Essentials of Cell Biology
Cells are fundamental units of life. All present day cells are believed to have evolved from an
ancestral cell that existed more than 3 billion years ago. - ANS-All cells are enclosed by a
plasma membrane, which separates the inside of the cell from its environment.
All cells contain DNA as a store of genetic material and information used to guide the synthesis
of RNA molecules and proteins - ANS-Cells in a multicellular organism, all contain the SAME
DNA while their structure, function, and appears can be very different. They turn on different
genes and sets of genes according to their developmental history and signals they receive from
an environment.
Animals and plant cells are typically 5-20 µm in diameter and can be seen with a LIGHT
MICROSCOPE. - ANS-A light microscope also reveals some of their internal components,
including the LARGER organelles
The ELECTRON MICROSCOPE reveals even the smallest organelles, but specimens require
elaborate preparation and cannot be viewed while alive. - ANS-The simplest of present-day
living cells are prokaryotes: although they contain DNA, they lack a nucleus and other
organelles and probably resemble most closely the ancestral cell.
Specific large molecules can be located in fixed or living cells with a FLUORESCENCE
MICROSCOPE - ANS-Different species of prokaryotes are diverse in their chemical capabilities
and inhabit an amazingly wide range of habitats. Two fundamental evolutionary subdivisions are
recognized: BACTERIA and ARCHAEA
Eukaryotic cells possess a nucleus and other organelles not found in prokaryotes. They
probably evolved in a series of stages, including the acquisition of mitochondria by engulfment
of aerobic bacteria and (for plant cells) the acquisition of chloroplasts by engulfment of
photosynthetic bacteria. - ANS-the nucleus of a cell contains the genetic information of the
eukaryotic cell, stored in DNA molecules.
The cytoplasm includes all of the cell's contents outside the nucleus and holds a variety of
membrane-enclosed organelles with specialized functions: - ANS-Mitochondria carries out the
final oxidation of food molecules; in plant cells, chloroplasts perform photosynthesis; the
endoplasmic reticulum and the Golgi apparatus synthesize complex molecules for export from
the cell and for insertion in cell membranes; lysosomes digest large molecules
Outside the membrane-enclosed organelles in the cytoplasm is the cytosol, a very concentrated
mixture of large and small molecules that carry out many essential biochemical
reactions/processes. - ANS-Free living, single-celled eukaryotic microorganisms are complex
cells that can swim, mate, hunt, and devour other microorganisms.
Cells are fundamental units of life. All present day cells are believed to have evolved from an
ancestral cell that existed more than 3 billion years ago. - ANS-All cells are enclosed by a
plasma membrane, which separates the inside of the cell from its environment.
All cells contain DNA as a store of genetic material and information used to guide the synthesis
of RNA molecules and proteins - ANS-Cells in a multicellular organism, all contain the SAME
DNA while their structure, function, and appears can be very different. They turn on different
genes and sets of genes according to their developmental history and signals they receive from
an environment.
Animals and plant cells are typically 5-20 µm in diameter and can be seen with a LIGHT
MICROSCOPE. - ANS-A light microscope also reveals some of their internal components,
including the LARGER organelles
The ELECTRON MICROSCOPE reveals even the smallest organelles, but specimens require
elaborate preparation and cannot be viewed while alive. - ANS-The simplest of present-day
living cells are prokaryotes: although they contain DNA, they lack a nucleus and other
organelles and probably resemble most closely the ancestral cell.
Specific large molecules can be located in fixed or living cells with a FLUORESCENCE
MICROSCOPE - ANS-Different species of prokaryotes are diverse in their chemical capabilities
and inhabit an amazingly wide range of habitats. Two fundamental evolutionary subdivisions are
recognized: BACTERIA and ARCHAEA
Eukaryotic cells possess a nucleus and other organelles not found in prokaryotes. They
probably evolved in a series of stages, including the acquisition of mitochondria by engulfment
of aerobic bacteria and (for plant cells) the acquisition of chloroplasts by engulfment of
photosynthetic bacteria. - ANS-the nucleus of a cell contains the genetic information of the
eukaryotic cell, stored in DNA molecules.
The cytoplasm includes all of the cell's contents outside the nucleus and holds a variety of
membrane-enclosed organelles with specialized functions: - ANS-Mitochondria carries out the
final oxidation of food molecules; in plant cells, chloroplasts perform photosynthesis; the
endoplasmic reticulum and the Golgi apparatus synthesize complex molecules for export from
the cell and for insertion in cell membranes; lysosomes digest large molecules
Outside the membrane-enclosed organelles in the cytoplasm is the cytosol, a very concentrated
mixture of large and small molecules that carry out many essential biochemical
reactions/processes. - ANS-Free living, single-celled eukaryotic microorganisms are complex
cells that can swim, mate, hunt, and devour other microorganisms.
