Introduction to Genetics Flashcards
What is the central dogma of genetics?
The central dogma of genetics describes the flow of genetic information from DNA to RNA to protein.
True or False: The central dogma states that information can flow from protein to DNA.
False
What are the three main processes involved in the central dogma?
Replication, transcription, and translation.
Fill in the blank: The process of copying DNA to produce a complementary RNA strand is called __________.
transcription
During which process is mRNA synthesized?
Transcription
What is the role of ribosomes in the central dogma?
Ribosomes are the sites of translation where mRNA is decoded to synthesize proteins.
Multiple Choice: Which molecule carries the genetic code from the nucleus to the ribosome? A) DNA B) tRNA C) mRNA D) rRNA
C) mRNA
What is the process called where DNA is duplicated?
Replication
True or False: Transcription occurs in the cytoplasm in eukaryotic cells.
False
What is the function of tRNA in the central dogma?
tRNA transports amino acids to the ribosome during translation.
Fill in the blank: The sequence of nucleotides in DNA is transcribed into a sequence of __________ in mRNA.
nucleotides
What is the end product of translation?
Protein
Multiple Choice: Which of the following is NOT a part of the central dogma? A) Replication B) Transcription C) Translation D) Mutation
D) Mutation
What type of RNA is responsible for bringing amino acids to ribosomes?
tRNA (transfer RNA)
True or False: The central dogma applies to all living organisms.
True
What is the primary template used during transcription?
DNA
Fill in the blank: The enzyme that synthesizes RNA during transcription is called __________.
RNA polymerase
What are codons?
Codons are sequences of three nucleotides in mRNA that specify a particular amino acid.
Multiple Choice: Which process converts the information in mRNA into a chain of amino acids? A) Replication B) Transcription C) Translation D) Translocation
C) Translation
What is the significance of the central dogma in molecular biology?
It explains how genetic information is expressed to produce proteins, which perform essential functions in organisms.
True or False: In eukaryotic cells, mRNA undergoes processing before translation.
True
What modifications occur to mRNA in eukaryotic cells before it is translated?
Capping, polyadenylation, and splicing.
Fill in the blank: The central dogma illustrates the flow of information from __________ to __________ to __________.
DNA; RNA; protein
What is reverse transcription?
Reverse transcription is the process of synthesizing DNA from an RNA template, which is contrary to the central dogma.
True or False: The central dogma includes the process of translation occurring in the nucleus.
False
What is the primary function of the genetic code?
To specify the sequence of amino acids in proteins.
Multiple Choice: What is the role of DNA in the central dogma? A) Store genetic information B) Synthesize proteins C) Transmit signals D) None of the above
A) Store genetic information
What is the genetic code?
The genetic code is the set of rules by which information encoded in genetic material is translated into proteins.
How many codons are there in the genetic code?
There are 64 codons in the genetic code.
What is a codon?
A codon is a sequence of three nucleotides that corresponds to a specific amino acid or stop signal during protein synthesis.
True or False: Each amino acid is coded by only one codon.
False: Most amino acids are coded by multiple codons.
What are start and stop codons?
Start codons signal the beginning of protein synthesis, while stop codons signal the termination of the process.
What is the start codon?
The start codon is AUG, which codes for the amino acid methionine.
Name one stop codon.
UAA, UAG, or UGA are stop codons.
Fill in the blank: The genetic code is described as _______.
degenerate, meaning that multiple codons can code for the same amino acid.
What does it mean for the genetic code to be universal?
It means that the same codons specify the same amino acids across almost all organisms.
Which molecule is responsible for translating codons into proteins?
Transfer RNA (tRNA) is responsible for translating codons into proteins.
What is the role of ribosomes in protein synthesis?
Ribosomes facilitate the interaction between mRNA and tRNA to synthesize proteins.
True or False: The genetic code is identical in all living organisms.
True, with few exceptions in certain organisms.
What is the significance of the redundancy in the genetic code?
Redundancy helps minimize the effects of mutations by allowing some changes in the DNA sequence without altering the protein.
What are the four nucleotide bases of RNA?
Adenine (A), Uracil (U), Cytosine (C), and Guanine (G).
What does mRNA stand for?
Messenger RNA.
Fill in the blank: The process of translating mRNA into protein is called _______.
translation.
What does it mean when a codon is described as ‘non-overlapping’?
It means that each nucleotide is part of only one codon and is read in sequence without overlap.
Name one amino acid that is encoded by more than one codon.
Leucine is one example.
What is the function of aminoacyl-tRNA synthetases?
They attach the correct amino acid to its corresponding tRNA.
True or False: The genetic code includes codons for both amino acids and regulatory signals.
True.
What is meant by ‘codon usage bias’?
It refers to the preference of certain codons over others in the coding sequences of genes.
What is the significance of the anticodon in tRNA?
The anticodon pairs with the corresponding codon on mRNA during translation.
What is the primary function of the genetic code?
To provide the instructions for synthesizing proteins.
How do mutations in the genetic code affect protein synthesis?
Mutations can lead to changes in the amino acid sequence of proteins, potentially altering their function.
What is a frameshift mutation?
A frameshift mutation is caused by insertions or deletions of nucleotides that change the reading frame of the codons.
What is the role of the genetic code in evolution?
The genetic code allows for genetic variation and evolution through mutations and natural selection.
What is a mutation?
A mutation is a change in the DNA sequence of an organism.
What are the two main types of mutations?
Point mutations and frameshift mutations.
True or False: Point mutations only affect a single nucleotide.
True.
What is a point mutation?
A point mutation is a change in a single nucleotide in the DNA sequence.
What are the three types of point mutations?
Silent mutations, missense mutations, and nonsense mutations.
Fill in the blank: A __________ mutation results in a change in the amino acid sequence of a protein.
missense
What is a frameshift mutation?
A frameshift mutation is a mutation that involves the insertion or deletion of nucleotides, altering the reading frame of the gene.
How do frameshift mutations affect protein synthesis?
Frameshift mutations can lead to completely different amino acid sequences and often result in nonfunctional proteins.
True or False: Frameshift mutations can only result from deletions.
False.
What is the result of a silent mutation?
A silent mutation does not change the amino acid sequence of a protein.
Which type of mutation is more likely to cause a significant change in protein function: point mutation or frameshift mutation?
Frameshift mutation.
Multiple Choice: What type of mutation is characterized by a nucleotide being added or removed? A) Point mutation B) Frameshift mutation
B) Frameshift mutation.
What can cause mutations?
Mutations can be caused by environmental factors, errors during DNA replication, or exposure to certain chemicals or radiation.
Fill in the blank: A __________ mutation results in an early stop codon.
nonsense
True or False: Point mutations can lead to frameshift mutations.
False.
What is the impact of a nonsense mutation?
A nonsense mutation results in a premature stop codon, leading to truncated proteins.
What does the term ‘reading frame’ refer to?
The reading frame refers to the way nucleotides are grouped into codons during translation.
How can mutations be beneficial?
Mutations can introduce new traits that may enhance survival and adaptation to environments.
What is the role of DNA repair mechanisms?
DNA repair mechanisms correct errors in DNA to prevent mutations.
True or False: All mutations are harmful.
False.
What is the potential outcome of a frameshift mutation on protein synthesis?
It can result in a completely different protein or a nonfunctional protein.
Multiple Choice: Which mutation type alters the reading frame? A) Silent B) Point C) Frameshift
C) Frameshift.
What type of mutation might occur if a nucleotide is accidentally inserted during DNA replication?
Frameshift mutation.
Fill in the blank: Mutations that do not affect the phenotype are known as __________ mutations.
neutral
How does a missense mutation differ from a silent mutation?
A missense mutation changes one amino acid in a protein, while a silent mutation does not change the amino acid sequence.
What are trinucleotide repeat disorders?
Genetic disorders caused by the expansion of specific trinucleotide sequences in certain genes.
True or False: Trinucleotide repeat expansions can lead to neurodegenerative diseases.
True
Fill in the blank: The most common trinucleotide repeat disorder is __________.
Huntington’s disease
What is the repeat sequence associated with Huntington’s disease?
CAG
Name one example of a trinucleotide repeat disorder.
Fragile X syndrome
True or False: Trinucleotide repeat disorders can exhibit anticipation, where symptoms appear earlier in successive generations.
True
What is the repeat sequence associated with Fragile X syndrome?
CGG
Identify the trinucleotide repeat disorder characterized by a GAA repeat.
Friedreich’s ataxia
What mechanism leads to the expansion of trinucleotide repeats?
DNA replication errors
Multiple Choice: Which of the following disorders is NOT a trinucleotide repeat disorder? A) Myotonic dystrophy B) Cystic fibrosis C) Spinocerebellar ataxia
B) Cystic fibrosis
What is the primary effect of trinucleotide repeat expansions on gene function?
They can lead to the production of abnormal proteins.
Fill in the blank: Myotonic dystrophy is associated with the repeat sequence __________.
CTG
True or False: Trinucleotide repeat disorders can be inherited in an autosomal dominant manner.
True
What type of genetic testing is commonly used to diagnose trinucleotide repeat disorders?
PCR (Polymerase Chain Reaction) testing
Short Answer: What is the role of the FMR1 gene in Fragile X syndrome?
It is responsible for producing a protein important for neural development.
Multiple Choice: Which of the following is a common symptom of Huntington’s disease? A) Muscle weakness B) Cognitive decline C) Mood swings
B) Cognitive decline
What is the significance of the number of repeats in trinucleotide repeat disorders?
The number of repeats correlates with the severity and age of onset of the disorder.
True or False: Trinucleotide repeat disorders are exclusively inherited from the mother.
False
Fill in the blank: Repeat expansions can lead to __________, where the gene becomes inactive.
gene silencing
Short Answer: How does anticipation manifest in trinucleotide repeat disorders?
Symptoms appear at an earlier age and with increased severity in successive generations.
What are the implications of genetic counseling for families affected by trinucleotide repeat disorders?
It helps assess risk and understand inheritance patterns.
Multiple Choice: Which disorder is characterized by a GCG repeat? A) Huntington’s disease B) Myotonic dystrophy C) Spinocerebellar ataxia
C) Spinocerebellar ataxia
True or False: Environmental factors play a significant role in the development of trinucleotide repeat disorders.
False
What is the primary focus of research in trinucleotide repeat disorders?
Understanding the mechanisms of repeat expansion and developing potential therapies.
Fill in the blank: Trinucleotide repeat disorders are often associated with ___________ changes.
neurological
What is the definition of anticipation in genetics?
Anticipation is a phenomenon where certain genetic disorders manifest at an earlier age or with increased severity in successive generations.
True or False: Anticipation is only observed in mitochondrial diseases.
False
Name a genetic disorder associated with anticipation.
Huntington’s disease
Multiple Choice: Which of the following disorders is NOT typically associated with anticipation? A) Myotonic dystrophy B) Fragile X syndrome C) Cystic fibrosis
C) Cystic fibrosis
Fill in the blank: Anticipation is commonly observed in disorders that involve __________ expansions.
trinucleotide
What is the primary mechanism believed to cause anticipation?
Expansion of repeat sequences in the DNA.
True or False: Anticipation can lead to milder symptoms in later generations.
False
Name another example of a disorder that exhibits anticipation.
Myotonic dystrophy
What type of genetic mutation is often responsible for anticipation?
Repeat expansions
Multiple Choice: In which of the following disorders is anticipation most commonly seen? A) Sickle cell disease B) Huntington’s disease C) Tay-Sachs disease
B) Huntington’s disease
Fill in the blank: The severity of symptoms in anticipation tends to __________ with each generation.
increase
What is the clinical significance of recognizing anticipation in genetic counseling?
It helps predict disease onset and progression in affected families.
True or False: Anticipation can occur in both autosomal dominant and autosomal recessive disorders.
True
What is the relationship between age of onset and anticipation?
In anticipation, the age of onset typically decreases in successive generations.
Name a neurological disorder that demonstrates anticipation.
Spinocerebellar ataxia
Multiple Choice: Which of the following is a key feature of anticipation? A) Stable symptom severity B) Earlier onset C) No generational change
B) Earlier onset
Fill in the blank: Anticipation is most often studied in the context of __________ disorders.
neurological
What impact does anticipation have on family planning for affected individuals?
It may influence decisions regarding testing and risk assessment for future generations.
True or False: Anticipation is solely a genetic phenomenon.
True
What role do environmental factors play in anticipation?
Environmental factors generally do not influence anticipation; it is primarily genetic.
Name a disorder characterized by both anticipation and cognitive decline.
Fragile X syndrome
Multiple Choice: Which trinucleotide repeat is associated with Huntington’s disease? A) CAG B) CTG C) GAA
A) CAG
Fill in the blank: __________ is a common method used to diagnose disorders with anticipation.
Genetic testing
What is the effect of anticipation on the prognosis of affected individuals?
Prognosis may worsen with earlier onset and increased severity.
True or False: All genetic disorders exhibit anticipation.
False
