Short Questions Flashcards
What are the four levels of protein structure?
- Primary structure
- Secondary structure
- Tertiary structure
- Quaternary structure
Primary structure refers to the sequence of amino acids, secondary structure involves local folding into alpha helices and beta sheets, tertiary structure is the overall 3D shape, and quaternary structure is the assembly of multiple polypeptide chains.
How does RNA splicing contribute to protein diversity?
RNA splicing allows for the removal of introns and the joining of exons, leading to different combinations of exons in mature mRNA.
This process can generate multiple protein isoforms from a single gene.
What is the difference between transcription and translation?
Transcription is the process of synthesizing RNA from a DNA template, while translation is the process of synthesizing proteins from an mRNA template.
What are the three stages of transcription?
- Initiation
- Elongation
- Termination
These stages describe the process of RNA synthesis from DNA.
What is the role of tRNA in protein synthesis?
tRNA (transfer RNA) transports specific amino acids to the ribosome during translation, matching them to the corresponding codons on the mRNA.
How does a mutation in a gene affect protein function?
A mutation can alter the amino acid sequence of a protein, potentially affecting its structure and function.
What is the purpose of alternative RNA splicing?
Alternative RNA splicing allows a single gene to produce multiple protein variants, increasing protein diversity.
What happens during metaphase of mitosis?
Chromosomes align at the cell’s equatorial plane, preparing for separation.
What is the function of oncogenes in cancer development?
Oncogenes promote cell growth and division, and mutations can lead to uncontrolled cell proliferation, contributing to cancer.
How does crossing over contribute to genetic variation?
Crossing over during meiosis exchanges genetic material between homologous chromosomes, creating new allele combinations.
Explain the impact of a nonsense mutation on protein function.
A nonsense mutation introduces a premature stop codon, leading to a truncated and often nonfunctional protein.
How does the lac operon regulate gene expression in bacteria?
The lac operon is a set of genes that are regulated by the presence or absence of lactose, allowing bacteria to adapt to available sugars.
What is the difference between silent, missense, and nonsense mutations?
Silent mutations do not change the amino acid sequence, missense mutations change one amino acid, and nonsense mutations create a premature stop codon.
Silent mutations do not affect protein function, while missense mutations can alter function, and nonsense mutations typically lead to loss of function.
How do tumor suppressor genes prevent cancer?
Tumor suppressor genes prevent cancer by regulating cell division and promoting apoptosis.
They act as a brake on cell proliferation, and mutations in these genes can lead to uncontrolled growth.
Describe how signal transduction pathways regulate cell growth.
Signal transduction pathways regulate cell growth by transmitting signals from the cell surface to the nucleus, affecting gene expression and cell cycle progression.
These pathways can involve growth factors, receptors, and a series of intracellular signaling molecules.
What is the function of histones in chromatin structure?
Histones package and order DNA into structural units called nucleosomes, enabling DNA compaction and regulation of gene expression.
They play a crucial role in the accessibility of DNA for transcription.
How does independent assortment contribute to genetic diversity?
Independent assortment contributes to genetic diversity by allowing alleles of different genes to segregate independently during gamete formation.
This results in new combinations of traits in offspring.
Explain the role of telomeres in DNA replication and aging.
Telomeres protect the ends of chromosomes from deterioration and prevent the loss of genetic information during DNA replication.
Shortening of telomeres is associated with aging and cellular senescence.
How do chromosomal translocations contribute to cancer?
Chromosomal translocations can lead to cancer by disrupting normal gene function or creating fusion genes that promote uncontrolled cell growth.
These genetic alterations can result in oncogene activation or tumor suppressor gene inactivation.
What is the role of ubiquitin in protein degradation?
Ubiquitin tags proteins for degradation by the proteasome, regulating protein turnover and maintaining cellular homeostasis.
This process is crucial for removing damaged or misfolded proteins.
