Biology Chapter 10: Cell Biology and Development

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Questions and Answers

What are the predominant cells involved in phagocytosis?

Macrophages are the predominant cells involved in phagocytosis.

Describe the role of receptor proteins in receptor-mediated endocytosis.

Receptor proteins bind to specific ligands, which triggers the inward folding of the membrane to form vesicles.

What is an example of a process facilitated by clathrin-mediated endocytosis?

Iron-bound transferrin recycling is an example of a process facilitated by clathrin-mediated endocytosis.

What type of transport is used for the uptake of large solids, such as starch?

Phagocytosis is used for the uptake of large solids, including starch. Signup and view all the answers

What distinguishes receptor-mediated endocytosis from general endocytosis?

Receptor-mediated endocytosis involves specific binding between ligands and receptors, unlike general endocytosis. Signup and view all the answers

What role do growth factors play in the development of the ectoderm during organogenesis?

Growth factors signal cells in the ectoderm to form the neural plate, guiding the development of the neural tube. Signup and view all the answers

Describe the fate of the neural tube after its formation.

The neural tube will develop into the brain and spinal cord. Signup and view all the answers

How does mesoderm differentiation contribute to vertebrate body structure?

The mesoderm differentiates into various connective tissues, including the ribs, spine, skeletal muscle, and lungs. Signup and view all the answers

What is the primary function of the endoderm in organogenesis?

The endoderm forms the lining of the digestive tract and various internal organs. Signup and view all the answers

Explain how disruptions in growth factor signaling affect ectoderm differentiation.

Disruptions in growth factor signaling can lead to the entire ectoderm differentiating into neural tissue. Signup and view all the answers

What structures arise from the somites formed in the mesoderm?

Somites develop into the ribs, lungs, and segmental muscle tissues. Signup and view all the answers

What is the significance of the notochord in embryonic development?

The notochord serves as the central axis and provides structural support within the developing embryo. Signup and view all the answers

How does the endoderm change morphologically during organogenesis?

The endoderm transitions from flattened cells to columnar epithelial cells. Signup and view all the answers

What is osmosis?

Osmosis is the diffusion of water through a selectively permeable membrane from high water concentration to low water concentration. Signup and view all the answers

Define osmotic pressure.

Osmotic pressure is the minimum pressure required to prevent the inward flow of pure solvent across a semipermeable membrane. Signup and view all the answers

What happens to a cell during plasmolysis?

During plasmolysis, a cell loses turgor pressure and collapses as water moves out by osmosis. Signup and view all the answers

What role does turgor pressure play in plants?

Turgor pressure is the internal pressure exerted on a plant cell wall when water enters the cell, maintaining its structure. Signup and view all the answers

How do contractile vacuoles function in protists like paramecium?

Contractile vacuoles collect excess water and pump it out to prevent over-expansion in protists. Signup and view all the answers

Differentiate between isotonic, hypertonic, and hypotonic solutions.

Isotonic solutions have equal solute concentrations, hypertonic solutions have higher solute concentrations, and hypotonic solutions have lower solute concentrations than the cell. Signup and view all the answers

What adaptation do saltwater fish have to manage osmotic pressure?

Saltwater fish have specialized gills that pump out excess salt to prevent dehydration. Signup and view all the answers

Explain the process of facilitated diffusion.

Facilitated diffusion is the process where specific particles move across membranes through transport proteins. Signup and view all the answers

What happens to bcl-2 following cellular stress and how does this relate to apoptosis?

Bcl-2 relocates to the mitochondria where it interacts with pro-apoptotic proteins, disrupting its normal function and potentially leading to the release of cytochrome C. Signup and view all the answers

Describe the role of cytochrome C in the apoptosis pathway.

Cytochrome C, once released from the mitochondria, interacts with Apaf-1 and recruits pro-caspase 9 to form the apoptosome, which activates the caspase cascade. Signup and view all the answers

What process involves the material being forced out of a cell in bulk and requires energy?

Exocytosis Signup and view all the answers

Identify one example of materials released from cells via exocytosis.

Hormones or wastes Signup and view all the answers

How do caspases contribute to the morphological changes observed during apoptosis?

Caspases activate DNases, inhibit DNA repair enzymes, and degrade structural proteins, leading to cellular shrinkage and chromatin condensation. Signup and view all the answers

Explain the formation of apoptotic bodies during apoptosis.

Apoptotic bodies are formed by the fragmentation of cells and nuclei, remaining membrane-bound and containing organelles and nuclear fragments. Signup and view all the answers

What is the role of the sodium-potassium pump in cellular function?

To generate an electrochemical gradient Signup and view all the answers

What triggers autophagy in cells and what is its primary function?

Autophagy is triggered by inadequate nutrient supply, allowing cells to cannibalize internal organelles for resource re-use. Signup and view all the answers

How many sodium ions bind to the sodium-potassium pump during its activation?

Three sodium ions Signup and view all the answers

Discuss the difference between apoptosis and necrosis in terms of inflammatory responses.

Apoptosis occurs without an inflammatory reaction, whereas necrosis is typically accompanied by inflammation. Signup and view all the answers

What occurs to ATP during the activation of the sodium-potassium pump?

ATP is hydrolyzed Signup and view all the answers

What change in the sodium-potassium pump occurs after the phosphorylation of aspartate?

A structural change exposing Na to the exterior Signup and view all the answers

What is the role of PARP in the apoptosis pathway?

PARP is involved in DNA repair and is inhibited during apoptosis, contributing to the cleavage of chromosomal DNA. Signup and view all the answers

How does autophagy relate to cellular stress responses?

Autophagy is a response mechanism that removes damaged proteins and organelles, especially during stress conditions like starvation. Signup and view all the answers

Which Nobel Prize was awarded in 1997 related to the sodium-potassium pump, and to whom?

Half of the Nobel Prize in Chemistry to Jens Christian Skou Signup and view all the answers

What is one of the primary functions of co-transporters in cellular transport?

To facilitate the transport of solutes using an electrochemical gradient Signup and view all the answers

What is the significance of the deletion of the elastin gene in individuals with Williams syndrome?

It contributes to the developmental disorder affecting connective tissue and the central nervous system. Signup and view all the answers

Describe the structure of laminin and its role in the extracellular matrix.

Laminin is a protein of about 850 kDa that consists of three polypeptide chains forming a cruciform shape, aiding in anchoring the lamina to cells. Signup and view all the answers

What role does fibronectin play in the extracellular matrix?

Fibronectin is crucial for cell adhesion and migration within the ECM, containing an RGD sequence that binds to integrins. Signup and view all the answers

What distinguishes proteoglycans from glycoproteins?

Proteoglycans have a much higher carbohydrate content, often making up to 95% of their weight, and contain glycosaminoglycans covalently linked to core proteins. Signup and view all the answers

What are glycosaminoglycans (GAGs) and name at least three examples?

Glycosaminoglycans are long unbranched polysaccharides, with examples including hyaluronic acid, chondroitin sulfate, and heparin. Signup and view all the answers

Explain the process of passive transport and list its three main types.

Passive transport is the movement of substances across cell membranes without energy use, including diffusion, facilitated diffusion, and osmosis. Signup and view all the answers

What is the primary energy requirement for active transport mechanisms in cellular transport?

Active transport requires cellular energy, typically in the form of ATP, to move substances against their concentration gradient. Signup and view all the answers

What is endocytosis and how does it relate to active transport?

Endocytosis is a form of active transport where cells engulf materials using energy to form vesicles. Signup and view all the answers

Study Notes

Introduction to Embryonic Development

A multicellular organism develops from a single cell (the zygote) into a collection of diverse cell types, organized into tissues and organs.
Development involves cell division, body axis formation, tissue and organ development, and cell differentiation (acquiring a specific cell type identity).
During development, cells use both intrinsic (inherited) information and extrinsic (neighboring cell signals) to determine their behavior and identity.
Cells become progressively more restricted in their developmental potential (the kinds of cell types they can become) as development progresses.

Embryonic Stages

Zygote (fertilized egg): a single-celled structure.
2-celled zygote: cleavage begins after fertilization.
4-celled zygote: further cell division.
Morula: a solid mass of cells.
Blastula: a hollow ball of cells with a fluid-filled cavity (blastocoel).
Gastrula: a three-layered embryo with a developing gut (archenteron).
Neurula: an embryo with a neural tube developing.
Organogenesis: formation of organs from the respective germ layers.

Gametogenesis

The process of forming gametes (sperm and ova).
Undergoes meiosis, undergoing chromosomal and morphological changes to produce mature haploid gametes.
Spermatogenesis (in testes): leads to sperm production.
Oogenesis (in ovaries): leads to ovum production.

Common Terms

Animal pole: the pole of the egg with the least yolk concentration.
Animal hemisphere: the hemisphere of the egg containing the animal pole.
Vegetal pole: the pole of the egg with the most yolk concentration.
Vegetal hemisphere: the hemisphere of the egg containing the vegetal pole.

Fertilization

The fusion of two gametes (sperm and ovum) to form a zygote.
Involves several steps, including sperm-egg contact, sperm entry, and fusion of the nuclei.
Results in combining of genes from both parents- creating a new organism.

Cleavage

A series of rapid mitotic cell divisions of the zygote to form a multicellular structure (morula).
Blastomeres are the cells produced during cleavage, becoming increasingly smaller with each division.
The type and pattern of cleavage differentiate between species.

Blastulation

The production of a multicellular blastula as a result of cleavage.
Blastomeres (cells) within the blastula arrange to form a hollow ball (blastula) with a fluid-filled cavity (blastocoel).

Gastrulation

Rearranges the blastula's cells, creating a three-layered (triploblastic) embryo called a gastrula.
The gastrula features a primitive gut (archenteron), and cell movements (invagination, ingression).

Neurulation

The formation of the neural tube in chordates (animals with a notochord).
Ectodermal cells form a neural plate, which then sinks and forms a neural groove; the groove edges then fuse to create the neural tube.
The anterior end of the neural tube becomes the brain and the posterior end becomes the spinal cord.

Organogenesis

The formation of organs from the three germ layers (ectoderm, endoderm, and mesoderm).
The process involves differentiation of embryonic stem cells into more specialized cell types.
Signaling cascades guide the differentiation process.
Ectoderm, involved in nervous and epidermal systems
Mesoderm, involved in circulatory, musculoskeletal, excretory, and reproductive systems
Endoderm, involved in digestive and respiratory systems

Cell Injury

Cells facing stress or injury may undergo changes, classified as reversible or irreversible cell injury (death).
Causes include oxygen deprivation, physical agents, chemical agents, infections, immunologic reactions, genetic defects, and nutritional imbalances.
Important targets for injury include aerobic respiration, cell membranes, protein synthesis, cytoskeleton, and the genetic apparatus.

Cell Death

Necrosis: tissue death by enzymatic digestion of damaged cells, involving inflammation.
Apoptosis: programmed cell death that occurs during development and in response to certain signals, causing no inflammation.

Apoptosis

A programmed form of cell death characterized by morphological changes.
Involved in development, removal of damaged cells, and maintaining a healthy cell population.
Regulated by a cascade of molecular events (e.g., caspase activation).

Autophagy

A regulated process for removing damaged proteins and organelles within cells under certain conditions (e.g., starvation).
Involves the formation of autophagosomes, which then fuse with lysosomes for degradation.

Homeotic Genes (Hox Genes)

Master regulator genes that control the development of body segments or structures.
Mutations in Hox genes can significantly alter body plan development.
Crucial role in specifying the identity of different body regions.

Metamorphosis

A transformation in the body form and characteristics of organisms during their development.
Complete metamorphosis: egg -> larva -> pupa -> adult (e.g., butterfly).
Incomplete metamorphosis: egg -> nymph -> adult (gradual changes, e.g., grasshopper).

Cell Signaling

Cells communicate via chemical signals (ligands).
Signaling involves ligand binding to receptors initiating a chain of events inside the target cell(signal relay pathways).
Different pathways involving phosphorylation or second messengers relay signals.
Types of signaling include paracrine, autocrine, endocrine, and juxtacrine.

Membrane Proteins

Integral proteins span the membrane with hydrophobic regions and often coiled within.
Plays roles in transportation (channels and pumps), receptors for signal reception, and enzymes localized at the membrane.
Additional roles include cell-cell recognition and linking to the cytoskeleton.

Cell Junctions

Structures that connect cells providing contact, adherence, interactions, and communication, both in plants (plasmodesmata) and animals (tight junctions, desmosomes, and gap junctions).
Cell walls and ECM play supporting roles.

Plasma Membrane

A selectively permeable boundary separating the internal and external environments of a cell.
Composed of a phospholipid bilayer with hydrophobic tails and hydrophilic heads.
Also includes proteins and carbohydrates.
Fluid nature allows flexibility in the membrane.

ECM (Extracellular Matrix)

Extracellular structural components found outside the cell membrane.
In animals, it's made up of proteins like collagen, elastin, and fibronectin along with proteoglycans (large molecules with specific carbohydrates and proteins)
Provide mechanical support to cells, help with cell adhesion and migration processes, and play a signaling role.

Transport Across Membranes

Simple diffusion: movement of substances down their concentration gradient- passive, no energy required
Facilitated diffusion: passive movement of substances through specific membrane proteins, no energy required.
Active transport: movement of substances against their concentration gradient, requiring energy (ATP).

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Description

This quiz covers key concepts in cell biology and organogenesis, focusing on processes such as phagocytosis, endocytosis, and the roles of different cell types in embryonic development. Participants will explore the significance of growth factors and the distinctions between various cellular mechanisms. Additionally, the quiz addresses morphological changes during organogenesis.