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Chapter 6: A Tour of the Cell - Coggle Diagram
Chapter 6: A Tour of the Cell
Parts of the Cell
Nucleus
Contains most of the cell's genes and is usually the most conspicuous organelle
Nuclear Envelope
Encloses the nucleus, separating is from the cytoplasm
Is a double membrane
Each membrane consists of a lipid bilayer
Nuclear Lamint
Lines the nuclear side of the envelope
Composed of proteins and maintains the shape of the nucleus
Chromosomes
A structure within cells that contains DNA
Able to be seen during the Prophase stage of Mitosis
Chromotin
A complex of DNA and proteins found in eukaryotic cells
Each chromosome contains one DNA molecule associated with proteins
Chromotids
One of the two identical halves of a duplicated chromosome
Able to be seen during the Interphase stage of Mitosis
Nucleolus
A prominent structure within the nucleus of eukaryotic cells
Located within the nucleus
The site pf ribosomal RNA (rRNA) synthesis
Ribosomes
Complexes made of ribosomal RNA and protein
Responsible for building proteins
There's two locations
In the cytosol (free ribosomes)
On the outside of the endoplasmic reticulum (ER) or the nuclear envelope (bound ribosomes)
Endoplasmic Reticulum
Responsible for moving packaged substances
There's two regions: Smooth and Rough
Endomembrane System
The collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
Vesicles
Small, membrane-bound sacs within cells that play crucial roles in transporting substances
Nuclear Envelope
A double membrane that encloses the nucleus in eukaryotic cells, separating its contents from the cytoplasm
Endoplasmic Reticulum
An extensive membranous network in eukaryotic cells
Accounts for more than half of the total membrane in many eukaryotic cells
Smooth ER
That portion of the endoplasmic reticulum that is free of ribosomes
Functions
Synthesizes lipids
Detoxifies drugs and poison
Stores Calcium Ions
Rough ER
That portion of the endoplasmic reticulum with ribosomes attached
Functions
Has bound ribosomes, which secrete glycopoteins
Distributes transport vesicles, secretory proteins surrounded by membranes
Is a membrane factory for the cell
Golgi Apparatus
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates
Cisternae
Flattened, membrane-bound sacs that are a key component of the Golgi apparatus
Functions
Modifies products of the ER
Manufactures certain macromolcules
Sorts and packages materials into transport vesicles
Lysosomes
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists
Can digest macromolecules
Function
Digest materials taken into the cell through processes
Can be known as the trashcan of the cell
Phagocytosis
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell
Vacuoles
A membrane-bounded vesicle whose specialized function varies in different kinds of cells
Large vesicles derived from the ER and Golgi Apparatus
Functions
Store things
Depends on where they're found is what they'll be carrying
Food Vacuoles
A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell
Contractile Vacuoles
A membranous sac that helps move excess water out of certain freshwater protists
Central Vacuoles
A large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances
In plant cell, they have a large central vacuole
In animal cells, they have a small vacuole
Plasma Membrane
A semi-permeable barrier and allows small, nonpolar, and uncharged molecules
Microscopy
Types of Microscopes
Light Microscope (LM)
An optical instrument with lenses that refract (bend) visible light to magnify images of specimens
In the LM, visible light is passed through a specimen and then through glass lenses
Electron Microscopy (EM)
Scanning Electron Microscope (SEMS)
Focuses a beam of electrons onto the surface if a specimen, providing images that look 3D
Transmission Electron Microscope (TEMS)
Focuses a beam of electrons through a specimen
Mainly used to study the internal structure of cells
Cryo-Electron Microscope (Cryo-EM)
Observes biological specimens at extremely low temperatures
Important Parameters
Magnification
The ratio of an objects image size to its real size
Light microscopes can magnify effectively to about 1,000 times the actual size of the specimen
At greater magnifications, additional details cannot be seen clearly
Resolution
The measure of the clarity of the image, or the minimum distance of two distinguishable points
It is the minimum distance two points can be separated and still be distinguished as separate points
Contrast :
Visible differences in brightness between parts of the sample
The difference in brightness between the light and dark areas of an image
Methods for enhancing contrast include staining or labeling cell components to stand out visually
Mitochondria/Chloroplasts and Cytoskeleton
Mitochondria/Chloroplasts
Mitochondria
An organelle in eukaryotic cells that serves as the site of cellular respiration
The metabolic process that uses oxygen to generate ATP
Found in both Animal and Plant cells
Chloroplasts
Chlorophyll
A green pigment found in the chloroplasts of plants, algae, and some bacteria
An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water
The sites of photosynthesis
Structure
Thylakoids
Membranous sacs, stacked to form a graum
Stroma
The internal fluid
Endosymbiont Theory
The theory that mitochondria and plastids originated as prokaryotic cells engulfed by a host cell
The engulfed cell and its host cell then evolved into a single organism
States that an early ancestor of eukaryotic cells (a host cell) engulfed an oxygen-using nonphotosynthetic prokaryotic cell
Eventually, the engulfed cell formed a relationship with the host cell in which it was enclosed, becoming an endosymbiont
Over the course of evolution, the host cell and its endosymbiont merged into a single organism, a eukaryotic cell with the endosymbiont having become a mitochondrion
At least one of these cells may have then taken up a photosynthetic prokaryote, becoming the ancestor of eukaryotic cells that contain chloroplasts
Peroxisomes
An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide
Functions
Some use oxygen to break fatty acids into smaller molecules, eventually used for fuel for respiration
In the liver, they detoxify alcohol and other harmful compounds
Glyoxysomes in the fat-storing tissues of plant seeds, convert fatty acids to sugar to feed the emerging seddling
Cytoskeleton
A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions
Helps support the cell and maintain its shape
Motor Proteins
Interacts with these proteins to produce cell motility
A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell
Three Main Types of Fibers
Microtubules
The thickest of the three components of the cytoskeleton
A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella
Animal Cells
Centrosome
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division
Centrioles
A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets
Eukaryotic Cells
Flagella
A long cellular appendage specialized for locomotion
Cilia
Hair-like structures that extend from the surface of eukaryotic cells
Functions
Shaping the cell
Guiding movement of organelles
Separating chromosomes during cell division
Microfilaments
Also called Actin Filaments
Actin
A globular protein that links into chains
The thinnest of the three components
A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell
Pseudopodia
Cell crawl along a surface by extending pseudopodia and moving toward them
A cellular extension of amoeboid cells used in moving and feeding
Functions
Helps support the cell's shape
Form cortex to help support the cell's shape
Bundles make up the core of microvilli of intestinal cells
Intermediate Filaments
A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments
Functions
Support cell shape
Fix organelles in place