DNA Flashcards
How does the Hershey Chase experiment demonstrate that DNA is the building block of Genetic Information and Not proteins
2 part experiment where radioactive proteins coated ( But not radioactive DNA )viruses were allowed to infect bacteria.
These viruses put their DNA inside the bacteria but the new DNA wasn’t radioactive.
2nd part allowed radioactive DNA viruses but not with a radioactive protein coat to infect the bacteria.
The radioactive DNA was passed on to the bacteria.
Purine bases for DNA
Adenine & Guanine
Pyrimide bases for DNA
Thymine & Cytosine
Which nucleotide contains a double ring?
Purine base: Adenine & Guanine
All nucleotides contain:
Phosphate, 5-Carbon Sugar, Nitrogen- Containing base
Chargaffs rules: (2)
The amount of A, T, C, G varies in species to species
In each species the amount of A = T & C =G
What does antiparallel mean in the description of DNA
The sugar-phosphate groups that are chained together make each strand are oriented in opposite directions.
Where is the phosphate located?
5’ posistion of the sugar
What type of bond occurs in the nitrogen bases of DNA
Hydrogen Bonds
The process of DNA replication that results in 2 double helix molecules, each having one parental and one new strand
Semiconservative replication
Three main events in DNA replication:
Unwinding of DNA molecule, complementary base pairing, joining of new DNA strands
Separates double-stranded DNA into single strands
DNA helicase
Binds to single-stranded DNA and prevents it from reforming a double helix
Single-Stranded binding protiens (SSB)
Synthesizes short RNA primers
DNA primase
Synthesizes DNA in the leading and lagging strands, RNA Primers, Filling the gaps with more DNA, and proofread newly made DNA
DNA polymerase
Covalently attaches adjacent Okazaki fragments in the lagging strand
DNA ligase
Where specifically does DNA replication start at
Origin of replication site
List steps and enzymes used to replicate DNA
- DNA helicase unzips the double helix
- Single stranded binding proteins (SSB) attach to separated DNA strands preventing them from reforming.
- DNA primase places short primers on the strand to be Replicated
- DNA polymerase synthesizes new DNA forming complementary base pairs ( proofreading too )
Then
Converts the RNA sequences to DNA
- DNA ligase glues the Okazaki fragments together
Which strand are the Okazaki fragments found on?
The lagging strand
How does chemotherapy drugs stop cancer
They mimic one of the nucleotides used in DNA creation.
When a cancer uses these base pairs, replication stops and the cell dies.
Area of active replication is called:
The replication fork
Enzyme used to make sure areas outside of the replication fork do not super coil
DNA gyrase
Explain why replication must occur differently on the leading strand vs the lagging strand
Replication can only take place on the 5’ - 3’ direction.
Replication of the lagging stand must work backwards in the 5’ - 3’ direction
Compare DNA replication in prokaryotes and eukaryotes
Prokaryotic begins at a single origin places and works in both directions towards the termination region
Eukaryotic DNA replication begins at multiple orgins of replication and continues until the replication forks meet
Transfer of information from genetic material (DNA) to RNA, and then onto a protein
Gene expression
Nucleic acid produced from covalent bonding of nucleotides monomers that contain the sugar ribose; occurs in many forms such as… messenger, ribosomal, and transfer
RNA
What are the base pairs in DNA & RNA
DNA
Adenine & Thymine Cytosine & Guanine
RNA
Adenine & Uracil Cytosine & Guanine
The process of _______ solves the problem of how to convert 4 bases found in the DNA to the 20 amino acids in a two step process
Gene Expressions
The first step in Gene expression is….
What problem does it solve
Transcription
How to get the DNA info found in the nucleus to the ribosomes in the cytoplasm
How does Transcription get the DNA info out of the nucleus?
By making a complementary base pair of RNA using mRNA
Type of RNA formed from a DNA template and bearing coded information for the amino acid sequence of a polypeptide
mRNA
Type of RNA that transfers a particular amino aicd to a ribosome during protein synthesis
Contains an anticodon that binds to an mRNA codon
tRNA
Along with ribosomal protiens makes up the ribosomes
rRNA
Each codon refers to a(n)…..
Amino acid
During ______ genetic information is used to make a polypeptide chain
Translation
Where does translation happen
Cytoplasm at the ribosomes
During ______, the mRNA transcript is read by a ribosome and converted into the sequence of amino acids in a polypeptide
Translation
Processes that dictate the flow of information from the DNA to RNA to a protein in a cell
Central dogma
Allows for conversion of DNA and RNA’s chemical code to a sequence of amino acids in a protein
Genetic Code
What does tRNA do?
Brings amino acids to the ribosomes during protein synthesis
What is meant when it is said that the genetic code is “Degenerate”
That several codons may specify the same amino acid
Transcription begins when _________ attaches to a region of DNA called _________
RNA polymerase
The promoter
3 stages of Transcription
Initiation, elongation, termination
The cap and the tail of pre-mRNA consists of what and their functions are:
Cap is modified Guanine nucleotide that helps tell a ribosome where to attach when translation begins
Tail is a chain of 150-200 Adenine, that facilitates the transport of mRNA out of the nucleus, start of transition, and delays degradation of mRNA by hydrolytic enzymes
This part of the gene gets expressed
This part gets cut out
This complex joins together the expressed genes
Exon
Intron
Spliceosome
How does mRNA leave the nucleus
A nuclear pore
_______ contains both exons and introns
Pre-mRNA
In lower eukaryotes how do introns get removed?
They are self splicing and don’t require a splicesome
How does the spileosome remove the introns
Ribozyme
Explain the role of RNA polymerase
When mRNA is Synthesized, RNA polymerase joins the nucleotides together in a 5’ to 3’ direction
3 major modifications that occur during the processing of mRNA
Introns removed, Exons joined together, 5’ guanosine and 3’ poly-A tail are added
For example
tRNA that has the anticodon 5’ AAG 3’ binds to the mRNA codon 5’______3’
CUU
Where is rRNA produced?
Describe the ribosomal subunits
Nucleolus
2 subunits one larger than the other
During translation codons of an mRNA base pair with….
Anti codons of the tRNA
This stage during protein synthesis is when a polypeptide increases in length one amino acid at a time
Elongation
Can more than 1 tRNA be at a ribosome at the same time?
Yea
Termination of polypeptide synthesis occurs at a ….
Stop codon
All components of the translational complex, including the first tRNA carrying methionine, are assembled
Initiation
Amino acids are delivered one by one as tRNA molecules pair with the codons on the mRNA
Elongation
A stop codon is reached, a release factor binds to it, and the completed protein is cleaved from the last tRNA as ribosomal subunits dissociate
Termination
