When viewing a specimen through a light microscope, scientists use ________ to distinguish the individual components of cells.
a beam of electrons
radioa... [Show More] ctive isotopes
special stains
high temperatures
C
The ________ is the basic unit of life.
organism
cell
tissue
organ
B
In your everyday life, you have probably noticed that certain instruments are ideal for certain situations. For example, you would use a spoon rather than a fork to eat soup because a spoon is shaped for scooping, while soup would slip between the tines of a fork. The use of ideal instruments also applies in science. In what situation(s) would the use of a light microscope be ideal, and why?
A light microscope would be ideal when viewing a small living organism, especially when the cell has been stained to reveal details.
In what situation(s) would the use of a scanning electron microscope be ideal, and why?
A scanning electron microscope would be ideal when you want to view the minute details of a cell's surface, because its beam of electrons moves back and forth over the surface to convey the image.
In what situation(s) would a transmission electron microscope be ideal, and why?
A transmission electron microscope would be ideal for viewing the cell's internal structures, because many of the internal structures have membranes that are not visible by the light microscope.
What are the advantages and disadvantages of each of these types of microscopes?
The advantages of light microscopes are that they are easily obtained, and the light beam does not kill the cells. However, typical light microscopes are somewhat limited in the amount of detail they can reveal. Electron microscopes are ideal because you can view intricate details, but they are bulky and costly, and preparation for the microscopic examination kills the specimen.
cell theory
see unified cell theory
electron microscope
an instrument that magnifies an object using a beam of electrons passed and bent through a lens system to visualize a specimen
microscope
an instrument that magnifies an object
light microscope
an instrument that magnifies an object using a beam visible light passed and bent through a lens system to visualize a specimen
unified cell theory
a biological concept that states that all organisms are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells
Prokaryotes depend on ________ to obtain some materials and to get rid of wastes.
ribosomes
flagella
cell division
diffusion
D
Bacteria that lack fimbriae are less likely to ________.
adhere to cell surfaces
swim through bodily fluids
synthesize proteins
retain the ability to divide
A
Antibiotics are medicines that are used to fight bacterial infections. These medicines kill prokaryotic cells without harming human cells. What part or parts of the bacterial cell do you think antibiotics target? Why?
The cell wall would be targeted by antibiotics as well as the bacteria's ability to replicate. This would inhibit the bacteria's ability to reproduce, and it would compromise its defense mechanisms.
Explain why not all microbes are harmful.
Some microbes are beneficial. For instance, E. coli bacteria populate the human gut and help break down fiber in the diet. Some foods such as yogurt are formed by bacteria.
nucleiod
central part of a prokaryotic cell in which the chromosome is found
prokaryote
unicellular organismi that lacks a nucleus or any other membrane-bound organelle
Peroxisomes got their name because hydrogen peroxide is:
used in their detoxification reactions
produced during their oxidation reactions
incorporated into their membranes
a cofactor for the organelles' enzymes
B
Which of the following is surrounded by two phospholipid bilayers?
the ribosomes
the vesicles
the cytoplasm
the nucleoplasm
D
In plant cells, the function of the lysosomes is carried out by __________.
vacuoles
peroxisomes
ribosomes
nuclei
A
Which of the following is found both in eukaryotic and prokaryotic cells?
nucleus
mitochondrion
vacuole
ribosomes
D
You already know that ribosomes are abundant in red blood cells. In what other cells of the body would you find them in great abundance? Why?
Ribosomes are abundant in muscle cells as well because muscle cells are constructed of the proteins made by the ribosomes.
What are the structural and functional similarities and differences between mitochondria and chloroplasts?
Both are similar in that they are enveloped in a double membrane, both have an intermembrane space, and both make ATP. Both mitochondria and chloroplasts have DNA, and mitochondria have inner folds called cristae and a matrix, while chloroplasts have chlorophyll and accessory pigments in the thylakoids that form stacks (grana) and a stroma.
cell wall
rigid cell covering made of cellulose that protects the cell, provides structural support, and gives shape to the cell
central vacuole
large plant cell organelle that regulates the cell's storage compartment, holds water, and plays a significant role in cell growth as the site of macromolecule degradation
centrosome
region in animal cells made of two centrioles
chlorophyll
green pigment that captures the light energy that drives the light reactions of photosynthesis
chromatin
protein-DNA complex that serves as the building material of chromosomes
chloroplast
plant cell organelle that carries out photosynthesis
chromosome
structure within the nucleus that is made up of chromatin that contains DNA, the hereditary material
cytoplasm
entire region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals
cytosol
gel-like material of the cytoplasm in which cell structures are suspended
eukaryotic cell
cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs
lysosome
organelle in an animal cell that functions as the cell's digestive component; it breaks down proteins, polysaccharides, lipids, nucleic acids, and even worn-out organelles
mitochondria
(singular = mitochondrion) cellular organelles responsible for carrying out cellular respiration, resulting in the production of ATP, the cell's main energy-carrying molecule
nuclear envelope
nuclear envelope
double-membrane structure that constitutes the outermost portion of the nucleus
nucleolus
darkly staining body within the nucleus that is responsible for assembling the subunits of the ribosomes
nucleoplasm
semi-solid fluid inside the nucleus that contains the chromatin and nucleolus
nucleus
cell organelle that houses the cell's DNA and directs the synthesis of ribosomes and proteins
organelle
compartment or sac within a cell
peroxisome
small, round organelle that contains hydrogen peroxide, oxidizes fatty acids and amino acids, and detoxifies many poisons
plasma membrane
phospholipid bilayer with embedded (integral) or attached (peripheral) proteins, and separates the internal content of the cell from its surrounding environment
ribosome
cellular structure that carries out protein synthesis [Show Less]
