DNA Flashcards
What are the three main components of a neucleotide
deoxyribose sugar
phosphate group
nitrogenous base
What are the four different nitrogenous bases
Adenine (A)
Guanine (G)
Thymine (T)
Cytosine (C)
Explain Chargoff’s rule
in a single given sample of DNA…
- proportion of A will be same as T
- proportion of G will be same as C
what does it mean to be antiparallel
one strand will be directed from 3’ to 5’
the other will be from 5’ to 3’
opposites
how are the 3’ and 5’ ends different
3’ end had a free OH group on the 3rd carbon on the sugar
5’ end has a phosphate group attached to the 5th carbon on the sugar
is DNA conservative, semi-conservative or dispersive
semi-conservative
what does gyrase do
relieves any tension from the unwinding strands
what does DNA helicase do
unwinds the double helix (breaks the H-bonds between base pairs)
what does SSBP do
binds to the exposed strands and stop them from reattaching (annealing)
what does RNA primase do
lays down primers on each parent strand to make starting point
what does DNA polymerase III do
adds complimentary nuceleotides to the new, growing strands
what does DNA polymerase I do
removes the primers that RNA primase put down and replaces them with the correct nucleotides
which three enzymes aid in DNA strand separation
Gyrase
DNA helicase
SSBP
what is the purpose of DNA and RNA
direct the growth and development of every living thing by means of a chemical code
what is DNA and RNA made up of
nucleotides
what is mispairing
new nucleotides mispair with another on template strands
ex. T goes with G instead of A
what is strand slippage
additions or emissions of nucleotides
if a neucloetide slips out on the template strand, the newly synthesized strand will be made missing one of the neuclotides- completely altering the genetic code
if a neucleotide slips out on the synthesized strand, a new one will be added to ensure the balance is regained- but when it goes on to become a template strand, the syntehsized strand from that will have an extra nucleotide also altering the code
how are errors in DNA replication corrected
DNA polymerase II proofreads the new DNA, identifying any errors.
if one is found, replication stalls
DNA polymerase I corrects the error
DNA replication continues
how often does the correction of errors in DNA replication work
99% of the time
where does transcription occur
in the nucleus
where does translation occur
in cytoplasm on ribosomes
what are the three types of RNA
mRNA- messenger RNA
tRNA- transfer RNA
rRNA- ribosomal RNA
what is mRNA
messenger RNA
forms a code (sequence of bases)
what is tRNA
transfer RNA
uses mRNA to link amino acids
what is rRNA
ribosomal RNA
structural component of ribosomes
what are codons
sequence of 3 bases in mRNA
codes for a specific amino acid
some are “start” and “stop” codons
what does RNA polymerase do
reads the coding strand and arranges mRNA accordingly
what does the promotor region do
moderates the speed of transcription
high in A-T and T-A
what is transcription (vague)
DNA to mRNA
describe the initiation phase of transcription
RNA polymerase binds to DNA next to one of its start codons in the promotor region
opens up the helix- exposing the template strand
describe the elongation phase of transcription
RNA polymerase starts adding nucleotides together using the template strand to match the correct base
this occurs in the 5’ to 3’ direction
explain the termination phase of transcription
RNA polymerase reaches the end of the gene (a terminator sequence) transcription stops mRNA separates from the DNA DNA double helix reforms mRNA is modified
how it mRNA modified during the termination phase of transcription
- a 5’ cap added to start
- poly-A tail added to end
- introns cut out (splicing)
what is an intron
non-coding region of DNA
what is an exon
a coding region of the DNA
what is a mutation
a permanent change in the nucleotide sequence of a cells DNA
what is a single gene mutation
a mutation that involves changes in the nucleotide sequence of one gene
what is a point mutation
a mutation involving a single base pair substitution, insertion or deletion
what is a frameshift mutation
a mutation caused by the deletion or addition of a number of nucleotides not divisible by 3, resulting in a change of the reading frame
what is a silent mutation
a mutation that doesn’t change the amino acid sequence of a protein
what is a missense mutation
a mutation that changes the amino acid sequence of a protein
what is a chromosome mutation
a mutation that involves changes in chromosomes and may involve many genes
example of the chromosomal mutation: deletion
abCDEFgh TO abgh
example of the chromosomal mutation: inversion
abCDEfgh TO abEDCfgh
example of the chromosomal mutation: duplication
aBCDefgh TO aBCDBCDefgh
example of the chromosomal mutation: translocation
abcdefgh TO abcdMNOP
IJKLMNOP TO IJKLefgh
is tRNA or mRNA linear
tRNA is not linear
mRNA is linear
explain the structure of tRNA
single strand of mRNA that has folded back on itself
contains an anticodon on one end and an amino acid on the other
translation represents going from what
mRNA and tRNA to proteins
transcription represents going from what to what
DNA to mRNA
explain the initiation phase of translation
- ribosomal sub-unit attaches to the mRNA near the start codon (AUG)
- the first tRNA carrying mathionie is the initiator tRNA with a VAC anticodon
- tRNA enteres the psite (bringing the appropriate amino acid)
- a second tRNA enters the asite bringing another amino acid
- peptide bonds form between the two amino acids
- ribosome shifts over and original tRNA moves to esite
explain the elongation phase of translation
- third tRNA enters asite and peptide bonds form between amino acids again
- after the esite the tRNA will go out to the cytoplasm again
- this continues until the ribosome reaches a stop codon
put nucleotide, gene, codon, chromosome, nucleotide base, DNA, nucleus
nucleotide base, nucleotide, codon, gene, DNA. chromosome, nucleus
what is negative gene regulation?
the signaling molecules do not interact directly with the genes
what is positive gene regulation?
a signaling molecule generates a complex that interactes directly with the DNA (common in eukaryotes)
what do histones do?
they wrap up in DNA, preventing certain genes from being expressed
polymerase cannot reach it- doesn’t become mRNA
what was Friedrich Miescher contributions
“Discovered” the nucleic acid by isolating the nucleus of white blood cells taken from the pus bandages from a hospital.
what were Phoebus Levene ‘s contributions
discovered the difference between what is now DNA and RNA
also correctly stated what nucleotides are made up of
He suggested the idea that nucleic acids are long chains of nucleotides- which was later proved to be correct.
what were Oswald Avery, Colin MacLeod, Maclyn McCarty ‘s contributions?
They confirmed that DNA was in fact a hereditary material.
name three individuals and their contributions to genetics
depends on which i choose
answers may vary
what were Linus Pauling’s contributions
Developed 3D models of miniscule biological materials based on known distances and bond angles. He also discovered that many proteins have a helix shape.
what were Rosalind Franklin’s contributions
Used x-ray diffraction to analyze the structure of biological molecules. Franklin concluded that DNA has a defined helix structure. She also learned lots about the general structure of DNA altogether. The nitrogenous bases are located inside the helix, the sugar-phosphate backbone was on the outside.
what were Francis Crick, James Watson ‘s contributions
Using information taken from other scientists, they assembled a model of DNA which is now recognized as the molecular structure of DNA
