Chapter 4 College Biology
differential interference light microscopes amplify
differences in density so that structures in living cells appear almost three dimensional
Which of the following would distinguish a bacterial cell from an animal cell?
presence of a cell wall
intermembrane space
the fluid filled space between the inner and outer mitochondrial membranes
cellular metabolism
the many chemical activities of the cells, occurs within organelles
mitochondrial matrix
the mitochondrial DNA, ribosomes, and many enzymes that catalyze some of the reactions of cellular respiration
hydrophilic heads
water loving, face outward exposed to water
Which of the following clues would tell you whether a cell is prokaryotic or eukaryotic?
whether or not the cell is partitioned into compartments
Thylakoid
A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.
Cytoplasm
A jellylike fluid inside the cell in which the organelles are suspended
Cytoskeleton
A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement
endomembrane system
A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.
Centrosome
A structure in animal cells containing centrioles from which the spindle fibers develop.
Cyanide inhibits mitochondrial function; as a result, the rate of
ATP synthesis decreases
Magnification
An increase in the apparent size of an object
Lysosomes
An organelle containing digestive enzymes, made by the rough ER and processed in the Golgi apparatus
who discovered the microscope?
Antoine van Leeuwenhoek
the nucleus
Contains DNA and controls all cell activity by directing protein synthesis by making messenger RNA
Mitochondria and chloroplasts contain
DNA and ribosomes
Rough ER
ER that is dotted with ribosomes
Which of the following is part of the endomembrane system?
Golgi apperatus
Microfilaments
Long, thin fibers that function in the movement and support of the cell
In addition to phospholipids, the plasma membrane also contains proteins, many of which cross the width of the membrane. Which of the following statements best describes membrane-spanning proteins?
Membrane-spanning proteins contain both hydrophobic and hydrophilic amino acids and float freely in the membrane.
Mitochondria
Powerhouse of the cell, organelle that is the site of ATP (energy) production, carries out cellular respiration
who discovered cells?
Robert Hooke in 1665
Which of the following is a function of the central vacuole?
Storing compounds produced by the cell
smooth ER
That portion of the endoplasmic reticulum that DOES NOT have ribosomes.
What is the relationship between the Golgi apparatus and the plasma membrane?
The finished products of the Golgi apparatus may leave the cell through vesicles that fuse with the plasma membrane.
Microscopes have limitations
The human eye and the microscope have limits of resolution—the ability to distinguish between small structures. Therefore, the light microscope cannot provide the details of a small cell's structure.
Your intestine is lined with individual cells. No fluids leak between these cells from the gut into your body. Why?
The intestinal cells are bound together by tight junctions.
What do the rough endoplasmic reticulum, Golgi apparatus, and lysosomes have in common?
They are all membranous organelles comprising the endomembrane system.
Hydrophobic tails
Water fearing, face inward shielded from water
Resolution
a measure of the clarity of an image
Eukaryote cells are distinguished by having
a membrane enclosed nucleus and many membrane enclosed organelles that perform specific functions
a eukaryotic cell contains
a membrane-enclosed nucleus and various other organelles ("little organs"), which perform specific functions in the cell.
Which structure is exclusively associated with prokaryotic cells?
a nucleoid
prokaryote and eukaryote cells both have
a plasma membrane, cytosol (jellylike fluid), chromosomes that cary genes made of DNA, and ribosomes that make proteins
the nucleolus is
a prominent structure in the nucleus and the site of ribosomal RNA synthesis so ribosomes get made here
the rough ER makes
additional membrane for itself and secretory proteins
The membranous compartmentalization of a cell
allows different chemical conditions to be maintained in different parts of the cell
A scientist wants to magnify a pollen grain 8,000 times and examine the ridges and pores on its surface. Which instrument would be best?
an electron scanning microscope
vacuoles
are larges vesicles that have a variety of functions
Peroxisomes
are metabolic compartments that do not originate from the endomembrane system, unknown how they are related to other organelles. But they do break down fatty acids to be used as a cellular fuel
bound ribosomes
attached to the outside of the endoplasmic reticulum or nuclear envelope, makes proteins packed in certain organelles or exported
what is present in a plant cell but not an animal cell
cell wall containing cellulose, plasmodesmata, chloroplasts where photosynthesis occurs, and a central vacuole that stores water
_____ are found only in plant cells, but _____ are found in both plant and animal cells.
central vacuoles, ribosomes
The complex of proteins and DNA in a nondividing cell is called
chromatin
when a cell is not dividing, this complex of proteins and DNA appears as a diffuse mass within the nucleus
chromatin
DNA is associated with many proteins and is organized into
chromosomes
During cell reproduction, chromatin fibers coil up into structures called
chromosomes
The nucleoid region of a prokaryotic cell
contains the cell's DNA
The structural framework in a cell is the
cytoskeleton
what is involved in structural support, movement, and communication
cytoskeleton, plasma membrane, and cell wall
most animal cells are
embedded in an extracellular matrix.
membrane proteins are
embedded in the lipid bilayer
what is involved in the manufacture, distribution, and breakdown of molecules
endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes
the largest component of the endomembrane system is the
endoplasmic reticulum, an extensive network of flattened sacs and tubules
short projections
fimbriae that help attach prokaryotes to each other or their substrate
longer projections
flagella, propel a prokaryotic cell through its liquid environment
Stroma
fluid portion of the chloroplast, which contains chloroplast DNA, ribosomes, many enzymes, and a network of interconnected sacs
Cristae
folds in the inner membrane of mitochondria
Phospholipids
form a two layer sheet called a phospholipid bilayer in which hydrophilic heads and hydrophobic tails are
the plasma membrane
forms a flexible boundary between the living cell and its surroundings; made of phospholipids
intermediate filaments
found in the cells of most animals, reinforce cell shape and anchor some organelles and are often more permanent fixtures in the cell
What does a lysosome do?
fuse with food vacuoles and digest food, destroy bacteria engulfed by WBC or fused with other vesicles and break down damages organelles
The structures and organelles of eukaryotic cells perform four basic functions
genetic control, breakdown of molecules, energy processing, and structural support and movement
in plants, vacuoles functions
have digestive functions, contain pigments, or contain poisons that protect the plant
some protists have contractile vacuoles which
help to eliminate water from the protist
cell theory
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells
mitochondria have two internal compartments
intermembrane space and mitochondrial matrix
cells must be
large enough to house DNA, proteins, and structures needed to survive and reproduce but remain small enough to allow for a surface to volume ration that will allow adequate exchange within the environment
cells that make a lot of proteins have a
large number of ribosomes
light microscope
light passes through one or more lenses to produce an enlarged image of a specimen
Which of the following organelles is found only in animal cells and NOT in most plant cells?
lysosomes
Which organelle plays a role in intracellular digestion?
lysosomes
what is present in animals cells but not plant cells
lysosomes and centrosomes, sperm cells dont have flagella
What carries instructions for making proteins from the nucleus into the cytoplasm?
mRNA
The main function of the rough endoplasmic reticulum is the production of
membrane and proteins secreted by the cell.
what were some things founded by a light microscope?
microorganisms, animal and plant cells, and some structures within cells
electron microscope
microscope that forms an image by focusing beams of electrons onto a specimen
what is involved in energy processing
mitochondria and chloroplasts
endosymbiont theory
mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells
the endomembrane system includes the
nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles and the plasma membrane.
in a prokaryotic cell, the DNA is coiled into a region called
nucleoid
what is involved in the genetic control of the cell
nucleus and ribosomes
Chloroplast
organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy, site of photosynthesis
To enter or leave any cell, substances must pass through
plasma membrane
In plants, __________ are the cell junctions that allow the free exchange of small molecules that assist in communication. In animal cells, similar cell junctions are known as __________.
plasmodesmata ... gap junctions
the golgi apparatus serves as a molecular warehouse and processing station for
products manufactured by the ER, they travel in transport vesicles from the ER to the golgi
bacteria and archaea are
prokaryotic cells and are smaller and simpler in structure
Outside the plasma membrane of most prokaryotes is a fairly rigid, chemically complex cell wall, which
protects the cell and helps maintain its shape
ribosomes are involved in the cell's
protein synthesis, builds proteins from instructions from the nucleus
ribosomes are synthesized from
rRNA produced in the nucleolus
two sides of the golgi
recieving side that packages, and the shipping side
the double membrane nuclear envelope has pores that
regulate the entry and exit of large molecules and connects with the cell's network of membranes called the endoplasmic reticulum
electron microscopes can
resolve biological structures as small as 2 nanometers and magnify up to 100,000 times
Microtubules
shape and support the cell and act as tracks along which organelles equipped with motor proteins move
some proteins form channels that .... and other proteins serve as...
shield ions and other hydrophilic molecules as they pass through the hydrophobic center of the membrane, using energy to actively transport molecules into or out of the cell
some prokaryotes have surface projections (2 types)
short projections and longer projections
Where are lipids made in the cell?
smooth endoplasmic reticulum (ER)
granum
stack of thylakoids
Smooth endoplasmic reticulum
stores calcium ions in muscle cells
scanning electron microscope
study the detailed architecture of cell surfaces
transmission electron microscope
study the details of internal cell structure
free ribosomes
suspended in the cytosol, involved with making proteins in the cytoplasm
Smooth ER is involved in a variety of metabolic processes, including
the production of enzymes important in the synthesis of lipids, oils, phospholipids, and steroids, the production of enzymes that help process drugs, alcohol, and other potentially harmfal substances, and the storage of calcium ions
The stroma is the
thick fluid enclosed by the inner chloroplast membrane
The function of the nucleolus is
to manufacture ribosomal RNA
as cell size increases,
volume increases faster than surface area