Podcast
Questions and Answers
The parental molecule has two complementary strands of ______.
The parental molecule has two complementary strands of ______.
DNA
Nucleotides complementary to the parental strand are connected to form the backbones of the new ______ strands.
Nucleotides complementary to the parental strand are connected to form the backbones of the new ______ strands.
daughter
The results supported the semiconservative model of ______ replication.
The results supported the semiconservative model of ______ replication.
DNA
In the experiment, bacteria were cultured with a heavy ______.
In the experiment, bacteria were cultured with a heavy ______.
Signup and view all the answers
The hybrid molecules produced after the first replication eliminated the ______ model.
The hybrid molecules produced after the first replication eliminated the ______ model.
Signup and view all the answers
The second replication produced both light and ______ DNA.
The second replication produced both light and ______ DNA.
Signup and view all the answers
DNA replication allows genetic info to be inherited from generation to ______.
DNA replication allows genetic info to be inherited from generation to ______.
Signup and view all the answers
The parental strands separate and form a replication bubble with two ______.
The parental strands separate and form a replication bubble with two ______.
Signup and view all the answers
Replication proceeds in both directions until the ______ meet on the other side.
Replication proceeds in both directions until the ______ meet on the other side.
Signup and view all the answers
Each gene is a unit of hereditary information with a specific DNA ______.
Each gene is a unit of hereditary information with a specific DNA ______.
Signup and view all the answers
Alfred Hershey and Martha Chase found that the phage DNA entered the host cells but phage ______ did not.
Alfred Hershey and Martha Chase found that the phage DNA entered the host cells but phage ______ did not.
Signup and view all the answers
T2 attaches to the host cell and injects genetic material through the ______ membrane.
T2 attaches to the host cell and injects genetic material through the ______ membrane.
Signup and view all the answers
Unduplicated chromosome → DNA segment from chromosome → ______ begins at multiple origins.
Unduplicated chromosome → DNA segment from chromosome → ______ begins at multiple origins.
Signup and view all the answers
Frederick Griffith studied streptococcus pneumoniae to develop a ______.
Frederick Griffith studied streptococcus pneumoniae to develop a ______.
Signup and view all the answers
T2 infects E.coli and can turn an E.coli cell into a T2-______ factory.
T2 infects E.coli and can turn an E.coli cell into a T2-______ factory.
Signup and view all the answers
DNA carries the ______ information of the organism.
DNA carries the ______ information of the organism.
Signup and view all the answers
The process by which non-pathogenic bacteria became pathogenic due to external DNA is called ______.
The process by which non-pathogenic bacteria became pathogenic due to external DNA is called ______.
Signup and view all the answers
Bacteriophages, or phages, are viruses that infect ______.
Bacteriophages, or phages, are viruses that infect ______.
Signup and view all the answers
In the experiment, the mixture was ______ to free phage parts.
In the experiment, the mixture was ______ to free phage parts.
Signup and view all the answers
The final step involved ______ the mixture to separate the bacteria from the phage parts.
The final step involved ______ the mixture to separate the bacteria from the phage parts.
Signup and view all the answers
The substance responsible for transformation was determined to be ______.
The substance responsible for transformation was determined to be ______.
Signup and view all the answers
Radioactive labeling showed that while proteins remained outside the cells, ______ was found inside the cells.
Radioactive labeling showed that while proteins remained outside the cells, ______ was found inside the cells.
Signup and view all the answers
Erwin Chargaff determined that DNA is a polymer made up of ______.
Erwin Chargaff determined that DNA is a polymer made up of ______.
Signup and view all the answers
Watson and Crick constructed a model of DNA using knowledge from prior ______.
Watson and Crick constructed a model of DNA using knowledge from prior ______.
Signup and view all the answers
The next RNA primer starts the next ______ fragment, extended by DNA polymerase III.
The next RNA primer starts the next ______ fragment, extended by DNA polymerase III.
Signup and view all the answers
DNA polymerase I replaces RNA primers with ______.
DNA polymerase I replaces RNA primers with ______.
Signup and view all the answers
DNA ligase joins fragments into a continuous ______.
DNA ligase joins fragments into a continuous ______.
Signup and view all the answers
Helicase unwinds the parental DNA double ______.
Helicase unwinds the parental DNA double ______.
Signup and view all the answers
Single-strand binding proteins stabilize the separated ______.
Single-strand binding proteins stabilize the separated ______.
Signup and view all the answers
The leading strand is synthesized continuously by DNA polymerase in the ______ to 3' direction.
The leading strand is synthesized continuously by DNA polymerase in the ______ to 3' direction.
Signup and view all the answers
Using parental DNA as a template, DNA pol III synthesizes a new DNA strand by adding ______ to an RNA primer.
Using parental DNA as a template, DNA pol III synthesizes a new DNA strand by adding ______ to an RNA primer.
Signup and view all the answers
Enzymes detect and repair DNA damage that distorts the ______.
Enzymes detect and repair DNA damage that distorts the ______.
Signup and view all the answers
A Nuclease is a DNA-cutting ______ that helps in the erosion of genes.
A Nuclease is a DNA-cutting ______ that helps in the erosion of genes.
Signup and view all the answers
The basic unit of DNA packing is called a ______.
The basic unit of DNA packing is called a ______.
Signup and view all the answers
Euchromatin is characterized as being less compacted and more ______.
Euchromatin is characterized as being less compacted and more ______.
Signup and view all the answers
Each ______ consists of a DNA molecule packed together with proteins.
Each ______ consists of a DNA molecule packed together with proteins.
Signup and view all the answers
The string between nucleosomes is referred to as ______ DNA.
The string between nucleosomes is referred to as ______ DNA.
Signup and view all the answers
DNA ligase joins Okazaki fragments of the ______ strand.
DNA ligase joins Okazaki fragments of the ______ strand.
Signup and view all the answers
DNA polymerase synthesizes new nucleotides to fill in the missing part, using the ______ strand as a template.
DNA polymerase synthesizes new nucleotides to fill in the missing part, using the ______ strand as a template.
Signup and view all the answers
Upon finding an incorrectly paired nucleotide, polymerase removes the ______ nucleotide.
Upon finding an incorrectly paired nucleotide, polymerase removes the ______ nucleotide.
Signup and view all the answers
Most DNA polymerases require a primer and a DNA ______ strand.
Most DNA polymerases require a primer and a DNA ______ strand.
Signup and view all the answers
The rate of elongation is about 500 nucleotides per second in ______.
The rate of elongation is about 500 nucleotides per second in ______.
Signup and view all the answers
Mismatch repair enzymes remove and replace incorrectly paired ______ that have resulted from replication errors.
Mismatch repair enzymes remove and replace incorrectly paired ______ that have resulted from replication errors.
Signup and view all the answers
Telomeres are special nucleotide sequences at the ______ of Eukaryotic chromosomal DNA.
Telomeres are special nucleotide sequences at the ______ of Eukaryotic chromosomal DNA.
Signup and view all the answers
Errors may arise after replication, but changes are usually ______.
Errors may arise after replication, but changes are usually ______.
Signup and view all the answers
Study Notes
Nucleic Acids and Inheritance
- DNA replication allows genetic information to be passed from one generation to the next.
- Unduplicated chromosome -> DNA segment from chromosome -> Replication begins at multiple origins, forming a replication bubble -> Duplicated and condensed chromosome -> Two DNA molecules.
- Each gene is a unit of hereditary information with a specific DNA sequence.
- Initially, proteins were thought to carry genetic information.
Frederick Griffith
- Studied streptococcus pneumoniae (causes pneumonia) to develop a vaccine.
- Mixed remains of pathogenic bacteria with non-pathogenic bacteria, resulting in the non-pathogenic bacteria becoming pathogenic.
Transformation
- Change in genotype and phenotype due to the assimilation of external DNA by a cell.
- The transforming substance was DNA.
Evidence that DNA Programs Cells
- Bacteriophages (phages), viruses that infect bacteria, were used as tools by researchers.
- Viruses are much simpler than cells, consisting mainly of DNA or RNA enclosed by a protein coat.
- They infect a cell and take over cellular processes.
Alfred Hershey and Martha Chase
- DNA is the genetic material of the T2 virus.
- T2 infects E. coli, turning it into a T2-producing factory.
- T2 reprograms the E. coli cell to produce viruses.
- The T2 enters E. coli.
- DNA entered host cells but phage protein did not, demonstrating DNA as the genetic material.
- DNA carries genetic information during infection.
Experiment in Steps
- Batch I: Radioactive sulfur for protein.
- Batch II: Radioactive phosphorus for DNA.
- Mixed radioactively labeled phages with bacteria and agitated the mixture in a blender to separate phage parts from bacteria.
- Centrifuged the mixture to separate bacteria (pellet) and phage parts (liquid).
- Measured radioactivity.
Results & Conclusions
- Radioactivity from protein remained outside the cells, and radioactivity from DNA was found inside the cells.
- Phage DNA entered bacterial cells, but phage proteins did not, further supporting that DNA is the genetic material.
Other Notable Experiments: Erwin Chargaff
- DNA is a polymer of nucleotides.
Structure of DNA
- Contains a nitrogenous base, deoxyribose sugar, and phosphate group.
- Adenine, thymine, guanine, and cytosine are the nitrogenous bases.
- Analyzed the base composition of DNA.
- DNA base composition varies between species.
- For each species, A = T and G = C; the amount of adenine equals the amount of thymine, and guanine equals the amount of cytosine.
Watson and Crick
- Constructed a model of DNA in which the two sugar-phosphate backbones run antiparallel.
- Created a rope ladder model.
DNA Replication
- Base pairing rules: A with T and G with C.
- Two strands are complementary and each stores the information needed to reconstruct the other.
Models of Replication
- Semiconservative: each of the two daughter molecules will have one old strand and one newly made strand.
- Conservative: all four DNA strands are present after replication.
- Dispersive: all four strands have a mixture of old and new DNA
Hershey and Stahl experiment
- Supported the semiconservative model by showing that DNA replication is semi-conservative.
Replication Process
-
DNA replication begins at origins of replication.
-
Short stretches of DNA sequence initiate the process.
-
Proteins attach to the DNA and separate the two strands (forming a replication bubble), opening up a replication bubble.
-
Replication proceeds in both directions (forming replication forks).
-
Eukaryotic chromosomes may have hundreds or thousands of replication origins.
-
Replication bubbles fuse, speeding up the copying process.
Synthesizing a New DNA Strand
- DNA polymerases need a primer and start synthesizing from the 3' end of the primer.
Continuous vs Discontinuous Synthesis
- Leading strand synthesis is continuous
- Lagging strand synthesis is discontinuous
- The lagging strand is synthesized as Okazaki fragments
- Okazaki fragments are then joined by DNA ligase.
DNA Replication Proteins
- Helicase unwinds parental double helix at replication forks.
- Single-strand binding proteins stabilize separated strands.
- Topoisomerase relieves overwinding strain.
- Primase synthesizes RNA primers at 5' end of leading strand and at 5' of each Okazaki fragment of lagging strand.
Bacterial vs Eukaryotic DNA Replication
- Prokaryotes have one replication origin, while eukaryotes have multiple.
- Bacterial replication is significantly faster than eukaryotic.
Errors in Replication
DNA Repair
- Enzymes detect and repair DNA damage; damaged DNA is cut out and replaced.
Mutation
- Permanent change in DNA sequence.
- Changes the phenotype of an organism.
Shortening of Linear DNA Molecules
- Shortening of linear DNA molecules occurs at the ends of eukaryotic chromosomes.
- Telomeres are special nucleotide sequences at the ends of chromosomes (prevent erosion of coding DNA).
Chromatin, Nucleosomes, Euchromatin, Heterochromatin
- DNA is packed into chromosomes using nucleosomes as the basic unit for DNA packing.
- Euchromatin is less compacted, more dispersed interphase chromatin.
- Heterochromatin is more compacted, denser.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your understanding of nucleic acids and their role in inheritance. This quiz explores DNA replication, genetic transformation, and the groundbreaking experiments of Frederick Griffith. Challenge yourself with key concepts related to genetics and molecular biology.
