chapter 6 tour of the cell Flashcards
What are the three main parameters of microscopy?
- Magnification
- Resolution
- Contrast
These parameters help differentiate and clarify microscopic images.
What is the main difference between scanning electron microscopy (SEM) and transmission electron microscopy (TEM)?
- SEM focuses a beam of electrons onto the surface, providing 3D images
- TEM focuses a beam of electrons through a specimen
SEM provides surface images, while TEM is used for internal structure analysis.
What is cell fractionation?
A process that takes cells apart and separates major organelles from one another
It enables scientists to study the functions of individual organelles.
What are the two main types of cells based on cellular structure?
- Prokaryotic cells
- Eukaryotic cells
Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both.
What is the role of ribosomes in eukaryotic cells?
Ribosomes use the information from DNA to make proteins
They can be free in the cytosol or bound to the rough endoplasmic reticulum.
What are the components of the endomembrane system?
- Nuclear envelope
- Endoplasmic reticulum
- Golgi apparatus
- Lysosomes
- Vacuoles
- Plasma membrane
These components are involved in regulating protein traffic and performing metabolic functions.
What functions does the smooth endoplasmic reticulum (ER) perform?
- Synthesizes lipids
- Metabolizes carbohydrates
- Detoxifies drugs and poisons
- Stores calcium ions
The smooth ER does not have ribosomes attached.
True or False: The Golgi apparatus modifies products of the rough endoplasmic reticulum.
True
It also manufactures certain macromolecules and sorts materials into transport vesicles.
What is the primary role of lysosomes?
Digest macromolecules using hydrolytic enzymes
They also recycle the cell’s own organelles through a process called autophagy.
What are the primary functions of mitochondria?
Sites of cellular respiration, generating ATP using oxygen
Mitochondria convert chemical energy into a usable form for the cell.
What is the function of chloroplasts?
Sites of photosynthesis
They capture light energy and convert it into chemical energy.
What is the endosymbiont theory?
States that some organelles in eukaryotic cells were once prokaryotic microbes
Mitochondria and chloroplasts are examples, as they have similarities with bacteria.
What are the three types of fibers that compose the cytoskeleton?
- Microtubules
- Microfilaments
- Intermediate filaments
These fibers organize structures and activities within the cell.
How do microtubules contribute to cell function?
Help shape the cell, guide movements of organelles, and separate chromosomes during cell division
They are the thickest component of the cytoskeleton.
What is the function of microfilaments?
Bear tension and resist pulling forces within the cell
They are involved in cellular motility and structural support.
What do plant cell walls protect against?
Excessive uptake of water and help maintain shape
They are made of cellulose fibers embedded in polysaccharides and proteins.
What is the extracellular matrix (ECM) in animal cells made of?
Glycoproteins such as collagen, proteoglycans, and fibronectin
The ECM provides support, adhesion, movement, and regulation.
List the types of intercellular junctions.
- Plasmodesmata
- Tight junctions
- Desmosomes
- Gap junctions
These junctions facilitate communication and adhesion between neighboring cells.
What are plasmodesmata?
Channels that perforate plant cell walls allowing water, small solutes, sugars, and sometimes proteins and RNA to pass from cell to cell
Plasmodesmata are essential for communication and transport between plant cells.
What is the function of tight junctions?
Prevent leakage of extracellular fluid by pressing membranes of neighboring cells together
Tight junctions are crucial for maintaining the integrity of epithelial tissues.
What are desmosomes?
Anchoring junctions that fasten cells together into strong sheets
Desmosomes provide mechanical stability to tissues that experience stress.
What is the role of gap junctions?
Allow small molecules to pass between adjacent cells, serving as communicating junctions
Gap junctions facilitate cell communication and coordination of activities.
What does it mean that the cell is a living unit greater than the sum of its parts?
Cells rely on the integration of structures and organelles to function effectively
This concept emphasizes the importance of cellular organization and cooperation among components.
Which components coordinate in a macrophage to destroy bacteria?
Cytoskeleton, lysosomes, and plasma membrane
The coordination of these components allows macrophages to effectively engulf and digest pathogens.
What is the core theme of biology?
Evolution accounts for the unity and diversity of life
How do scientists study nature?
By making observations and forming and testing hypotheses
What approach does science benefit from?
A cooperative approach and diverse viewpoints
List the properties of life
- Order
- Evolutionary adaptation
- Regulation
- Energy processing
- Growth and development
- Responses to the environment
- Reproduction
What is an example of evolutionary adaptation?
Camouflage
What does regulation refer to in the context of life?
Temperature control
What is energy processing in living organisms?
Getting fuel from somewhere to use that chemical energy
What is the basic unit of structure and function in biology?
The cell
What is reductionism in biology?
Studying smaller biological scales
Define emergent properties
New properties that arise with each step upwards in hierarchy of life
How are structure and function related?
They are correlated to one another
What do chromosomes contain?
DNA
What is a gene?
A unit of hereditary information consisting of a specific nucleotide sequence in DNA
What is required for work in living organisms?
Energy
How does energy enter ecosystems?
As light (sun)
What do chemicals do in ecosystems?
They are cycled through ecosystems and are used and recycled
What is feedback regulation?
Regulation of a process by its output or end product
What is negative feedback?
A loop where the response reduces the initial stimulus
What do biotic and abiotic factors do?
Interact in ecosystems
What is the definition of evolution?
The change in the genetic composition of a population from generation to generation
What is natural selection?
A process in which individuals with certain traits survive and reproduce better than those without the traits
How long does natural selection take?
Natural selection takes time
List the three domains of life.
- Bacteria
- Archaea
- Eukarya
What are the key differences between prokaryotic and eukaryotic cells?
Prokaryotic cells are simple structures, have no prominent nucleus, are small in size, have cell walls with peptidoglycan, are unicellular, and lack membrane-bound organelles. Eukaryotic cells are complex structures, have a prominent nucleus, are larger in size, have cell walls with chitin or cellulose, can be unicellular or multicellular, and contain membrane-bound organelles.
What is a prokaryotic cell?
A prokaryotic cell is a small single-celled organism, such as bacteria and archaea, that lacks a nucleus and membrane-bound organelles.
What are archaea?
Archaea are small single-celled organisms that usually inhabit extreme environments, such as deep-sea vents and hot springs.
What are eukaryotic cells?
Eukaryotic cells can be single-celled or multicellular organisms that have a complex structure, a prominent nucleus, and membrane-bound organelles.
What are protists?
Protists are a diverse collection of organisms that do not fit into animals, plants, bacteria, or fungi groups, primarily microscopic, and mostly unicellular.
List the key similarities between prokaryotes and eukaryotes.
- Contain DNA
- Contain ribosomes
- Have cell membranes
- Contain cytoplasm
What is the primary function of light microscopy?
Light microscopy is used to make small structures and samples visible by providing a magnified image using visible light.
What is electron microscopy?
Electron microscopy is a technique for obtaining high-resolution images of biological and non-biological specimens using electrons as the source of illumination.
How does cell shape relate to function?
Cell shape is related to function as it can influence the cell’s ability to interact with its environment and perform specific tasks.
What is the role of mitochondria?
Mitochondria generate most of the chemical energy needed to power the cell’s biochemical reactions and are known as the powerhouses of the cell.
What is the function of ribosomes?
Ribosomes are responsible for protein synthesis and can be found freely in the cytoplasm or attached to the rough endoplasmic reticulum.
What is the endomembrane system?
The endomembrane system is a group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.
What are lysosomes?
Lysosomes are membrane-bound organelles that contain enzymes for breaking down macromolecules and responding against foreign substances.
What is the function of the Golgi apparatus?
The Golgi apparatus processes proteins made by the ER before sending them out of the cell, modifying them as necessary.
What is the plasma membrane?
The plasma membrane is a double layer of lipids and proteins that surrounds a cell, controlling the movement of substances in and out.
what is a vacuole?
membrane-bound organelle within a cell that functions as a storage space, often containing water, food, or waste products.
What are the main components of the cytoskeleton in eukaryotic cells?
- Microfilaments
- Intermediate filaments
- Microtubules
What is the function of cilia and flagella?
Cilia and flagella are involved in movement, either moving the cell itself or moving other molecules.
What are chloroplasts?
Chloroplasts are organelles within plant cells and certain algae that are the site of photosynthesis.
What is the main role of peroxisomes?
Peroxisomes transform reactive oxygen species into safer molecules and play a role in fatty acid oxidation.
What is the function of the nucleolus?
The nucleolus is the site of ribosome and ribosomal RNA production within the nucleus.
What is chromatin?
Chromatin is DNA complexed with proteins, primarily histones, that help package DNA within the nucleus.
What is the significance of the nuclear envelope?
The nuclear envelope separates the cell’s genetic material from the rest of the cell, maintaining a distinct environment.
What is the role of the cytoplasm?
The cytoplasm is a thick solution that fills each cell, composed mainly of water, salts, and proteins.
What are the two types of endoplasmic reticulum?
- Rough endoplasmic reticulum
- Smooth endoplasmic reticulum
What is the function of the rough endoplasmic reticulum?
The rough endoplasmic reticulum is involved in protein synthesis and modification due to the presence of ribosomes.
What is the structure of the mitochondria?
Mitochondria have an outer membrane, inner membrane, cristae, and matrix, each playing a role in energy production.
What are the functions of microfilaments?
Microfilaments are involved in muscle contraction, cell movement, intracellular transport, and maintenance of cell shape.
What do intermediate filaments do?
Intermediate filaments maintain cell shape, bear tension, and provide structural support.
What is the role of the centrosome?
The centrosome is a microtubule organizing center from which microtubules radiate outwards.
What is the cytoplasm primarily composed of?
About 90% water
The cytoplasm is usually colorless.
What are the main components of the cytoplasm?
- Cytosol (gel-like substance)
- Organelles (the cell’s internal substructures)
- Cytoplasmic inclusions
- Secretory inclusions (proteins, enzymes, and acids)
- Nutritive inclusions (glycogen and lipids)
- Pigment granules (melanin)
What is the structure of the outer membrane of a chloroplast?
A semi-porous membrane that allows small molecules and ions to easily diffuse across.
What is the stroma in a chloroplast?
Protein-rich, alkaline, aqueous fluid within the inner chloroplast membrane.
What is the function of thylakoids?
Site of light-dependent reactions of photosynthesis with chlorophyll embedded in the membrane.
What are granum in chloroplasts?
Stacks of thylakoids.
What is the function of plasmodesmata?
Helps regulate the passage of small molecules and is responsible for cell-to-cell communication.
What is a cell wall?
A rigid, semi-permeable protective layer positioned next to the cell membrane.
What is the primary composition of the cell wall?
Mainly strong fibers of the carbohydrate polymer cellulose.
What are the functions of the cell wall?
- Provides mechanical protection
- Provides a chemically buffered environment
- Allows circulation and distribution of water, minerals, and nutrients
- Provides rigid building blocks for stable structures
- Acts as a storage site for regulatory molecules
What is the middle lamella?
Layer that lies between the two primary walls of adjacent cells, fastening them together.
What is the primary wall?
Thin, flexible, extensible layer produced in young growing cells.
What characterizes the secondary wall?
Present in specific cells, involved in mechanical support and water transportation, and has pits.
What are extracellular components?
Materials synthesized and secreted by most cells external to the plasma membrane.
What does ECM stand for?
Extracellular matrix.
What is the extracellular matrix?
A three-dimensional network of extracellular macromolecules and minerals that acts as connective material.
What are the functions of the extracellular matrix (ECM)?
- Provides structural and biochemical support
- Involved in cell adhesion, cell-to-cell communication, and differentiation.
What are intercellular junctions?
Multi-protein complexes that provide contact or adhesion between neighboring cells or between a cell and the ECM.
