Questions and Answers
What is the primary function of ribosomes in eukaryotic cells?
Which cellular structure is responsible for processing and packaging proteins?
What is the result of the semiconservative model of DNA replication?
Which of the following mutations is most commonly generated through deamination of cytosine?
Signup and view all the answers
Which syndrome is associated with enhanced susceptibility to oral cancer due to DNA repair mechanisms?
Signup and view all the answers
What is the role of the cytoskeleton in eukaryotic cells?
Signup and view all the answers
Which type of nucleic acid base pair must follow Chargaff's rule?
Signup and view all the answers
What factor mainly contributes to the stability of DNA's structure?
Signup and view all the answers
Which of the following mutations is corrected by the mismatch repair mechanism?
Signup and view all the answers
What characteristic is unique to stem cells compared to specialized cells?
Signup and view all the answers
Study Notes
Levels of Organization
- Nonliving: atoms, molecules; Living: cells, tissues, organs, organ systems, organisms.
- Organisms exhibit characteristics such as cellular structure, energy requirements, reproduction, homeostasis, organization, and responsiveness.
Molecules of Life
- Essential molecules include Sodium ions (Na+) and Water (H2O).
- Amino acids can exist as isomers: L-amino acids form proteins; D-amino acids are metabolized.
- Only D-glucose is utilized for amino acid synthesis; cellular structures differ between animal and bacterial cells.
Cell Diversity and Structure
- Cell specialization occurs, excluding stem cells which can differentiate into any cell type.
- Prokaryotic cells lack a nucleus and contain mitochondria, ribosomes, and DNA concentrated in a non-membrane-bound nucleoid.
- Eukaryotic cells have a phospholipid bilayer in their plasma membrane, with proteins and carbohydrates allowing selective permeability.
Eukaryotic Organelles
- Cytoplasm houses all organelles except the nucleus; it contains cytosol and a cytoskeleton (microfilaments, intermediate filaments, microtubules).
- Nucleolus directs RNA synthesis and ribosome formation.
- Rough Endoplasmic Reticulum (RER) has ribosomes attached for protein synthesis and modification; Smooth Endoplasmic Reticulum (SER) is involved in carbohydrate and lipid synthesis.
- Golgi apparatus functions as the cell's postal service for vesicle reception and packing.
- Mitochondria are crucial for energy production, with dysfunction accelerating aging. Replacement can rejuvenate cells.
Oral Cancer and Cell Communication
- Crosstalk between organelles is significant in oral cancer and sphingolipid synthesis.
- Increased sphingosine-1-phosphate enhances survival of oral cancer cells; its release from the SER results in cancerous signaling.
- High levels of ceramide inhibit cancer cell survival, synthesized in the SER to prevent conversion to sphingosine-1-phosphate.
DNA Replication
- Occurs during the S-phase, producing two identical DNA replicas.
- Nucleotides consist of a phosphate group (5' phosphate), pentose sugar (ribose or 2-deoxyribose), and nitrogenous bases (A, T, C, G, U).
- Chargaff's rule states that A pairs with T and G pairs with C.
- Replication direction: 5' to 3'; leading strand is synthesized continuously, lagging strand in fragments (Okazaki fragments).
- DNA exhibits right-handed helical structure, enhancing stability, and follows a semiconservative model.
DNA Damage and Repair
- Damage from chemicals/radiation leads to mutations; defects in repair mechanisms contribute to cancer.
- Accumulation of radical oxygen species (ROS) causes DNA damage, with common issues including point mutations and base pair mismatches.
- Repair mechanisms include mismatch repair for base pair mismatches, base-excision repair for damaged single-stranded DNA, and nucleotide excision repair for DNA adducts.
- Double-strand breaks are repaired through homologous recombination or non-homologous end joining.
Genetic Mutations and Oral Health
- Ataxia-Telangiectasia is characterized by dilated blood vessels, enamel hypoplasia, and increased susceptibility to periodontitis.
- Bloom Syndrome presents with absent lateral incisors and is linked to defects in DNA repair mechanisms, increasing oral cancer risk.
- Werner Syndrome exhibits signs of accelerated aging, including microdontia and xerostomia, affecting oral health.
- Cockayne Syndrome leads to dental anomalies and other oral features like thin lips.
- Fanconi Anemia is associated with leukoplakia and mucosal abnormalities, increasing the risk of oral infections and dental issues.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the various levels of organization in biology, from atoms and molecules to complex organisms. This quiz covers organism characteristics such as cellular structure, energy requirements, and homeostasis, as well as details about the molecules of life and cell diversity. Test your understanding of these foundational concepts in biology.
