Chapters 4-5 Flashcards
light microscope
can display living cells
resolution
- ability to distinguish two nearby objects as separate
- measure of the clarity of an image
cell theory
states that
- all living things are composed of cells
- all cells come from other cells
electron microscope
focuses a beam of electrons through a specimen or onto its surface
-can distinguish biological structures
scanning electron microscope
- used to study the detailed architecture of cell surfaces
- uses an electron beam to scan the surface of a cell or other sample.
transmission electron microscope
- used to study details of internal structure
- aims an electron beam through a very thin section of a specimen
what is the maximum size of a cell influenced by?
geometry.
- need to have a surface area large enough to service the volume of a cell
plasma/cell membrane
- forms a flexible boundary between the living cell and its surroundings
- a phospholipid bilayer with embedded proteins.
prokaryotic cells
- first to evolve
- earth’s sole inhabitants
- bacteria and archaea
eukaryotic cells
evolved from ancestral cells about 1.8 billion years ago
-everything else
how are eukaryotic cells distinguished from prokaryotic cells?
- have a membrane-enclosed nucleus
- larger and more complex
- many membrane-enclosed organelles that perform specific functions.
basic features of cells
-have cytosol, chromosomes, ribosomes, cytoplasm
cytosol
a thick, jelly-like fluid in the interior of all cells
chromosomes
carry genes made of DNA
ribosomes
- are composed of ribosomal RNA and proteins
- synthesize proteins according to directions from DNA.
cytoplasm
-in eukaryotic cells, term refers only to the region between the nucleus and the plasma membrane
plant cell structures that animal cells lack
- rigid, rather thick cell wall
- chloroplast
nucleus
contains the cell’s genetic instructions encoded in DNA
nucleolus
site in the nucleus where ribosomal RNA is synthesized according to instructions in the DNA
magnification
is the increase in an object’s image size compared with its actual size.
four basic groups of organelles and other structures of eukaryotic cells
- nucleus and ribosomes carry out the genetic control of the cell.
- Organelles involved in the manufacture, distribution, and breakdown of molecules include the endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes.
- Mitochondria in all cells and chloroplasts in plant cells function in energy processing.
- Structural support, movement, and communication between cells are the functions of the cytoskeleton, plasma membrane, and plant cell wall.
the ER
is a membranous network of tubes and sacs.
smooth ER
synthesizes lipids and processes toxins.
rough ER
produces membranes, and ribosomes on its surface make membrane and secretory proteins.
the Golgi apparatus
consists of stacks of sacs in which products of the ER are processed and then sent to other organelles or to the cell surface.
lysosomes
house enzymes that break down ingested substances and damaged organelles.
vacuoles
are large vesicles that have a variety of functions.
-Some protists have contractile vacuoles.
central vacuole
vacuole in plant cells that stores molecules and wastes and facilitates growth.
peroxisomes
are metabolic compartments that do not originate from the endomembrane system.
mitochondria
are organelles that carry out cellular respiration in nearly all eukaryotic cells.
2 internal compartments of mitochondria
- The intermembrane space is the narrow region between the inner and outer membranes.
- The mitochondrial matrix contains the mitochondrial DNA, ribosomes, and many enzymes that catalyze some of the reactions of cellular respiration
cellular respiration
A process that converts the chemical energy of food molecules to the chemical energy of ATP
photosynthesis
is the conversion of light energy from the sun to the chemical energy of sugar molecules.
chloroplasts
are the photosynthesizing organelles of plants and algae.
endosymbiont theory
states that mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells.
cytoskeleton
includes microfilaments, intermediate filaments, and microtubules. Their functions include -maintenance of cell shape -anchorage and movement of organelles -amoeboid movement, and muscle contraction.
Eukaryotic cilia and flagella
are locomotor appendages made of microtubules in a “9 + 2” arrangement.
extracellular matrix
- binds tissue cells together,
- supports the plasma membrane
- communicates with the cytoskeleton.
3 types of animal cells
- Tight junctions bind cells to form leakproof sheets.
- Anchoring junctions rivet cells into strong tissues.
- Gap junctions allow ions and small molecules to flow from cell to cell.
plasmodesmata
allow plant tissues to share water, nourishment, and chemical messages.
cell wall
- protects and provides skeletal support that helps keep the plant upright
- is primarily composed of cellulose.
Eukaryotic cell structures can be grouped on the basis of four functions
- genetic control,
- manufacturing, distribution, and breakdown of materials,
- energy processing
- structural support, movement, and intercellular communication.
what enables cells to survive and function
the plasma membrane and its proteins
fluid mosaic model
- biologists use to describe the membrane’s structure
- diverse protein molecules suspended in a fluid phospholipid bilayer.
diffusion
is the tendency of particles to spread out evenly in an available space.
passive transport
Diffusion across a cell membrane does not require energy
osmosis
The diffusion of water across a selectively permeable membrane
tonicity
describes the ability of a surrounding solution to cause a cell to gain or lose water.
hypertonic solution
cells shrink
hypotonic solution
cells swell
isotonic solution
animal cells are normal, but plant cells are flaccid.
hydrophobic substances
easily diffuse across a cell membrane
polar or charged substances
do not diffuse easily across cell membranes
facilitated diffusion
- polar or charged substances move across membranes with the help of specific transport proteins
- does not require energy
- relies on the concentration gradient
active transport
- a cell must expend energy to move a solute against its concentration gradient.
- The energy molecule ATP supplies the energy for most active transport.
A cell uses two mechanisms to move large molecules across membranes.
- Exocytosis is used to export bulky molecules, such as proteins or polysaccharides.
- Endocytosis is used to take in large molecules.
two kinds of endocytosis
-Phagocytosis is the engulfment of a particle by the cell wrapping cell membrane around it, forming a vacuole.
-Receptor-mediated endocytosis uses membrane receptors for specific solutes.
kinetic energy
the energy of motion.
potential energy
energy stored in the location or structure of matter and includes chemical energy.
laws of thermodynamics
- energy can change form but cannot be created or destroyed, and
- energy transfers or transformations increase disorder, or entropy, with some energy being lost as heat.
exergonic reactions
release energy.
endergonic reactions
require energy and yield products rich in potential energy.
metabolism encompasses…
all of a cell’s chemical reactions.
ATP
powers nearly all forms of cellular work.
enzymes
protein catalysts that decrease the activation energy needed to begin a reaction.
competitive inhibitor
competes with the substrate for the active site.
an enzyme’s substrate…
fits specifically in its active site.
noncompetitive inhibitor
alters an enzyme’s function by changing its shape
feedback inhibition
helps regulate metabolism.
