Dent remaining chapters :) Flashcards
1
Q
What do you need to be able to purify a gene
A
- A method of isolating the cell components
2, An assay for genetic materialness
2
Q
Hydrophobic interactions are important when forming what protein structures
A
Tertiary protein structures only
3
Q
The transport of sugar monomers from a higher concentration inside the cell than outside the cell is …
A
Sodium driven secondary active transport
4
Q
In oxidative phosphorylation, _______ is the most immediate energy source during ATP synthesis
A
the oxidation of glucose and other organic compounds
5
Q
Epithelial cells attach to the underlying extracellular matrix by …
A
focal adhesions
6
Q
RNA is not expected in what organelle
A
the golgi apparatus
7
Q
If the protein gradient is destroyed, what happens in the ETC
A
No ATP would be made by ATP synthase
8
Q
A human cell is haploid in what stage of meiosis
A
Metaphase II
9
Q
What is an assay
A
A way of measuring something (it can measure a substance or an abstract phenomenon)
10
Q
What is the transforming principle (friedrich griffon)
A
The term was given to the substance that could be transferred from non living cells to living cells, causing the living cell to show characteristics of the non living cell
11
Q
Describe Frederick Griffith’s experiment surrounding Streptococcus pneumoniae
A
He studied two strains: smooth (S), which were virulent, and rough (R), which were non-virulent. He found that heat-killed S bacteria, when mixed with live R bacteria, caused the R bacteria to transform into virulent S bacteria, killing the mice. This phenomenon suggested that the S strain somehow transferred a heritable trait to the R strain.
12
Q
What substance was transferred from S strain to R strain
A
DNA despite this people weren’t convinced this was hereditary it was either DNA or proteins
13
Q
How was it determined that DNA is the hereditary component not proteins
A
Hershey and Chase conducted an experiment where they radioactively labeled the virus’s DNA with 32P and its protein with 35S. After allowing the virus to infect bacteria and blending the mixture to shear off the protein coat, they found that the bacteria, which formed a pellet, produced more virus containing 32P but almost no 35S, showing that DNA, not protein, was the viral genetic material.
14
Q
What did Watson and Crick focus on to understand DNA?
A
Watson and Crick focused on determining the three-dimensional structure of DNA. They believed understanding its structure was key to explaining how DNA could replicate and determine an organism’s phenotype.
15
Q
What are the four nucleotides in DNA?
A
DNA consists of four types of nucleotides: deoxyadenosine (A), deoxyguanosine (G), deoxycytidine (C), and thymidine (T).
16
Q
What did Erwin Chargaff discover about DNA bases?
A
Erwin Chargaff discovered that in DNA, the amount of adenine (A) equals thymine (T) (2 bonds), and the amount of guanine (G) equals cytosine (C) (3 bonds). This finding was crucial in understanding base pairing and helped form the foundation for Watson and Crick’s double-helix model.
17
Q
What did Franklin and Wilkins discover about DNA?
A
They used X-ray diffraction to reveal that DNA is double-stranded and has a helical structure. Their discovery provided key data that helped Watson and Crick build their model of the DNA structure.
18
Q
What is the structure of the DNA molecule?
A
DNA has a double helix structure, with two strands running in opposite directions. The nitrogenous bases are located in the center, forming base pairs, while the sugar-phosphate backbone is on the outside, giving the molecule stability.
19
Q
Why is the DNA molecule antiparallel?
A
The two strands of DNA are antiparallel, meaning they run in opposite directions. This orientation is crucial for proper base pairing and ensures accurate replication of DNA during cell division.
20
Q
What is meant by “reverse complement” in DNA?
A
The two strands of DNA are reverse complements, meaning that the sequence on one strand dictates the sequence on the other, but in reverse order. This allows for the precise base pairing between adenine and thymine, and guanine and cytosine.
21
Q
What is the key feature of the DNA structure that allows for replication?
A
DNA’s complementary base pairing (A/T and G/C) ensures that each strand serves as a template for a new strand. This allows the DNA molecule to replicate accurately, creating two identical copies during cell division.
22
Q
What are the three proposed mechanisms for DNA replication?
A
The three proposed mechanisms for DNA replication were conservative replication, where the original strands stay together; semiconservative replication, where each old strand pairs with a new strand; and dispersive replication, where the DNA is fragmented and recombined.
23
Q
What experiment proved that DNA replication is semiconservative?
A
The Meselson and Stahl experiment showed that DNA replication is semiconservative. By using isotopes of nitrogen, they demonstrated that after one round of replication, the DNA molecules consisted of one old and one new strand.
24
Q
What is required for DNA synthesis in a test tube?
A
In a test tube, DNA synthesis requires template DNA, nucleotides, DNA polymerase, and a ragged end, or a partially single-stranded region, to begin the replication process. These components allow for the synthesis of a new DNA strand using the template.
25
What direction does DNA polymerase synthesize new DNA strands?
DNA polymerase synthesizes new DNA in the 5' to 3' direction. It adds nucleotides to the 3' end of the growing strand, using the 5' to 3' strand of the template as a guide.
26
What enzyme unwinds the DNA strands during replication?
Helicase is the enzyme responsible for unwinding the DNA double helix during replication. It uses energy from ATP to separate the two DNA strands, making them available for copying.
27
What is the role of primase in DNA replication?
Primase adds a short RNA primer to the template strand during DNA replication. This primer provides a starting point for DNA polymerase to begin adding nucleotides, allowing DNA replication to proceed.
28
Where does DNA replication start in cells (OR)?
DNA replication begins at specific locations on the DNA called origins of replication. In bacteria, there is usually one origin, while in eukaryotes, there are many origins along each chromosome to speed up the process.
29
What is the lagging strand in DNA replication?
The lagging strand is synthesized discontinuously in short fragments known as Okazaki fragments. This occurs because DNA polymerase can only synthesize in the 5' to 3' direction, and the lagging strand runs in the opposite direction.
30
What are Okazaki fragments?
Okazaki fragments are short segments of DNA that are synthesized on the lagging strand during DNA replication. These fragments are joined together later by DNA ligase to form a continuous strand.
31
What is the role of DNA polymerase I in DNA replication?
DNA polymerase I removes the RNA primers from the newly synthesized DNA strands and fills in the gaps with DNA. It helps ensure that the DNA strands are fully formed and correct after replication.
32
What is the difference between an auxotroph and a prototroph?
Auxotrophs are mutants that require specific compounds in their growth media to survive because they cannot produce certain metabolites. In contrast, prototrophs are wild-type organisms that can synthesize all compounds needed for growth.
33
What was the focus of Beadle and Tatum’s experiments?
Beadle and Tatum focused on identifying mutants that required specific metabolic precursors to grow. This allowed them to understand metabolic pathways and the enzymes involved.
34
What is an example of a metabolic pathway studied by Beadle and Tatum?
Beadle and Tatum studied the pathway for making arginine in Neurospora. They identified which enzymes were missing in mutants by supplementing the growth media with compounds downstream of the blocked pathway.
35
What are auxotrophs in metabolic research?
Auxotrophs are mutants that cannot produce certain compounds required for growth and must be supplemented with these compounds in the growth media. These are contrasted with prototrophs, which can synthesize all necessary compounds.
36
How did Beadle and Tatum identify the missing enzyme in a mutant?
By supplementing the growth media with compounds that are downstream of a blocked step in the metabolic pathway, Beadle and Tatum identified the missing enzyme. This was possible because the mutant could only grow with these additional compounds.
37
How is phenylalanine modified for use in protein synthesis?
Phenylalanine can be chemically modified by tRNA synthetase to be converted into alanine. Modified tRNAs carrying alanine can then be incorporated into proteins at positions where phenylalanine should have been.
38
What happens if the anticodon of a tRNA is mutated?
If the anticodon of a tRNA is mutated, for example, changing from phenylalanine to serine, the tRNA will still carry the wrong amino acid (serine) to the ribosome, incorporating it into the protein where the original amino acid (phenylalanine) should be.
39
How does the genetic code relate to language and arbitrariness?
The genetic code is arbitrary, similar to how different languages use different words to describe the same thing. The assignment of codons to amino acids occurred by chance and became fixed over time.
40
Why is the genetic code considered fixed?
The genetic code is fixed because altering it would produce nonfunctional proteins, which could impair an organism’s survival. This fixation ensures that organisms can communicate genetic information effectively.
41
How is the genetic code universal?
The genetic code is almost universal, meaning all organisms use the same codon-to-amino acid translation system. This suggests that all living organisms share a common ancestor that utilized the same genetic code.
42
Why can't the genetic code be easily changed in organisms?
Changing the genetic code would result in the production of nonsense proteins that cannot function properly. This would disrupt cellular processes and hinder the organism's survival.
43
How does the ribosome read the genetic code?
The ribosome reads the genetic code by matching codons on the mRNA with complementary anticodons on tRNA molecules, ensuring that the correct amino acid is added to the growing protein chain.
44
What was the role of the tRNA synthetase in the experiments?
tRNA synthetase plays a crucial role in charging tRNAs with the correct amino acid. In experiments, it could be modified to attach a different amino acid to a tRNA, affecting protein synthesis.
45
What does the concept of a "universal" genetic code imply?
The idea that the genetic code is universal suggests that the same codons specify the same amino acids across all forms of life. This supports the theory that all organisms share a common evolutionary ancestor.
46
What can happen if the codon usage is altered in an organism?
Altering codon usage in an organism could lead to the production of dysfunctional proteins. Since the genetic code is fixed, such changes would likely result in harmful mutations that prevent proper cellular function.
47
How does Beadle and Tatum’s work relate to enzyme deficiencies?
Beadle and Tatum’s work demonstrated that specific enzyme deficiencies in a metabolic pathway could be identified by growing mutants in media supplemented with the compounds downstream of the blocked step. This helped to link enzymes to specific metabolic functions.
48
What is epistasis?
Epistasis occurs when the expression of one gene is modified (ei masked, inhibited) by one or more genes
49
Give an example of epistasis in mice
The interaction between the albino (Aa) and agouti (Bb) loci. Albino (aa) blocks pigment production, overriding the effects of the agouti gene.
50
What did Garrod conclude about alkaptonuria?
He deduced that alkaptonuria results from the absence of a specific enzyme, indicating a link between genes and enzymes.
51
What is the central dogma of molecular biology?
Information flows from DNA to RNA to protein.
52
Where is DNA located, and where are proteins made?
DNA is in the nucleus; proteins are made in the cytoplasm by ribosomes.
53
What role does RNA play in protein synthesis?
RNA carries genetic information from the DNA to ribosomes for protein synthesis.
54
What enzyme transcribes DNA to RNA?
RNA polymerase.
55
In what direction does RNA polymerase synthesize RNA?
5’ to 3’ direction.
56
What determines how many amino acids are encoded by nucleotide sequences?
Three nucleotides per codon = 64 codons, encoding 20 amino acids.
57
What is tRNA’s role in translation?
tRNA carries amino acids and contains anticodons complementary to mRNA codons.
58
What is aminoacyl tRNA synthetase?
An enzyme that attaches the correct amino acid to its tRNA.
59
What is wobble base pairing?
Flexibility in the third base of a codon-anticodon pairing, allowing some redundancy.
60
What does it mean that transcription and translation are not strictly sequential?
In prokaryotes, translation can begin before transcription finishes; in both domains, proteins can begin functioning before translation ends.
61
What are the three main stages of translation?
Initiation, elongation, and termination.
62
What is the start codon in mRNA?
AUG, which codes for methionine.
63
What helps ribosomes identify the start codon in eukaryotes?
The ribosome binds near the 5’ cap and scans for the first AUG.
64
What is the Shine-Dalgarno sequence?
A ribosomal binding site in prokaryotic mRNA upstream of the start codon.
65
What are the three sites in the ribosome?
A site (aminoacyl), P site (peptidyl), and E site (exit).
66
What happens at the A site of the ribosome?
A new charged tRNA enters and pairs with the mRNA codon.
67
What happens at the P site of the ribosome?
The growing polypeptide is held and elongated by peptide bond formation.
68
What happens at the E site of the ribosome?
The empty tRNA exits the ribosome.
69
What catalyzes the formation of peptide bonds?
The ribosome’s rRNA (a ribozyme function).
70
What is translocation in translation?
The ribosome moves along the mRNA, shifting the tRNA from A to P to E.
71
What signals translation termination?
A stop codon (UAA, UAG, or UGA) in the mRNA.
72
What are release factors?
Proteins that recognize stop codons and terminate translation.
73
What is a polysome?
A cluster of ribosomes translating the same mRNA simultaneously.
74
How is translation energy provided?
By GTP and ATP hydrolysis during initiation and elongation.
75
What is the role of the 5’ cap and 3’ poly-A tail in translation?
They help stabilize mRNA and initiate translation in eukaryotes.
76
How does the ribosome know where to start translating in prokaryotes?
The Shine-Dalgarno sequence aligns the ribosome with the start codon.
77
What happens if there's a mutation in the start codon?
Translation may not begin, or it might start at the wrong site.
78
Why is the correct reading frame essential?
A shift in reading frame alters every downstream codon and can make nonfunctional proteins.
79
How do antibiotics target translation?
Many interfere with bacterial ribosomes without affecting eukaryotic ones, exploiting structural differences.
80
What are the criteria used to classify viruses?
Host specificity, genetic material (DNA or RNA, ss or ds), size/shape, presence of envelope, glycoproteins, lipid bilayer, and nucleocapsid.
81
What is a virion?
A complete virus particle consisting of nucleic acid enclosed in a protein coat, sometimes with a lipid envelope.
82
What is the difference between a lytic and lysogenic cycle?
Lytic cycle destroys the host cell; lysogenic cycle integrates viral DNA into the host genome, allowing replication without killing the cell immediately.
83
What is a prophage?
A phage genome that is integrated into the bacterial chromosome during the lysogenic cycle.
84
What triggers a prophage to enter the lytic cycle?
Environmental signals or stress can activate the prophage to excise and replicate.
85
How are retroviruses similar to lysogenic phages?
Retroviruses reverse-transcribe RNA into DNA, which integrates into the host genome and can remain inactive for long periods.
86
What is transformation in bacteria?
The uptake of naked DNA fragments from the environment by a bacterium.
87
What is transduction?
The transfer of bacterial DNA via a bacteriophage.
88
What is generalized transduction?
Random pieces of bacterial DNA are mistakenly packaged into phages and transferred to new hosts.
89
What is specialized transduction?
Only specific bacterial genes near the prophage site are transferred due to imprecise excision of the prophage.
90
What is conjugation?
Direct transfer of DNA between two bacterial cells through a pilus, usually involving a plasmid.
91
What is the role of the F plasmid in conjugation?
It allows F+ cells to form pili and transfer genetic material to F− cells.
92
What is an Hfr strain?
A bacterial strain with the F plasmid integrated into its chromosome, allowing chromosomal gene transfer during conjugation.
93
How can conjugation be used to map bacterial genes?
By interrupting conjugation at different time points and observing gene transfer order.
94
What are prototrophs?
Bacteria that can grow on minimal media, indicating they have all necessary biosynthetic genes.
95
What is an operon?
A group of genes under the control of a single promoter, transcribed together as one mRNA.
96
What is the lac operon?
A gene system in E. coli that is induced in the presence of lactose and encodes proteins to metabolize lactose.
97
What does the lac repressor do?
Binds the operator region to prevent transcription of the lac operon in the absence of lactose.
98
How does the trp operon differ from the lac operon?
Trp is a repressible operon (turned off by tryptophan), while lac is inducible (turned on by lactose).
99
How does the trp operon regulate gene expression in the presence of tryptophan?
When tryptophan is abundant, it acts as a co-repressor, binding to the trp repressor protein. This activated repressor then binds to the operator region of the operon, blocking RNA polymerase and inhibiting transcription. This is an example of negative feedback regulation.
100
What happens to the trp operon when tryptophan is scarce?
The repressor protein cannot bind to the operator without tryptophan as a co-repressor. This means the operon is not blocked, and transcription of genes for tryptophan biosynthesis proceeds, allowing the cell to produce its own tryptophan.
101
What are exons?
Exons are the regions of DNA within a gene that are transcribed and remain in the final mRNA product; they are the coding sequences used for protein synthesis.
102
What are introns and how are they removed?
Introns are non-coding regions within genes that are transcribed but then removed through RNA splicing before translation.
103
What experimental evidence supports the presence of introns?
Scientists mixed single-stranded DNA with mature mRNA, and upon annealing, loops formed—indicating the presence of DNA regions not present in the mRNA, i.e., introns.
104
What are snRNPs and what is their function?
snRNPs (small nuclear ribonucleoproteins) recognize specific intron-exon boundaries and catalyze the splicing reaction, removing introns and joining exons.
105
What is the 5’ cap and why is it important?
A methylated guanosine cap is added to the 5’ end of mRNA. It stabilizes the RNA and is crucial for translation initiation and nuclear export.
106
What is the purpose of the poly-A tail?
The poly-A tail is a string of ~100 adenines added to the 3’ end of mRNA, enhancing mRNA stability and aiding in translation and transport out of the nucleus.
107
What is telomerase and what role does it play?
Telomerase is an enzyme that extends telomeres (non-coding repeats at chromosome ends), preventing loss of genetic information during replication.
108
Why don’t most human cells express telomerase?
Telomerase is typically inactive in most somatic cells, leading to progressive telomere shortening, which contributes to cellular aging and limits cell division.
109
How is telomerase linked to cancer?
Many cancer cells reactivate telomerase, allowing them to replicate indefinitely and evade the normal limits on cell division.
110
What are centromeres composed of and why are they important?
Centromeres are composed of repetitive non-coding DNA that helps form the kinetochore, where spindle fibers attach during cell division.
111
What are transposable elements?
Transposable elements, or jumping genes, are DNA sequences that can move to new locations within the genome, often by encoding a transposase enzyme.
112
What are retrotransposons?
Retrotransposons move via an RNA intermediate and use reverse transcriptase to copy themselves back into DNA and insert into the genome.
113
What is a pseudogene?
A pseudogene is a non-functional gene copy, often formed when mRNA is reverse-transcribed and inserted into the genome without introns or proper regulatory elements.
114
What are processed pseudogenes?
These are pseudogenes created by reverse transcription of mRNA, lacking introns and regulatory sequences, and typically not expressed.
115
What are ribozymes?
Ribozymes are RNA molecules with enzymatic activity that can catalyze specific biochemical reactions, such as splicing.
116
How do ribozymes support the RNA world hypothesis?
Since ribozymes can store genetic information and catalyze reactions, they suggest that early life may have relied on RNA alone, supporting the RNA world hypothesis.
117
What is the RNA world hypothesis?
It proposes that early life forms used RNA for both genetic storage and enzymatic functions, preceding DNA and protein-based life.
118
What’s a key difference between DNA transposons and retrotransposons?
DNA transposons move directly as DNA, while retrotransposons use an RNA intermediate and reverse transcription to reintegrate.
119
How can transposable elements affect the genome?
They can cause mutations, gene disruption, or genome expansion; some may even influence gene regulation or genome evolution.
120
Why are telomeres often compared to protective caps?
Like caps, telomeres buffer the ends of chromosomes, protecting essential genes from degradation during DNA replication.
121
Why do different cells in the body appear different if they all have the same DNA?
Because they express different subsets of genes. Gene regulation determines which genes are turned on or off, leading to different cell types and functions.
122
What are housekeeping genes?
These are genes that are always expressed in all cells because they are essential for basic cellular functions like metabolism and transcription.
123
How is transcription regulated in eukaryotic cells?
Through promoters, transcription factors, enhancers, and silencers that influence whether RNA polymerase can initiate transcription.
124
What is the TATA box?
A DNA sequence found in many eukaryotic promoters that helps position RNA polymerase for transcription initiation.
125
What are the three types of eukaryotic RNA polymerases and their functions?
Pol I: makes rRNA
Pol II: makes mRNA
Pol III: makes tRNA and snRNA
126
What are enhancers?
Regulatory DNA sequences that increase transcription. They can be located far from the gene, work in any orientation, and regulate genes across long distances.
127
What are silencers?
DNA elements that bind transcriptional repressors to inhibit transcription of specific genes.
128
How can enhancers regulate genes on different chromosomes?
By binding transcription factors that interact with the transcription machinery, allowing co-regulation of multiple genes even across chromosomes.
129
What is X-inactivation and when does it occur?
The random inactivation of one X chromosome in females during early embryogenesis. This creates genetic mosaics and is seen as a Barr body.
130
What is euchromatin?
Lightly packed DNA that is transcriptionally active, often associated with gene-rich regions.
131
What is heterochromatin?
Densely packed DNA that is transcriptionally inactive, often containing repetitive sequences and structural elements.
132
What is the role of chromatin remodeling in gene expression?
Chromatin remodeling proteins reposition or remove histones, exposing DNA so transcription factors and RNA polymerase can bind.
133
What is alternative splicing?
A process where different combinations of exons are joined together from the same gene, producing different proteins in different cell types.
134
What is an example of alternative splicing?
The doublesex gene in fruit flies, which produces different protein isoforms in males and females to regulate sex-specific traits.
135
How does mRNA stability influence gene expression?
More stable mRNA stays in the cytoplasm longer, allowing more protein synthesis, while unstable mRNA is degraded quickly, reducing expression.
136
What determines mRNA stability?
The 5’ and 3’ untranslated regions (UTRs) and specific regulatory sequences that influence degradation.
137
What is RNA interference (RNAi)?
A mechanism where small RNA molecules, like siRNA, bind complementary mRNA and block translation or trigger degradation.
138
How is RNA interference triggered?
Often by the transcription of RNA that forms a hairpin loop, which is processed into siRNAs that silence specific mRNAs.
139
What is post-translational regulation?
Control of protein activity after translation, including modifications, activation/inhibition, or degradation.
140
What is ubiquitination and what does it signal?
The attachment of ubiquitin molecules to a protein, marking it for degradation by the proteasome.
141
What is genetic engineering?
Genetic engineering is the process of altering the genotype of an organism by inserting genes from another species or modifying native genes to create new traits or phenotypes.
142
What is selective breeding?
A non-technological method used for generations to improve crops and animals by choosing and breeding individuals with desired traits.
143
What is gene cloning and why is it done?
Gene cloning is the process of transferring a gene from one organism to another, often to study gene function or to express a protein in a new organism.
144
What is an example of gene cloning for medical use?
Human insulin production in bacteria: inserting the human insulin gene into bacteria so they can produce insulin for diabetic patients.
145
What happens in the body when glucose levels are high?
Pancreatic beta cells release insulin, signaling the liver to convert glucose to glycogen for storage.
146
What happens when glucose levels are low?
Pancreatic alpha cells secrete glucagon, prompting the liver to break down glycogen into glucose for energy.
147
Why did pig insulin eventually fail in diabetic patients?
Although initially effective, it caused immune reactions over time due to small differences in the genetic code between pig and human insulin.
148
How can we get the human insulin gene into a bacterium?
Use restriction enzymes like BamHI to cut DNA at specific sites, creating sticky ends that can be ligated into a plasmid.
149
What are sticky ends?
Short single-stranded DNA overhangs created by restriction enzymes that allow complementary base pairing and facilitate the insertion of new DNA.
150
What enzyme is used to join DNA fragments during cloning?
DNA ligase, which covalently links the sugar-phosphate backbones of the DNA strands.
151
What problem arises when inserting human genes into bacteria?
Human genes contain introns, which bacteria cannot splice, preventing them from producing functional proteins from genomic DNA.
152
How is the intron issue solved when cloning human genes into bacteria?
Use reverse transcriptase to make cDNA from mature human mRNA, which lacks introns.
153
What is cDNA?
Complementary DNA made from mRNA using reverse transcriptase; it represents the coding sequence of a gene without introns.
154
Why is gel electrophoresis used in gene cloning?
To verify the size of DNA fragments and ensure the correct gene was inserted into the plasmid.
155
What are restriction endonucleases and why are they important in cloning?
Enzymes that cut DNA at specific sequences; they allow precise editing and insertion of genes.
156
What is a plasmid and how is it used in cloning?
A small circular DNA molecule in bacteria that can replicate independently and serve as a vector to carry foreign genes.
157
What does it mean for a gene to be "expressed" in a new organism?
The gene is transcribed and translated, producing a functional protein in the host organism.
158
What is one major advantage of bacterial cloning systems?
Bacteria can rapidly replicate and produce large quantities of proteins like insulin at low cost.
159
What is a key challenge in expressing eukaryotic genes in prokaryotes?
Eukaryotic regulatory elements (like promoters or introns) may not function in bacteria, requiring special design of expression systems.
160
What is the main role of reverse transcriptase in genetic engineering?
To convert mature mRNA into DNA, which can then be cloned into vectors for expression in bacteria.
161
What is PCR and what is it used for?
Polymerase Chain Reaction (PCR) is a technique used to amplify specific DNA sequences rapidly in vitro. It requires DNA template, primers, DNA polymerase (like Taq), and nucleotides.
162
What are the three main steps in a PCR cycle?
Denaturation (94–96°C) – DNA strands separate
Annealing (50–65°C) – Primers bind to target sequences
Extension (72°C) – Taq polymerase synthesizes new DNA
163
What is DNA sequencing?
A technique used to determine the order of nucleotides (A, T, C, G) in a DNA molecule. Methods include Sanger sequencing and newer next-gen sequencing.
164
What is an RFLP?
Restriction Fragment Length Polymorphism (RFLP) is a difference in DNA sequence that alters restriction enzyme cut sites, resulting in DNA fragments of different lengths when digested and analyzed by gel electrophoresis.
165
How are RFLPs detected?
DNA is digested with a restriction enzyme, run on a gel, and probed with a DNA sequence that binds to a specific region. Differences in fragment lengths indicate polymorphisms.
166
What are RFLPs used for?
Used in genetic mapping, paternity testing, forensics, and diagnosing genetic disorders by detecting mutations that affect restriction sites.
167
Why are RFLPs useful in tracking genetic diseases?
If an RFLP is closely linked to a disease-causing gene, it can be used as a marker to track inheritance of the disease allele in families.
168
What is Cystic Fibrosis (CF)?
A genetic disorder caused by mutations in the CFTR gene, leading to thick, sticky mucus that affects the lungs, pancreas, and other organs.
169
What is the most common mutation in CFTR that causes cystic fibrosis?
deletion of 3 nucleotides -> removing phenylalanine
170
What is the relationship between CF and autosomal recessive inheritance?
CF is inherited in an autosomal recessive manner; an individual must inherit two defective CFTR alleles (one from each parent) to have the disease.
171
What is CF caused by?
- It is caused by a mutation in the gene encoding a chloride channel that regulates the flow of chloride across the plasma membrane of epithelial cells
- Specifically, the flow of chloride into the lung
- When chloride isn’t regulated correctly, mucus becomes sticky and bacteria are able to grow
