Molecular Basics of Genetics Flashcards
Who discovered the structure of DNA?
Watson and Crick
What are the polymers of Nucleotides?
DNA and RNA
What is a nucleotide?
building blocks of an nucleic acid, there are 3 parts: phosphate group, nitrogenous base and a sugar
What are the 3 differences between RNA and DNA
- DNA is a two stranded double helix, RNA only has 1 strand
- Uracil replaces Thymine as one of the bases in RNA
- RNA has 1 more oxygen atom in its sugar (deoxyribose vs ribose)
What is the structure of DNA?
Double helix, antiparallell base strands, nucleotides linked by hydrogen bonding between complimentary base pairs
What helps to supercoil DNA?
DNA gyrase
What is the role of DNA polymerase?
add nucleotides to the 3’ end of a primer so that its actually adding it 5’ to 3’
What are the two strands in DNA replication?
Leading strand and lagging strand
What strand has continuous replication?
Leading strand
What is an Okazaki fragment?
Section of lagging strand that had been replicated
What is helicase?
enzyme that unwinds the double helix by breaking hydrogen bonds in between bases, used to in the process of copying DNA
What is DNA gyrase?
enzyme that is essential in DNA supercoiling
What is DNA primase?
type of RNA polymerase
What is a dideoxyribonucleotide?
type of nucleotide which inhibits DNA polymerase
What are tandem repeats?
occur when a sequence of nucleotides repeats next to each other
What are the regions of DNA that do not code for proteins?
Regulators of gene expression, introns, telomeres, genes for tRNA
What is transcription?
synthesis of mRNA copied from the DNA base sequences
What is translation?
synthesis of polypeptides on ribosomes
How is the amino acid sequence determined?
codons on rna
What is a codon?
sequence of 3 nitrogenous bases
What codes for an amino acid?
A combination of 3 nitrogenous bases
What is an anticodon?
opposite three codons from those on mRNA
What does translation depend on?
complementary base pairing between complementary codons on mRNA and anticodons on tRNA
What are the 3 types of RNA?
Messanger, Transport, Ribosome
Which direction does transcription occur?
5’ to 3’
What helps regulate transcription in eukaryotes?
Nucleosomes, they can control how tightly a gene is wrapped so a section that is “turned off” is tightly wrapped and inaccessible
What is different between Eukaryotes and Prokaryotes mRNA after transcription?
Eukaryotic cells modify mRNA
What does splicing mRNA do?
increases the number of different proteins an organism can produce
What regulates gene expression?
proteins that bind to specific base sequences in DNA
What can impact gene expression?
environment of a cell, or the organism
What is the promoter?
region of DNA that initiates transcription for that gene
What is an example of non-coding DNA?
sequences that do not code for proteins
What does RNA polymerase add from the free end of an RNA nucleotide?
adds the 5’ end to the 3’ end of the mRNA molecule
What is the operon?
a unit made up of linked genes that is thought to regulate other genes responsible for protein synthesis
What is a polymer?
chain of monomers
What is a phosphodiester linkage?
bond between oxygen and phosphorus between the sugars attached to nitrogenous bases
Where does DNA polymerase 3 act?
Leading strand
Where does DNA polymerase 1 act?
Lagging strand
What direction does the leading strand go?
5’ to 3’
What direction does the lagging strand go?
3’ to 5’
What is a histone?
group of proteins found in chromosomes
How does DNA prepare for division?
Chromatin fibres spiral tightly to form chromosomes, this makes it so that after cell division they can unwrap and are accessible again
What are the steps in DNA replication?
- Helicase splits DNA molecule apart
- RNA primase inserts RNA nulcleoties at the incitation point
- DNA polymerase binds complimentary leading strand
- RNA primase attaches more RNA primer in the remaining gaps, creating okazaki fragments
What is RNA primase?
goes over a single DNA strand and creates RNA sequences called primers, which transcribe DNA into RNA
What is the sense strand?
coding strand that runs 5’ to 3’
What is the non-sense strand?
used as a template for mRNA
What is transcription?
making more mRNA
What is the process of transcription?
- promoter region allows DNA polymerase to initiate RNA synthesis
- DNA rewinds after DNA polymerase has passed
What is the role of RNA polymerase?
transcribes RNA
What does RNA polymerase II read?
TATAAAAA
What does RNA polymerase III read?
ATATTTTT
What happens to unedited mRNA after it is created?
- Introns are removed
- Methyl Guanine Cap (5’ cap)
- Poly - A Tail
What is an intron?
sequence of RNA or DNA that is not needed, or doesn’t code for proteins
What is an exon?
sequence of RNA that codes for proteins
What is the lac operon?
inducible expression
What is the tryp operon?
controlled expression
How does the lac operon work?
concentration of lactose fills the allosteric site on the repressor, turning it off so DNA polymerase can continue transcription
How does the tryp operon work?
Repressors are activated at the allosteric site, moves to cover part of the DNA so the section cannot be transcribed
What is the central dogma of biology?
DNA -> RNA -> Protein
What is replication?
DNA making more of itself
What is transcription?
DNA -> RNA
What is translation?
RNA -> Protein
Who was Chargaff?
He discovered that there were ratios between the use of A, T, C, and G
What is tRNA usually carrying?
Methionine
What is a primer?
3 Nucleotides added by RNA primase
What is splicing?
removing introns