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Bio Exam 3
| Term | Definition |
|---|---|
| Why do genes need to be regulated? | Gene regulation helps cells function properly and become specialized, even though they have the same DNA. |
| Why do different cells look different with the same DNA? | Gene expression varies in different cells, turning on/off specific genes based on cell function. |
| How is gene expression different in prokaryotes vs. eukaryotes? | Prokaryotes use operons for quick control; eukaryotes have complex control at many levels (DNA, RNA, protein). |
| What is an operon? | A group of genes in bacteria that are controlled together under one promoter. |
| What is the lac operon? | A bacterial gene system that turns on when lactose is present and glucose is low. |
| What is catabolite repression? | A way bacteria prefer glucose over lactose; glucose prevents lac operon from turning on. |
| lac operon vs. trp operon | lac = inducible (off until lactose is present); trp = repressible (on until tryptophan is present). |
| What is the transcription initiation complex in eukaryotes? | A group of proteins (including TATA box, GTFs) that help start transcription. |
| How are activators and repressors different in eukaryotes and prokaryotes? | Eukaryotes have more complex, distant enhancers/silencers; prokaryotes have simpler, direct regulators. |
| What is DNA packaging? | DNA is wrapped around histones: tightly packed = heterochromatin (off), loosely packed = euchromatin (on). |
| What is histone acetylation? | Adding acetyl groups to histones loosens DNA, making genes easier to express. |
| What is DNA methylation? | Adding methyl groups silences genes by making DNA tighter. |
| What is alternative splicing? | One gene makes multiple proteins by reusing pieces differently. |
| What are microRNAs? | Small RNAs that block translation or destroy mRNA to control gene expression. |
| How does translation regulation work? | E.g., Iron levels control translation of proteins that handle iron in cells. |
| What is post-translational regulation? | Control after proteins are made, like folding, cutting, or adding tags. |
| What is a mutation? | A change in DNA sequence. |
| Types of point mutations | Silent (no change), missense (changes amino acid), nonsense (stop), frameshift (shifts reading frame). |
| What causes sickle-cell anemia? | A missense mutation that changes hemoglobin shape and function. |
| Can mutations outside coding regions affect genes? | Yes, they can affect how genes are turned on/off. |
| Somatic vs germ-line mutation | Somatic = body cells (not inherited), Germ-line = sperm/egg (inherited). |
| Common causes of mutations | Radiation, chemicals, copying errors, base analogs. |
| How does UV cause mutations? | UV creates DNA damage; repair systems fix it. Defects cause diseases like Xeroderma pigmentosum. |
| What is cancer? | Uncontrolled cell growth from mutations. |
| What are proto-oncogenes and tumor suppressor genes? | Proto-oncogenes = promote growth; tumor suppressors = stop growth. Mutations can lead to cancer. |
| What mutations are linked to cancer? | Gene amplification, missense, chromosomal changes (e.g., Philadelphia chromosome). |
| What are cell cycle checkpoints? | Steps where the cell checks for damage before dividing. |
| What do cyclins and CDKs do? | Control cell cycle progression. |
| What is the p53 gene? | A tumor suppressor that stops damaged cells from dividing; often mutated in cancer. |
| What is the two-hit model of retinoblastoma? | Both copies of a tumor-suppressor gene must be mutated for cancer to develop. |
| What is chromatin? | DNA + proteins (histones) packed in the nucleus. |
| What are nucleosomes and 30-nm fibers? | Nucleosomes = DNA wrapped around histones. 30-nm fibers = more compact structure. |
| Mitosis vs. Meiosis | Mitosis = identical cells (growth), Meiosis = gametes (variation). |
| Order of stages in mitosis and meiosis | Prophase → Metaphase → Anaphase → Telophase → (Cytokinesis) |
| What is cytogenetics? | Study of chromosomes and their structure. |
| What is a karyotype? | Picture of chromosomes used to detect abnormalities. |
| Why are offspring more diverse than parents? | Meiosis mixes genes (crossing over and independent assortment). |
| What are trisomic and monosomic conditions? | Trisomic = extra chromosome (e.g., Down), Monosomic = missing chromosome. |
| Why is Mendel important? | He discovered basic inheritance rules using pea plants. |
| Monohybrid vs Dihybrid cross | Monohybrid = 1 trait, Dihybrid = 2 traits. |
| P, F1, F2 generations | P = parent, F1 = first kids, F2 = grandkids. |
| Homozygous vs heterozygous | Homo = same alleles, Hetero = different alleles. |
| Dominant vs recessive | Dominant = shows with one copy, Recessive = needs two copies. |
| Genotype vs phenotype | Genotype = genes, Phenotype = traits you see. |
| What is a test cross? | Cross with homozygous recessive to find unknown genotype. |
| Phenotypic/genotypic ratios | Monohybrid = 3:1 pheno, 1:2:1 geno; Dihybrid = 9:3:3:1. |
| Law of Segregation | Each parent gives one allele for a trait. |
| Chromosomal theory of inheritance | Genes are on chromosomes. |
| What is pedigree analysis? | Tracking inherited traits through families. |
| Cystic Fibrosis vs Huntington’s | CF = recessive, Huntington’s = dominant. |
| What are X-linked traits? | Traits on X chromosome; males more affected (1 X only). |
| Inheritance of Hemophilia A | X-linked recessive; mostly in males. |
| Why did Morgan use fruit flies? | Fast life cycle, easy traits. |
| Why white-eyed males in Morgan’s experiment? | Gene was X-linked; only males got it. |
| What is pleiotropy? | One gene affects many traits (e.g., Marfan syndrome). |
| What is polygenic inheritance? | Many genes affect one trait (e.g., skin color). |
| What is incomplete dominance? | Blending traits (e.g., red + white = pink flowers). |
| What are multiple alleles? | More than 2 allele options (e.g., ABO blood types). |
| Nature vs nurture | Both genes and environment shape traits. |
| What is epistasis? | One gene controls whether another gene shows. |
| What is recombination frequency? | % of offspring with new gene combos = distance between genes (in map units/cM). |
| What are linked genes? | Genes close together that travel together during meiosis. |
| What is cytoplasmic inheritance? | Genes from mitochondria/chloroplasts, mostly from mom. |
| What is epigenetic inheritance? | Gene changes not in DNA sequence; can be passed but often reversible. |
| What is X-inactivation? | One X in females turns off = Barr body; leads to calico cat fur patterns. |
| What is genomic imprinting? | Only mom’s or dad’s gene copy is active (e.g., Igf-2 in mice). |
| Structure of bacterial DNA | Circular chromosome in the cytoplasm. |
| What are plasmids? | Small DNA circles in bacteria; can carry useful genes. |
| How do bacteria reproduce? | Binary fission (copy and split). |
| DNA transmission methods in bacteria | Conjugation (cell-to-cell), Transformation (free DNA), Transduction (virus transfer). |
| What is conjugation? | DNA transfer using F factor (fertility plasmid). |
| What is horizontal gene transfer? | Gene sharing between different organisms (not parent to offspring). |
| Basic virus structure | DNA/RNA inside a protein coat. |
| Lytic vs Lysogenic cycle | Lytic = burst cell fast; Lysogenic = hide in DNA first. |
| HIV life cycle | Infects helper T-cells; uses reverse transcriptase to copy RNA into DNA. |
| What cell does HIV infect? | Helper T-cells (CD4+) |
| What is reverse transcriptase? | Enzyme that makes DNA from RNA (used by HIV). |
| What are prions? | Misfolded proteins that cause brain diseases (e.g., mad cow). |
Created by:
asteegman
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