What are organisms made of?
All organisms are made of cells
The _____ is the simplest collection of matter
that can be alive (think of hierarchy)
cell
What effects cellular function?
Cell structure is correlated to cellular function
all cells are related by their _______
descent from earlier cells
Scientists use _______ to visualize cells too
small to see with the naked eye
microscopes
In a ____________ , visible light is
passed through a specimen and then through
glass lenses
light microscope (LM)
________ refract (bend) the light, so that the image
is magnified
lenses
What are three important parameters of microscopy
magnification, resolution, contrast
What is magnification?
the ratio of an object's image size
to its real size (zoom in)
What is resolution?
a measure of the clarity of an image
What is contrast?
visible differences in parts of the sample
What is an electron microscope?
a microscope with high magnification and resolution, employing electron beams in place of light and using electron lenses.
How many different types of electron microscopes are there? (state names)
Two;
Transmission electron microscope (TEM)
Scanning electron microscope (SEM)
What is Transmission electron microscope (TEM)?
focus a beam of electrons through a specimen (INTERNAL)
Which electron microscope is used to study the internal structures?
� TEMs are used mainly to study the internal
structure of cells
What is a scanning electron microscope (SEM)?
focus a beam of electrons onto the surface of a
specimen, providing images that look 3D (SURFACE)
What is cell fractionation?
takes cells apart and separates the major organelles from one another
What is the role of centrifuges?
fractionate cells into their component parts
What does Cell fractionation enable?
Cell fractionation enables scientists to determine the functions of organelles
What does Biochemistry and cytology help?
It help correlate cell function with structure.
What do eukaryotic cells have?
internal membranes that compartmentalize their functions
What is the basic structural and functional unit of every organism?
is one of two types of cells: prokaryotic or eukaryotic
What do organisms consist of?
Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells
Protists, fungi, animals, and plants all consist of_____?
eukaryotic cells
What are the basic features of all cells?
Plasma membrane, Cytosol, Chromosomes, Ribosomes
Prokaryotic cells are characterized by having_______?
No nucleus, DNA in an unbound region (nucleoid), No membrane, Cytoplasm bound by the plasma membrane
Eukaryotic cells are generally larger than____?
Prokaryotic cells
Eukaryotic cells are characterized by having____?
DNA in a nucleus that is bounded by a membranous nuclear envelope
Membrane-bound organelles
Cytoplasm in the region between the plasma membrane and nucleus
The plasma membrane is a selective barrier that allows____?
sufficient passage of oxygen, nutrients, and waste to service the volume of every cell.
The general structure of a biological membrane is a_____?
a double layer of phospholipids
The surface area to volume ratio of a cell is
critical
Metabolic requirements set upper limits on the size of
cells
As the surface area increases by a factor of n2,
the volume increases by a factor of n3.
Small cells have a greater surface area relative to
volume.
A eukaryotic cell has internal membranes that partition the cell into
organelles
Plant and animal cells have most of the same
organelles
The nucleus contains most of the ____ in a eukaryotic cell.
Dna
Ribosomes use the information from the DNA to
make proteins
The nucleus contains most of the cell's ____ and is usually the most conspicuous _______.
genes, organelle
The ________ encloses the nucleus, separating it from the cytoplasm.
nuclear envelope
The ______ is a double membrane; each membrane consists of a lipid bilayer.
nuclear membrane
____ regulate the entry and exit of molecules from the nucleus.
Pores
The shape of the nucleus is maintained by the ______, which is composed of protein
nuclear lamina
In the nucleus, DNA is organized into discrete units called
chromosomes
Each____ is composed of a single DNA molecule associated with proteins.
chromosome
The DNA and proteins of chromosomes are together called
chromatin
Chromatin condenses to form discrete _____ as a cell prepares to divide
chromosomes
The ____ is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis.
nucleolus
Ribosomes
are particles made of ribosomal RNA and protein
Ribosomes carry out protein synthesis in two locations----
In the cytosol, On the outside of the endoplasmic reticulum or the nuclear envelope
What are components of the endomembrane system.
Nuclear envelope
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles/vesicle
Plasma membrane
These components are either continuous or connected via transfer by
Vesicles
The ER membrane is continuous with the
nuclear envelope
The ____ accounts for more than half of the total membrane in many eukaryotic cells
endoplasmic reticulum (ER)
There are two distinct regions of ER
Smooth ER, which lacks ribosomes
Rough ER, surface is studded with ribosomes
What does the smooth ER do?
Synthesizes lipids
Metabolizes carbohydrates
Detoxifies drugs and poisons
Stores calcium ions
What does the rough ER do?
Has bound ribosomes, which secrete glycoproteins Distributes transport vesicles, proteins surrounded by membranes
Is a membrane factory for the cell
The Golgi apparatus consists of flattened membranous sacs called
cisternae
What are the Functions of the Golgi apparatus?
Modifies products of the ER
Manufactures certain macromolecules
Sorts and packages materials into transport vesicles
A lysosome is a
membranous sac of hydrolytic enzymes that can digest macromolecules
Lysosomal enzymes can
hydrolyze proteins, fats, polysaccharides, and nucleic acids
Lysosomal enzymes work best in the
acidic environment inside the lysosome
Some types of cell can engulf another cell by _____; this forms a food vacuole
phagocytosis
A _____ fuses with the food vacuole and digests the molecules
lysosome
______ also use enzymes to recycle the cell's own organelles and macromolecules, a process called autophagy
Lysosomes
A plant cell or fungal cell may have one or several ______, derived from endoplasmic reticulum and Golgi apparatus
vacuoles
Food vacuoles are formed by
phagocytosis
What vacuoles found in many freshwater protists, pump excess water out of cells
Contractile vacuoles
What vacuoles found in many mature plant cells, hold organic compounds and water
Central vacuoles
The ____ is a complex and dynamic player in the cell's compartmental organization.
endomembrane system
are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP
Mitochondria
What is found in plants and algae, are the sites of photosynthesis
Chloroplasts
What are oxidative organelles
peroxisomes
Mitochondria and chloroplasts have similarities with bacteria
Enveloped by a double membrane
Contain free ribosomes and circular DNA molecules
Grow and reproduce somewhat independently in cells
An early ancestor of eukaryotic cells engulfed a _____ prokaryotic cell, which formed an ________ relationship with its host
nonphotosynthetic ; endosymbiont
____ are in nearly all eukaryotic cells
mitochondria
Mitochondria have a smooth outer membrane and an inner membrane folded into ---
cristae
Mitochondria: The inner membrane creates two compartments:
intermembrane space and mitochondrial matrix
mitochondrial matrix
Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix
_____ present a large surface area for enzymes that synthesize ATP
Cristae
______ contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis
Chloroplasts
Chloroplasts are found in
leaves and other green organs of plants and in algae
Chloroplast structure includes
Thylakoids, membranous sacs, stacked to form a granum
Stroma, the internal fluid
The chloroplast is one of a group of plant organelles called
plastids
Peroxisomes are
are specialized metabolic compartments bounded by a single membrane
Peroxisomes produce
hydrogen peroxide and convert it to water
The cytoskeleton is a
network of fibers extending throughout the cytoplasm
Cytoskeleton organizes
the cell's structures and activities, anchoring many organelles
Cytoskeleton is composed of three types of molecular structures
Microtubules
Microfilaments
Intermediate filaments
The cytoskeleton helps to support the __ and maintain its ___
cell, shape
Cytoskeleton interacts with ___ to produce motility
motor proteins
Inside the cell, vesicles can travel along _____ provided by the cytoskeleton
monorails
Recent evidence suggests that the ____ may help regulate biochemical activities
cytoskeleton
What are three main types of fibers that make up the cytoskeleton
Microtubules are the thickest of the three components of the cytoskeleton
Microfilaments, also called actin filaments, are the thinnest components
Intermediate filaments are fibers with diameters in a middle range
Microtubules are
hollow rods about 25 nm in diameter and about 200 nm to 25 microns long
Functions of microtubules
Shaping the cell
Guiding movement of organelles
Separating chromosomes during cell division
In many cells, microtubules grow out from a _____ near the nucleus
centrosome
The centrosome is a
microtubule organizing center
In animal cells, the centrosome has a pair of ______, each with nine triplets of microtubules arranged in a ring
centrioles
Microtubules control the beating of ____and_____, locomotor appendages of some cells
cilia and flagella
What common structure do Cilia and flagella share?
A core of microtubules sheathed by the plasma membrane
A basal body that anchors the cilium or flagellum
A motor protein called dynein, which drives the bending movements of a cilium or flagellum
How dynein "walking" moves flagella and cilia
Dynein arms alternately grab, move, and release the outer microtubules
Protein cross-links limit sliding
Forces exerted by dynein arms cause doublets to curve, bending the cilium or flagellum
Microfilaments
are solid rods about 7 nm in diameter, built as a twisted double chain of actin subunits
The structural role of microfilaments is
to bear tension, resisting pulling forces within the cell
Microfilaments form a 3-D network called the ___ just inside the plasma membrane to help support the cell's shape
cortex
Bundles of microfilaments make up the core of
microvilli of intestinal cells
Microfilaments that function in cellular motility contain the protein ____ in addition to actin
myosin
In muscle cells
thousands of actin filaments are arranged parallel to one another
Thicker filaments composed of myosin interdigitate with the
thinner actin fibers
Localized contraction brought about by actin and myosin also drives amoeboid movement
...
Pseudopodia (cellular extensions) extend and contract through the reversible assembly and contraction of actin subunits into microfilaments
...
Cytoplasmic streaming is a circular flow of cytoplasm within cells
...
This streaming speeds distribution of materials within the cell
...
In plant cells, actin-myosin interactions and sol-gel transformations drive cytoplasmic streaming
...
_______ range in diameter from 8-12 nanometers, larger than microfilaments but smaller than microtubules
Intermediate filaments
________ support cell shape and fix organelles in place
Intermediate filaments
________ are more permanent cytoskeleton fixtures than the other two classes
Intermediate filaments