unit 5 molecular genetics Flashcards
What is the defintion of genetic transformation and how does it work?
The information for the traits/features of an organism is contained in the nucleic acids
If another organism receives these nucleic acids, it may express the same traits as the original
What was Rosalind Franklin’s contribution to DNA research/
produced the X-ray diffraction photograph implying DNA’s double helix structure
what was griffith’s contribution to DNA research?
proved that changes in the genotype and phenotype of bacteria are due to the assimilation of external DNA by the cell
what was Avery’s contribution to DNA research?
verified Griffith’s theory that changes inthe genotype are due to assimilation of external DNA
- proved that DNA was responsible for the GENETIC TRANSFORMATION of bacterial cells
what was Hershey-Chase’s contribution to DNA research?
determined that the DNA and not the proteins of a bacteriophage is injected into a host bacterial cell during infection
what are the 3 key roles of DNA?
-storage of genetic information: the instructions needed for an organisms growth, development, and function, carried in codons of nitrgoenous bases that determine traits.
replication for cell division: occurs during the s phase of interphase
protein synthesis: DNA provides the instructions for making proteins. This occurs during two processes: transcription (DNA to mRNA) and translation (mRNA to protein)
list the chemical components of DNA
The chemical components of DNA include:
Deoxyribose Sugar – A five-carbon sugar that forms part of the backbone of DNA.
Phosphate Group – Connects to the sugar to form the sugar-phosphate backbone.
Nitrogenous Bases – The four bases that store genetic information:
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
These components combine to form nucleotides, which are the building blocks of DNA.
what researchers in chronological order verified the structure of DNA?
Chargaff, Pauling, Wilkins+Franklin, Watson+Crick
what was Chargaff’s contribution to the verification of the structure of DNA?
determined that the ration of A:T and C:G were equal
what was Pauling’s contribution to the verification of the structure of DNA?
proposed the heliacal structure of DNA
what was Wilkins+Franklin’s contribution to the verification of the structure of DNA?
proved through the x-ray diffraction photograph that DNA had a double helix structure
Watson+Crick
publicsehd the paper “ the molecular structure of nucleic acids.”
Deduced that the sugar and phosphate groups of the nucleotides formed the backbones of the DNA molecule and the nitrogenous bases form pairs that compose the ruigs of the double helix
what is the difference between prokaryotes nad eukaryotes in DNA replication?
prokaryotes: DNA replication start at one point and moves in two directions until the whole DNA is copied .THis is because prokaryotes have a single, circular DNA strand.
Eukaryotes: DNA replication start at many points along the DNA and occurs concurrently . This takes longer!
what was miescher’s contribution to the discovery of DNA being the source of all genetic material?
the first to isolate nucleic acids
what was Griffith’s contribution to the discovery of DNA being the source of all genetic material?
discovered the source of genetic information in bacteria through the pneumonia mice experiment.
-discovered bacterial transformation, which caused him to determine that changes in the genotype and phenotype are due to the assimilation of external DNA by the cell
what was Avery’s contribution to the discovery of DNA being the source of all genetic material?
Verified Griffith’s protocol and determined that DNA was responsible for the genetic transformation of the bacteria cells
What has hershey-chase’s contribution to the discovery of DNA being the source of all genetic material?
Determined that the DNA and not the proteins of a bacteriophage, a virus, is injected into a host bacterial cell during infection
what molecule type is DNA?
a nucleic acid and polymer
the monomer of the polypeptide DNA?
nucleotide
what is the composition of a nucleotide in DNA? what is the composition of a nucleotide in RNA?
DNA: deoxyribose sugar, nitrogenous base, phosphate group
RNA: ribose sugar, nitrogenous base, phosphate group
what are purines?
type of nitrogenous base, including adenine and guanine
what are pyrmidines?
type of nitrogenous base, including thymine, cytosine, and uracil
What is base pairing?
-the pariing of purines and pyrimidines that MUST occur for the double helix to form, because they form hydrogen bonds
what are the DNA levels of organization?
DNA-Gene-Chromosomes-Genome
What does semiconservative mean in the context of DNA replication?
it means that each daughter cell gets one strand of the original DNA and one strand of the replicated DNA?
when does DNA replication occur?
during the S phase of interphase
when does transcription occur?
Techincally can occur during any phase of interphase, but mostly occurs during G1 and G2
What are the steps of DNA replication?
- Helicase unwinds/unzips the DNA double helix by breaking the hydrogen bonds between the nitrogenous bases
- DNA polymerases continuously replicate the leading strand using free nucleotides in the 5’-3’ direction.
- The lagging strand is synthesized discontinuously in segments with the aid of DNA polymerases. The lagging strand is synthesized in the opposite direction of the leading strand.
- DNA ligases induce the covalent bonding of the sugar phosphate backbone in the segments of the lagging strand.
what is DNA ligase and what is it used for? when
DNA ligase is an enzyme that “glues together the gap” between the fragments of synthesized DNA on the lagging strand (IN THE 3’-5’ direction
- IT DOES THIS BY SEALING BREAKS IN THE SUGAR-PHOSPHATE BACKBONE by inducing polar covalent bonds
- NOT NEEDED ONTHE LEADING STRAND BECAUSE IT CAN BE CONTINUOUSLY COPIED
- used after step 3 of DNA replication
in which direction is the leading strand? in which direction nis the lagging strand? WHY IS THIS IMPORTANT?
-dna can only be read ( and replicated) along the 5’-3’ direction!
- this is why the lagging strand of DNA is replicated in fragments
what kind of bonds are formed in the sugar-phosphate backbone?
polar covalent bonds
What are the steps of DNA transcription in prokaryotes? what about in eukaryotes?
prokaryote: DNA–> mrna transcription–> translation
eukaryotes DNA–> pre-mrna transcription–>mRNA processing–> translation
RNA vs DNA
Single helix vs. double helix
Ribose sugar vs. deoxyribose sugar
Uracil vs. thymine
what is the function of mRNA?
carries information specifying amino acid sequences of proteins from DNA in the nucleus to the ribosome in the cytoplasm (these are the CODONS of TRANSLATION)
what is the function of tRNA?
: Carries amino acids to the ribosome for protein synthesis.
(these are the ANTICODONS of translation)
what is a gene?
a large DNA sequence containing many codons.A gene is a segment of DNA that carries instructions for making a protein or a functional RNA molecule
what is the function of ribosomal RNA?
a type of RNA that forms a key structural and functional part of ribosomes, the cellular machinery responsible for protein synthesis. It helps read mRNA, correctly positions tRNA, and catalyzes the formation of peptide bonds between amino acids, ensuring proper protein assembly.
How does transcription occur?
RNA polymerase unwinds the DNA double helix and adds free RNA nucleotides to the 3’-5’ strand of DNA(the gene) creating an RNA transcript (pre-MRNA)
what is the RNA transcript the same as?
-pre-MRNA in eukaryotes and MRNA in PROKARYOTES
wht is RNA processing and in what cells does it occur?
-RNA processing is when EUKARYOTIC cells edit the initial RNA transcript (aka, PRE-MRNA IN EUKARYOTES)
- IN this process, introns are removed and exons are spliced together to form the final mRNA transcript!
what are introns?
the parts of the pre-mRNA that contains non-coding DNA.
what are exons?
he parts of the pre-mRNA that contains the coding DNA.
what are the steps of the process of translation?
- The small subunit of the ribosome (aka, RRNA) binds to the mRNA transcript to begin translation
-tRNA ANTICODONS begin to matchup with the complementary codons from the mRNA transcript
-Each tRNA carries an amino acid which is peptide bonded to the newly created amino acid chain
what are mutations?
- HERITABLE changes in genetic information
What are point mutations
Point mutations; (substitution) → one change in DNA template, only one mRNA codon is shifted
-substitutions usually only affect one AA or may have no effect at all
what is a missense mutation?
-a type of point mutation (substitution) that changes the amino acid produced
what is a silent mutation and why does it occur?–
-a type of point mutation that does not change the amino acid
-occurs because of the WOBBLE POSITION (the last nucleotide in a codon can be changed bc there are many different combinations for the same amino acid (but only the last codon can be changed))
what is a nonsense mutation
changes the amino acid to “stop,” which leaves it malformed and therefore dysfunctional
What is a frameshift mtuation?
insertion or deletion) → all mRNA codons are shifted
what are the effects of frameshift mutations on the cell?
-can change every AA that follows the point of the mutation
-insertions or deletions can alter a protein so much that it is unable to perform its normal functions
what is the definition of a harmful mutation?
ones that dramatically change proteins structure or gene activity
what is the definition of helpful mutations?
ones that may produce proteins with new or altered functions that can be useful to organisms in different or changing environments
what are mutagens and what are their categories?+examples
chemical or physical agents in the environment that cause a mutation
chemical mutagens - certain pesticides, environmental pollutants, etc.
-physical mutagens - forms of radiation like X-rays and UV light
why are mutagens so dangerous?
If these agents interact with DNA, they can produce mutations at high rates, increasing the chance of cancer
in what direction do enzymes such as dna/rna polymerase read DNA? WHY?
v enzymes like DNA polymerase and RNA polymerase always read their template strand in the 3’ to 5’ direction so they can build a new complementary strand in the 5’ to 3’ direction.
