Download Chapter 6 Guided Notes

Chapter 6  A Tour of the Cell
Student Guided Notes
Overview: The Fundamental Units of Life

The cell is the simplest collection of matter that can be alive.

Cells are an organism’s basic units of ___________________________.

Evolution is the unifying biological theme.
Concept 6.1 Biologists use microscopes and the tools of biochemistry to study cells

In a light microscope (LM), ___________________________________________________________
__________________________________________________________________________________.
○ Magnification is __________________________________________________________________.
○ Resolution is a measure of image clarity, _______________________________________________
________________________________________________________________________________.

An electron microscope (EM) _________________________________________________________
___________________________________________________________________________________.

Scanning electron microscopes (SEMs) are useful for studying _______________________________
___________________________________________________________________________________.

Transmission electron microscopes (TEMs) are used to study ________________________________
___________________________________________________________________________________

Although EMs reveal organelles that are impossible to resolve with LMs, the methods used to
prepare cells for viewing under an EM kills them.

Cytology combined with biochemistry, ___________________________________________________
___________________________________________________________produced modern cell biology.
Cell biologists can isolate organelles to study their functions.

Cell structure and function can by studied by cell fractionation, a technique _________________
______________________________________________________________________________.
○ A centrifuge spins test tubes holding mixtures of disrupted cells.
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○ The resulting forces cause a fraction of the cell components to settle to the bottom of the tube,
forming a pellet.
Concept 6.2 Eukaryotic cells have internal membranes that compartmentalize their functions
Prokaryotic and eukaryotic cells differ in size and complexity.

All cells are surrounded by a ______________________________.

The semifluid substance within the membrane is the cytosol.

All cells contain chromosomes and all cells have ribosomes.
○ In a eukaryotic cell, most of the DNA is in the _______________________________________.
○ In a prokaryotic cell, the DNA is concentrated in the __________________________________.

The interior of a prokaryotic cell and the region between the _________________________ and the
_____________________________________ of a eukaryotic cell is the cytoplasm.

The logistics of carrying out cellular metabolism set limits on cell size.

The plasma membrane functions as a __________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________.

As a cell increases in size, its volume increases faster than its_________________________________.
Internal membranes compartmentalize the functions of a eukaryotic cell.

A eukaryotic cell has extensive and elaborate internal membranes, which partition the cell.
○ These membranes also participate directly in metabolism.

Each type of membrane has a unique combination of lipids and proteins for its specific functions.
Concept 6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the
ribosomes

The nucleus contains ______________________________________________________________.

The nucleus is separated from the cytoplasm by a double membrane called the ____________________
______________________________ .
○ The envelope is perforated by pores.
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The nuclear side of the envelope is lined by the nuclear lamina, _____________________________
__________________________________________________________________________________.

The DNA and associated proteins are organized into _______________________________________.
○ Each chromosome contains _________________________________________________________
_______________________________________________________________________________.

Each eukaryotic species has a characteristic number of chromosomes.
○ A typical human cell has ________ chromosomes.

In the nucleus is ____________________________________________________________________.

In the nucleolus, ribosomal RNA (rRNA) is synthesized and assembled with proteins to form ribosomal
subunits.

The nucleus directs protein synthesis by _________________________________________________.
Ribosomes are protein factories.

Ribosomes, containing rRNA and protein carry out ________________________________________.

Free ribosomes _____________________________________________________________________.
Bound ribosomes are attached to the ___________________________________ or
__________________________________.
○ Bound ribosomes synthesize proteins that are ___________________________________________
_______________________________________________________________________________.
Concept 6.4 The endomembrane system regulates protein traffic and performs metabolic functions in the
cell
Many of the internal membranes are part of the endomembrane system, which includes ___________
____________________________________________________________________________________
____________________________________________________________________________________
____________________________________________________________________________________

The tasks include _____________________________________________________________________
___________________________________________________________________________________
__________________________________________________________________________________.

These membranes are either directly continuous or connected via ______________________________.
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The endoplasmic reticulum manufactures membranes and performs many other biosynthetic functions.

The endoplasmic reticulum (ER) includes a network of membranous tubules and sacs called
_____________________________________ that separate the __________________________
___________________________________.

There are two regions of ER.
○ Smooth ER looks smooth because ____________________________________________________.
○ Rough ER looks rough because ______________________________________________________.

Smooth ER is rich in enzymes and plays a role in a variety of metabolic processes, including
____________________________________________________________________________________
___________________________________________________________________________________.

In the smooth ER of the liver, enzymes help _______________________________________________
___________________________________________________________________________________.

Rough ER is especially abundant in cells that ______________________________________________.

Most secretory polypeptides are glycoproteins.

Secretory proteins are packaged in ____________________________________________.

Rough ER is also a ____________________________________ factory for the cell.
The Golgi apparatus is the shipping and receiving center for cell products.

Many transport vesicles from the ER travel to the Golgi apparatus for modification of their contents.

The Golgi apparatus is a center of ______________________________________________________
_________________________________________________________________________________.

The Golgi apparatus consists of flattened membranous sacs—cisternae—that look like a stack of pita
bread.

One side of the Golgi apparatus, the cis face, ___________________________________________.

Golgi products that will be secreted depart from the _______________________________________.
○ Transport vesicles from the Golgi may have external molecules that recognize “docking sites” on the
surface of specific organelles or on the plasma membrane.
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Lysosomes are digestive compartments.

A lysosome is ______________________________________________________________________
__________________________________________________________________.
○ Some lysosomes arise by __________________________________________________________
_______________________________________________________________________________.

Lysosomes carry out intracellular digestion in a variety of circumstances.
○ Amoebas eat by _________________________________________________________________.
○ Human macrophages help defend the body by ___________________________________________
__________________________________________________________.

Lysosomes can play a role in _________________________________________________________
______________________________________________. This recycling, or
___________________________________, renews the cell.

In people who have Tay-Sachs disease, a _________________________________________________
is missing or inactive, and the brain becomes impaired by ____________________________________
__________________________________________________________________________________.
Vacuoles have diverse functions in cell maintenance.

Food vacuoles are formed by ____________________________________________ and fuse with
_______________________________.

Contractile vacuoles, found in freshwater protists, __________________________________________.

In plants and fungi, vacuoles carry out enzymatic hydrolysis, like animal lysosomes do.

A large central vacuole is found in ______________________________________________________.
○ The vacuolar membrane is selective in its transport of solutes into the central vacuole.

The functions of the central vacuole include ________________________________________________
____________________________________________________________________________________
___________________________________________________________________________________.
Concept 6.5 Mitochondria and chloroplasts change energy from one form to another

Mitochondria are the sites of __________________________________________________________
___________________________________________________________________________________.
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Chloroplasts, found in plants and algae, are the sites of _____________________________________
___________________________________________________________________________________.
Mitochondria and chloroplasts have a similar evolutionary origin.

The endosymbiont theory states that ____________________________________________________
___________________________________________________________________________________

There is considerable evidence to support the endosymbiont theory for the origin of mitochondria and
chloroplasts.
○ Each mitochondrion or chloroplast has two membranes.
○ Mitochondria and chloroplasts contain ribosomes and __________________________________.
○ Mitochondria and chloroplasts grow and reproduce as ____________________________________.
Mitochondria convert chemical energy within eukaryotic cells.

Almost all eukaryotic cells have mitochondria.
○ The number of mitochondria is correlated with __________________________________________.
○ Mitochondria have a smooth outer membrane and a convoluted inner membrane with infoldings
called ___________________________.
○ The inner membrane encloses the _____________________________________________________
__________________________________________________________________.
Chloroplasts capture light energy and convert it to chemical energy.

Chloroplasts contain the green pigment ___________________________________.

Inside the innermost membrane is a fluid-filled space, the stroma, in which float __________________
___________________________________________________________________________________.
○ In some regions, thylakoids are stacked like ____________________________________________.

The chloroplast belongs to a family of plant structures called plastids.
○ Amyloplasts are __________________________________________________________________.
○ Chromoplasts ____________________________________________________________________.
The peroxisome is an oxidative organelle.

Peroxisomes contain enzymes that transfer ________________________________________________
_______________________________, producing __________________________________________
as a byproduct.
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
Some peroxisomes use oxygen to ________________________________________________________.

The H2O2 formed is toxic, but peroxisomes contain _________________________________________
___________________________________________________________________________________.
Concept 6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell
The cytoskeleton provides support, motility, and regulation.

The cytoskeleton is _________________________________________________________________
_________________________________________________________________________________
________________________________________________________________________________.

The cytoskeleton provides anchorage for many organelles and enzymes.

The cytoskeleton also plays a major role in cell motility.
○ ________________________________ bring about movements of cilia and flagella.
Three main types of fibers make up the cytoskeleton: ________________________________________,
____________________________________, and ____________________________________________.

Microtubules are the thickest of the three types of fibers; microfilaments (or ___________________
filaments) are the thinnest; and intermediate filaments are fibers with diameters in a middle range.

Microtubules are ___________________________________________________________________.

Microtubules shape and support the cell and serve as tracks to guide motor proteins.

In many animal cells, microtubules grow out from a _________________________near the nucleus.

Within the centrosome is a pair of centrioles, each with ____________________________________
_________________________________________________________________________________.

Although centrosomes with centrioles may help organize microtubule assembly in animal cells, they are
not essential for this function.

A specialized arrangement of microtubules is responsible for the beating of _____________________
and ____________________________________.
○ The sperm of ____________________________, _____________________________ , and some
_______________________have flagella.
○ Cilia lining the trachea _____________________________________________________________
________________________________________________________________________________.
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
Cilia usually occur in large numbers on the cell surface and there are usually just one or a few
flagella per cell.

The cilium or flagellum is anchored in the cell by a ________________________________________,
__________________________________________________________________________________.

Each outer doublet also has pairs of ___________________________________________________
that are responsible for the bending movements.

Microfilaments or ________________________________ are _______________________________.

The structural role of microfilaments in the cytoskeleton is to ________________________________.

Microfilaments are important in cell motility, especially in ______________________________ cells.
○ In muscle cells, thousands of actin filaments are arranged parallel to one another; actin and myosin
work together for muscle contraction.

In plant cells, actin-myosin interactions drive cytoplasmic streaming, which creates_______________
__________________________________________________________________________________.

Intermediate filaments are larger than microfilaments but smaller than microtubules, built from
__________________________________________________________________________________
__________________________________________________________________________________.

__________________________________________ are more permanent fixtures of the cytoskeleton.
Concept 6.7 Extracellular components and connections between cells help coordinate cellular activities
Plant cells are encased by cell walls.

In plants, the cell wall ________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________.

The basic design of cell walls consists of ______________________________.

A young plant cell secretes a relatively thin and flexible wall called the __________________________.

Between the primary walls of adjacent cells is a middle lamella, a thin layer with sticky polysaccharides
called __________________________________ that _______________________________________.
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
When a plant cell stops growing, it ____________________________________________________or
by adding a secondary cell wall.
○ __________________________ consists mainly of secondary walls.
The extracellular matrix of animal cells provides support, adhesion, movement, and regulation.

Though lacking cell walls, animal cells do have an elaborate extracellular matrix (ECM).

The primary constituents of the ECM are _______________________________________________
_________________________________________________________________________________

In many cells, fibronectins in the ECM connect to ________________________________, ________
___________________________________________________________________________________
___________________________________________________________________________________.

The ECM can regulate cell behavior.
○ The ECM can influence the activity of genes.
Intercellular junctions help integrate cells into higher levels of structure and function.

Plant cells are perforated with plasmodesmata, ____________________________________________
___________________________________________________________________________________.

Animals have three main types of intercellular links.

In tight junctions, _____________________________________________________________
_____________________________________________________________________________.

Desmosomes (or anchoring junctions) ______________________________________________.

Gap junctions (or communicating junctions)_________________________________________
_____________________________________________________________________________.
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