gene expression Flashcards
What is the role of transcription and translation in gene expression?
They regulate the metabolic activities of cells, enabling specialization by expressing specific genes to form tissues and organs.
What are totipotent stem cells and where are they found?
Totipotent stem cells can divide and produce any type of body cell and are present in the early divisions of a mammalian embryo.
What is a pluripotent stem cell and how is it different from a multipotent stem cell?
Pluripotent stem cells can develop into most body cell types and divide in unlimited numbers, whereas multipotent stem cells can only develop into a limited range of cell types.
What is the significance of iPS cells in medicine?
Induced pluripotent stem cells can be created from somatic cells using transcription factors, offering potential for personalized medicine without using embryos.
What is a transcription factor and its role in gene expression?
A transcription factor is a protein that binds to specific DNA sequences to regulate the transcription of genes, acting as an activator or repressor.
How does oestrogen affect gene transcription?
Oestrogen binds to the ERα receptor in the cytoplasm, allowing it to enter the nucleus and stimulate transcription of target genes.
What is RNA interference (RNAi) and its components?
RNAi inhibits translation of mRNA using molecules like siRNA and miRNA, which bind to target mRNA and block or degrade it.
How can environmental factors influence gene expression epigenetically?
Environmental changes can increase DNA methylation or decrease histone acetylation, condensing chromatin and inhibiting transcription.
What are the two main types of tumours and how do they differ?
Benign tumours grow slowly and do not spread, while malignant tumours grow rapidly, invade surrounding tissues, and can metastasize.
What is the role of tumour suppressor genes in cancer prevention?
They inhibit cell division, and mutations or hypermethylation can inactivate them, leading to uncontrolled cell growth.
How does PCR amplify DNA?
PCR amplifies DNA by denaturation (95°C), annealing of primers (55°C), and synthesis by DNA polymerase (70°C), repeated in cycles.
What is recombinant DNA technology?
A technique to transfer DNA between organisms, producing transgenic organisms capable of expressing the transferred genes.
How are DNA fragments separated in electrophoresis?
DNA fragments are separated based on size by applying an electric field in a gel; smaller fragments move further towards the positive electrode.
What are VNTRs and how are they used in genetic fingerprinting?
VNTRs are variable number tandem repeats of non-coding DNA. Their unique patterns are used for identifying individuals.
What are the ethical concerns of using recombinant DNA technology?
Concerns include monoculture, environmental impact, corporate dominance, and potential misuse for ‘designer babies.’
What are the types of gene mutations and examples?
Substitution (e.g., ATG.CCT to ATT.CCT), Deletion (e.g., ATG.CCT to ATC.CT), Addition (e.g., ATG.CCT to ATG.ACC.T), Duplication, Inversion, and Translocation.
How do mutagenic agents increase the mutation rate?
Base analogs substitute bases (e.g., 5-bromouracil for thymine), alkylating agents change base pairing, and UV radiation alters DNA structure.
Why do additions, duplications, and deletions often have severe effects on proteins?
They cause frameshift mutations, altering downstream codons and the amino acid sequence.
What is the difference between coding and non-coding DNA in terms of translation?
Most of a cell’s DNA is non-coding and not translated, serving regulatory or structural functions instead.
What are the roles of promoter and terminator regions in gene expression?
Promoter regions signal RNA polymerase where to start transcription; terminator regions signal where to stop.
What are the differences between siRNA and miRNA in RNA interference?
siRNA binds fully to target mRNA and degrades it, while miRNA binds partially, blocking translation and storing mRNA.
What is the role of DNA methylation in epigenetics?
Increased methylation inhibits gene expression by making DNA less accessible for transcription.
What is the significance of acetylation in epigenetic regulation?
Decreased acetylation condenses chromatin, preventing transcription.
What are proto-oncogenes and how do they contribute to cancer when mutated?
Proto-oncogenes stimulate normal cell division, but mutations or hypomethylation can turn them into oncogenes, leading to uncontrolled division.
How can genome projects aid vaccine production?
Sequencing simpler organisms’ genomes helps identify their proteomes, including antigens for vaccines.
What is the role of restriction endonucleases in recombinant DNA technology?
They cut DNA at specific palindromic sequences, creating sticky ends for recombination.
What is the function of DNA ligase in recombinant DNA technology?
DNA ligase joins DNA fragments, annealing donor and vector DNA to form recombinant DNA.
What are the steps in amplifying DNA in vivo using bacterial cells?
- Isolate gene with restriction enzymes. 2. Insert gene into vector (plasmid). 3. Introduce plasmid into host cells. 4. Culture bacteria for protein production.
What are the concerns with monoculture in transformed crops?
Monoculture reduces biodiversity and may allow crossbreeding with wild plants, creating superweeds.
How does Southern blotting contribute to genetic fingerprinting?
DNA fragments are transferred to a nylon membrane and hybridized with labeled probes for detection.
What is the genetic code, and why is it described as ‘degenerate’?
The genetic code specifies how base sequences in DNA or mRNA correspond to amino acids. It is degenerate because multiple codons can code for the same amino acid.
What are the main types of stem cells?
Totipotent (can form any cell type), Pluripotent (can form most cell types), Multipotent (can form a limited range of cells), and Unipotent (can form only one cell type).
What are the ethical considerations in using embryonic stem cells?
Embryonic stem cell research involves destroying embryos, raising ethical concerns about the beginning of human life.
How are iPS cells generated, and why are they advantageous?
iPS cells are created by reprogramming somatic cells using transcription factors, avoiding the ethical issues of embryonic stem cells.
What is the effect of increased methylation of tumor suppressor genes?
It silences these genes, preventing them from inhibiting cell division and potentially leading to cancer.
How can mutations lead to non-functional proteins?
Mutations can alter the primary structure of a protein, disrupting bonds in the tertiary structure and affecting function, such as enzyme active site shape.
What are the three main steps of PCR and their temperatures?
- Denaturation at 95°C. 2. Annealing at 55°C. 3. Extension at 70°C.
How does miRNA regulate gene expression in mammals?
miRNA forms a complex with proteins to bind target mRNA, blocking its translation or marking it for degradation.
What are some applications of genome sequencing?
Applications include identifying disease genes, improving crops, creating vaccines, and studying evolutionary relationships.
What are the two types of genetic markers used to identify transformed cells?
- Antibiotic resistance genes. 2. Fluorescent or radioactive tags.
How does gel electrophoresis separate DNA fragments?
DNA fragments are separated by size as they migrate through a gel towards the positive electrode under an electric field.
What are the steps of genetic fingerprinting?
- Extract DNA. 2. Amplify VNTRs using PCR. 3. Separate fragments by gel electrophoresis. 4. Visualize bands under UV light.
What are the benefits of recombinant DNA technology in agriculture?
Higher yields, pest-resistant crops, and enhanced nutritional content.
What are the risks associated with gene therapy?
Risks include immune reactions, insertional mutagenesis, and ethical concerns regarding germline modifications.
What is the difference between somatic and germline gene therapy?
Somatic gene therapy alters body cells to treat diseases, while germline therapy modifies gametes, affecting future generations.
