Biology Chapter 12 Test Questions – Flashcards
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What did Frederick Griffith want to learn about bacteria?
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Griffith wanted to learn how bacteria makes people sick
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The strain of bacteria that caused pneumonia grew into ___________ colonies on culture plate; harmless bacteria produced colonies with ____________ edges.
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Smooth, Rough
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What is true about Griffith's experiment?
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Mice injected with a mixture of bacteria from smooth colonies dead; mice injected with a mixture of bacteria from heat-killed smooth colonies and live rough colonies deaded
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What result from Griffith's experiment suggested that the cause of pneumonia was not a chemical poison released by the disease-causing bacteria?
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The mice surviving from the heat-killed, disease-causing , and harmless bacteria.
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What is transformation?
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When a strand of bacteria had apparently been changed permanently into another.
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What hypothesis did Griffith form from the results of his experiment?
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That when the live, harmless bacteria and the heat-killed bacteria were mixed some factor was transferred from the heat-killed cells into the live cells.
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T or F? Avery and his colleagues thought that the molecule required in transformation might also be the molecule of the gene.
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True
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Briefly describe how Avery and his group determined which molecule was most important for transformation?
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They carefully treated the extract with enzymes that destroyed proteins, lipid, carbs, and other molecules, including the nucleic acid RNA.
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Transformation didn't occur when _________ was destroyed.
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RNA
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What was the conclusion from Avery's experiment?
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That the nucleic acid DNA stores and transmits the genetic information from one generation of organism to the next.
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What is a bacteriophage?
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A virus that infects bacteria
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What makes up a bacteriophage?
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Protein coat and DNA core
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What happens when a bacteriophage infects a bacterial cell?
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The virus attaches to the surface of the cell and injects its genetic information into it.
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How would Hershey and Chase learn whether genes were made of protein or DNA?
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They grew viruses in cultures containing radioactive isotopes of (32P) and (35S)
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What molecule is used as a radioactive marker for (32P)?
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DNA
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T or F? If (35S) was found in the bacteria, it would mean that the virus' DNA had been injected into the bacteria.
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True
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What results did Hershey and Chase observe?
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They observed the genetic material wasn't protein.
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Hershey and Chase concluded that the genetic material of the bacteriophage was ________
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DNA
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List 3 critical things that genes were known to do.
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1. Genes had to carry information from one generation to the next. 2. They had to put that information to work by determining the heritable characteristics of organisms 3. Genes had to be easily copied.
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Adenine, guanine, cytosine, and thymine are four kinds of _______ bases in DNA
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Nitrogenous
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T or F? Adenine and guanine are larger molecules than cytosine and thymine because they have two rings in their structure.
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False
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What forms the backbone of a DNA chain?
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It's formed by sugar and phosphate groups of each nucleotide
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T or F? The nucleotides must be joined together in a specific order.
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False
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According to Chargaff's rules, the percentages of ________ are equal to thymine and the percentages of ________ are equal to guanine in the DNA molecule.
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Adenine, Cytosine
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Rosalind Franklin's work with X-ray diffraction showed that the DNA molecule is shaped like a(an) _________ and contains __________ strands.
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X, Parallel
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How did Francis Crick and James Watson try to understand the structure of DNA?
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They made three-dimensional models of the molecule using cardboard and wire.
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How did Watson and Crick describe the structure of DNA?
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They said a double helix looks like a twisted ladder or spiral staircase.
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T or F? According to the principle of base pairing, hydrogen bonds could form only between adenine and cytosine.
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False
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What is the location of DNA in prokaryotic cell?
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Cytoplasm
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T or F? Most prokaryotes contain a single, circular DNA molecule.
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True
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Eukaryoric DNA is generally located in the cell's _______ in the form of a number of chromosomes.
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Nucleus
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T or F? All organisms have the same number of chromosomes.
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False
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T or F? The E. coli chromosome is longer than the diameter of an individual E. coli bacterium.
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False
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What is true about chromosome structure?
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A human cell contains more than 1 meter of DNA
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Eukaryotic chromosomes contain both DNA and protein, packed together to form ___________.
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Chromatin
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What are histones?
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A protein molecule around DNA that is also tightly coiled in chromatin.
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Why are individual chromosomes visible only during mitosis?
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During mitosis the fibers of each individual chromosome are drawn together forming the tightly packed chromosomes you can see through a light microscope in dividing cells
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T or F? Changes in chromatin structure and histone-DNA binding are associated with changes in gene activity.
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False
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What do nucleosomes do?
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Nucleosomes seem to be able to fold enormous lengths of DNA into the tiny space available in the cells nucleus.
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What are 3 main differences between DNA and RNA?
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RNA has one strand, the sugars are different, and RNA has uracil instead of thymine
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T of F? RNA is like a disposable copy of DNA segment.
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True
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What is the importance of the cells ability to copy a single DNA sequence into RNA?
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It makes it possible for a single gene to produce hundreds or even thousands of RNA molecules
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What is one job in which most RNA molecules are involved?
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Protein synthesis or the assembly of amino acids into proteins is controlled by RNA.
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Many RNA molecules from eukaryotic genes have sections called __________ edited out of them before they become functional. The remaining pieces, called _________ are spliced together.
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nucleus, exons
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T or F? RNA editing occurs in the cytoplasm of the cell.
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False
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What are 2 reasons for why some RNA molecules are cut and spliced?
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The introns are cut out of RNA molecules while they are still in the nucleus. The remaining exons are the spliced back together to form the final mRNA.
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Proteins are made by joining ________ into long chains called polypeptides.
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Amino Acids
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How can 4 bases in RNA carry instructions for 20 different amino acids?
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The amino acids use a polypeptide.
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What is a codon?
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It consists of three consecutive nucleotides that specify a single amino acid that is to be added top the polypeptide.
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How many possible 3-base codons are there?
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4
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T or F? All amino acids are specified by only one codon.
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False
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What is the starting codon for protein synthesis?
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AUG
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What occurs during the process of translation?
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During translation, the cell uses information from messenger RNA to produce proteins.
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Where does translation take place?
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Translation takes place on ribosomes.
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What is anti-codon?
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A group of 3 bases on a RNA molecule that are complementary to an mRNA codon.
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What is the role of DNA?
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master planner, remains in the nucleus
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What is role of RNA?
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goes to the ribosome in the cytoplasm, makes blueprint
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Many proteins are ____________, which catalyze and regulate chemical reactions.
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enzymes
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T or F? Genes are the keys to almost everything that living cells do.
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True
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What are mutations?
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The changing of the structure of a gene resulting in a variant form that may be transmitted to subsequent offspring.
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T or F? Chromosomal mutations result from changes in a single gene.
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True
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Mutations that occur at a single point in the DNA sequence are __________ mutations.
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Point
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A mutation involving the insertion or deletion of a nucleotide is a __________ mutation
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Frameshift
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What is deletion?
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The loss of all or a part of a chromosome
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What is duplication?
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It produces extra copies of parts of a chromosome.
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What is inversion?
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Part of a chromosome becomes oriented in the reverse of its usual direction.
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What is trans-location?
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Occur when part of one chromosomes breaks off and attaches to another.
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What is true about gene mutation?
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Point mutations that involve the insertion or deletion of nucleotide change the reading frame of the genetic message. Frameshift mutations affect every amino acid that follows the point of the mutation.
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Mutations that cause dramatic changes in protein structure are often _________.
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Harmful
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Mutations are a source of ________ in a species.
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Genetic Variability
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What is polyploidy?
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Condition in which an organism has extra sets of chromosomes.
