genotype to phenotype
Where does translation and transcription occur in prokaryotes?
cytoplasm and can occur simultaneously
Where does translation and transcription occur in eukaryotes?
transcription and processing of precursor mRNA molecules occurs in nucleus and translation occurs in the cytoplasm
do not happen simultaneously
1896 Garrod studied a hereditary disease called alkaptonuria. Patients inherit a ____________ resulting in abnormal cellular metabolism
mutated gene coding for a defective enzyme
1940s Beadle and Tatum hypothesized that genes encode enzymes that function at each __________ needed to make an essential nutrient
step of a biochemical pathway
Review diagram on slide 3
Mutating a gene encoding an enzyme would cause a _______ in the metabolic pathway and the organism can no longer synthesize the needed nutrient (__________)
block; auxotroph
Isolation of arginine auxotrophic mutants essential to life
- Involved isolating mutants that failed to grow in the absence of arginine
- each mutant has defective gene for enzyme needed to synthesize an intermediate product to produce arginine
Understand diagram of Precursor - Arginine pathway on slide 4
Genes encode for which two types of RNA?
coding (mRNA) & non-coding (tRNA, rRNA, snRNA, microRNA)
coding rna
codes for protein/polypeptide through translation
Information for the genetic code is contained in _______________ in DNA or RNA sequences
4 nucleotide bases
non-coding rna
does not code for protein
DNA has a three-letter code called a
triplet
RNA has a three letter code called a
codon - refers to mRNA
Genetic code is _______-
universal
Universal genetic code cal allow foreign genes to be __________ and ______________ in different host organisms
transferred; expressed
For every gene, a RNA molecule is transcribed from ___________.
the template strand
The other DNA strand is called the ________ and has the same orientation and sequence as mRNA molecules except _______ is substituted with _____-.
non-template/coding strand; uracil; thymine
mRNA is synthesized in the _____ direction by __________-
5’-3’; RNA polymerase
Do u know how to identify which is template strand?
slide 8
On chromosomal maps, genes are shown on the ________ strand
coding
Reverse transcription
RNA –> DNA
- reverse transcriptase is found in viruses with RNA genomes
- doesn’t have proofreading so it generates lots of mutations
- viral RNA needs to be converted into viral DNA in order to integrate into host’s chromosome
- host’s transcription and translation machinery is hijacked to produce viral proteins from viral DNA
3 important enzymes in the life cycle of HIV
reverse transcriptase, integrase, protease
Life Cycle of SARS-CoV-2
- doesn’t have lysogeny
- genome = + sense ssRNA (same sequence as mRNA)
- 28 viral proteins
- RNA-dependant - RNA polymerase synthesizes - sense ssRNA for viral transcription and replication
(reads a template RNA strand, converts + strand to - strand) - ACE2 receptors are abundantly expressed in alveolar lung cells, heart cells, and intestinal cells
What came first - DNA or RNA?
likely RNA because besides being able to store genetic info (code for aa like DNA), it also catalyzes reactions (not very stable)
- so if there is mutation in RNA, it can’t be fixed cuz its single stranded
DNA developed later with more advantages, ie. more stable, double stranded that allows complementary strand to be used as template for repair of damaged strand
Ribozymes (ribonucleic acid enzymes)
can catalyze their own synthesis and cleave RNA molecules (2 deg. structure)
