Chapter 3. Cells
In animal cells, cell junctions called ______ junctions form barriers between cells that prevent leaking of fluids and water-soluble molecules.
tight
fuse cell membranes of adjacent animal cells, forming a barrier
tight junctions
Plant cells have large central ______ where water, salts, and sugars are stored and where materials are broken down and recycled with enzymes similar to lysosomes in animal cells.
vacuoles
Membranous spheres that transport materials inside the cell as part of the endomembrane system are called __________.
vesicles
What are the structures indicated by the arrows in the picture that have pinched off the Golgi apparatus and will deliver their contents to another part of the cell?
vesicles
connect animal cells to the extracellular matrix or to adjacent animal cells in one place
anchoring junctions
The ______ is a protein network that occurs within the cytosol, provides support, and helps form ______.
cytoskeleton; cell to cell connections
What is the network of sacs and tubules that extends off the nuclear envelope and is where proteins and lipids are produced?
endoplasmic reticulum
Organelles called lysosomes contain ______ that break down food particles, old organelles, and other cellular debris.
enzymes
Proteins that increase the speed of chemical reactions on the cell membrane and in other parts of the cell are called __________.
enzymes
The digestive ______ that end up inside lysosomes are made in the rough ER, and then the Golgi apparatus packages them into vesicles, forming lysosomes.
enzymes
What type of membrane protein speeds up chemical reactions?
enzymes
What are the tail-like structures indicated by letter A in the picture of a bacterium?
flagella
The cell membrane can be described as a(n) __________ mosaic because many of the diverse components can move freely within the cell membrane.
fluid mosaic
What type of microscope passes light through a transparent specimen to generate true-color views of cells?
light microscope
Cytoplasm can flow between adjacent plant cells through special openings in the cell wall called __________.
plasmodesmata
Tunnels called ______ occur in the cell walls of two adjacent plant cells and allow the cells to communicate and exchange materials with each other.
plasmodesmata
What is the most ancient type of life on Earth?
prokaryotes
all cell contents except the nucleus
cytoplasm
The ______ is a series of flattened sacs that sorts and packages materials into vesicles to be sent to the cell membrane.
Golgi apparatus
Protists, plants, fungi, and animals are organisms in the domain ______.
Eukarya
The organelle that is the site of photosynthesis in plant cells is the __________, which is a type of plastid.
chloroplast
The cell membrane is composed of a type of lipid molecule called a(n) ______, which has two fatty acids and a phosphate group extending from a glycerol molecule.
phospholipid
The two-layered nuclear envelope separates the nucleus of a cell from the __________.
cytoplasm
What is the network of protein fibers and tubules inside the cell that provides support and aids in cell division and movement?
cytoskeleton
Select all of the following that are true about organisms in Domain Bacteria. - Earth's oldest organisms - important decomposers and producers - most lack cell walls - some live in human intestines and help with digestion - some are used to make pharmaceuticals - contain multiple nuclei in each cell
- Earth's oldest organisms - important decomposers and producers - some live in human intestines and help with digestion - some are used to make pharmaceuticals
Select the three components of the cell theory devised in the mid-1800s. - All cells have nuclei. - The cell is the fundamental unit of all life. - All organisms are made of one or more cells. - All cells originate from preexisting cells. - All cells can arise from spontaneous generation.
- The cell is the fundamental unit of all life. - All organisms are made of one or more cells. - All cells originate from preexisting cells.
Select all of the following that may be components of cell membranes. - steroids - mitochondria - proteins - phospholipids
- steroids - proteins - phospholipids
Select a component of the cell membrane that is able to move laterally within the membrane, giving it the description of a fluid mosaic.
Proteins
______ microscopes bounce electrons off the outside of a metal-coated three-dimensional object to observe the exterior texture.
Scanning electron
True or false: Bacteria are the most abundant and diverse organisms.
True
What surrounds the cell membrane of most bacteria and provides structure and protection?
cell wall
Whether bacterium or blue whale, every organism is made of __________
cells.
What type of light microscope uses two or more lenses to focus visible light through a living or preserved specimen?
compound microscope
The __________ includes a fluid matrix of dissolved substances and also includes organelles and the cytoskeleton. It is found between the cell membrane and the nucleus.
cytoplasm
channels for the exchange of substances between adjacent animal cells
gap junctions
The phosphate "head" end of a phospholipid is ______, meaning its polar covalent bonds attract water, but the tails of a phospholipid are ______ and thus face away from water.
hydrophilic; hydrophobic
In the cytoskeleton, ______ are made of different proteins (depending upon the cell type) and act to maintain cell shape and bind certain cells together.
intermediate filaments
The area within the cytoplasm of a prokaryotic cell where the circular DNA molecule is found is called the ______ and is not bounded by a membrane.
nucleoid
In eukaryotic cells, the DNA that codes for the cell's proteins is stored in a membrane-bounded organelle called the __________.
nucleus
Biological membranes are selectively ______, meaning they allow only specific types of molecules to pass into or out of the cell.
permeable
What organelle protects all eukaryotic cells from toxic substances or toxic by-products of chemical reactions?
peroxisome
Organelles that originate in the ER and contain enzymes that dispose of toxic substances are called __________.
peroxisomes
Select all of the following that are able to pass freely through the phospholipid bilayer without the assistance of transport proteins. - O2 and CO2 - small nonpolar molecules - ions and polar molecules - lipids
- O2 and CO2 - small nonpolar molecules - lipids
Select all of the following that are functions of the cytoskeleton in the cell. - detoxification of chemicals - production of most of the cell's ATP - aid for cell division - transportation - structural support
- aid for cell division - transportation - structural suppory
Select all of the following that are present in both prokaryotic cells and eukaryotic cells. - nucleus - cytoplasm - pigments - DNA - RNA - ribosomes
- cytoplasm - DNA - RNA - ribosomes
What plant organelle is shown in the image and contains photosynthetic pigments?
Chloroplast
the cell's genetic information
DNA
In a cell, ______ is the genetic information of the cell, and RNA plays a role in the production of ______.
DNA; proteins
______ cells are the simplest forms of life and lack a nucleus.
Prokaryotic
______ are flattened membrane sacs within a chloroplast where photosynthetic pigments, such as chlorophyll, are embedded.
Thylakoids
Domain Eukarya includes ______.
all organisms with eukaryotic cells
Microfilaments, intermediate filaments, and microtubules comprise the ______, which is a network of proteins that provide a structural framework within the cell.
cytoskeleton
The __________ theory states that all life is composed of one or more cells, which are the fundamental units of all life.
cell
lipid-rich boundary between the cells and outside environment
cell membrane
All living things consist of one or more __________.
cells
The cell wall openings in plant cells called plasmodesmata are most similar to __________ junctions in animal cells.
gap
What organelle of the endomembrane system breaks down debris, food, and old cell parts with special dismantling enzymes?
lysosome
All cells have a cell ______ that surrounds the cytoplasm and forms a boundary between the cell and its environment.
membrane
Cytoskeletal components called ______ are long, thin rods of actin protein that are used in muscle contractions, stretching and compression, and anchoring of cells.
microfilaments
Cellular respiration extracts energy from food and takes place in the organelle called a __________.
mitochondria
What eukaryotic organelle is shown in the picture and functions in the production of cellular energy by cellular respiration?
mitochondrion
The ______ found within the nuclear envelope are specialized channels that are composed of proteins and that allow the transport of substances into and out of the nucleus.
nuclear pores
In prokaryotic cells, DNA congregates in an area called the __________.
nucleoid
What type of cell membrane proteins help the body identify its own cells?
recognition proteins
The endoplasmic ______ is a network of membranes originating at the nuclear envelope and winding through the cell.
reticulum
The cell structure that manufactures proteins is called a __________.
ribosome
structures that manufacture proteins
ribosome
The nucleolus is a dense spot in the nucleus where components of ______ are assembled.
ribosomes
Proteins to be secreted outside the cell are formed at ribosomes on the surface of the ______ endoplasmic reticulum.
rough
What is the function of recognition proteins in the plasma membrane?
serve as "name tags" for the cell
Archaea are __________.
single-celled prokaryotes
Lipids, detoxifying enzymes, and membrane components are produced and stored in the __________ endoplasmic reticulum.
smooth
Molecules called ______, which include cholesterol, are membrane components that aid in membrane fluidity.
steroids
What is a correct description of a confocal microscope?
A laser is focused through a lens to the object, and the emitted light passes through a pinhole.
Select all the roles that membranes play in cells. - enclose organelles in eukaryotic cells - transcribe DNA into RNA and assemble ribosomes - transport substances into and out of the cell - receive and respond to external stimuli
- enclose organelles in eukaryotic cells - transport substances into and out of the cell - receive and respond to external stimuli
Select all of the following that are found in the cytoplasm, outside the nuclear membrane. - ions and enzymes - nucleolus - organelles - DNA-RNA complexes - cytoskeleton
- ions and enzymes - organelles - cytoskeleton
Select all of the following that differ between domains Bacteria and Archaea. - presence of cell wall in most - molecules that compose the membranes - evolutionary relationship to eukaryotes - location of DNA - cell size
- molecules that compose the membranes - evolutionary relationship to eukaryotes
Select all of the following that correctly describe Archaean cells. - arose before Bacteria - most have cell walls - lack nuclei and organelles - can have flagella - eukaryotic
- most have cell walls - lack nuclei and organelles - can have flagella
Select all of the following types of organisms that usually have cell walls. - plants - bacteria - archaea - animals - fungi - algae
- plants - bacteria - archaea - fungi - algae
Select all of the functions of cell walls. - store genetic material - organize microtubules - regulate cell volume - impart shape - prevent the cell from bursting
- regulate cell volume - impart shape - prevent the cell from bursting
Select all of the characteristics of organelles. - studded with membrane proteins - surrounded by membranes - only found in animal cells - contain distinct proteins - all types contain the same set of enzymes
- studded with membrane proteins - surrounded by membranes - contain distinct proteins
Key genetic sequences suggest that archaea are more closely related to members of domain ______ than they are to members of Domain Bacteria.
Eukarya
Lysosomes originate from vesicles that bud from the ______, and the enzymes contained in lysosomes are synthesized in the ______.
Golgi apparatus; rough ER
What is the function of a ribosome?
To manufacture proteins
______ proteins are embedded in the cell membrane and act as passageways for water-soluble materials into or out of the cell.
Transport
What type of cell membrane protein allows molecules and ions to enter or exit the cell?
Transport proteins
What plant cell organelle can occupy up to 90% of the cell volume and can exert turgor pressure against the cell membrane when it acquires water?
central vacuole
The rigid ______ of most bacterial cells surrounds the cell membrane, protecting the cell and giving the cell shape.
cell wall
In some types of bacteria, appendages called ______ rotate like a propeller and allow movement forward or backward.
flagella
All cells are surrounded by cell membranes, also called plasma membranes, that separate the cytoplasm from the __________.
outside environment
tunnels for the exchange of substances between adjacent plant cells
plasmodesmata
Folds in the membrane of an organelle provide tremendous amount of ______ for cellular reactions without significantly increasing the volume of the organelle.
surface area