Bio Ch 4 Flashcards
Cell Theory
(1) All organisms are composed of cells (2) cells are the basic units of structure and function in organisms, & (3) cells come only from preexisting cells because cells are self-reproducing
Cell
smallest unit of living matter
Surface-area-to-volume ratio
ratio of a cell’s outside area to its internal volume; the relationship limits the maximum size of a cell
Compound light microscope
uses a set of glass lenses to focus light rays passing through a specimen to produce an image that is viewed by the human eye
Transmission Electron Microscope (TEM)
uses a set of electromagnetic lenses to focus electrons passing through a specimen to produce an image that is projected onto a fluorescent screen or photographic film
Scanning Electron Microscope (SEM)
uses a narrow beam of electrons to scan over the surface of a specimen that is coated with a thin metal layer; secondary electrons given off by the metal are detected and used to produce a 3D image on a tv screen
Magnification
ratio between the size of an image and its actual size
Resolution
minimum distance between 2 objects that allows them to be seen as separate objects
Contrast
difference in the shading of an object compared to its background
Confocal microscopy
uses a laser beam scanned across the specimen to focus on a single shallow plane within the cell
Video-enhanced contrast microscopy
computer makes the darkest areas of the original image much darker and the lightest areas of the original much lighter
Prokaryotic cells
cells which lack a membrane-enclosed nucleus
Eukaryotic cells
cell with a nucleus
Archaeans
cells possessing qualities of both prokaryotes and eukaryotes
Bacillus
a rod-shaped bacterium
Coccus
a spherical-shaped bacterium
Spirillum (plural, spirilla)
long, rod-shaped bacterium that is twisted into a rigid spiral
Spirochete
Long, rod-shaped bacterium that is twisted into a flexible spiral
Cell envelope
in bacteria, includes the plasma membrane, the cell wall, and the glycocalyx
Plasma membrane
phospholipid bilayer with embedded proteins; regulates the entrance and exit of substances into and out of the cytoplasm
Mesosomes
internal pouches of the plasma membrane in prokaryotes
Cell wall
when present, maintains the shape of the cell, even if the cytoplasm should happen to take up an abundance of water
Glycocalyx
layer of polysaccharides that lies outside the cell wall in some bacteria; aids against drying out and helps bacteria resist a host’s immune system; also helps bacteria attach to almost any surface
Capsule
well-organized layer of polysaccharides that lies outside the cell wall in some bacteria
Cytoplasm
semifluid solution composed of water and inorganic and organic molecules encased by a plasma membrane
Nucleoid
region of prokaryotic cells where DNA is located; it is not bounded by a nuclear envelope
Plasmids
many bacteria have these extrachromosomal pieces of circular DNA; routinely used in biotechnology labs as a molecular vehicle to transport DNA from different organisms, including humans, into a bacterium
Vector
in genetic engineering, a means to transfer foreign genetic material into a cell (a plasmid)
Ribosomes
tiny structures that = site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA)
Cyanobacteria
bacteria that are capable of photosynthesis in the same manner as plants
Flagella
appendages on motile bacteria the propel themselves in water
Thylakoids (Cyanobacteria)
extensive internal membranes of cyanobacteria where chlorophyll and other pigments absorb solar energy for the production of carbohydrates
Fimbriae
small, bristle-like fibers that sprout from the cell surface
Conjugation pili
rigid tubular structures use by bacteria to pass DNA from cell to cell
Endosymbiotic Theory
explanation of the evolution of eukaryotic organelles by phagocytosis of prokaryotes
Organelles
compartments of eukaryotic cells; carry out specialized functions that together allow the cell to be more efficient and successful
Vesicles
membranous sacs that enclose molecules made by enzymes in the organelles’ membranes and keep them separate from the cytoplasm
Cytoskeleton
vesicles move around by means of this extensive network or lattice of protein fibers; maintains cell shape and assists with cell movement
Chromatin
network of DNA strands and associated proteins observed within the nucleus of a cell
Nucleoplasm
semifluid medium of the nucleus containing chromatin
Chromosomes
structure that transmits the genetic material from one generation to the next; composed of condensed chromatin; each species has a particular number of these that are passed on to the next generation
Genes
composed of DNA; = units of heredity located on the chromosomes
3 types of RNA produced in the nucleus
ribosomal RNA (rRNA), messenger RNA (mRNA), & transfer RNA (tRNA); rRNA produced in nucleolus; ribosomes = small bodies in cytoplasm that facilitate protein synthesis; mRNA (mobile molecule) acts as an intermediary for DNA (a sedentary molecule which specifies the sequence of amino acids in a protein); tRNA participates in the assembly of amino acids into a polypeptide by recognizing both mRNA and amino acids during protein synthesis
Nucleolus
dark region of chromatin where rRNA joins with proteins to form the subunits of ribosomes
Nuclear envelope
physically separates the cytoplasm from the nucleus by a double membrane
Nuclear pores
of sufficient size (100 nm) to permit the passage of ribosomal subunits and mRNA out of the nucleus into the cytoplasm, and the passage of proteins from the cytoplasm into the nucleus
Polyribosomes
string of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis
Signal peptide
sequence of amino acids that binds with a signal recognition particle (SRP) causing a ribosome to bind to the endoplasmic reticulum (ER)
Central dogma of molecular biology
DNA-mRNA-protein sequence of events
Endomembrane system
nuclear envelope, the membranes of the endoplasmic reticulum, the Golgi apparatus, and several types of vesicles
Endoplasmic reticulum (ER)
complicated system of membranous channels and saccules (flattened vesicles); physically continuous with the nuclear envelope; consists of rough ER and smooth ER
Rough ER
studded with ribosomes on the side of the membrane that faces the cytoplasm, giving it the capacity to produce proteins
Smooth ER
continuous with the nuclear envelope and the rough ER; does not have attached ribosomes
Golgi apparatus
stack of 3-20 slightly curved, flattened saccules whose appearance can be compared to a stack of pancakes; contains enzymes that modify the carbohydrate chains first attached to proteins in the rough ER; it can change or modify one sugar into another sugar on glucoproteins
Secretion
release of a substance from a cell by exocytosis
Lysosomes
membrane-bound vesicles produced by the Golgi apparatus
Peroxisomes
membrane-bound vesicles that enclose enzymes which are synthesized by free ribosomes and transported into one of these from the cytoplasm
Vacuoles
membranous sacs; larger than vesicles; usually store substances
Central vacuole
takes up to 90% of volume of plant cells; filled with a watery fluid called cell sap that gives added support to the cell; maintains hydrostatic pressure or turgor pressure in plant cells, which provides structural support
Chloroplasts
use solar energy to synthesize carbohydrates, which serve as organic nutrient molecules for plants and all living things on Earth
Mitochondria
break down carbohydrate-derived products to produce ATP
Photosynthesis equation
solar energy + carbon dioxide + water –> carbohydrate + oxygen
Cellular respiration equation
carbohydrate + oxygen –> carbon dioxide + water + energy
Stroma
region within a chloroplast that surrounds the grana; contains enzymes involved in the synthesis of carbohydrates during the Calvin cycle of photosynthesis
Granum
stack of thylakoids
Thylakoids (Plants)
flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur
Plastids
plant organelles that are surrounded by a double membrane and have varied functions
Chromoplasts
contain pigments that result in a yellow, orange, or red color
Leucoplasts
generally colorless plastids that synthesize and store starches and oils
Cristae
increase the surface area of the inner membrane of mitochondria
Matrix
inner membrane encloses this semifluid structure in mitochondria; contains mitochondrial DNA and ribosomes
Actin filaments (formerly microfilaments)
long, extremely thin, flexible fibers that occur in bundles or meshlike networks; 7 nm diameter; each filament contains 2 chains of globular actin monomers twisted about 1 another in a helical manner; provide structural support, facilitate cellular movement; in plant cells, form the tracks along which chloroplasts circulate; associated with myosin
Motor molecules
proteins that can attach, detach, and reattach farther along an actin filament; uses ATP to pull actin filaments along
Intermediate filaments
in between the size of actin filaments and microtubules (8-11 nm in diameter); ropelike assembly of fibrous polypeptides, but filament type varies according to the tissue; some support the nuclear envelope, others support the plasma membrane and take part in the formation of cell-to-cell junctions
Microtubules
small, hollow cylinders (25 nm diameter) made of globular protein called tubulin (alpha & beta); 13 rows of tubulin dimers; assembly under regulatory control of a ____ organizing center; motor molecules kinesin and dynein are associated with these
Centrosome
in most eukaryotic cells, the main MTOC (microtubule organizing center); lies near the nucleus; microtubules radiate from this, helping to maintain the shape of the cell and acting as tracks along which organelles can be moved
Centrioles
short cylinders with a 9+0 pattern of microtubule triplets (9 sets of triplets in an outer ring, the center does not contain a microtubule)
Basal body
organelle that lies at the base of cilia and flagella and may direct the organization of microtubules within these structures; centrioles believed to give rise to these in cells with cilia and flagella
Cilia & flagella
hairlike projections that can move either in an undulating fashion, like a whip, or stiffly like an oar
