Topic 1.4: Structure and Function of the Cell Flashcards
Explain why humans are made up of trillions of cells instead of just one.
If humans were made up of one cell, they wouldn’t be able to efficiently expel as many wastes or absorb as many nutrients. For instance, we wouldn’t be able to expel carbon dioxide.
Explain why the cell is the basic unit of life
As the cell theory states, all organisms are made up of basic living units called cells, and all cells come only from previously existing cells.
Describe the metabolic challenges of a large cell compared to a smaller size
When a cell is larger, the surface-area-to-volume ratio is smaller than that of a smaller cell, making it difficult to excrete and absorb as much waste or nutrients.
What is a prokaryotic cell?
A cell that lacks a membrane-bound nucleus.
The domains Archaea and Eubacteria consist of prokaryotic cells. Prokaryotes generally exist as single celled organisms or as simple strings and clusters.
What is a plasma membrane?
A plasma membrane is the boundary that separates the living contents in the cell from its surrounding environment. It regulates the entrance and exit of molecules into and out of the cytoplasm.
What is a cytoplasm?
The cytoplasm is a semifluid composed of water, salts, and dissolved organic molecules. It is the medium for chemical reaction. It provides a platform upon which other organelles can operate within the cell. All of the functions for cell expansion, growth and replication are carried out in the cytoplasm of a cell.
What is a cell wall?
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism
What is a ribosome?
A site of protein synthesis in a prokaryotic cell.
What is a flagellum/flagella?
Rotating filament present in some bacteria that pushes the cell forward.
What is a fimbriae?
Hairlike bristles that allow adhesion to surfaces.
What is a nucleoid?
Location of the bacterial chromosome
What is a plasma membrane?
Sheath around cytoplasm that regulates entrance and exit of molecules.
What is a cell wall?
Covering that supports, shapes and protects cell.
What is a capsule?
Gel-like coating outside cell wall.
What is peptidoglycan?
Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall characteristic of most bacteria
Explain the function of the plasma membrane
To form a barrier between the inside and outside of the cell and regulate what crosses the barrier.
Identify the key bacterial structures and their function
Ribosome: site of protein synthesis
Flagellum: rotating filament present in some bacteria that pushes the cell forward
Fimbriae: hairlike bristles that allow adhesion to surfaces
Nucleoid: location of the bacterial chromosome
Plasma-membrane: sheath around cytoplasm that regulates entrance and exit of molecules
Cell-wall: covering that supports, shapes, and protects cell
Capsule: gel-like coating outside cell wall
Explain the general differences among archaea, bacteria, and eukaryotic cells.
Archaea
*Has a cell wall, but with no peptidoglycan
*Does not have a nucleus
*Does not have membrane-bound organelles
Bacteria
*Has a cell wall, WITH peptidoglycan
*No nucleus
*No membrane-bound organelles, but some possess internal membranes where chemical reactions may occur
Eukaryotic cells
*Sometimes has a cell wall, never with peptidoglycan
*HAS nucleus and membrane-bound organelles
What is the principle distinguishing feature of eukaryotic cells?
The presence of a nucleus, which separates the genetic material from the cytoplasm of the cell.
What is a nucleus?
Command center of cell
What is inside the nucleus?
Nuclear envelope
Nucleolus
Chromatin
Nuclear pore
What is chromatin?
Network of DNA strands and associated proteins observed within a nucleus of a cell.
What is a chromosome?
The structure that transmits the genetic material from one generation to the next; composed of condensed chromatin; each species has a particular number of chromosomes that is passed on to the next generation.
Human cells contain 46 chromosomes
What is a nucleoplasm?
Semifluid medium of the nucleus, containing chromatin
What is a nucleolus?
Dark-staining, spherical body in the nucleus that produces ribosomal subunits.
What is a nuclear envelope?
Double membrane that surrounds the nucleus in eukaryotic cells and is connected to the endoplasmic reticulum; has pores that allow substances to pass between the nucleus and the cytoplasm.
Define nuclear pore.
Opening in the nuclear envelope that permits the passage of proteins into the nucleus and ribosomal subunits out of the nucleus.
Define ribosome
Site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA).
Define polyribosome
String of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis.
Define endoplasmic reticulum (ER)
System of membranous saccules and channels in the cytoplasm, often with attached ribosomes.
Define rough ER (endoplasmic reticulum)
Membranous system of tubules, vesicles, and sacs in cells; has attached ribosomes.
Define smooth ER (endoplasmic reticulum)
Membranous system of tubules, vesicles, and sacs in eukaryotic cells; site of lipid synthesis; lacks attached ribosomes.
Define Golgi apparatus
Organelle consisting of sacs and vesicles that processes, packages, and distributes molecules about or from the cell.
Define lysosome
Membrane-bound vesicle that contains hydrolytic enzymes for digesting macromolecules and bacteria; used to recycle worn-out cellular organelles.
Define vacuole
Membrane-bound sac, larger than a vesicle; usually functions in storage and can contain a variety of substances. In plants, the central vacuole fills much of the interior of the cell.
Define peroxisome
Enzyme-filled vesicle in which fatty acids and amino acids are metabolized to hydrogen peroxide that is broken down into harmless products.
Define chloroplast
Membrane-bound organelle in algae and plants with chlorophyll-containing membranous thylakoids; where photosynthesis takes place.
Define mitochondria
(sing., mitochondrion) Membrane-bound organelle in which ATP molecules are produced during the process of cellular respiration.
Define photosynthesis
Process, usually occurring within chloroplasts, that uses solar energy to reduce carbon dioxide to carbohydrate.
Define cellular respiration
Metabolic reactions that use the energy from carbohydrate, fatty acid, or amino acid breakdown to produce ATP molecules.
Define stroma
Region within a chloroplast that surrounds the grana; contains enzymes involved in the synthesis of carbohydrates during the Calvin cycle of photosynthesis.
Define thylakoid
Flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur.
Define grana
(sing., granum) Stack of chlorophyll-containing thylakoids in a chloroplast.
Define matrix
Unstructured semifluid substance that fills the space between cells in connective tissues or inside organelles.
Define cristae
(sing., crista) Short, fingerlike projections formed by the folding of the inner membrane of mitochondria.
Explain the function of a cell wall in eukaryotes
Protecting the cell while remaining permeable (allowing liquids/gasses to pass through)
Describe how the endomembrane systems acts as a transport system
The endomembrane system transports molecules throughout the cell because the organelles that compose it are connected directly or by transport vesicles
Explain why plant cells need both chloroplast and mitochondria
Plant cells make their food. Chloroplasts allow them to capture solar energy to produce organic molecules. Plant cells need mitochondria to break down the organic molecules to produce ATP which is used for energy in their metabolism
Define cytoskeleton
Internal framework of the cell, consisting of microtubules, actin filaments, and intermediate filaments.
Define actin filament
Component of the cytoskeleton; plays a role in the movement of the cell and its organelles; a protein filament in a sarcomere of a muscle, its movement shortens the sarcomere, yielding muscle contraction.
Define motor molecule
Protein that moves along either actin filaments or microtubules and translocates organelles.
Define intermediate filament
Ropelike assemblies of fibrous polypeptides in the cytoskeleton that provide support and strength to cells; so called because they are intermediate in size between actin filaments and microtubules.
Define microtubule
Small, cylindrical organelle composed of tubulin protein around an empty central core; present in the cytoplasm, centrioles, cilia, and flagella.
Define centrosome
Central microtubule organizing center of cells. In animal cells, it contains two centrioles.
Define centriole
Cell structure, existing in pairs, that occurs in the centrosome and may help organize a mitotic spindle for chromosome movement during animal cell division.
Define cilia
(sing., cilium) Short, hairlike projections from the plasma membrane, occurring usually in larger numbers.
Identify the structural makeup of actin filaments, intermediate filaments, and microtubules.
All 3 are part of the cytoskeleton and are dynamic. Intermediate filaments play a structural role, while both actin filaments and microtubules have a structural and a movement role. Actin filaments are composed of actin monomers, microtubules are composed of tubulin monomers, and intermediate filaments are composed of various types of polypeptides.
Contrast the function of cilia, flagella, and centrioles
Centrioles function in the process of cell division.
Flagella and centrioles function in the process of locomotion
Explain how cilia and flagella are involved in movement
The dynein side arms of the microtubule doublets slide passed each other using the energy of ATP
What is the endosymbiotic theory?
Explanation of the evolution of eukaryotic organelles by phagocytosis of prokaryotes.
Recognize the evidence that suggest that chloroplasts and mitochondria were once independently living eukaryotes
*similar to bacteria in size and structure
*are bound by a double membrane
*divide by splitting
*have their own ribosomes (similar to prokaryotic ribosomes) and produce some protiens
*have similar ribosomal RNA sequences similar to prokaryotic rRNA sequences
