Studied by 8 peoplepyrimidines
single ringed structure
U, C, T
Purines
double-ringed structure
G, T
What has circular chromosomes
Prokaryotes
What has multiple linear chromosomes
Eukaryotes
DNA and in some cases RNA is the primary source of…
Heritable information
Semiconservative DNA replication
each strand of DNA serves as a template strand for the synthesis of the complementary strand
Direction of nucleotides added in replication
Nucleotides are added from the 5’ - 3’ direction
leading strand
strand that is continuously synthesized
lagging strand
strand that is synthesized in fragments
helicase
unwinds DNA
Topoisomerase
relaxes the supercoil at the replication fork
replication fork
where the two strands of DNA are seperated
DNA polymerase
Synthesizes new strands of DNA
Ligase
joins DNA on lagging strand
how to genetic information flow
DNA → RNA → Protein
DNA transcription
DNA unzips and RNA Polymerase synthesizes mRNA in the 5’-3’ direction on the DNA template strand (noncoding strand)
mRNA
carries the genetic information from the DNA to the ribosome
Codon
3 base sequence of nucleotides found on mRNA
anticodon
3 base sequence that attaches to the opposite bases of the codon which results in the addition of an amino acid to the polypeptide chain and the release of the tRNA
rRNA
responsible for protein assembly. anticodon - codon pairing occurs in ribosomes
mRNA transcript in eukaryotes
addition of a poly a tail
additon of GTP cap
introns
sequences of mRNA that don’t code for amino acids
not included in mature mRNA transcript
Exons
sequences of mRNA that do code for amino acids and are connected to each other to make the mature mRNA transcript
alternative splicing
process of splicing (removing introns) and then connecting the remaining exons
exons combinations
different combinations of exons on a transcript encode for different proteins
exons - 1,2,3,4
transcript - 1,2,3 or 1,2,4
Translation
process in which the mRNA is used to generate polypeptides
occurs on ribosomes
translation steps
Initiation - start the process of making a polypeptide
Elongation - polypeptide grows
termination - stop the process and the polypeptide is cut off
Retrovirus
introduce viral RNA into the host cell and goes from RNA to DNA where the DNA is then transcribed and translated
Initiation
rRNA interacts with mRNA at the first start codon (AUG)
Elongation
tRNA brings another amino acid which gets added to the polypeptide chain
Termination
when a tRNA brings an amino acid sequence for a stop codon the polypeptide is released
Gene expression
the process by which instructions in the DNA are transcribed and translated into a functional protein
regulatory sequences
stretches of DNA that can be used to promote or inhibit protein synthesis
transcription factors
proteins that promote or inhibit transcription of a gene
Inducible
is inhibiting until an inducer comes and removes it
EX - lac operon.
inhibits the breakdown of lactose until there is a lot of lactose that attaches to the operon and removes it allowing lactose to be broken down
what initiates transcription
interaction between regulatory proteins, regulatory genes, and transcription factors
negative regulatory molecules
block the RNA poly from attaching to the promoter so transcription cannot occur
mutations
changes of a genome in an organism
can be positive, negative, or neutral
primary source of genetic variation
substitution mutation
switching a nucleotide with another
EX - ACG changes to ACA
deletion mutation
deleting a nucleotide
EX - ACG changes to AC_
insertion mutation
adding a new nucleotide
EX - ACG changes to ACGC
triploidy
having 3 copies a particular chromosome
polyploidy
having multiple sets of homologous chromosomes
electrophoresis
DNA is negatively charged and is loaded into the gel.
smaller fragments move faster and further towards the positive side while bigger fragments move slower and shorter
polymerase chain reaction
Copies a small amount of DNA into a lot of DNA
Note 
Flashcard (96)