DNA Structure and Replication Flashcards
Who discovered the Transforming Principle and when?
Frederick Griffith in 1928.
What is DNA replication?
Process of creating an exact copy of a molecule of DNA.
What does semi-conservative replication mean?
Each new molecule of DNA contains one strand of the original complementary DNA and one new strand.
What happens during termination in DNA replication?
Completion of new DNA.
What catalyzes the formation of new DNA molecules during replication?
DNA polymerase
It plays a crucial role in synthesizing new DNA strands.
What happened when heat-killed pathogenic bacteria were treated with a DNA-destroying enzyme?
Transformation did not occur.
What happens to the DNA strands after they are newly formed?
They rewind automatically into their chemically stable helix structure
This is a natural process following replication.
What is a primer in DNA replication?
A short strand of RNA that is complementary to a DNA template and serves as a starting point for the attachment of new nucleotides.
What are the four bases found in DNA nucleotides?
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)
What is found in a single-stranded form at the replication fork?
Only a very short region of DNA
This region is crucial for the replication process.
What is a nucleic acid?
Weakly acidic phosphorus-containing substance that can be isolated from the nuclei of white blood cells
Nucleic acids include DNA and RNA.
When was the Human Genome Project completed?
2003
It was a monumental effort to sequence the entire human genome.
What is the replication machine?
A complex involving dozens of different enzymes and proteins that work together in the process of DNA replication.
Define DNA polymerase.
An enzyme that uses the parent strands as a template to add nucleotides to make complementary strands.
What was the first entire genome to be sequenced?
The virus 0X174 in 1977
This marked a significant milestone in genomics.
What is the process of identifying the precise nucleotide sequence of a DNA fragment called?
DNA Sequencing
DNA sequencing has become routine with advancements in technology.
What occurs during termination of DNA replication?
The completion of new DNA strands and the dismantling of the replication machine
This marks the end of the replication process.
What are helicases?
Enzymes that cleave and unravel short segments of DNA just ahead of the replicating fork during DNA replication.
Define gene.
A specific sequence of DNA that encodes a protein, tRNA, rRNA molecule or regulates the transcription of such a sequence.
What is a genome?
The sum of all the DNA carried in an organism’s cells, including genes and regions of non-coding DNA.
What is DNA made up of?
Two strands of nucleotides bound together to form a double helix
Each strand has a backbone made of sugar and phosphate molecules.
What did Phoebus Levene isolate in the early 1900s?
DNA and RNA
He also showed that chromosomes are made up of a combination of DNA and proteins.
What did Watson and Crick publish in 1953?
A paper describing the molecular structure of DNA
This research identified DNA as the material of heredity.
What is the significance of the Human Genome Project?
It determined the sequence of the three billion base pairs making up the human genome
This has important applications in medicine and other sciences.
What are the three key differences between RNA and DNA?
- Sugar component of RNA is ribose rather than deoxyribose
- RNA does not have thymine (T), it has uracil (U) instead
- RNA remains single-stranded
How does replication occur on the leading and lagging strands?
In slightly different ways
This difference is essential for the efficiency of DNA replication.
What happened when heat-killed pathogenic bacteria were treated with a protein-destroying enzyme?
Transformation still occurred.
Which bases are complementary in DNA?
- Adenine (A) and Thymine (T)
- Cytosine (C) and Guanine (G)
This base pairing is essential for DNA replication.
What holds the two strands of DNA together?
Hydrogen bonds between pairs of complementary bases
The nitrogenous bases project out from the backbone.
What is a nucleotide?
Units making up nucleic acids such as DNA and RNA, composed of a five-carbon sugar, a phosphate group, and one of five nitrogen-containing bases.
What did Rosalind Franklin contribute to the understanding of DNA?
Provided crucial information about the molecular structure of DNA using X-ray photography.
What are complementary base pairs in DNA?
Hydrogen-bonded pairs of adenine and thymine and cytosine and guanine.
What did Griffith discover about dead pathogenic bacteria?
They passed on their disease-causing properties to live, non-pathogenic bacteria.
What are Okazaki fragments?
Short nucleotide fragments synthesized during DNA replication of the lagging strand.
Define Ribonucleic Acid (RNA)
A nucleic acid that plays a role in gene expression and protein synthesis, shares similar structure with DNA
RNA is single-stranded and contains uracil instead of thymine.
What is the Transforming Principle?
The ability of dead pathogenic bacteria to pass on their disease-causing properties to live, non-pathogenic bacteria.
What does antiparallel mean in the context of DNA?
Describes the property by which the 5’ to 3’ phosphate bridges run in opposite directions on each strand of nucleotides.
What is the double helix structure of DNA?
A threadlike molecule made up of two long strands of nucleotides bound together in a spiral shape.
What is the role of DNA ligase?
Enzyme that splices together Okazaki fragments during DNA replication on the lagging strand.
What did Hershey and Chase demonstrate in 1952?
Genes are made of DNA using radioactive labelling.
What is Chargaff’s Rule?
In any sample of DNA, the amount of adenine is always approximately equal to the amount of thymine, and the amount of cytosine is always approximately equal to the amount of guanine.
What is a replication bubble?
Oval-shaped unwound area within a DNA molecule that is being replicated.
Define Deoxyribonucleic Acid (DNA)
Nucleic acid molecule that governs the process of heredity in all plant and animal cells
DNA is often referred to as the genetic material.
