DNA Replication
the process of making identical copies of DNA before cell division
Origin of Replication
Specific sequence of DNA where DNA synthesis begins.
replication fork
A Y-shaped region on a replicating DNA molecule where new strands are growing. (The replication fork is half of the replication bubble.)
Semiconservative replication
Each half of an original DNA molecule serves as a templete for a new strand, and the two new DNA molecules each have one old and one new strand.
helicase
An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.
DNA Polymerase
Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule.
RNA Primer
Sequence of RNA nucleotides bound to a region of single-stranded DNA to initiate DNA replication.
leading strand
the strand of DNA that is continuously synthesized during replication
lagging strand
The strand that is synthesized in fragments using individual sections called Okazaki fragments
Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
DNA ligase
enzyme which connects the individual okazaki fragments on the lagging strand by forming covalent bonds
direction of replication
[5' to 3' direction]; enzyme can only add on the 3 prime end, leading to okazaki fragments
double helix
The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
RNA primase
An enzyme that creates a short RNA primer for initiation of DNA replication.
adenine
A nitrogen base found in DNA and RNA. It pairs with thymine in DNA and with uracil in RNA
guanine
A nitrogen base found in both DNA and RNA; pairs only with cytosine.
thymine
A nucleotide that pairs with adenine. Found only in DNA.
cytosine
A nitrogenous base found in DNA and RNA; pairs with guanine
hydrogen bond
A weak chemical bond formed when the slightly positive hydrogen atom of a polar molecule is attracted to the slightly negative atom of another polar molecule. It holds the DNA molecules together.
complimentary
Refers to the base-pairing rules where A matches T and C matches G. (Apple in the tree. Car in the garage.)
base pairs
Any of the pairs formed between complimentary bases in the two nucleotide chains of DNA, such as A-T and C-G (DNA); A-U and C-G (RNA).
mutation
A change in the order of the bases in an organism's DNA; by deletion, insertion, or substitution.
trait
A characteristic that an organism can pass on to its offspring through its genes.
Griffith Experiment
- injected mice with harmful bacteria and they died.
- injected mice with harmless bacteria and they lived.
Heat-killed harmful bacteria mixed live harmless bacteria killed the mice in a process called transformation.
Rosalind Franklin
British scientist who took excellent x-Ray diffraction pictures that provided evidence of double helix.
Maurice Wilkins
Used X-ray crystallography to study the molecular structure of DNA. Worked with Franklin (did not collaborate well) to create a picture of the DNA molecule which allowed Watson and Crick to deduce the double helix structure of two strands.
Watson & Crick
-Used Chargraff's Rules and Rosalind Franklins X-Ray diffraction to proposed DNA as a right handed double helix in which the two strands are antiparellel & the bases are stacked on one another
antiparallel
Format of two strands in DNA (one 3' to 5', other 5' to 3')
RNAase/ RNA nuclease
catalyzes RNA hydrolysis (destroys RNA)
tRNA
Anticodons are found in this molecule
rRNA
makes up ribosomes
ribosome
brings codons of mRNA in association with tRNA to assemble proteins
When the ribosome comes to a stop codon
Protein synthesis stops. The protein is released.
Start codon
AUG
What amino acid is coded for by the start codon?
Methionine
intron
A noncoding, intervening sequence within a eukaryotic gene.
exon
sequence of mRNA that is spliced together to form the final mRNA sequence
Uracil
in RNA, binds to Adenine
What protects mRNA from destruction by RNA nuclease?
poly A tail and G cap
Where does replication take place?
In the nucleus
Where does translation take place?
In the cytoplasm
When a mutation changes the codon to a stop codon and prematurely halts translation
Nonsense mutation
A mutation that inserts or deletes a base pair in a sequence of DNA
Frame shift mutation
A mutation in the 3rd nucleotide of a codon is often a
Silent mutation
The process that removes unused sequences of mRNA from a strand of mRNA and adds sequences to the ends to protect it is called
Post-transcriptional processing
What determines which side of the strand of DNA is used in transcription?
RNA polymerase runs in a 5' to 3' direction, so it attaches to that side of DNA for transcription.
The binding sequence for RNA polymerase in transcription
a promoter
____________must be present for RNA polymerase to bind to a promoter region in transcription.
transcription factors