Unit 3 (Week 8 Nucleic Acid Structure DNA Replication and Chromosome Structure) Flashcards
What carries the genetic instructions for living things and, for example, enables a fertilized egg to develop into an embryo and eventually into an adult organism?
DNA
What provides the blueprint to create specific enzymes for the digestion of certain foods?
DNA
What are the four key criteria for something to be genetic material?
Information - The genetic material must contain the information necessary to construct an entire organism.
Replication - The genetic material must be accurately copied, a process known as replication.
Transmission - After it is replicated, the genetic material can be passed from parent to offspring. It also must be passed from cell to cell during the process of cell division.
Variation - Differences in the genetic material must account for the known variation within each species and among different species.
What is a discrete unit of genetic material composed of DNA and associated proteins?
Chromosomes. Eukaryotes have chromosomes in their cell nuclei and in plastids and mitochondria.
Greek from chromo and soma meaning colored body, refers to the early observation by microscopists that chromosomes are easily stained by colored dyes.
What is a discrete unit of genetic material composed of DNA and associated proteins?
Chromosomes. Eukaryotes have chromosomes in their cell nuclei and in plastids and mitochondria.
Greek from chromo and soma meaning colored body, refers to the early observation by microscopists that chromosomes are easily stained by colored dyes.
In the late 1920s, an English microbiologist, Frederick Griffith, studied what type of bacteria and injected mice with two strains: Type S for smooth and Type R for rough?
Pneumococci or Streptococcus pneimoniae.
What is a type of gene transfer between bacteria in which a segment of DNA from the environment is taken up by a competent cell and incorporated into the bacterial chromosome?
This was shown to happen with strep in mice.
Transformation.
How did Avery, MacLeod, and McCarty, in their experiment, prove that DNA from S type strep was responsible for transforming R type strep into S type strep?
They purified samples of DNA from S type strep, added them to mixtures of R Type bacteria and then added different enzymes such as DNase, RNase, and proteases to different mixtures to essentially denature their respective substrates. Once this was complete, and an antibody was added to remove any non-transformed R type strep, the results were centrifuged, causing all non transformed R type strep to form a pellet at the bottom.
The resulting S type was left over in each of the test tubes. The only test tube to remain “rough” was the one with DNase. This means that DNA of S type was the transforming principle in this experiment.
What is an enzyme that digests DNA?
DNase
What is an enzyme that digests RNA?
RNase
What is an enzyme that cuts proteins into smaller polypeptides?
Proteases
Explain the characteristics of the S. pneumoniae strains that made them particularly well suited for the researchers’ experiment.
Previous studies had indicated that mixing different strains could lead to transformation, or the changing of a strain into a different one. Griffith had shown that mixing heat-killed type S with living type R bacteria would result in the transformation of the type R to type S. Though mutations could cause a change of identity of certain strains, the type R to type S transformation was not due to mutation but was more likely due to the transmission of a biochemical substance between the two strains. Griffith recognized this and referred to the biochemical substance as the “transformation principle.” If Avery, MacCleod, and McCarty could determine the biochemical identity of this “transformation principle,” they could identify the genetic material for the bacteria.
What is a DNA extract?
A DNA extract contains DNA that has been purified from a sample of cells.
In the experiment of Avery, MacLeod, and McCarty, what was the purpose of using protease, RNase, and DNase if only the DNA extract caused transformation?
The researchers could not verify that the DNA extract was completely pure, that is, lacking small amounts of contaminating molecules, such as proteins and RNA. The researchers were able to treat the extract with enzymes to degrade proteins (using protease), RNA (using RNase), or DNA (using DNase). Eliminating the proteins or RNA did not alter the transformation of the type R to type S strains. Only the enzymatic degradation of DNA disrupted the transformation, indicating that DNA is the genetic material.
[Nucleic Acid Structure] What is an organic macromolecule composed of nucleotides?
Nucleic acid. The two types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
How was the name nucleic acid coined?
When Swiss physician Friedrich Miescher in 1869 discovered a phosphorous-containing substance from the nuclei in white blood cell in waste surgical bandages, he named the substance nuclein. Later on, they were gound to be acidic molecules, which means they release hydrogen ions (H+) in solution and have a net negative charge at neutral pH. Thus, the name of nucleic acid was coined.
What is an organic molecule having three components: one or more phosphate groups, a five-carbon sugar (either deoxyribose or ribose), and a single or double ring of carbon and nitrogen atoms known as a base?
Nucleotide
What is the structure of of DNA (or RNA) formed by the covalent linkage of nucleotides in a linear manner?
Strand
What are two strands of DNA hydrogen-bonded with each other?
Double Helix. Two DNA strands are twisted together to form a structure that resembles a spiral staircase.
What allows DNA to associate into a compacted structure like a chromosome?
The wide array of different proteins to form chromosomes.
What is the complete genetic material of an organism or species?
The genome
[Review] What are the three components of a nucleotide?
A phosphate group, a 5-carbon sugar, and a nitrogen-containing base.
What pentoses are found in DNA? What about RNA?
Deoxyribose and ribose. This, their phosphate groups, and nitrogen base.
How many different bases are there and how are they categorized?
There are five different bases, only one per any given nucleotide. The bases are categorized into pyrimidines and purines.