Studied by 0 peoplewho discovered that harmless bacteria can turn into bacteria that can cause disease?
fredrick griffith
how did fredrick griffith discovered it?
by a factor in heat that killed disease causing bacteria
when did fredrick griffith discover his discovery?
1928
what did Oswald Avery determine?
determined that genes are made of DNA
when did Oswald Avery discover this?
1944
who verified Avery's results?
Hersey and Chase
how did hersey and chase verify this?
by using bacteriophages
when did hersey and chase discover this?
1952
what did Watson and Crick discover?
Developed the double helix model of DNA.
when did Watson and Crick discover this?
1953
genes are made of?
DNA
what 3 things must DNA do?
must transfer information from one generation to the next, must determine inheritable traits, dna must be easily copied
dna is made up of?
nucleotides
each nucleotide has how many parts?
3
what are the 3 parts in nucleotide?
5 carbon sugar, phosphate group, nitrogenous base
what is the 5 carbon sugar called?
deoxyribose
What forms the backbone of the DNA molecule?
sugar and phosphate group
what hangs off the side of the sugar molecule?
nitrogen base
what are the 2 groups of nitrogen base?
purine group and pyrimidine group
what does a purine group contain?
the bases of adenine (A) and guanine (G)
what are the 2 ringed structures?
A and G
what does a pyrimidine group contain?
the bases of thymine (T) and cytosine (C) and uracil (U)
what are 1 ringed structures?
T, C and U
when does nitrogen bases occur?
occurs in any order
what does the order of the nitrogen bases determined?
the specific amino acid sequence
a purine base will always pair with what base?
pyrimidine base to form complementary base pairs
what are the pairs in base pairing?
A always pairs with T and G always pairs with C
the number of A =
the number of T
how does A and T connect?
with a double bond
the number of G =
the number of C
how does C and G connect?
with a triple bond
what is the structure of a DNA
double helix
what are the 2 strands of DNA connected by?
hydrogen bonds between the nitrogen bases
DNA must make an exact copy of...
itself
semi-conservative replication
old strand of DNA is paired with a new strand
DNA template
each strand unwinds and is used as the template
pairing old with new DNA guarantees what?
an exact copy is made because of the base pairing rule
what is the end result of DNA replication?
2 copies of DNA, each made with one old strand and one new strand. total of 4 individual strands.
RNA
"decoded" DNA that make proteins
what are the 3 types of RNA?
messenger RNA, ribosomal RNA, and transfer RNA
messenger RNA (mRNA)
carries the copies of DNA to the rest of the cell
ribosomal RNA (rRNA)
makes up most the ribosome where proteins are made
transfer DNA (tRNA)
transfers amino acids to ribosomes during translation
What are the differences between DNA and RNA?
DNA: double stranded, has deoxyribose sugar, bases: adenine, guanine, cytosine, thymine
RNA: single stranded, has ribose sugar, bases: adenine, guanine, cytosine, uracil
why are dna sugars called deoxyribose
their 2' carbon does not have a hydroxyl group (-OH)
the "top" of the sugar is called what? what is it connected to?
5' end and is connected to the phosphate group
the "bottom" of the sugar is called what? what is it connected to?
3' end and is connected to the hydroxyl group
DNA nucleotides have which nitrogen bases?
A, G, T, and C
RNA nucleotides have which nitrogen bases?
A, G, U, and C
anti-parallel
The opposite arrangement of the sugar-phosphate backbones in a DNA double helix. For example, 3' end and 5' end is reversed to 3' and 5' end.
Why are the 3' and 5' ends important?
when the cells wants to add nucleotides to an existing strand, nucleotides can only be added to an existing strand of DNA on the strand's 3' end
helicase
job is to break the hydrogen bonds between nitrogen bases
gyrase
job is to reduce tension in unwinding DNA
primase
job is to create small RNA primers for DNA Polymerase to bond to
what's the purpose for DNA replication
so the cell can divide and give each daughter cell a correct DNA sequence
origins of replication
Sites where the replication of a DNA molecule begins.
replication fork
A Y-shaped region on a replicating DNA molecule where new strands are growing.
RNA nucleotides are what?
primers for DNA polymerase
primases move along what strand?
the existing strand's 3' to 5' direction.
DNA Polymerase I
removes RNA primers + inserts the correct DNA nucleotide; near completion of DNA replication
DNA Polymerase II
proof reading the new strand at end of DNA replication
DNA Polymerase III
attaches DNA nucleotides to make the new DNA strand
what must DNA Polymerase need/has to do?
must have RNA primers to start and travel from the 5' to 3' on the new strand
leading strand
a strand that is producing in a continuous manner
lagging strand
a strand that is built discontinuously
okazaki fragments
small segments of DNA found on the lagging strand
single stranded binding proteins (SSBP)
provide stability to keep the helix open
DNA Polymerase III will move where in the lagging strand?
move towards the origin of replication
DNA Polymerase III will move where in the leading strand?
moves away from the origin of replication
ligase
an enzyme that closes the gaps and connects the okazaki fragments into one continuous strand of DNA.
when does ligase happen?
after DNA Polymerase I
what are the DNA polymerase in chronological order?
III, I, II
are hydrogen bonds considered to be weak bonds or strong bonds?
weak
why is it useful for the base pairs of DNA to be held together by hydrogen bonds instead of covalent bonds?
hydrogen bonds are easier to break allowing for DNA copying
DNA is short for?
deoxyribonucleic acid
RNA is short for?
ribonucleic acid
when DNA polymerase III is added what happens to the primases?
moves away from helicases
Is RNA shorter than DNA? Which one is 1 gene long?
RNA is short, only 1 gene long. DNA is very long and contains many genes.
the information in DNA is in the form of what?
specific sequences of nucleotides along the DNA strands
the dna inherited by an organism leads to specific traits by
directing the synthesis of proteins
transciption and translation
the two stages that process by which DNA directs protein synthesis
central dogma
DNA -> RNA -> Protein
cells are governed by what?
a cellular chain of command
transcription
the synthesis of RNA under the direction of DNA
transcription produces what?
produces messenger RNA (mRNA)
transcription occurs where?
in the nucleus
translation
the actual synthesis of a polypeptide, which occurs under the direction of mRNA
where does translation occur?
occurs on ribosomes
RNA synthesis is based on information stored in?
DNA
transcription is started by?
RNA polymerase II
what does the RNA polymerase II do?
pries the DNA strands apart and hooks together the RNA nucleotides
mRNA goes from ____ to ____
pre-mRNA to mature-mRNA
RNA processing occurs when?
prior to leaving the nucleus before mRNA leaves through a nuclear pore.
how is the RNA copy of a gene converted into mature mRNA?
the cell adds a protective cap to one end, and a tail of A's to the other end. pre-mRNA is made of regions called introns and exons
introns
nonsense regions which need to be removed
exons
coding regions which need to stay put
splicing
the process of removing introns to produce mature messenger RNA (mRNA)
genetic information is encoded as a sequence of what?
nonoverlapping base triplets or codons
codons
3 bases on mRNA code for the production of a specific amino acid
3 nucleotides on mRNA =
1 codon = 1 amino acid
Note
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