Genetics Basics
What is the study of how traits pass from parents to offspring called?
What is genetics?
What are the four bases found in DNA?
Adenine, thymine, cytosine, and guanine (A, T, C, G).
What is a mutation?
A change in a DNA sequence.
What is the sugar found in milk called?
What is lactose?
A student has brown eyes. Is brown eye color the student's genotype or phenotype?
Phenotype, because it is an observable trait.
This molecule stores hereditary instructions and contains the bases A, T, C, and G.
What is DNA?
What is the process called when DNA information is copied into mRNA?
What is transcription?
What is gene expression?
Using information in a gene to make a product, often a protein.
What enzyme breaks down lactose during digestion?
What is lactase?
A gene has the DNA base sequence A, T, C, G. What does the order of these bases help determine?
The genetic information, which affects the mRNA made and may influence the protein produced.
This molecule stores hereditary instructions and contains the bases A, T, U, and G.
What is RNA?
What is the process called when a ribosome reads mRNA to help build a protein?
What is translation?
What type of mutation changes the number or structure of a chromosome?
What is a chromosome mutation?
In the lab, what does a glucose test strip detect after lactose is broken down?
What is glucose?
A mutation occurs in a DNA region that controls whether a gene is used. The protein's instructions are unchanged, but less protein is made. Explain why.
The mutation may affect gene regulation and reduce transcription, so less mRNA and less protein are produced.
What is the difference between genotype and phenotype?
Genotype is an organism's alleles or genetic makeup; phenotype is its observable trait.
This molecule brings transcribed DNA to the Ribosome for translation into a protein.
What is RNA?
How can increased DNA methylation (the addition of methyl groups) affect transcription?
Methyl groups attached to DNA can block transcription, leading to less mRNA and potentially less protein production.
How can a change in a regulatory region of DNA affect lactose tolerance?
It can affect whether or how much the lactase gene is expressed. Continued lactase production can allow lactose digestion into adulthood.
A researcher finds that people exposed to famine had differences in gene expression. Does this automatically prove that their DNA base sequences changed? Explain.
No. Environmental conditions can affect gene expression without necessarily changing the DNA base sequence.
A chromosome contains many of these DNA sections. Each section can provide instructions for making a protein. What are they?
What are genes?
A DNA change changes an mRNA codon, which changes an amino acid. Explain how this could affect an organism's trait.
The amino acid change may alter the protein's structure or function, which may affect cell function and the organism's trait.
Two cells contain the same gene, but one produces much more of its protein. Explain how this can happen without changing the DNA base sequence.
The gene may be expressed at different levels. Regulatory mechanisms, including DNA methylation, can affect how much transcription occurs.
A population has heritable differences in lactose tolerance. In an environment where digesting milk provides an advantage, explain how lactose tolerance could become more common over many generations.
Individuals with heritable traits that help them survive and reproduce may pass those alleles to offspring. Over generations, the alleles associated with lactose tolerance may become more common.
A mutation occurs, but the amino acid sequence of the protein does not change. Explain why the mutation may have no effect on the trait.
The DNA change may not change the mRNA codon in a way that changes the amino acid. If the protein remains unchanged, its function and the trait may also remain unchanged.