Codon Table (for preschoolers)
Your dog's Genetics and Inheritance
Molecular Biology??
DNA & RNA
(for college students)
(for college students)
Gene Expression & Regulation
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REVOLUTION
100
What amino acid does the mRNA codon AUG code for?
AUG codes for methionine (Met), which is also the start codon that signals the beginning of translation.
100
What is the main function of the SRY gene, and which chromosome is it found on?
The SRY gene is found on the Y chromosome. Its main function is to start the process of male development by turning on genes that form male reproductive structures.
100
What does it mean that DNA is semi conservative?
Each new DNA molecule is composed of one parental strand and one new strand.
100
What is the function of these enzymes in DNA replication?
Helicase:
Topoisomerase:
Primase:
Ligase:
Helicase: Unwinds DNA.
Topoisomerase: Relieves tension ahead of fork.
Primase: Lays RNA primer.
Ligase: Joins Okazaki fragments.
100
In a repressible operon, such as the trp operon, what is required for the repressor to bind to the operator and block transcription?
A corepressor molecule
100
What is the result of a frameshift mutation?
A) It changes only one amino acid in the protein sequence.
B) It shifts the reading frame, often resulting in a nonfunctional protein.
C) It has no effect on the protein sequence.
D) It adds extra codons without affecting protein function.
B) It shifts the reading frame, often resulting in a nonfunctional protein.
200
An segment of mRNA sequence reads:
-UGA-
Use a codon table to determine the amino acid sequence that would be produced during translation. What does the UGA codon do in this sequence?
UGA = Stop codon
200
If a mother dog has a mutation in her mitochondrial DNA, which of her children are likely to inherit the mutation?
Ideal Answer:
All of her children—both sons and daughters.
What is this an example of?
200
Describe the central dogma of molecular biology. Include the roles of DNA, RNA, and proteins.
The central dogma describes the flow of genetic information in cells:
DNA → RNA → Protein.
200
What was the outcomes of the Hershey-Chase experiments?
They proved that DNA carries genetic instructions, not protein.
200
What is the trp operon?
a group of genes that work together to produce the amino acid tryptophan
it's normally on, but can be switched off when tryptophan is abundant
200
What happens in a nonsense mutation?
A) A codon is changed to a stop codon, causing the protein to be too long.
B) A codon is changed to a stop codon, causing the protein to be shortened.
C) The amino acid sequence of the protein is unchanged.
D) The protein folds incorrectly but remains functional.
B) A codon is changed to a stop codon, causing the protein to be shortened.
300
You are given the following mRNA sequence:
5′-AUG UUU UGC-3′
a) Use a codon table to determine the amino acid sequence.
b) What are the corresponding tRNA anticodons?
a) Codons:
AUG = Methionine (Met)
UUU = Phenylalanine (Phe)
UGC = Cysteine (Cys)
Amino acid sequence: Met – Phe – Cys
b) tRNA anticodons (complementary to mRNA codons):
AUG → UAC
UUU → AAA
UGC → ACG
300
In a dog family, the dog mother is a carrier for an X-linked recessive condition (XᴬXᵃ), and the dog father is unaffected (XᴬY).
What is the probability that their dog son will have the condition?
There is a 50% chance their dog son will inherit the condition.
Sons inherit their X chromosome from their mother and their Y chromosome from their father. Since the mother is a carrier (XᴬXᵃ), there’s a 50% chance she passes on the recessive allele (Xᵃ). If the son inherits Xᵃ, he will express the condition because he only has one X chromosome and no second X to mask the recessive allele.
300
Why do eukaryotic chromosomes get shorter with each round of DNA replication, and how do some cells counteract this issue?
DNA polymerase cannot fully replicate the 3′ end of the lagging strand; telomerase extends these ends in specific cells.
300
What is read and what is generated in transcription vs translation?
Transcription: reads DNA, produces pre-mRNA
Translation: reads mRNA, produces protein
300
What causes a repressor protein to remain bound to the operator in a repressible operon like the trp operon?
Binding of a corepressor molecule, which activates the repressor
300
Which of the following concepts does NOT support Lamarck's theory of evolution?
A) Traits acquired during an organism's lifetime, like muscle development or scars, are passed to offspring.
B) Natural selection drives the evolution of species based on genetic variation.
C) Inherited traits, not acquired traits, are passed to the next generation.
D) The environment can influence an organism’s traits over generations.
A) Traits acquired during an organism's lifetime, like muscle development or scars, are passed to offspring.
400
You are given the following mRNA sequence:
5′-AUG UGC UUU-3′
a) Use a codon table to determine the amino acid sequence.
b) What are the corresponding tRNA anticodons?
c) What is the DNA template strand that was used to create this mRNA?
a) Codons:
AUG → Methionine (Met)
UGC → Cysteine (Cys)
UUU → Phenylalanine (Phe)
Amino acid sequence: Met – Cys – Phe
b) tRNA anticodons
(complementary to mRNA codons):
AUG → UAC
UGC → ACG
UUU → AAA
c) To get the DNA template strand (complementary to mRNA, written 3′→5′):
mRNA: 5′-AUG UGC UUU-3′
DNA template: 3′-TAC ACG AAA-5′
400
A woman with a mitochondrial disorder has three children—two daughters and one son. Her son grows up and has two children of his own.
Which individuals in this family are expected to inherit the disorder, and why?
The woman’s three children (both daughters and the son) are expected to inherit the disorder because mitochondrial DNA comes from the mother.
However, none of the son’s children will inherit the disorder because mitochondrial DNA is not passed down through sperm—only through the egg. Only the daughters can pass it to the next generation.
400
Which of the following best explains why telomerase activity is often elevated in cancer cells?
A) Cancer cells require shorter chromosomes to replicate faster.
B) Telomerase suppresses cell division, preventing uncontrolled growth.
C) Cancer cells activate telomerase to maintain chromosome length and divide indefinitely.
D) Telomerase triggers apoptosis, which helps cancer cells survive chemotherapy.
C) Cancer cells activate telomerase to maintain chromosome length and divide indefinitely.
400
During DNA replication, what would most likely occur if DNA ligase were nonfunctional?
Okazaki fragments on the lagging strand would remain unconnected.
The enzyme Ligase: joins Okazaki fragments
400
Describe the transcriptional state of a repressible operon like the trp operon?
It is normally on but can be turned off when a repressor binds with a corepressor.
400
What is the consequence of a nonsense mutation in a coding sequence?
A) It results in the addition of an amino acid to the protein chain.
B) It causes premature termination of protein synthesis, producing a truncated protein.
C) It causes the entire protein to be translated into RNA instead of amino acids.
D) It results in the substitution of one amino acid with another without affecting protein function.
B) It causes premature termination of protein synthesis, producing a truncated protein.
500
You are given the following mRNA sequence:
5′-AUG CCC GAU UGA-3′
a) Use a codon table to determine the amino acid sequence.
b) Write the tRNA anticodons that would match the mRNA during translation.
c) Determine the DNA template strand (the strand that was used to make the mRNA).
a) amino acid sqeuence
AUG → Methionine (Met, start codon)
CCC → Proline (Pro)
GAU → Aspartic acid (Asp)
UGA → Stop codon (terminates translation)
Final amino acid sequence: Met – Pro – Asp
b) tRNA Anticodons
tRNA anticodons are complementary to mRNA codons
AUG → UAC
CCC → GGG
GAU → CUA
UGA → No anticodon → It’s a stop codon, no tRNA binds
Final: UAC – GGG – CUA
c) DNA Template Strand
The DNA template strand is complementary to the mRNA and is written 3′ → 5′.
mRNA:
5′-AUG CCC GAU UGA-3′
Complementary DNA
(template strand, 3′ → 5′):
3′-TAC GGG CTA ACT-5′
500
A couple learns through genetic testing that they are both carriers for a rare autosomal recessive disease. Neither shows any symptoms. They want to know the risk to their children.
Using your understanding of Mendelian genetics, explain the possible genotypes and phenotypes of their offspring, and the probabilities of each.
AA (normal): 25% chance – the child will not have the disease and will not be a carrier.
Aa (carrier): 50% chance – the child will not have the disease but will carry the gene for it.
aa (diseased): 25% chance – the child will have the disease, as they inherit two copies of the recessive allele.
500
What is the primary role of telomerase in eukaryotic cells?
It synthesizes new DNA at the ends of chromosomes to prevent shortening.
500
Where does transcription occur in the cell of eukaryotes?
happens in nucleus.
500
Is tryptophan important? Why?
Tryptophan is an essential amino acid
your body can't produce it and you must get it from your diet
plays a vital role in protein synthesis and is a precursor to serotonin and melatonin that influence mood, sleep, and other bodily functions
500
THE FOUR Natural Selection prerequisites
Variation in traits
Traits must be heritable
Differential survival/reproduction
Leads to adaptation over generations