Biology Chapter 12 Questions
How did Hershey and Chase confirm Avery's results?
Avery and other scientists discovered that DNA stores and transmits genetic information from one generation of bacteria to the next. Hershey and Chase confirmed Avery's results by testing experiments with DNA and proteins. Their results concluded that the genetic material of the bacteriophage was DNA(not protein), which was what Avery said
Why is the pairing of bases during replication essential for the transmission of inherited traits from parent to offspring
The fir between A and T and G and C is nearly perfect. It's nearly perfect so these codes are copied correctly everytime. This base pairing during replication is essential because offspring get the same sequence of bases that their parents had
What is the first step in eukaryotic DNA replication
the strands of the double helix begin unwinding and separating, forming replication forks
By 1952, many scientists were convinced that genes are made of DNA, but they did not yet know how DNA worked. Why was it important to determine the structure of DNA to understand how DNA stored, copied, and transmitted information
the structure probably had instruction on storing It had to have had something in its structure that allowed DNA to copy itself for cell division and allow it to pass from generation to generation
What structural problem prevents adenine from pairing with guanine
they bases are both long
What was the purpose of Oswald Avery's experiment
to determine which molecule in the heat-killed bacteria was most important fro transformation
What was Rosalind Franklin's contribution to solving the structure of DNA
used x-ray diffraction to take a picture of DNA to get information about the structure of the DNA molecule. These pictures carried important clues to identifying the structure of DNA
What experiments did Avery do?
They extracted a mixture of various molecules from heat-killed bacteria. They treated this mixture with enzymes that destroyed proteins, lipids, carbs, and RNA. Transformation still occurred so the molecules were broken down. Then, he used enzymes that broke down DNA, transformation did not occur.
How did Avery build on Griffith's work
by determining which molecule in the heat killed bacteria was most important for transformation; avery discovered that DNA stores and transmits genetic information from one generation of bacteria to the next)
The cells of most prokaryotes have single, _______ DNA molecule in the cytoplasm. Eurkaryotic cells have much more DNA. Nearly all of it is contained in __________, which are in the nucleus.
circular chromosomes
DNA is a nucleic acid made up of nucleotides joined into long strands or chains by _______ bonds. Nucleotides can be joined in any order. A DNA nucleotide is a unit made of a _______ base, and 5-carbon sugar called ________, and a ______ group. DNA has four kinds of nitrogenous bases: _________,___________,__________, and ________-
covalent nitrogenous, deoxyribose, phosphate adenine, guanine, cytosine, and thymine
What was Erwin Chargaff's contribution to the structure of DNA
discovered that the percentages of adenine and thymine and cytosine and guanine in any sample of DNA are almost always equal (A=T, C=G)
Why are the strands of a DNA molecule said to be complementary
each strand can be used to make the other strand
How does the structure of DNA allow it to store information
each strand of the double helix carries a sequence of nucleotides arranged almost like letters in a four-letter alphabet
Because the base pairing in DNA, the percentages of thymine molecules in DNA is about _______ to the percentages of adenine molecules
equal
_______ _______ are weak bonds that hold the two strands of DNA together, but also allow the DNA to separate and replicate. Chromatin contains proteins called ________. The tips of chromsomes are _______. DNA replication is carried out by a series of ________.
hydrogen bonds histones telomeres enzymes
During DNA replication, what two processes must occur before the two strands of a DNA molecule can seperate
hydrogen bonds between base pairs must be broken and the molecule must unwind
Only the DNA from the bacteriophage showed up in the ________ cell. Hershey and Chase concluded that the genetic material in bacteriophage was _______. Their work confirmed Avery's results, convincing many scientists that DNA was the genetic material found in genes-not just viruses and bacteria, but in all ____________ cells.
infected DNA living
How did Hershey and Chase know that it was the DNA that had infected the bacterial cells in their experiment
nearly all the radioactivity in the bacteria was from 32P, the marker found in DNA no radioactivity of 35S was found inside the other bactiera
Does DNA replication take place in the same direction along both strands of the DNA molecule that is being replicated
no, replication takes place in opposite directions between replication forks
The building blocks of DNA are ___________. They can by joined in any order by ______ bonds
nucleotides covalent
The model also shows how each strand carries a sequence of __________, arranged in almost like the letters in a fourletter alphabet for recording genetic information. ________ bonds hold the strands together. The bonds are easily broken allowing DNA strands to separate. _______ bonds form only between certain base pairings (a-t, c=g). this is called _______ _________-
nucleotides hydrogen hydrogen base pairing
What is location of DNA, amount of DNA, and starting point(s) for replication in eukaryotes
packaged into chromosomes in the nucleus up to 1000x more than prokaryotes may begin at dozens or even hundreds of places on the DNA molecule
Hershey and Chase Experiment: What happened to the bacteriophage with the phosphorus-32 in DNA and the bacteriophage with sulfur-35 in protein coat
phosphorus 32- phage infects bacterium and there is radioactivity inside bacterium sulfur 35- phage infects bacterium and there is no radioactivity inside of bacterium
What binds to the prokaryotic chromosome to start DNA replication
regulatory proteins
The two strands of the double helix unzip, forming _______ _____. New bases are added following the riles of base pairing. Each new DNA molecule has one __________ strand and one _____ strand. _____ ___________ is an enzyme that joins individual nucleotides to produce a new strand of DNA. During replication, DNA may be lost from the tips of chromosomes, which are called _______.
replication forks original and new DNA polymerase telomeres
How did scientists determine that DNA is responsible for storing, copying, and transmitting genetic information
scientists studied genes and how they work. from the experiments with bacteria and viruses they performed, they discovered that genes are composed of DNA
How does the structure of DNA allow it to transmit information
sequence of base pairs is copied when DNA is copied; genetic material is able to pass from generation to generation without being changed
In which cells is the accurate transmission of information most important
sex cells
Replication in most prokaryotic cells starts from a ______ point and proceeds in two direction until the ______ chromosome is copied. In eukaryotic cells, replication may begin at dozens or _______ of places on the DNA molecule, proceeding in both direction until _____ chromosome is completely copied
single entire hundreds each
What is location of DNA, amount of DNA, and starting point(s) for replication in prokaryotes
single circular DNA molecule in the cytoplasm less than eukaryotes a single point
The DNA that makes up genes must be capable of ___________,__________, and _________ the genetic information in a cell
storing, copying, and transmitting
What enzyme makes it less likely that DNA will be lost from telomeres during replication? How does this enzyme work?
telomerase it adds short, repeated DNA sequences to the telomeres
Each time a chromosome is replicated, some DNA may be lost from the tip of the chromosome, or ______________. Griffith's experiments showed that some chemical compound in cells mist be responsible for bacterial _________. Hershey and Chase studied a _______ that was composed of a DNA core and a protein coat.
telomere transformation bacteriphage
What happened when Griffith injected mice with the pnemunia causing strain of bacteria that had been heat killed? What happened when Griffith injected mice with a mixture of heat killed, pneumonia causing bacteria and live bacteria of the harmless type?
the mice survived. The mice developed pneumonia and many died
How do cells copy their DNA
Cells copy their DNA by replication. The DNA molecule seperates into 2 strands and then produces 2 new complementary strands following the rules of base pairing. Each strand of the double helix serves as a template or model for the new strand.
The double-helix model explains __________ rule of base pairing and how the two strands of DNA are held together. The model showed how two strands in the double helix run in ________ directions, with the nitrogenous bases in the center.
Chargaff's opposite
Avery's experiment worked because bacteriophages and bacteria share what component
DNA
Why did Hershey and Chase label the viral DNA with radioactive phosphorus and not radioactive sulfur
DNA contains phosphorus and no sulfur
What did Avery conclude
DNA must be the transformation factor
What adds base pairs to the strand
DNA polymerase
Why is storing information important and what is an example
DNA that controls patterns of development and carries characteristics of different kinds of organisms. The instructions cause a single cell to develop into an oak tree must be written into the DNA of an organism
What did Avery conclude caused transformation
DNA was the transforming factor
__________ ___________ showed that percentages of adenine and thymine are almost always equal in DNA. The percentages of guanine and cytosine are also almost equal. _________ __________ x-ray diffraction studies revealed the double-helix structure of DNA. ____________ ___________ and __________ _______ built a model that explained the structure of DNA>
Erwin Chargaff Rosalind Franklin James Watson and Francis Crick
Which scientists made x-ray diffraction photos of DNA
Franklin
In 1928, _______ ________ found that some chemical factor from heat-killed bacteria of one strain could change the inherited characteristics of another strain. He called the process _______ because one type of bacteria(a harmless form) had been changed permanently into another(disease-carrying form) Because the ability to cause disease was inherited by the offspring of the transformed bacteria, he concluded that the transforming factor had to be a _______.
Frederick Griffith transformation gene
Why was the fact of transformation so important to the study of DNA's role? What did transformation demonstrate?
It showed that DNA determines what a cell becomes. A cell changes if the DNA in the cell changes. Transformation demonstrated that DNA is found in all living cells and that it controls the fate of cells
DNA is like a book titled How to Be a Cell. Explain why that title is appropriate for each of DNA's three function
Storing info-has all info needed to direct cells activites Copying info=multiple copies can be printed each time cell divided so the daughter cells know what to do Transmitting info-copies are able to be passed down from parents to offspring, so the offspring have the instructions it needs to function
Why is transmitting information important and what is an example
Genetic information must be carefully sorted and passed from one generation to the next during cell division. The reproductive cells of the oak tree carry information from parents to offspring so the offspring can develop into an oak tree
why is copying information important and what is an example
Genetic information must be copied correctly before a cell can divide. After mitosis occurs, each daughter cell of the oak tree will have the same genes and chromosomes as the parent cell
What did Hershey and Chase conclude? why?
Genetic material of the bacteriophage was DNA, not protein. That's because nearly all the radioactivity in the bacteria was from phosphorus p-32, the marker found in DNA
Is DNA replication always a foolproof process?
Not always. Although a number of proteins check DNA for chemical damage or base pair mismatches prior to replication, damaged regions of DNA are sometimes replicated. This can result in changes to DNa base sequences that may alter certain genes and produce serious consequences
In 1944, _______ _______ tested the transforming ability of many substances. Only ______ caused transformation. By observing bacterial transformation, he and other scientists discovered that the _____ ______ DNA stores and transmits information from generation of bacteria to the next
Oswald Avery DNA nucleic acid
How was the structure of DNA discovered
Rosalind Franklin used x-ray diffraction to get a picture of a DNA molecule. The clues from Franklin x-ray enabled Watson and Crick to build a model that explained the specific structure and properties of DNA
What was James Watson and Francis Cricks contribution to solving the structure of DNA
built a 3D model of the DNA molecule that explained the specific structure and properites of Dna (double helix)
What is a replication fork
a point in a DNA molecule where the 2 strands separate during replication
A __________ is a kind of virus that infects bacteria. When it enters a bacterium, it attaches to the surface of the bacterial cell and injects its _______ material into it. In 1952, __________ _________ and _______ ____________ used radioactive tracers to label proteins and DNA in bacteriophages/
bacteriophage genetic Alfred Hershey and Martha Chase
The center of the DNA strand exhibits ________________. The enzyme that proofreads each new DNA strand so that each molecule is a near perfect copy of the original is ___________________. In eukaryotic cells, _________ can begin at dozens or even hundreds of places on the DNA molecule
base pairing DNA polymerase replication
Each strand of the double helix has all the information needed to reconstruct the other half by the mechanism of _______ __________. Because each strand can be used to make the other strand, the strands are said to be _____________. DNA copies itself through the process of ____________.
base pairing complementary replication
The double-helix model explains Chargaff's rule of __________. The DNA molecule separates into two strands during _________. The principal enzyme involved in DNA replication is __________________.
base pairing replication DNA polymerase
How does the structure of DNA allow it to copy information
base pairing can be copied when the hydrogen bonds are broken and the strands pull apart
What would Hershey and Chase have concluded if both radioactive 32P and 35S were found in the bacteria in their experiment
both the virus's protein coat and its DNA were injected into the bacteria
