COLLEGE PHYSICS - Chapter 4 CELL STRUCTURE

This set of flashcards covers key concepts from Chapter 4 on Cell Structure, including cell definition, organization, microscopy types, cell theory, prokaryotic and eukaryotic cell characteristics, organelles, the endomembrane system, and cell connections.

What are the learning objectives for studying cells in Chapter 4?

To describe the role of cells in organisms, compare and contrast light microscopy and electron microscopy, and summarize cell theory.

What are cells considered in relation to all organisms?

Cells are the building blocks of all organisms.

What is the organization hierarchy in multicellular organisms?

Cells form tissues, tissues combine to form organs, organs working together make up an organ system, and multiple systems form the entire organism.

Why are microscopes necessary for studying most cells?

Most cells are too small to be seen by the naked eye.

What are the two most important parameters in microscopy?

Magnification and resolving power.

What is magnification in microscopy?

Magnification is the process of enlarging an object in appearance.

What is resolving power in microscopy?

Resolving power is the ability of a microscope to distinguish two adjacent structures as separate.

How do compound light microscopes produce images?

They bend visible light to provide magnification.

What is a characteristic feature of samples and preparation for light microscopy?

Transparent objects (like cells) must be treated with chemical stains to distinguish different parts.

How do electron microscopes achieve higher magnification and resolution?

They use beams of electrons.

What are the two types of electron microscopes and what do they show?

Transmission electron microscopes (TEM) show fine detail within cells, while scanning electron microscopes (SEM) provide 3-D exterior views.

What are the three core principles of Cell Theory?

Cells are basic units of life, all living organisms are made of cells, and all cells come from preexisting cells.

What are the four common components shared by all cells?

An enclosing plasma membrane, cytoplasm, DNA (genetic material), and ribosomes.

What is a key characteristic of prokaryotic cells regarding internal structures?

Prokaryotes lack membrane-enclosed internal nuclei and organelles.

Which two domains of organisms are prokaryotes?

Archaea and Bacteria.

Where is chromosomal DNA localized in a prokaryotic cell?

In a nucleoid region.

Why are prokaryotic cells typically smaller than eukaryotic cells?

Their surface area to volume ratio is more favorable for moving material in and out of the cell, and they lack modifications found in eukaryotes that aid internal transport.

What is the primary factor limiting cell size?

The surface area-to-volume ratio.

What is the role of the eukaryotic plasma membrane?

It controls the passage of molecules into and out of the cell.

What is the cytoplasm?

The region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in gel-like cytosol plus the cytoskeleton.

What is the primary function of the nucleus in a eukaryotic cell?

It stores DNA.

What is the function of the nucleolus?

It directs the synthesis of ribosomes from rRNA and protein.

What is the function of the nuclear envelope?

It separates DNA from the cytoplasm and transcription from translation.

What are ribosomes made of and what is their function?

Ribosomes are made of two different-sized subunits of special RNA (rRNA) and proteins, and they serve as platforms for the assembly of amino acids into proteins during protein synthesis.

What is the primary function of the mitochondrion?

It is the site for the conversion of stored energy into a more useful form (ATP) through cellular respiration, earning it the nickname 'powerhouse of the cell.'

What unique features do mitochondria possess?

They have their own DNA (maternal) and ribosomes, and their inner membrane is folded into cristae.

What are the functions of peroxisomes?

They are sites for reactions that break down fatty acids and amino acids, may detoxify poisons, and contain the enzyme catalase which breaks down hydrogen peroxide into water and oxygen.

What is the difference between vesicles and vacuoles?

Both are membrane-bound sacs for storage and transport, but vacuoles are generally larger than vesicles.

What structures are present in animal cells but not plant cells?

A centrosome (with centrioles) and lysosomes.

What structures are present in plant cells but not animal cells?

A cell wall, chloroplasts, and a large central vacuole.

What is the function of lysosomes in animal cells?

They contain digestive enzymes that break down large biomolecules and worn-out organelles.

What is the primary function of the centrosome in animal cells?

It is the microtubule organizing center (MTOC) that directs the assembly of microtubules.

What is the composition of the plant cell wall and what is its function?

It is a rigid protective structure external to the plasma membrane, made up of cellulose, and maintains cell shape.

What is the function of the large central vacuole in plant cells?

It helps regulate water concentration under changing environmental conditions and contributes to cell expansion.

What is the function of chloroplasts?

They contain the pigment chlorophyll that captures solar energy for photosynthesis, producing sugars from CO2, water, and sunlight.

What unique features do chloroplasts possess?

They are double-membrane organelles, have their own ribosomes and DNA like mitochondria, and contain interconnected and stacked fluid-filled membrane sacs called thylakoids (grana).

What is the endosymbiosis hypothesis regarding mitochondria and chloroplasts?

It is hypothesized that mitochondria and chloroplasts originated as independent prokaryotic organisms that became endosymbionts of the prokaryotic ancestors of eukaryotes.

What does the endomembrane system consist of?

It consists of internal membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.

What are the components of the endomembrane system?

The nuclear envelope, lysosomes, vesicles, endoplasmic reticulum, Golgi apparatus, and plasma membrane.

What is the structure of the Endoplasmic Reticulum (ER)?

It is an interconnected network of membranous sacs and tubules, with its membrane continuous with the nuclear envelope.

What are the primary functions of the Rough Endoplasmic Reticulum (RER)?

It modifies proteins synthesized on its attached ribosomes and synthesizes phospholipids for cellular membranes.

What are the primary functions of the Smooth Endoplasmic Reticulum (SER)?

It synthesizes carbohydrates and lipids, produces steroid hormones, detoxifies medications and poisons, and stores Ca++.

What is the function of the Golgi apparatus?

It sorts, packages, and tags lipids and proteins received from the ER so they can reach their correct destinations.

What is the cytoskeleton?

A network of protein fibers that maintains cell shape, holds organelles in specific positions, allows movement of cytoplasm and vesicles, and enables cell movement.

What are the three components of the cytoskeleton?

Microfilaments, intermediate filaments, and microtubules.

What is the primary function of intermediate filaments?

They are purely structural, bearing tension to maintain cell shape and anchor the nucleus and other organelles in place.

What are microfilaments made of and what are their functions?

Microfilaments are made from actin monomers and are involved in the movement of the entire cell or internal parts, determine and stabilize cell shape, and, with myosin, are involved in muscle contraction.

What are microtubules made of and what are their functions?

Microtubules are made of tubulin dimers and form a rigid internal skeleton for some cells, providing a framework for motor proteins to move structures within the cell.

What are cilia and flagella used for and what is their composition?

They are composed of microtubules and are used for the motility of the cell or something outside of the cell. Cilia are shorter and more numerous, while flagella are longer.

What are plasmodesmata?

Channels that pass between cell walls in plants to connect cytoplasm and allow materials to move from cell to cell.

What are tight junctions and where are they found?

Watertight seals between animal cells that prevent materials from leaking between cells, found in epithelial cells lining internal organs and cavities.

What are desmosomes?

Short proteins (cadherins) in the plasma membrane that act as spot welds, joining adjacent cells in tissues that stretch, such as the heart, lungs, and muscles.

What are gap junctions?

Channels formed by connexons (six proteins) that allow ions, nutrients, and other materials to move directly between adjacent animal cells.

What is the extracellular matrix (ECM) and what are its components?

Found only in animal cells, it holds cells together and facilitates communication. Its components include collagens and other fibrous proteins, glycoproteins called proteoglycans, and linking proteins.