BIOL 1306 EXAM 5

Ch 11, 15, 18, 20

Q: What are the three stages of cell communication?

A: A: Controlled cell death to remove damaged, unnecessary, or harmful cells without damaging nearby cells.Reception (signal detection by receptors), Transduction (signal conversion via pathways), and Response (cell reaction).

Q: What is apoptosis?

A: Controlled cell death to remove damaged, unnecessary, or harmful cells without damaging nearby cells.

Q: What proteins carry out apoptosis?

A: Caspases (enzymes that break down cell components).

Q: Why is apoptosis important?

A: Shapes body parts during development, prevents cancer, and removes infected or damaged cells.

Q: What is the law of segregation?

A: Alleles for each gene separate into different gametes during meiosis.

Q: What is the law of independent assortment?

A: Genes on different chromosomes are inherited independently of each other.

Q: What happens during nondisjunction?

A: Chromosomes fail to separate properly during meiosis, causing abnormal chromosome numbers.

Q: Name an example of a chromosomal disorder caused by nondisjunction.

A: Down Syndrome (trisomy 21) or Turner Syndrome (XO).

Q: What is a homologous chromosome?

A: A pair of chromosomes, one from each parent, that carry the same genes but possibly different alleles.

Q: What is the lac operon?

A: A group of genes in bacteria activated only when lactose is present.

Q: What are transcription factors?

A: Proteins in eukaryotes that help RNA polymerase start transcription.

Q: How does chromatin structure regulate gene expression?

A: Tightly packed chromatin turns genes off; loosely packed chromatin allows genes to be turned on.

Q: What is epigenetics?

A: Heritable changes in gene expression caused by modifications like methylation, not changes to DNA sequence.

Q: Name two types of post-transcriptional gene regulation.

A: RNA splicing (removal of introns) and protein modification (like adding chemical groups).

Q: What does PCR do?

A: Amplifies a specific DNA sequence, creating billions of copies.

Q: What is gel electrophoresis used for?

A: Separating DNA fragments by size.

Q: What is CRISPR-Cas9?

A: A gene-editing tool that can cut and modify specific DNA sequences.

Q: What is DNA cloning?

A: Inserting a gene into a plasmid and using bacteria to replicate it or produce its protein.

Q: What is gene therapy?

A: Treating diseases by adding, fixing, or silencing genes in a patient’s cells.

Q: What is the role of caspases in apoptosis?

A: Breaking down cell components during programmed cell death.

Q: What are the three parts of cell communication?

A: Reception, Transduction, Response.

Q: What happens if nondisjunction occurs?

A: Gametes have too many or too few chromosomes, causing genetic disorders.

Q: How do transcription factors help gene expression?

A: By enabling RNA polymerase to bind DNA and start transcription.

Q: What does gel electrophoresis separate DNA based on?

A: Size of DNA fragments.

Q: What is quorum sensing?

A: A process where bacteria sense population density and coordinate behaviors like toxin secretion or biofilm formation.

Q: What are the two main types of cell signaling?

A: Local signaling (autocrine, paracrine, synaptic) and long-distance signaling (endocrine).

Q: What is signal transduction?

A: The process of converting a signal into a cellular response via a pathway of molecules.

Q: What is the chromosome theory of inheritance?

A: Genes are located on chromosomes, which are segregated and assorted during meiosis.

Q: What did Thomas Hunt Morgan demonstrate with fruit flies?

A: Genes are located on chromosomes, and some are sex-linked (e.g., eye color mutation in males).

Q: What triggers male development in humans?

A: The SRY gene on the Y chromosome.

Q: What is X-inactivation, and what does it create?

A: One X chromosome in females is randomly inactivated, forming a Barr body.

Q: What are the four types of chromosomal structural changes?

A: Deletion, Duplication, Inversion, Translocation.

Q: What is polyploidy, and where is it common?

A: Having more than two sets of chromosomes, common in plants but rare in animals.

Q: What is a repressible operon, and give an example?

A: Usually "on" but can be turned off when the product is abundant (e.g., trp operon).

Q: What is positive gene regulation?

A: When activator proteins, like CRP, enhance transcription under specific conditions.

Q: What is the function of microRNAs (miRNAs)?

A: To bind mRNA and either degrade it or block its translation.

Q: What is DNA methylation?

A: A process where methyl groups are added to DNA, reducing gene transcription.

Q: How do transcription factors regulate genes?

A: By binding to enhancers or promoters to activate or repress transcription.

Q: What are restriction enzymes, and what do they create?

A: Proteins that cut DNA at specific sequences, creating sticky ends for recombination.

Q: What are the three steps of PCR?

A: Denaturation (separating DNA strands), Annealing (binding primers), Extension (synthesizing new DNA).

Q: What is the purpose of a plasmid in DNA cloning?

A: It acts as a vector to introduce foreign DNA into a host cell.

Q: What are transgenic organisms?

A: Organisms that contain genes from another species.

Q: Name one medical application of biotechnology.

A: Producing recombinant proteins like insulin using genetically modified bacteria.

Q: What is next-generation sequencing (NGS)?

A: A fast and cost-effective method to sequence entire genomes.