Studied by 6 peopleWhat are the 2 types of nucleic acids?
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
Where were nucleic acids first discovered ?
cell nucleus
What viruses uses RNA as their genetic material ?
coronavirus, HIV
Why does RNA viruses not falsify the claim that all living things use DNA as genetic material ?
Reproduction is a fundamental property of living organisms and viruses cannot reproduce instead they rely on host cells.
What is the primary function of nucleic acids ?
Storage and Expression of hereditary information
What are the components of a nucleotide ?
sugar ( deoxyribose or ribose ) , phosphate group, nitrogenous base
Label a nucleotide including carbons of pentose sugar
phosphate, sugar, base
1 starting from right
How are nucleotides connected to form a nucleic acid polymer ?
covalent bonds are formed between the phosphate of one nucleotide and the pentose sugar of the next nucleotide
Define backbone
The backbone is the portion of DNA that provides structural support. It consists of alternating sugar and phosphate groups that helps to conserve the sequences of bases
What nitrogenous bases are found in DNA?
Adenine, Thymine, Guanine, Cytosine
What nitrogenous bases are found in RNA ?
Adenine, Uracil, Guanine, Cytosine
Similarities and differences between nitrogenous bases
All contain nitrogen
Differences: Adenine and guanine are purine bases ( 2 carbon nitrogen rings ) Thymine and Guanine are pyrimidine bases ( 1 carbon nitrogen ring )
How does the sequence of bases form as a code ?
The sequence of bases is how information is stored ( in a coded form ) this is a universal genetic code shared by all organisms
Define gene
segment of DNA that codes for a characteristic
How are RNA nucleotides linked?
through a condensation reaction
Describe the condensation reaction that occurs to combine 2 molecules
Hydroxyl groups (OH) on the phosphate of one nucleotide and the pentose sugar of another are used. One OH group is removed entirely while another OH group loses its Hydrogen. This produces water and the remaining oxygen will form a new covalent bond that links the 2 nucleotides.
What is the monomer and polymer of an RNA molecule ?
Monomer: Nucleotide Polymer: Collection of nucleotides bonded together
What does a DNA molecule consist of ?
2 strand of nucleotides that are linked together by their bases. The links between bases are hydrogen bonds.
What are the complementary base pairs of DNA ?
Adenine and thymine ( double hydrogen bond ) Guanine and Cytosine ( triple hydrogen bond )
Why are DNA strands said to be antiparallel ?
The two strands are said to be antiparallel because they run in opposite 5ꞌ to 3ꞌ directions from each other.
One strand ends with the phosphate group while the other strand ends with a deoxyribose.
What is a helix?
a coiled structure that has a constant diameter of 2 nanometres
Difference in DNA and RNA structure
on the 2nd carbon DNA has H and RNA has OH
DNA has 1 fewer O across the structure
2 polymers in DNA while only 1 in RNA
Difference in DNA and RNA bases
DNA: adenine, thymine, guanine, cytosine RNA: adenine, uracil, guanine, cytosine
Compare the locations of DNA and RNA in prokaryotic and eukaryotic cells
Prokaryotic: coiled loop floating in cytoplasm Eukaryotic: Inside nucleus`
What is replication?
Process by which DNA copies itself
What is a replication fork?
A replication fork is a point in a DNA molecule where the two strands separate during replication.
Each original strand serves as a guide or template for the creation of a new strand
How does complementary base pairing help maintain the DNA sequence ?
Each nucleotide added will carry the complementary base to the template strand. This means that the newly created strand will have the exact same base sequence as the template
What is semi- conservative replication?
Each new DNA molecule is made of one of the old strand and one of the new strand
What is gene expression?
the process by which DNA directs the synthesis of proteins
What nitrogenous bases are found in DNA?
The process of making RNA from a DNA template
Describe the transcription process
The first stage involves the copying of base sequences but the copy is RNA rather than DNA, so adenine pairs with uracil rather than thymine
What is translation?
turning RNA to protein
Describe the translation process
The base of the RNA molecule is translated into a amino acid sequence of a protein. This will be reliant upon the complementary base sequences.
Why is there a limitless diversity of DNA base sequences ?
The range of possible sequences is limitless because as the number of bases increases so does the number of possible sequences. There is no limit on the number of bases as it can be stored into small volumes.
What is the universal genetic code ?
All known living organisms use the same genetic code
What is a codon?
Adenine, Uracil, Guanine, Cytosine
How many codons are there?
64
What are the 3 meanings of a codon ?
most codons specify one particular amino acid
one codon signals that protein synthesis should start
three codons signal that protein synthesis should stop
Why is conservation of genetic code evidence of common ancestry ?
As genetic codes have altered very slightly over billions of years it means that all forms of life essentially still follow the same genetic language.
How are nucleotides linked ?
Phosphate group of one nucleotide is linked to the pentose sugar of the next nucleotide
How do DNA/RNA strands have directionality ?
As a result of the continuous linkage they are all orientated the same way leading to directionality
What is the 3' terminal ?
The side that has the unlinked pentose sugar
3' because C3 ( carbon 3 ) is available for linkage to another nucleotide
What is the 5' terminal ?
The side that has the unlinked phosphate group
5' because within a nucleotide the phosphate group is attached to C5 of pentose sugar
What processes does directionality affect ?
Replication, Transcription, Translation
Outline the impact of directionality on these processes
DNA and RNA strands and nucleotides must be facing the right way in order for them to fit the active sites of enzymes and ribozymes.
What direction does replication occur in ?
5' to 3'
DNA nucleotides are added to the 3' end
The 5' phosphate of the free nucleotide is added to the 3' end of the growing polymer
What direction does transcription occur in ?
5' to 3' RNA nucleotides are added to the 3' end of the growing polymer of nucleotides. 5' phosphate of free nucleotide is added to ribose sugar at 3' end of polymer
What direction does translation occur in ?
5' to 3' Molecule of RNA carries the sequence information by linking amino acids together. Ribosome moves along RNA molecule towards the 3' end
What component ensures DNA helix stability ?
Each base pair has one purine and one pyrimidine base joined by hydrogen bonds
What are the purine bases?
Adenine and Guanine
Molecules that have 2 rings of atoms
What are the pyrimidine bases?
Cytosine and Thymine and Uracil
Molecules that have 1 atom ring
What bases bond with each other in DNA?
Each base pair has one purine and one pyrimidine base
What's a consequence of purine to pyrimidine bonding in DNA ?
The sequence of bases is how information is stored ( in a coded form ) this is a universal genetic code shared by all organisms
How is eukaryotic DNA structured?
A string of nucleosomes ( replicates a string of beads ). At the core of each nucleosome there are 8 histone proteins.
What does H1 do?
reinforces the binding of DNA to the nucleosome core
may also help in packaging of chromosomes when nucleus is preparing to divide
Why is bacteria's DNA 'naked' ?
Because it is not associated with any histones
What is histone's structure ?
2 copies of 4 different types makes up a disc like structure
DNA molecule is wound twice around the core
What was being tested in Hershey and chase's experiment ?
Whether the genetic material in a cell came from the proteins or the DNA in a chromosome
What bacteria's were used in the Hershey and Chase's experiment ?
Used T2 bacteriophage to identify genetic material They cultured viruses that contained proteins with radioactive sulfur (35) and other viruses with DNA that contained radioactive phosphorus (32). Two seperate groups of bacteria were then infected with the virus
Describe the procedure of the Hershey and Chase experiment
For each group of infected bacteria cells they used a blender to separate the non-genetic component of the virus.
solution was then centrifuged to concentrate cells into pellets
radioactivity of the pellet was the measured
What did Hershey and Chase conclude?
The genetic material of the bacteriophage was DNA, not protein
How are radioisotopes used in research ?
follow material in the body and detect abnormalities in size and shape of organs. Also used as tracers or tagged atoms and can be detected as they move from one compound to another.
Explain the role of falsifiability in determining the structure and function of DNA
Hershey and chase experiment falsified the hypothesis that proteins are the genetic material.
Chargaff's analysis falsified the tetranucleotide hypothesis that the 4 DNA bases occur in equal amounts
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