Chapter 4 Cells Flashcards
Scientist ______ discovered cells in the year _____
Robert Hooke; 1665
Who proposed the Cell Theory
Mathias Schleiden and Theodor Schwann
What are the 3 components of the Cell Theory
- All organisms are composed of one or more cells
- Cells are the smallest living units of all living organisms
- Cells arise only by division of a previously existing cell
Names some cells
A. Bacterium
B. Archaean
C. Amoeba
D. Algae
E. Fungal Cells
F. Animal Cells
G. Plant Cells
Light microscopes characteristics
-use magnifying lens with visible light
-resolve structures that are 200nm apart
-limit to resolution using light
Electron Microscopes characteristics
-use beam of electrons
-resolve structures that are 0.2nm apart
What is Bright Field Microscopy
Light passes through specimen. Dye staining used to enhance contrasts, but this kills the cells
What microscopy stains molecules with specific fluorescent dyes? What kind of light is used to illuminate the cells?
Fluorescence microscopy; Ultraviolet light
What is transmission electron microscopy?
A beam of electrons focused on thin section of specimen in a vacuum
Nomarski (differential interference contrasts gives the cell a _____
3D appearance due to lenses that enhance differences in density
Lasers that scan a specimen in 3D localizing fluorescence emitted from each point is ______ microscopy
Confocal laser scanning microscopy
Super resolution fluorescent microscopy
Precisely targets the laser light that stimulates fluorescence
Scanning Electron Microscopy
Beam of electrons is scanned across a whole cell and electrons on surface are converted to a 3D image
Cell size is limited because…
of Surface Area to Volume Ratio
Surface Area determines what
the amount of substances that can be exchanged between a cell and the outside environment
Doubling the diameter of a cell increases the Surface Area by ____ and volume by _____
4 times; 8 times
Cells can increase surface area with what
extensions or folds
What is the Plasma membrane?
a phospholipid bilayer with embedded protein molecules that bounds cells
The phospholipid bilayer is a hydrophobic barrier to what?
water soluble substances
Anything can pass through the phospholipid bilayer. (T/F) If false, what can?
False. Only selected substances through transport protein channels
Selective transport of ions and water-soluble moleules maintain what?
specialized internal environments required for cellular life
DNA molecules are found in which area of all cells?
Central Region
The cytoplasm contains what?
cytosol and cytoskeleton
Where is the cytoplasm found?
Between the plasma membrane and central region
What is cytosol? What does it contain?
Aqueous solution containing ions, various organic molecules, and organelles
Cytoskeleton maintains _____ and plays a role in _________ and __________.
Cell shape; cell division; chromosome segregation
What domains are prokaryotes?
Bacteria and Archaea
What kind of cells are Eukaryotes (domain Eukarya)
Animal, Plant, Fungi, Protista
There is a nucleus in prokaryotes (T/F)
false, no membrane around nucleoid region
Prokaryotes have few internal membranes (T/F)
True
Nucleus seperates what in Eukaryotic cells?
the DNA (nucleoid region) and cytoplasm
What are cell walls in prokaryotic cells coated with?
polysaccharides (glycocalyx)
When Glycocalyx is looselt associated with the cell it is a….
slime layer
When Glycocalyx is firmly attached it is a…
capsule
The plasma membrane in prokaryotic cells contains molecular systems that metabolize food into ATP. (T/F)
true
Many bacteria and archaeans move with what?
Flagella
The bacteria flagellum moves by?
rotating in a socket and pushes the cell through a liquid medium
Pili attach the cell to other cell surfaces (T/F)
true
What are the three most common shapes among prokaryotes?
spherical, rodlike and spiral
What is DNA in a single circular molecule called
prokaryotic chromosome
DNA info is copied to ____ and carried to _____ in the cytoplasm to assemble Amino Acids into _____
mRNA; ribosomes; proteins
Where is DNA is the eukaryotic cell found
Nucleus within the Nuclear Envelope
Eukaryotes are compartmentalized by an endomembrane system (T/F)
true
There are no membrane bound organelles in eukaryotes (T/F)
false
What do plant cells have that animal cells don’t?
chloroplasts, central vacuole and a cell wall
Cell fractionation is used to
isolate and study organelles
How many nucleuses are found in a eukaryotic cell
one
Where does ribosomal RNA synthesis take place?
Nucleolus
Nuclear envelope is made of…
2 phospholipid bilayers
Protein filaments called _____ reinforce the nuclear envelope
lamins
Nuclear pores control and regulate….
the passage of molecules in and out of the nucleus
DNA is divided into multiple linear chromosomes in eukaryotes (T/F)
true
Liquid within the nucleus is called
the nucleoplasm
Chromatin is a combo of….
DNA and protiens
Nuclear Localization Signal
Tells proteins where to go (into nucleus)
What Amino Acids control the Nuclear Localization Signal
127-133
the eukaryotic ribosome consists of
a large and small subunit
ribosomes are made of what?
ribosomal RNA and proteins
Ribosomal subunits are assembled in the nucleus (T/F)
true
Ribosomes can only be freely suspended in the cytosol (T/F)
false. They can also attach to membranes
Microtubules are the largest of the filaments (T/F)
true-25nm in diameter
What are microtubules made of?
alpha- and beta- tubulin dimers
Microtubule has a (+) and (-) end organized how?
head-to-tail in each side by side filament
What are the three types of cytoskeleton filaments?
Microfilament, Microtubule, and Intermediate Filaments
What is the cytoskeleton?
interconnected system of protein fibers and tubes that extend throughout the cytoplasm
What does the cytoskeleton do?
maintain cell shape and internal organization, helps function in movement
What is the endomembrane system?
a series of membranes throughout the cytoplasm dividing the cell into compartments where different cellular functions occur
How are membranes connected?
Directly or indirectly by vesicles
What are vesicles?
small membrane-bound sacs that transfer substances between parts of the system
Endoplasmic Reticulum (ER) is an extensive interconnected network of channels and cisternae (T/F)
true
ER occurs in what two forms
rough ER and smooth ER
Mitochondria and Chloroplast do not have their own DNA (T/F)
false
Mitochondria has 2 phospholipid bilayers. What are they called?
Outer and inner membranes. (Inner creates cristae)
What do mitochondria do?
Cellular Respiration, break down energy rich food and capture ATP
Is oxygen required for cellular respiration?
yes
Chloroplasts contain compartments of stacked _____ containing ______
grana; thylakoids
What is the endosymbiotic theory?
Mitochondria haveoriginated from mutualistic relationship between ingested prokaryotic cell
What are peroxisomes?
enzyme-bearing, membrane-enclosed vesicles
Peroxisomes contain enzymes that are involved in oxidation of…..
fatty acids
What is a by-product of peroxisomes rendered harmless by catalase
Hydrogen Peroxide
Explain vesicle traffic in the cytoplasm
Proteins made by ER ribosomes enter ER membrane where modifications are made. Vesicles bud from ER membrane and transport proteins to Golgi. Protein modification is completed in Golgi and sent by secretory vesicle to PM. Products released by exocytosis.
Where are lysosomes formed?
Trans-Golgi Network
Lysosomes are found in animals not plants (T/F)
true
What do lysosomes do?
breakdown macromolecules, destroy cells or foreign matter (phagocytosis), and digest worn-out damaged organelles (autophagy)
The pH in lysosomes is more basic than the cytosol (T/F)
false. Lysosomes are more acidic
What makes rough ER “rough”
ribosomes attached to outer surface
Where do proteins in rough ER fold into final form and chemical modifications occur?
ER lumen
What does smooth ER synthesize?
lipids that become a part of cell membranes
What network compartments are found in the Golgi?
cis-, medial-, & trans-
What side do proteins enter and exit the Golgi?
enter on the cis and exit on the trans
What is the function of the Golgi?
collect, package and distributes molecules using vesicles
final protein folding
How does exocytosis work?
Membrane of vesicle fuse and becomes apart of the plasma membrane.
