chapter 4 Flashcards
Organelles
The membrane-enclosed structures within eukaryotic cells.
Light microscope (LM)
Visible light is passed through the specimen and then through the glass lenses.
Electron microscope (EM)
Focuses a beam of electrons through the specimen onto its surface.
Scanning electron microscope (SEM)
Focuses a beam of electrons onto the surface of a specimen, producing images that look three-dimensional.
Transmission electron microscopes (TEM)
Focuses a beam of electrons through a specimen. Mainly used to study the internal structure of cells.
Cell
The simplest collection of matter that can be alive. All organisms are made of cells.
Prokaryotic cells
No nucleus, DNA in an unbounded region called the nucleoid, no membrane enclosed organelles.
Eukaryotic cells
Most of the DNA is in the nucleus, has membrane enclosed organelles. Generally larger than prokaryotic cells.
Cytoplasm
Plasma which contains the organelles. Found in both eukaryotic and prokaryotic cells.
Plasma membrane
A selective barrier that allows oxygen and nutrients to enter the cell. Is a double layer of phospholipids.
Ribosomes
Organelles which use the information from the DNA to make proteins.
Nucleus
Contains most of the cells genes.
Nuclear Envelope
Encloses the nucleus, separating it from the cytoplasm.
Nuclear Lamina
Maintains the shape of nucleus, composed of protein filaments.
Chromosomes
Discrete units of DNA. Each is one long DNA molecule associated with proteins.
Chromatin
The DNA and proteins of chromosomes together. Condenses to form chromosomes as a cell prepares to divide.
Nucleolus
Located within the nucleus, site of RNA synthesis.
Ribosomes
Carry out protein synthesis in the cytosol (free ribosomes) and on the outside of the ER or nuclear envelope (bound ribosomes).
Components of the Endomembrane System
Nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, plasma membrane
Endoplasmic Reticulum (ER)
Two distinct regions of ER, smooth ER lacks ribosomes, rough ER surface has ribosomes.
Functions of smooth ER
synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions
Functions of rough ER
bound proteins secrete glycoproteins, distributes transport vesicles, manufactures membrane for the cell
Glycoproteins
Proteins covalently bonded to carbohydrates.
Transport Vesicles
Proteins surrounded by membranes.
Functions of the Golgi Apparatus
Modifies products of the ER, manufactures certain macromolecules, sorts and packages materials into transport vesicles.
Lysosome
A membranous sac of enzymes that can digest macromolecules.
Phagocytis
Process by which some types of cells can engulf another cell forming a food vacuole. A lysosome fuses with the food vacuole and its enzymes digest the molecules.
Autophagy
A process by which lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules.
Vacuoles
Large vesicles derived from the endoplasmic reticulum and Golgi apparatus.
Food Vacuoles
Are formed by phagocytis.
Contractile Vacuoles
Found in many freshwater protists, pump excess water out of cells.
Central Vacuoles
Found in many mature plant cells, serve as a repository for inorganic ions, including potassium and chloride.
Mitochondria
The sites of cellular respiration, a metabolic process that uses oxygen to generate ATP.
Chloroplasts
The sites of photosynthesis, found in plants and algae.
Endosymbiont Theory
An early ancestor of eukaryotic cells engulfed nonphotosynthetic prokaryotic cell. They merged into a single organism. One of these cells may have then taken in a photosynthetic prokaryote becoming the ancestor of plant cells.
Cytoskeleton
A network of fibers extending throughout the cytoplasm. Organizes the cell’s structures and activities.
Components of the cytoskeleton
Microtubules, Microfilaments, Intermediate filaments
Microtubules
Thickest components of the cytoskeleton.
Microfilaments
Thinnest components of the cytoskeleton. Bear tension, resisting pulling forces within the cell.
Intermediate filaments
Fibers with diameters in a middle range. Reinforce cell shape and fix organelles in place.
Functions of Microtubules
Shape and support the cell, guide movement of organelles, separate chromosomes during cell division.
Centrosome
Where microtubules grow out of near the nucleus in animal cells. Organizes the microtubules.
Cilia and Flagella
Microtubule-containing extensions projecting from some cells.
Cell Wall
Extracellular structure found in plant cells. Protects the cell, maintains its shape and prevents excessive water uptake.
Layers of the cell wall
Primary cell wall (relatively thin and flexible), Middle lamela (thin layer between primary walls of adjacent cells), Secondary cell wall (between cell membrane and primary cell wall).
4 types of intercellular junctions
Plasmodesmata, tight junctions, desmosomes, gap junctions
Cell junctions
Facilitate neighboring cells to adhere, interact, and communicate through direct physical contact.
Three type of cell junctions of animal cells
tight junctions, desmosomes, gap junctions
