DNA Structure
What are the three components of DNA?
Sugar, phosphate, and a base.
What is the purpose of the sugar and the phosphate molecules in DNA?
They make up the backbone of the DNA. This backbone provides structural support and protects the genetic code.
What is the best explanation of a gene?
A segment of DNA that codes for a specific protein.
What is the first step in protein synthesis?
Located or find the gene for the protein you need to create.
Which base is excluded in RNA?
Thymine
Where is the DNA located?
In the nucleus of every cell.
What is the purpose of the bases in DNA?
The bases can form different sequences that code for different proteins. This is the genetic code.
What factor determines the trait that a given gene will express?
The particular sequence of bases in a gene.
What is the second step of protein synthesis? What does this word mean?
Transcription, to copy.
Go to the board and write out the complementary DNA strand for:
ATCGATAG
TAGCTATC
What are the bases associated with DNA?
Adenine, Thymine, Cytosine, Guanine
Why is it that every cell in the body has identical DNA, yet, there are different types of cells in the body?
Proteins regulate which genes within a cell are activated and which are not.
What does the term gene expression mean?
When a gene is being expressed, it is being “turned on.”
When a gene is not being expressed it is essentially “turned off.”
What is the role of RNA Polymerase in the second step of protein synthesis?
RNA polymerase unzips the DNA and creates a strand of mRNA.
Go to the board and write out the complementary mRNA strand for the DNA strand:
ATGCATACG
UACGUAUGC
What would the complementary strand of DNA be if the original strand was composed of the bases, ATACTGC
TATGACG
The function of chromosomes can best be described as what?
Organizing the DNA and regulating the production of specific proteins.
Why is it important that gene expression is regulated?
If gene expression wasn’t regulated, the genes responsible for things beyond what a particular cell needs could potentially be turned on. Imagine if the gene for digestive enzymes was turned on in your eyeball cells!
What is the last step of protein synthesis? Describe what happens in this step.
Translation.
During translation the mRNA is read by the ribosome. The ribosome reads the mRNA codons one by one to determine which amino acids are necessary. As the ribosome reads the mRNA, tRNAs bring the appropriate amino acids until a protein is eventually created.
Go to the board and write out the tRNA anticodon for the mRNA strand:
UACGACUAG
AUGCUGAUC
What is the composition of a chromosome?
Chromosomes are very long structures consisting of two DNA polymers, joined together by hydrogen bonds connecting complementary base pairs. A chromosome is divided into segments of double-stranded DNA called genes.
A point mutation is when a single nucleotide is changed. In a point mutation, nucleotides can be deleted, changed, or damaged. How might the function of DNA change if the structure experiences a point mutation.
If there was a point mutation, some particular gene would be impacted. If this gene were impacted, the protein it would code for would also be impacted. The mutation would ultimately result in a protein that was different from the original.
What was the example of the transcription factor that regulated gene expression on the daf-2 gene that impacted lifespan?
FOXO
In humans, the CFTR gene is responsible for a protein that regulates the components of sweat, digestive fluids, and mucus.
Individuals with a mutated version of this gene develop Cystic Fibrosis. What could be a possible research question that would provide data for clarifying the role of DNA in the development of this disease?
Is Cystic Fibrosis present in individuals who have a normal, non-mutated copy of the CFTR gene?
What would the amino acid be if the mRNA strand contained the codon:
AUG
And the tRNA anticodon was:
UAC
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