Biol Units 20-25 review

Steroid Hormones

Lipophilic molecules that regulate gene expression by binding to specific receptors in target cells.

Chemical Modifications

Modifications like DNA methylation and histone acetylation that influence gene expression by altering chromatin structure.

Small RNAs

miRNAs and siRNAs regulate gene expression post-transcriptionally by inhibiting mRNA translation or promoting degradation.

Galactose Induction

Galactose binds GAL3 protein, causing a conformational change in GAL80, which releases GAL4 to activate transcription.

GAL4

Transcription activator in yeast.

GAL80

Transcription repressor that inhibits GAL4 in the absence of galactose.

Mechanism of Steroid Hormone Action

Steroid hormones pass through membranes, binding to specific receptors that regulate gene expression.

Steroid Hormone Receptors Structure

Receptors have a DNA binding domain, transcription activation domain, HSP90 interaction domain, and ligand-binding domain.

Hormone Response Elements (HREs)

DNA sequences like ERE and GRE that receptors bind to for gene regulation.

DNA Methylation

Addition of a methyl group to cytosine, associated with gene silencing.

Histone Modifications

Chemical changes like acetylation and methylation on histones, influencing gene expression.

Writers, Readers, Erasers

Enzymes that add, recognize, or remove histone modifications, respectively.

miRNAs

Small RNAs that regulate gene expression by binding to mRNA, inhibiting translation, or promoting degradation.

siRNAs

Small interfering RNAs involved in RNA interference (RNAi), targeting mRNA for degradation.

Pioneer Transcription Factors

Factors that can bind occluded DNA sites, initiating gene expression in previously silent genes.

Transcription Activators

Proteins that recruit the preinitiation complex and RNA polymerase II to the promoter for transcription initiation.

Chromatin Remodeling

Repositioning or evicting nucleosomes to make DNA accessible for transcription.

Epigenetic Effects of Environment

Environmental factors like famine can cause long-term epigenetic changes influencing gene expression across generations.

RNAi Mechanism

Small RNAs like miRNAs degrade mRNA or inhibit translation, regulating gene expression post-transcriptionally.

RNAi Applications

Gene silencing technique using siRNAs to study gene function or develop therapies.

Forward Genetics

Identifying genes based on mutant phenotypes; involves mutagenesis, screening, and gene identification

Reverse Genetics

Understanding gene function by starting with a known gene and studying its effects through genetic manipulation.

Model Organisms

Organisms like E. coli and Arabidopsis used in genetic studies due to their simplicity and tractability.

Mutagens

Chemicals or radiation used to induce mutations for genetic screening.

Dominant Mutations

Mutations that manifest in the immediate generation, often gain-of-function mutations.

Recessive Mutations

Mutations that require two copies of the mutant allele to manifest, typically loss-of-function.

Conditional Mutations

Mutations that express phenotypes only under specific environmental conditions.

Complementation Tests

Used to determine if mutations causing similar phenotypes are in the same gene (no complementation) or different genes (complementation).

Mutagenesis

Inducing mutations using chemicals or radiation to study gene functions.

Mutant Screen

Identifying phenotypic changes in a population after mutagenesis to find mutants of interest.

Beadle and Tatum

Pioneering work using Neurospora to link genes with biochemical functions.

Recombinant DNA Technology

Used to modify genes to study their function.

Gene Modification

Creating GMOs or altering gene expression (under/over-expressing) to study gene function.

Reporter Genes

Genes that provide visual markers of gene expression patterns.

ABC Model

Explains flower organ identity through gene classes.

Class A

Sepals

Class B

Petals

Class C

Stamens and carpels

Arabidopsis as a Model

Widely used for plant genetics, particularly flower development due to its short lifecycle and ease of genetic manipulation.

T-DNA and Transposon Insertions

Mutagenesis techniques used to disrupt genes and observe phenotypic changes.

PCR/Southern Blotting

Techniques for identifying genes disrupted by T-DNA or transposons.

High-Throughput Sequencing

Used to identify and map mutations by comparing mutant genomes to the wild-type.

Class D and E Genes

Added to the ABC model to further refine understanding of flower development.

Neoplasm

A disorder of cell growth caused by mutations, leading to excessive, uncontrolled cell proliferation.

Benign Tumor

Non-cancerous, usually removable, and unlikely to spread.

Malignant Tumor

Cancerous, capable of invading tissues and metastasizing (spreading to distant organs).

Metastasis

The spread of cancer cells from the primary tumor to other parts of the body, often via the bloodstream or lymphatic system.

Liquid Tumors

Cancers like leukemia that do not form solid masses.

Biopsy

A tissue sample used for cancer diagnosis, analyzed through microscopy after staining (e.g., hematoxylin and eosin).

Carcinomas

Cancers originating in epithelial cells (e.g., breast, prostate, colon).

Sarcomas

Cancers from connective tissues (e.g., bone, muscle).

Leukemias

Blood cancers originating in bone marrow.

Lymphomas

Cancers starting in immune cells.

CNS Cancers

Tumors arising in the brain and spinal cord.

Risk Factors

Factors like environmental exposure and genetic predisposition influencing cancer development.

Racial Disparities

Variations in cancer incidence and outcomes among different racial groups.

Uncontrolled Growth

Cancer cells bypass normal regulatory mechanisms for growth and division.

Genetic and Epigenetic Instability

Cancer cells often have high mutation rates and chromosomal abnormalities.

Telomerase Activation

Cancer cells may produce telomerase to prevent telomere shortening and escape senescence.

DNA Alterations

Cancer is caused by genetic mutations (oncogenes) and epigenetic changes.

BCR-ABL Fusion Gene

Found in Chronic Myeloid Leukemia (CML), leading to uncontrolled cell growth.

Hereditary Cancers

Result from germline mutations, e.g., BRCA1 mutations increase breast cancer risk.

Sporadic Cancers

Caused by somatic mutations, not inherited.

Oncogenes

Mutated proto-oncogenes that promote cancer by stimulating cell division.

Tumor Suppressor Genes

Genes that inhibit cell division to prevent cancer; examples include Rb and p53.

Signal Transduction Pathways

Mutations in pathways like Ras or MYC can lead to persistent cell growth signaling.

Angiogenesis

Tumors induce blood vessel growth (via VEGF) to supply nutrients, essential for tumor growth and metastasis.

Chronic Inflammation

Long-term inflammation, such as from infections, can increase cancer risk.

Immune Response to Cancer

T-cells can destroy cancer cells, but some tumors evade immune detection.

Prevention

Lifestyle changes and vaccinations (e.g., HPV vaccine) reduce cancer risk.

Treatment

Includes surgery, chemotherapy, radiation, targeted therapies, and immunotherapies, often used in combination for better outcomes.

Recombinant DNA Technology

Techniques for manipulating DNA in vitro and in vivo.

Genetic Engineering

Modifying DNA to produce organisms with desirable traits

Restriction Enzymes

Proteins that cut DNA at specific sequences.

DNA Cloning

Inserting foreign DNA into plasmids for replication.

Polymerase Chain Reaction (PCR)

Technique to amplify DNA through thermal cycles.

Gene Sequencing

Determines DNA sequence using methods like Sanger and NGS.

Next-Generation Sequencing (NGS)

High-throughput sequencing revolutionizing genomic analysis.

Molecular Pharming

Using GMOs to produce pharmaceuticals cost-effectively.

Gene Therapy

Altering genetic material to treat diseases.

Genomic Libraries

Contain entire genome fragments for sequencing.

cDNA Libraries

Represent expressed genes from mRNA via reverse transcription.

Agrobacterium-Mediated Transformation

Inserting DNA into plant genomes using Agrobacterium.

Golden Rice

Engineered rice producing beta-carotene for vitamin A deficiency.

Transgenic Animals

Animals with modified DNA created via various methods.

AquAdvantage Salmon

Genetically engineered salmon that grows faster.

Cloning

Reproducing genetically identical organisms with challenges.

Induced Pluripotent Stem Cells (iPSCs)

Stem cells generating patient-specific cells for therapy.

Non-targeted DNA Insertion

Random DNA insertion disrupting normal gene function.

CRISPR

Genetic editing tool allowing precise DNA modifications.

Cas9

Enzyme that cuts DNA at specific locations.

PAM (Protospacer Adjacent Motif)

Short DNA sequence essential for Cas9 recognition.

Genome Editing Mechanism

RNA guides Cas9 to target DNA for cutting.

Meganucleases

Recognize long DNA sequences creating double-strand breaks.

Zinc Finger Nucleases (ZFNs)

Combine DNA-binding and cleavage domains for editing.

TALENs

Recognize single base pairs requiring large constructs.

Ethical Considerations

Concerns about environmental impact and health risks.

Germline Editing

Editing embryos raises designer baby concerns.

Public Perception

Concerns over GMOs highlight need for transparent communication.