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Genetics & Molecular Biology - Vocabulary Flashcards (Video Lecture)

The Weekly Process

  • Outside of class: Read the book & complete Canvas quiz from the unit “FROM CELLS TO ORGANISMS.”

  • Topics covered include: Cellular respiration, photosynthesis, and core biology concepts (e.g., the First Cell, Life’s Origin).

  • In class: Instructor highlights key material and students work on exercises.

Why Genetics Matters

  • (Content listed as a slide title; no detailed bullet content provided in transcript.)

Precision Medicine and Real-World Applications

  • Precision medicine definition: a medical approach that customizes healthcare treatments and decisions to individual patients based on their unique genetic makeup, environment, and lifestyle.

  • Examples in practice:

    • Cancer treatment: Targeted therapies based on specific genetic mutations in tumors (e.g., HER2 inhibitors for breast cancer).

    • Pharmacogenomics: Adjusting drug types or doses based on how an individual metabolizes medications.

    • Chronic diseases: Tailoring interventions for diabetes or heart disease based on lifestyle and genetic risk factors.

Genetic Diseases and Gene Therapies

  • Sickle Cell Disease

  • Beta Thalassemia

  • Spinal Muscular Atrophy

  • Inherited Renal Disease

  • Hemophilia B

  • Metachromatic Leukodystrophy

  • Note: Gene therapies have FDA approval for various conditions; ongoing clinical trials for many others.

Genomics in Agriculture, Conservation, and Global Health

  • Genomics accelerates development of high-yield, pest-resistant, and climate-resilient crops.

  • Global hunger context (2023): ~733 million people faced hunger; about 1 in 11 people globally, and ~1 in 5 in Africa (WHO).

  • Genomic selection and editing enhance breeding programs in cattle, pigs, and chickens to improve disease resistance and productivity.

  • Genomics enables de-extinction-like approaches, e.g., bringing species like the Northern White Rhino back from the brink.

  • Genetically modified bacteria are being engineered to break down plastics in oceans.

Public Health Metrics

  • Influenza mortality (per 1,000 people): Early 20th century ≈ 41; Today ≈ 8.1.

Data Privacy, HIPAA, and Direct-to-Consumer Genetic Data

  • 23andMe and similar DTC genetics companies are not fully covered by HIPAA because they operate outside traditional health care settings.

  • Data from DTC firms can be vulnerable due to a patchwork of state laws; potential for sale or sharing with law enforcement if not protected by robust regulations.

DNA, RNA, and Nucleic Acids

  • DNA = Deoxyribonucleic Acid; RNA = Ribonucleic Acid.

  • Nucleic acids include DNA and RNA, built from nucleotides.

DNA Structure and Orientation

  • DNA structure features:

    • 5' end and 3' end orientations are opposite on the two strands (antiparallel).

    • Backbone composed of sugar-phosphate chains.

    • Nitrogenous bases pair via hydrogen bonds: Adenine (A) with Thymine (T) in DNA; Adenine (A) with Uracil (U) in RNA; Guanine (G) with Cytosine (C).

  • Diagrammatic key: 5' — P — sugar — phosphate — 3' on one strand; 3' — sugar — phosphate — 5' on the complementary strand.

Nucleotides and Their Components

  • A nucleotide consists of three parts:

    • Phosphate group (–P(=O)(–O)–O–)

    • Pentose sugar (deoxyribose in DNA; ribose in RNA)

    • Nitrogenous base (A, T/U, C, G)

  • Each nucleotide links to form the DNA backbone via phosphodiester bonds between the phosphate of one nucleotide and the sugar of the next.

  • Components of a nucleotide:

    • Phosphate group

    • Sugar (deoxyribose in DNA; ribose in RNA)

    • Nitrogenous base (A, C, G, T in DNA; A, C, G, U in RNA)

Nucleic Acid Bases and Pairing

  • Two categories of bases:

    • Purines: Adenine (A) and Guanine (G) — double-ring structures.

    • Pyrimidines: Cytosine (C) and Thymine (T) in DNA; Cytosine (C) and Uracil (U) in RNA — single-ring structures.

  • Base-pairing rules (complementarity):

    • In DNA: A pairs with T; G pairs with C.

    • In RNA: A pairs with U; G pairs with C.

  • The genetic code is read in a 5' to 3' direction on the mRNA strand.

Base Pairing and Codons

  • Codons are triplets of nucleotides in mRNA that encode amino acids.

  • Each codon corresponds to one amino acid or a stop signal.

  • Start codon: AUG (Methionine, Met).

  • Stop codons: UAA, UAG, UGA.

  • Degeneracy: more than one codon can code for the same amino acid; the genetic code is redundant.

The Genetic Code: Codon-to-Amino Acid Mapping (Overview)

  • The genetic code uses triplet codons to specify amino acids.

  • Example mappings (representative samples):

    • Phenylalanine (Phe, F): UUU, UUC

    • Leucine (Leu, L): CUU, CUC, CUA, CUG

    • Serine (Ser, S): UCU, UCC, UCA, UCG

    • Tyrosine (Tyr, Y): UAU, UAC

    • Cysteine (Cys, C): UGU, UGC

    • Tryptophan (Trp, W): UGG

    • Lysine (Lys, K): AAA, AAG

    • Methionine (Met, M): AUG (start)

    • Valine (Val, V): GUU, GUC, GUA, GUG

    • Glutamic acid (Glu, E): GAA, GAG

  • Codon structure: First, second, and third letters determine the amino acid; the genetic code is organized by first, second, and third letter positions.

Transcription and Translation: The Flow of Genetic Information

  • Central idea: DNA is transcribed into RNA, which is translated into protein.

  • Cellular locations in eukaryotes: transcription occurs in the nucleus; translation occurs in the cytoplasm at the ribosome.

  • Transcription (DNA -> RNA):

    • Initiation: RNA polymerase binds to a promoter; DNA unwinds at the transcription start site.

    • Elongation: RNA polymerase moves along the template DNA strand, synthesizing a complementary RNA strand.

    • Termination: RNA polymerase reaches a terminator sequence and releases the mRNA.

  • Key players: RNA polymerase, promoter, DNA template strand, terminator, RNA.

  • Translation (RNA -> Protein):

    • Initiation at the ribosome with start codon (AUG).

    • Elongation: tRNA brings amino acids in order specified by codons on the mRNA; ribosome catalyzes peptide bond formation.

    • Termination: stop codon signals release of the completed polypeptide.

  • Cellular context: In eukaryotes, transcription in nucleus produces pre-mRNA; processing yields mature mRNA that exits to cytoplasm for translation by ribosomes.

Key Elements of Transcriptional Machinery

  • Promoter: DNA region where RNA polymerase binds to initiate transcription.

  • DNA template strand: directionality and complementarity guide RNA synthesis.

  • RNA polymerase unwinds DNA and synthesizes RNA in a 5' to 3' direction.

  • Terminator: sequence signaling the end of transcription.

  • Example transcription sequence flow (illustrative): DNA template strand 3'–T C C G A T C T–5' yields complementary mRNA 5'–A G G C U A G A–3' after transcription and processing.

The Process: From DNA to mRNA to Protein (Worked Example)

  • Given a DNA template strand segment: 3'–AGG CCT G–5', the mRNA would be complementary and antiparallel: 5'–UCC GGA C–3' (illustrative).

  • The resulting mRNA codons are read 5' to 3' to assemble a polypeptide.

Regulation of Gene Expression (Prokaryotes and Eukaryotes)

  • Gene expression is highly regulated because it is energy-intensive; cells produce only needed proteins.

  • Prokaryotic regulation often occurs via operons: clusters of genes transcribed together.

  • Promoter and operator roles:

    • Promoter: RNA polymerase binding site to initiate transcription.

    • Operator: regulatory proteins bind to this region, influencing RNA polymerase activity.

  • Repressor proteins block transcription when the gene products are not needed (e.g., lactose absent).

  • Lactose presence can bind to the repressor, causing a conformational change and releasing the operator to allow transcription of lactose-digesting enzymes.

  • In multicellular organisms, regulation of transcription is especially important to control development, cell differentiation, and response to environmental cues.

  • Video and discussion prompts (for classroom): discuss similarities with other regulatory proteins, and why transcriptional regulation is crucial in multicellular organisms.

Chromosome Organization and Cellular Reproduction

  • How is DNA organized? DNA is packaged into chromosomes to facilitate handling and segregation during cell division.

  • Chromosome concept:

    • In the nucleus, DNA is wrapped around histone proteins to form chromatin, which condenses into chromosomes during cell division.

  • Diploid cells contain two sets of chromosomes (two homologous copies): one from each parent.

  • Humans have 23 homologous pairs of chromosomes:

    • 22 autosomes (the same in males and females).

    • 1 pair of sex chromosomes (XX in females, XY in males).

  • Chromosomes in homologous pairs carry the same genes but may carry different alleles (alternative versions of the same gene).

  • Karyotype: a visual display of all chromosomes in a diploid cell, showing homologous pairs and sex chromosomes.

  • Zygote development:

    • Zygote grows and develops by mitosis, producing trillions of identical cells.

  • Mitosis vs Meiosis: Mitosis builds a multicellular organism from a single zygote; meiosis produces gametes (sperm and egg) with half the chromosome number for sexual reproduction.

Mutations and Genetic Variation

  • A mutation is a change in a cell's DNA sequence. Variants arise via multiple mechanisms and can be categorized by their effect on the protein.

  • Mutation types (illustrative):

    • Substitution (missense): changes one amino acid; e.g., a base change that alters serine to threonine.

    • Nonsense: creates a premature stop codon, truncating the protein.

    • Insertion (frameshift): insertion of nucleotides alters the reading frame, changing downstream amino acids.

    • Deletion (frameshift): removal of nucleotides alters the reading frame.

    • Expanding repeat: increases the number of repeats in a region, affecting gene function.

  • Mutations can cause disease (example: mutation in hemoglobin gene leading to sickle cell disease).

  • Not all mutations are harmful; many generate genetic variation that drives evolution and can be leveraged in plant breeding to create new varieties.

  • Synonymous (silent) vs. nonsynonymous substitutions:

    • Synonymous: codon changes that do not alter the encoded amino acid.

    • Non-synonymous: codon changes that do alter the amino acid.

  • The impact of substitutions depends on the specific codon and its effect on the protein’s function or regulation.

Synonymous vs Nonsynonymous Substitution: Implications

  • Importance in immune recognition, vaccine design, and pathogen evolution (e.g., antigen proteins).

  • After a pathogen exposure, different populations may acquire distinct mutations in key antigens, affecting vaccine efficacy and booster requirements.

Summary: Why This Matters

  • Gene expression is regulated to conserve energy and ensure proper development.

  • DNA organization into chromosomes enables accurate inheritance and cell division.

  • The genetic code translates nucleotide sequences into functional proteins that drive phenotype.

  • Mutations and genetic variation underlie evolution, disease, and medical advances (precision medicine, gene therapy).

  • Ethical, privacy, and legal considerations govern how genomic data is collected, stored, shared, and used (HIPAA implications for DTC companies).

Quick Reference: Key Concepts and Terms

  • DNA, RNA, Nucleotides, Backbone, Phosphate group, Pentose sugar, Nitrogenous base

  • Purines vs Pyrimidines: A/G vs C/T/U

  • Base pairing: A-T (DNA), A-U (RNA), G-C

  • Antiparallel strands, 5' to 3' directionality

  • Codons, Start/Stop codons, Reading frame

  • Transcription: Initiation → Elongation → Termination

  • Translation: Ribosome, tRNA, Codons, Amino acids, Polypeptide

  • Operon, Promoter, Operator, Repressor

  • Karyotype, Diploid, Autosomes, Sex chromosomes

  • Mutation types: Substitution, Nonsense, Insertion, Deletion, Expanding repeat

  • Synonymous vs Non-synonymous substitutions

  • Precision medicine, Pharmacogenomics, Targeted therapies

  • Ethical, legal, privacy considerations in genomics

Additional Context and Data Points from the Slides

  • Global hunger context from 2023: ~733 million people affected; 1 in 11 globally, 1 in 5 in Africa.

  • Influenza mortality trends show large improvements over the last century (from 41 per 1,000 to 8.1 per 1,000).

  • In-protocol examples: Precision medicine includes cancer therapy personalization, pharmacogenomics-guided drug choice, and lifestyle/genetic risk-based interventions.

Note on Study Process and Resources

  • Regular pre-class reading and Canvas quizzes reinforce weekly topics.

  • Instructor-led highlights during class free up time for practice problems and discussion.

  • Supplementary resources include text materials and external videos for deeper understanding (e.g., lac operon video discussion).