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Biology
Ch. 12
| Question | Answer |
|---|---|
| What did Frederick Griffith want to learn about bacteria? | How bacteria makes people sick and how certain types of bacteria produces a serious lung disease known as pneumonia |
| The strain of bacteria that caused pneumonia grew into _______ colonies on culture plates; harmless bacteria produced colonies with ______ edges. | smooth/rough |
| Mice injected with bacteria from ______ coloonies died. | smooth |
| Mice injected with a mixture of bacteria from heat-killed smooth colonies and live rough colonies _____, | died |
| What result from Griffith's experiment suggested that the cause of pneumonia was not a chemical poison released by the disease-causing bacteria? | because the mice survived when injected with the heat-killed bacteria |
| What is transformation? | a process when a harmless strain of bacteria changed into a disease-causing strain. |
| What hypothesis did Griffith form from the results of his experiments? | When the live, harmlss bacteria & the heat-killed bacteria were mixed together, some factor was transferrd from the heat-killed cells into the live cells. That factor might contain a gene w/ info that could change harmless bacteria in2 disease causin ones |
| T/F Avery and his colleagues thought that the molecule required in transformtaion might also be the molecule of the gene. | true |
| Briefly describe how Avery and his group determined which molecule was most important for transformation? | Avery and his colleagues made an extract (juice) from the heat killed bacteria, treated it w/ enzymes that killed proteins, lipids, and carbs, transformation occured. |
| Transformation did not occur when _____________ was destroyed. | nucleic acid DNA |
| What was the conclusion from Avery's experiments? | DNA is the nucleic acid that stores and transmits the genetic info from one generation of an organism to the next. |
| What is a bacteriophage? | One kind of virus that infects and kills bacteria |
| What makes up bacteriophage? | Protein coat & DNA core |
| What happens when a bacteriophage infects a bacterial cell? | The virus attaches to the surface of the cell and injects DNA into it. The viral genes produce new bacteriophages and they gradually destroy the bacterium. When the cell splits open, hundreds onf new viruses break out. |
| How would Hershey and Chase learn whether genes were made of protein or DNA? | Grew viruses in cultures containing radioactive isotopes of phosphorus - 32 (32P) and sulfer -35(35S). Proteins contain almost no phosphorus and DNA contains almost no sulfur |
| Which molecule for which phosphorus-32 (32P) is used as a radioactive marker. | DNA |
| T/F If 35S was found in the bacteria, it would mean that the viruses' DNA had been injected into the bacteria. | false |
| What results did Hershey and Chase observe? | The genetic material of the bacteriophage was DNA not protein. |
| Hershey and Chase concluded that the genetic material of the bacteriophage was _____. | DNA |
| What are 3 critical things that genes were known to do? | 1Carry info from one generation to the next 2Put that info to work by determining the heritable characteristics of organisms 3Genes had to be easily copied, b/c all of a cell's genetic info is replicated every time a cell divides |
| Adenine, guanine, cytosine, and thymine are 4 kinds of ___________ bases in DNA. | nitrogenous |
| T/F Adenine and guanine are larger molecules than cytosine adn thymine because they have 2 rings in their structure. | true |
| What forms the backbone of a DNA chain? | sugar and phosphate groups of each nucleotide |
| T/F The nucleotides must be joined together in a specific order. | false |
| According to Chargaff's rules, the %s of _________ are equal to thymine and the %s of ________ are equal to guanine in the DNA molecule. | Guanine/cytosine |
| Rosalind Franklin's work with X-ray diffraction showed that the DNA molecule is shaped like a _______ and contains ______ strands. | helix/two |
| How did Francis Crick and James Watson try to understand the structure of DNA? | by building tree-dimensional models of the molecule |
| How did Watson and Crick describe the structure of DNA? | double helix, two strands were wound around eachother |
| T/F According to the principle of base pairing, hydrogen bonds could form only between adenine and cytosine. | false |
| What is the location of DNA in prokaryotic cells? | cytoplasm |
| T/F Most prokaryotes contian a single, cingular DNA molecule. | true |
| Eukaryotic DNA is generally located in the cell _______ in the form of a number of chromosomes. | nucleus |
| T/F All organisms have the same number of chromosomes. | false |
| T/F The E. Coli chromosome is longer than the diameter of an individual E. Coli bacterium. | true |
| T/F The DNA in a eukaryotic cell is very loosely packed. | False |
| T/F Prokaryotic cells contian more DNA than eukaryotic cells. | False |
| T/F A human cell contains more than 1 meter of DNA | True |
| The DNA of the smallest human chromosome is nearly 10 times as long as many bacterial chromosomes. | True |
| Eukaryotic chromosomes contian both DNA and protein, packed together to form _________. | chromatin |
| What are histones? | DNA that is tightly coiled around proteins |
| Why are individual chromosomes visible only during mitosis? | The fibers of each individual chromosome are drawn together forming the tightly packed chromosomes you can see through a light microscope in dividng cells |
| T/F Changes in chromatin structure and histone-DNA binding may be associated with changes in gene activity. | true |
| 2 Roles of nucleosomes | 1Fold enormous lengths of DNA into the tiny space available in the cell nucleus 2Regulate how genes are "read" to make proteins |
| What occurs during the process of replication? | the DNA molecule separates into 2 strands, then produces 2 new complementary strads following the rules of base pairing. |
| The DNA molecule ________, or unzips, into two strands. | separates |
| Each strand serves as a ____________, or model, to produce the new strands. | template |
| Two new ____________ strands are produced, following the rules of ___________. | complementary/base pairing |
| T/F In eukaryotic chromosomes, DNA replication begins at a single point in the chromosome and proceeds in two directions. | true |
| The sites where DNA replication and separation occur are called ________________. | replication forks |
| What occurs when a molecule of DNA is "unzipped"? | When the hydrogen bonds between the base pairs are broken and the two strands of the molecule unwind |
| What is the complementary strand of bases for a strand with the bases TACGTT? | ATGCAA |
| T/F Each DNA molecule resulting from replication has one original strand and one new strand. | true |
| 2 Major roles of DNA polymerase in the process of DNA replication | 1Polymers individual nucleotides to produce DNA 2"Proofreads" each new DNA strand, helping to maximize the odds that each molecule is a perfect copy of the original DNA |
| 3 Main Differences between RNA and DNA | 1Sugar in RNA is ribose instead of deoxyribose 2RNA is generally single-stranded 3RNA contains uracil in place of thymine |
| T/F RNA is like a disposable copy of a DNA segment. | true |
| What is the importance of the cell's ability to copy a single DNA sequence into RNA? | Makes it possible for a single gene to produce hundreds or even thousands of RNA molecules |
| What is the one job in which most RNA molecules are involved? | protein synthesis |
| What is the function of messenger RNA? | Carries copies of the instructions for assembling amino acids from DNA to the rest of the cell. |
| What is the function of Ribosomal RNA? | makes up part of ribosomes |
| What is the function of transfer RNA? | Transfers each amino acid to the ribosome to help assemble proteins |
| T/F During transcription, DNA polymerase binds to RNA and separates the DNA strands. | false |
| T/F RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA. | true |
| T/F RNA polymerase binds only to DNA promoters, which have specific base sequences | true |
| T/F Promoters are signals in RNA that indicate to RNA polymerase when to begin transcription | false |
| Many RNA molecules from eukaryotic genes have sections, called ________, edited out of them before they become functional. The remaining pieces, called ________, are spliced together. | introns/exons |
| T/F RNA editing occurs in the cytoplasm of the cell. | false |
| What are 2 explanations for why some RNA molecules are cut and spliced? | 1So a single gene can produce several forms of RNA 2Introns and exons may play a role in evolution; small changes in DNA sequences have dramatic effects in gene expression |
| Proteins are made by joining _____________ into long chains called polypeptides. | amino acids |
| How can only 4 bases in RNA carry instructions for 20 differenct amino acids? | The genetic code is read 3 letters at a time so that each "word" of the coded message is 3 bases long |
| What is a codon? | Each 3 letter "word" in mRNA; consists of 3 consecutive nucleotides that specify a single amino acid that is to be added to the polypeptide |
| What is the number of possible 3 base codes | 64 |
| T/F All amino acids are specified by only one codon. | false |
| What is the codon that serves as the "start" codon for protein synthesis? | AUG |
| What occurs during the process of translation? | The cell uses information from messenger RNA to produce proteins |
| Where does translation occur? | cytoplasm |
| T/F Before translation can occur, messenger RNA must be transcribed from DNA in the nucleus. | true |
| T/F Translation occurs in the nucleus | false |
| T/F It is the job of transfer RNA to bring the proper amino acid into the ribosome to be attached to the growing peptide chain. | true |
| T/F When the ribosome reaches a stop codon, it releases the newly formed polypeptide and the mRNA molecule. | true |
| What is an anticodon? | the three bases on the tRNA molecule;complementary to one of the mRNA codons |
| Master plan (DNA/RNA) | DNA |
| Goes to ribosomes in the cytoplasm (DNA/RNA) | RNA |
| Blue print (DNA/RNA) | RNA |
| Remains in nucleus (DNA/RNA) | DNA |
| Many proteins are _________, which catalyze and regulate chemical reactions. | enzymes |
| T/F Genes are the keys to almost everything that living cells do | false |
| What are mutations | changes in the DNA sequence that affect genetic information |
| T/F Chromosomal mutations result from changes in a single gene. | false |
| Mutations that occur at a single point in the DNA sequence are ______ mutations. | point |
| A mutation involving the insertion or deletion of a nucleotide is a ___________ mutation. | frameshift |
| T/F Point mutations affect just one nucleotide. | true |
| T/F The substitution of one nucleotide for another in the gene never affects the function of the protein. | false |
| T/F Point mutations that involve the insertion or deletion of a nucleotide change the reading frame of the genetic message. | true |
| T/F Frameshift mutations affect every amino acid that follows the point of the mutation. | true |
| What is deletion? | The loss of all or part of a chromosome |
| What is duplication? | A segment of a chromosome is repeated |
| What is inversion? | Part of a chromosome becomes oriented in the reverse of its usual direction |
| What is translocation? | Part of one chromosome breaks off and attaches to another, nonhomologous chromosome |
| What does RNA polymerase bind? | promoters |
| T/F The actions of DNA binding proteins help to determine wheter a gene is turned on or turned off. | true |
| What is an operon? | A group of genes that operate together; must be epressed in order for the bacterium to be able to use the sugar lactose as food; called lac operon |
| What is the function of the genes in the lac operon? | Take lactose across its cell membrand and then break the bond between glucose and galactose; transcribe genes; produced proteins |
| T/F Lactose is a simple sugar. | false |
| T/F To use lactose for food, E coli must take lactose across its cell membrane. | true |
| T/F The bond between glucose and galactose must be broken in order for E. coli to use lactose for food. | true |
| T/F Proteins encoded by the genes of the lac operon are needed only when E. coli is grown on a medium containing glucose. | false |
| How many genes in the lac operon are found in E. coli? | 3 |
| What turns the lac operon off and on? | Repressors turn them off and the presence of lactose turns them on |
| Repressors bind to __________. | operator region |
| Lactose binds to ____________. | repressor protein |
| How does the repressor protein prevent transcription? | When lactose is not present, the repressor binds to the operator region, preventing RNA polymerase from beginning transcription |
| How does lactose cause the lac operon to turn on? | lactose added to medium, a few sugar molecules diffuse in2 cell & bind to repressor proteins. binding of lactose causes repressor protein to change shape in a way that completely alters its DNA binding site, causing repressor to fall off operator. |
| T/F The lac operon is the only example of genes regulated by repressor proteins. | false |
| T/F Many other genes are regulated by repressor proteins. | true |
| T/F Some genes are regulated by proteins that enhance the rate of transcription. | true |
| T/F Celss cannot turn their genes on and off as needed. | false |
| T/F Operons are frequently found in eukaroytoes. | false |
| How are eukaryotic genes usually controlled? | Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex than those of the lac operon |
| What is the function of the TATA box? | helps position RNA polymerase by marking a point just before the point at which transcription begins |
| Eukaryotic promoters are usually found just _______ the TATA box, and they consist of a series of short ______ sequences. | before/DNA |
| 3 Ways in which proteins that bind to enhancer sequences of a gene can work to regulate gene expression. | 1Enhance transcription by opening up tightly packed chromatin. 2Attract RNA polymerase 3Block access to genes |
| Why is gene regulation in eukaryotes more complex than in prokaryotes? | For proper overall function, only a tiny fraction of the available genes needs to be expressed in cells of different tissues throughout the body. The complexity of gene regulation in eukaryotes makes this specificity possible |
| What role do the hox genes play in the development of an organism? | Control the organs and tissues that develop in various parts of the embryo; determine an animal's basic body plan |
| T/F A mutation in a hox gene has no effect on the organs that develop in specific parts of the body. | false |
| T/F In fruit flies, a mutation affecting the hox genes can replace a fly's antennae with a pair of legs. | true |
| T/F The function of the hox genes in humans seems to be almost the same as it is in fruit flies. | true |
| T/F A copy of the gene that controls eye growth in mice does not function in fruit flies. | false |
| Why do common patterns of genetic control for development exist among animals? | All these genes have dexcended from the genes of common ancestors. |
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