CELL 1010 Chapter 4: A Tour of the Cell
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424 Terms
What are the parts of cell theory?
all living organisms are made of one or many cells
cells are the fundamental unit of life
new cells arise from old cells through division
What are cell biologists?
scientists that study the cell
What is a microscope?
tool of magnification
What are the smallest thing the naked eye can see?
frog eggs
How small can the naked eye see?
>100 micrometers
How small of a specimen can an electron microscope magnify?
anything as small as 2 nanometers
How small of a specimen can a light microscope magnify?
anything as small as 0.2 micrometers
Which can magnify more: an electron or light microscope?
electron microscope
Why can electron microscopes magnify more?
electrons have a shorter wavelength
What is the key word for magnification?
enlargement
What is magnification?
size of image as projected by microscope
What is the key word for resolution?
clarity
What is clarity?
capacity to identify two adjacent objects as being DISTINCT
What is the key word for contrast?
visualize
What is contrast?
capacity to visualize two objects as being DIFFERENT
What are some examples of contrast?
dyes, stains, radioactivity, etc
How does a light microscope have contrast?
with stained slides or without stained slides
Which type of contrast never uses stains?
phase contrast
How does phase contrast work?
modify light that falls on specimen
How do new cells arise in prokaryotic cells?
binary division
How do new cells arise in eukaryotic cells?
mitosis
How does contrast allow us to determine which structures are different?
density of composition of substances
What do phase contrast microscopes look at?
live specimen
How do phase contrast light microscopes work?
high refractility (light rays get scattered)
How do Nomarsky light microscopes work?
modify light emitted from specimen
What effect do Nomarsky microscopes have?
3D effect
How do fluorescent light microscopes work?
absorb light at certain frequency and emit light at higher frequency
What types of light to confocal microscopes use?
laser
Which type of light microscope has the best resolution?
confocal
What type of image do the laser in confocal microscopes allow for?
3D images
How do electron microscopes work?
stain specimen with heavy metal
What do scanning electron microscopes allow scientists to see?
topography of membrane
How do scanning electron microscopes affect electrons?
all electrons will be reflected
What do transmission electron microscopes allow scientists to see?
parts of a cell
How do transmission electron microscopes affect electrons?
some electrons scatter and some electrons pass through
Which type of microscope has the best resolution out of ALL microscopes?
transmission electron microscope
What is another name for cell franctionation?
centerfugation
What is cell fractionation?
exposing cell to G forces —> cell breaks up into pellet and supernatant
What are the characteristics of cells?
made of matter
source of information
organized
use energy
What are cell structures?
plasma membrane, cytoplasm, DNA, ribosomes, etc
What is the shape of DNA in prokaryotes?
circular
What is the shape of DNA in eukaryotes?
linear
What do archaea have that bacteria do not have?
introns, complicated cell membranes
What form when bacteria are stressed (in unfavorable conditions)?
endospores
What do endospores do?
form around bacteria to protect DNA
Bacteria are always __________ but not always ___________
present, harmful
What are the types of bacteria?
cocci, bacillus, spirochete
What is the shape of cocci bacteria?
small and circular
What is the shape of bacillus bacteria?
rod shaped
What is the shape of spirochete bacteria?
coils
Which types of bacteria form in colonies?
cocci and bacillus
Which types of bacteria are solitary?
spirochete
What type of DNA is in bacteria?
haploid
What are pili?
bacterial structures used for conjugation, tool for horizontal gene transfer, gives fertility
What is the plasmid?
DNA in bacteria that is non essential for survival but used in horizontal gene transfer
What is the function of the cell wall in bacteria?
have tiny pores for water, protection
Where is the glycocalyx in bacteria?
outside the cell wall
What is glycocalyx made of?
carbohydrates and water
What is the consistency of the glycocalyx?
viscous (like syrup) but can become a thick capsule (like jelly) when virulent
What is the function of the glycocalyx?
protects from dehydration and allows bacteria to adhere to surfaces
What is the flagella made of?
one sheet of protein (flagellin)
What is the function of the flagella?
gives motility
What is the structure indicated by gram +?
thick layer of peptidoglycan (carb mesh with small amino acid chains connecting it)
What color do gram + specimen appear?
purple
Is gram + virulent or nonvirulent?
nonvirulent
What is the structure indicated by gram -?
thin layer of peptidoglycan and thick layer of lipopolysaccharide (lipids and carbs)
What color do gram - specimen appear?
pink (more washes out)
Is gram - virulent or nonvirulent?
virulent
What are characteristics of eukaryotic cells?
DNA in nucleus, compartmentalized (membrane-bound organelles), cell specialization
How do cells display specialization?
differential gene expression
concentration and persistence of proteins
alternative splicing
covalent modifications
What is differential gene expression?
up/down regulation, proteins produced in some cells might not be in other cells
What is concentration and persistence of proteins?
proteins are kept in high concentrations if uses consistently (ex. myosin and actin are constantly present in limbs for movement but are only synthesized in cheek cells when needed)
What is alternative splicing?
cutting out some introns and/or exons, changing protein structure to best suit its function to a location in the body
When does alternative splicing occur?
between transcription and translation
What is covalent modification?
adding or removing functional groups to activate or deactivate a protein (can only remove a functional group if it was previously added)
What are the characteristics of the plasma membrane?
semi permeability, universally present, formidable barrier, flexible
What do transport proteins provide to the plasma membrane?
selective permeability
What do receptor proteins provide to the plasma membrane?
receives signals to allow cell to communicate with environment
What do adhesive proteins provide to the plasma membrane
adhesive properties between cells
Which types of cells have permanent adhesive properties?
tissues
Which types of cells have temporary adhesive properties?
circulatory system
What is the cytosol?
region outside the organelles but inside plasma membrane
What importance does the cytosol have within a cell?
central coordinating region of the cell: anabolic and catabolic reactions, translation
What does the cytoplasm include?
complexes (ribosomes and signal recognition particles)
What did peroxisomes used to be considered?
semiautonomous organelles
Why were peroxisomes once thought to be semiautonomous organelles?
they do not require a vesicle to absorb cargo
Why are peroxisomes no longer classified as semiautonomous organelles?
they have no nucleoid region or DNA
Why is actin and myosin a good example of concentration and persistence of proteins and cell specialization?
actin and myosin are present for long periods of time in limbs but in low concentrations in cheeks
What is the result of alternative splicing?
some amino acids will be missing causing different proteins to form from the same identical gene sequence
What is the result of covalent modifications of proteins
proteins are present in every cell but some are inactive in specific cells
What does protein analysis identify?
cell type, function, and health
What makes the plasma membrane flexible?
components of the membrane can move around allowing small nonpolar molecules to come into contact with
What does a formidable barrier mean?
any membrane will only allow things to enter or exit that aren’t supposed to
What are receptors?
signal receivers
Why do cells need receptors?
communication (all cells need to work together)
What types of receptors do unicellular organisms require?
receptors for outside the organism
What types of receptors do multicellular organisms require?
receptors for inside and outside the organism
What do adhesive proteins do?
anchor cell
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What is the cytoplasm?
anything inside the plasma membrane