Tour of the Cell Flashcards
how do biologists study cells
microscopes and biochemistry tools
what do eukaryotic cells have that compartmentalizes their functions
internal membranes
what organelle is probably going to be seen first when examing a cell
the nucleus
where is genetic instruction housed in eukaryotic cells
the nucleus
what carries the genetic instructions in eukaryotic cells
the ribosomes
what is not an organelle in cells
ribosomes
what does the endomembrane system regulate
- protein traffic
- performs metabolic functions
mitochondria and chloroplasts can do what
change energy from one form or another
what does the cytoskeleton do in the cell
organizes structures and activties
extracellular components and connections between cells do what
helps coordinate cellular activties
all organisms are made from
cells
what is the simplest collection of matter that can e alive
cells
all cells are related by
descent from earlier cells
what does being alive mean
able to reproduce itself
cell _____ is correlated to cell ______
structure and function
cell theory
- cells are the fundamental unit of life
- simplest unit capable of independent existent
- living things have to be made from cells
viruses are ______ because they need _______ to survive
not alive and a host cell
why are microscopes used
to visualize cells
why are cells complex
they are self sustaining units
Light microscope
visible light is passed through a specimen and then through glass lenses
how can the image be magnified
the lens refracts the light
three important parts of microscopy
- magnification
- resolution
- contrast
magnification
ratio of an object’s image size to its real size
resolution
the minimum distance of two points that are still distingushable
what is a measure of clarity
resolution
contrast
visible difference in parts of the sample
(light vs dark areas)
what magnification does an LM do to a specimen
about 1000 times actual size
what techniques can make specimen more clear for LM
- fluorene
- stains
- pigments
what is too small to be seen by LM
organelles
unstained specimen of LM has
little contrast
stained specimen of LM has
enhanced contrast
what happens to the stained cell during microscopy
its killed
LM phase-contrast used for
living unpigmented cells
Lm differential-Interference Contrast results in
a 3D image
Fluorescence microscopy of LM uses
antibodies to see specific molecules
what LM advances allow a sharper 3D image
confocal microscopy and deconvolution microscopy
confocal microscopy of LM
laser produces sharper images and allows 3D image reconstruction
Types of electron microscopy (EM)
- scanning electron microscopes (SEM)
- transmission electron microscopes (TEM)
scanning electron microscopes (SEM)
provides a 3D image of the surface of the specimen
scanning electron microscopes (SEM) focus electrons ____ the specimen
onto the surface of
transmission electron microscopes (TEM)
provides a study of the internal structures
transmission electron microscopes (TEM) focus electrons _____ the specimen
through
super-resolution microscopes
Able to “break” the resolution barrier and distinguish structures as small as 10-20 nm across
greater magnification means
additional details cannot be seen clearly
Electron Microscopes
advantage
Revealed many subcellular structures impossible to see with LM
Electron Microscopes
disadvantage
Methods used to prepare the speciment kills the cells
Electron Microscopes
disadvantage
Methods used to prepare the specimen kills the cells
cell fractionation
cells are broken open and separated into their components
______ is used to separate organelles from one another by ______ _____ the centrifugation ____
centrifuges, gradual increasing, speed
the _____ of organelles can be studied when
function and isolated from other components
cells are made from _____ _____
90% and water
two types of cells
prokaryotic and eukaryotic
what two domains of life are fully prokaryotic cells
bacteria and archae
domains in eukaryotic cells
animal, fungi, plant and protist
what 4 features do ALL cells have
- plasma membrane
- cytosol
- chromosomes
- ribosomes
what carries the genes
chromosomes
what makes proteins
ribosomes
PROKARYOTIC CELLS are characterized by
- no nucleus
- DNA is unbound in the nucleoid
- no membrane-bound organelles
- cytoplasm bound by plasma membrane
similarities between PROKARYOTIC and EUKARYOTIC cells
- both have DNA as genetic material
- both are membrane-bound
- both have ribosomes
- both have similar metabolism
differences between PROKARYOTIC and EUKARYOTIC cells
- Eukaryotes have a nucleus AND membrane-bound organelles
- Prokaryotic DNA floats freely while Eukaryotic DNA is held in the nucleus
- Eukaryotic cells are about 10 x bigger
- DNA of eukaryotes is more complex
- Prokaryotes have a cell wall made from peptidoglycan while eukaryotes don’t have cell walls made from that
the cell wall is found in
bacteria, fungi and plants
what makes prokaryotic cell walls unique from all other eukaryotic cell walls
made from peptidoglycan
EUKARYOTIC cells are characterized by
- membrane-bound organelles
- bigger size
- have DNA in nucleus, surrounded by nuclear envelope
- cytoplasm between nucleus and plasma membrane
the plasma membrane is what kind of barrier
selective barrier
what does the plasma membrane allow passage of
- oxygen
- nutrients
- waste
what does the passage of the plasma membrane do for the cell
supports the cell volume
what is the structure of the biological membrane
phospholipid bilayer
what makes species unique from each other
glycoprotein
what is unique to each cell
DNA
how do animal and plant cells differ
from their structure
how is the membrane fixed
from vesicles transporting materials from the ER or golgi
the membrane has of what organelle has no phospholipid membrane
ribosomes
all the organelles in the endomembrane system have
membranes surrounding them
unique structures to plant cell structures
- chloroplasts
- large central vacuoles
- cell walls
- plasmodesmata
how do ribosomes make proteins
by using the information from the DNA
what is the most conspicuous organelle
the nucleus
the ______ encloses the nucleus
nuclear membrane
the nuclear membrane has ____ parts each consisting of a _____
two and lipid bilayer
chromatin
the folding and positioning define what the cell can do
what regulates entry and exit of molecules from the nucleus
pores
what determines the shape of the nucleus
nuclear lamina
what is the nuclear lamina made from
proteins
what are the sections of the DNA called in the nucleus
chromosomes
what is a chromosome made from
single DNA molecule with proteins
what is DNA and proteins on chromosome called
chromatin
nucleolus
site of rRNA synthesis in nucleus
what are ribosomes made from
rRNA and protein
nuclear envelope
encloses the nucleus and separates its contents from the cytoplasm
Nuclear matrix
framework of protein fibers that extend throughout the nuclear interior
what two parts of the nucleus help organize the genetic material so it functions efficiently
nuclear lamina and matrix
what reduces the length of the DNA so it fits in the nucleus
chromatin
two types of ribosomes
free and bound
free ribosomes are
suspended in the cytosol
bound ribosomes are found
attached to the outside of the endoplasmic reticulum or nuclear envelope
components of the endomembrane system
a. Nuclear envelope
b. Endoplasmic reticulum
c. Golgi apparatus
d. Lysosomes
e. Kinds of vesicles
f. Vacuoles
Plasma membrane
what components of the endomembrane system are physically connected
- nuclear envelope
- ER
ER membrane is
continuous with the nuclear envelope
ER accounts for _____ of total membrane in eukaryotic cells
more than half
two types of ER
smooth ER and Rough Er
smooth ER
has NO ribosomes
smooth ER functions
Synthesis of lipids
Metabolism of carbohydrates
Detoxification of drugs and poisons
storage of calcium ions
what cells have lots of smooth ER
muscle cells
Rough ER
has ribosomes on the surface
Rough ER functions
- site for synthesis of all proteins of the endomembrane system
- produces transport vesciles
what do the ribosomes on the Rough ER do
synthesis glycoproteins
what are transport vesicles
distribute lipids and proteins to other components of the endomembrane system
Golgi apparatus
a flattened membranous sac
what is the flattened membranous sac called for the golgi
cisternae
what are the two faces of the Golgi
cis and trans face
what does the cis face do in Golgi
receives vesicles from the ER
After leaving the ER, transport vesicles travel to the
Gogi
what is the Golgi tasked with
receiving, storing, shipping and sometimes manufacturing products
what direction do the cisternae move forward in
from the cis face to the trans face
what does the trans face do in Golgi
vesicles are shipped from the Golgi and sent to other parts of the cell
functions of the Golgi
- modify products of the Er
- make certain macromolecules
- sorts and packages materials into transport vesicles
lysosomes
Membranous sac of hydrolytic enzymes
what conditions do lysosomes work best in
acidic enviroments
what are lysosomes used for
digest macromolecules
recycle cells own damaged material
what is autophagy
Recycle the cell’s own organic material
what can enzymes hydrolyze
- fats
- proteins
- polysaccharides
- nucleic acids
phagocytosis
cells that engulf another cell by forming a food vacoule
how does phagocytosis work
- lysosome fuses with food vacuole
- enzymes in the lysosome digest the food
- digestion products pass into the cytosol and become nutrients for the cell
what allows the cell to continuality reuse itself
lysosomes
Vacuoles are what
Large vesicles from the Er and Golgi apparatus
the vacuole membrane is ______ in transporting solutes
selective
Types of vacuoles
food vacuoles
contractile vacuoles
central vacoule
Food vacoules
Formed by phagocytosis
Contractile vacuoles
Pump excess water out of the cell
Central vacuole formed by
the merging of smaller vacuoles
central vacuole
- Growth of plant cells
- holds organic compounds and water
what occupies the majority of the plant cell’s volume
one large central vacuole
mitochondria
Sites of cellular respiration that uses oxygen to create ATP by extracting energy from sugars, fats and other fuels
Chloroplasts is the site of what
photosynthesis
chloroplasts convert
solar energy to chemical energy by absorbing sunlight and using it to synthesis of organic compounds (sugars)
Endosymbiont theory
a. An early ancestor if eukaryotic cells engulfed an oxygen-using no photosynthetic prokaryotic cell
b. The engulfed cell formed a relationship with the host cell
c. Became endosymbiont (cell living within a cell)
d. Host cell and endosymbiont merged into a single organism (eukaryote cell with a mitochondrion)
what supports the endosymbiont theory
b. Both have two membranes surrounding them
c. Like prokaryotes, both contain ribosomes and multiple circular DNA molecules
d. Both are autonomous (independent) organelles that grow and reproduce within the cell
Found in nearly all eukaryotic cells
Mitochondria
the mitochondria have ___ membranes enclosing as a ____ bilayer
two and phospholipid
membranes of the mitochondria
Outer membrane is smooth
The inner membrane is convoluted with foldings
what are the foldings called on the inner mitochondrial membrane
cristae
what is enhancing the productivity of cellular respiration
the inner membrane large surface area
two internal compartments of the mitochondrion
intermembrane space
mitochondrial matrix
intermembrane space of mitochondria
narrow region between the inner and outer membrane
mitochondrial matrix
Contains many different enzymes, mitochondrial DNA and ribosomes enclosed by inner wall
Chloroplasts have a
Green pigment chlorophyll with enzymes and other molecules work in the photosynthesis production of sugar
chloroplasts are found in
leaves and other green organs of plants and algae
how are the Contents of chloroplasts separate from the cytosol
by an envelope consisting of two membranes
Inside the chloroplast is a membranous system
- stroma
- granum
- thylakoids
stroma
The fluid outside the thylakoids
granum
These thylakoids are often stacked and each stack
thykaloids
Flattened interconnected sacs
Three compartments of the chloroplast allow the conversion of light energy to chemical energy
a. The intermembrane space
b. The stroma
The thylakoid space
Peroxisomes
A specialized metabolic compartment that converts h2o2 to water
Glyoxysomes
Contain enzymes that initiate the conversion of fatty acids to sugar in plants
Roles of Cytoskeleton
Gives mechanical support to the cell and maintains the shape
Anchors for many organelles and some cytosolic enzyme molecules
Cell motility
why is the cytoskeleton important in animals
they lack cell walls
Components of the cytoskeleton
Microtubules
microfilaments
intermediate filaments
Thickest of the three components
Microtubules
The thinness of the three components
Microfilaments
Diameters in a middle range
intermediate filaments
Microtubules are
Hollow rods are made by a globular protein called tubulin
what is tubulin
a dimer made from both beta and alpha tubulin
functions of microtubules
- shape the cell
- guided movement of organelles
- separating chromosomes during cell division
microtubules grow out from a ______ near the _____
centrosome and nucleus
a centrosome is a
microtubule-organizing centre
centrosome has a pair of _____ each with nine _____ of microtubules in a _____
centrioles, triplets, ring
Flagella motion
has an undulating motion like a tail of a fish
Cilia motion
work more like the oars of a boat - waving back and forth
common structures of cilia and flagella
a core of microtubules sheathed by the plasma membrane
Basal body
motor protein called dynein
basal body
microtubule assembly of a cilium or flagellum is anchored in the cell by this
Bending movement comes from
large proteins called dynein
what controls the beating of cilia and flagella
microtubules
how does dynein work
- the dynein arms alternatively grab, move and release outer microtubules
- protein-cross links limit the amount of sliding
- Two “feet” walk along the microtubule of the adjacent doublet using ATP energy
Microfilaments
solid rods built from twisting double chains of actin
functions of Microfilaments
- helps with motility
- structural role to bear tension (pulling forces)
what is the cortex for microfilaments
the 3D network inside the plasma membrane that helps support the cell’s shape
bundles of microfilaments make up
core of microvilli of intestinal cells
what do microfilaments contain in reference to motility
actin but also myosin
myosin
its a motor protein
how are the actin filaments arranged in muscle cells
parallel to each other
examples of microfilaments and mobility
- pseudopodia
- cytoplasm streaming
pseudopodia
cells crawl along a surface by extending cellular extensions called pseudopodia
Cytoplasmic streaming
in plant cells its the circular flow of cytoplasm within cells
cytoplasmic streaming speeds up what
the distribution of materials within a cell
what is cytoplasmic streaming driven by
actin-myosin interactions and so-gel transformations
Intermediate filaments are composed of
different proteins
what is a more permanent structure of the cytoskeleton
Intermediate filaments
the function of Intermediate filaments
- support cell shape
- fix organelles in place
- specialized for bearing tension
____ and _____ are consistent in diameter and composition in all eukaryotic cells while ______ are not.
Microtubules and microfilaments, intermediate filaments
what do most cells do in regards to the plasma membrane
synthesize and secrete materials outside of the cell
extracellular structures include
- cell walls
- extracellular matrix
- interceulluar junctions
One of the features that distinguish plant cells from animal cells
cell wall
cell wall functions
- Wall protects the plant cell
- Maintains its shape
Prevents excessive uptake of wate
- Maintains its shape
when does a cell strengthen its cell wall
when it is mature and stopped growing
Cell wall design
Microfibrils made of cellulose are synthesized by an enzyme and secreted to the extracellular space
sections of the cell wall
- primary cell wall
- middle lamella
- secondary cell wall
Primary cell wall
Young plant cell’s first secretes a relatively thin and flexible wall
where does the cellulose become embedded in the cell wall
polysaccharides and proteins
Middle Lamella
Middle lamella glues adjacent cells together
Secondary cell wall
- Used to strengthen the cell wall
Extracellular Matrix (ECM) of Animal Cells made from
glycoproteins and other carbohydrate-containing molecules
purpose of the ECM
- support
- adhesion
- movement
- regulation
what kinds of glycoproteins are ECM made from
- collagen
- proteoglycan
3, fibronectin
what are integrins
cell surface receptors used by fibronectin to bind
Most abundant glycoprotein in ECM
collagen
how can the ECM regulate a cell’s behaviour
the communication through integrins
the ECM can influence the activity of ____-in the nucleus
genes
______ signals may occur through the cytoskeletal changes and trigger _____ signal in the cell
mechanical and chemical
what are cell junctions
- Neighbouring cells often interact and communicate by sites of direct physical contact
plasmodesmata in plant cells
Channels that connect cells
what can pass through plasmodesmata in plant cells
water
small solutes
junctions in animal cells
- tight junction
- desmosomes
- gap junctions
what connections unify most of the plants into one continuum
the plasmodesmata in plant cells
tight junctions
Plasma membranes of neighbouring cells are very tightly pressed against each other
tight junctions form what
continuous seals around the cell
what prevents leakage of extracellular fluid across a layer of epithelial cells
tight junctions
Desmosomes
Fastening cells together into strong sheets
Gap junctions
Cytoplasmic channels from one cell to an adjacent cell
Necessary for communications between cells in many types of tissues
gap junctions
what is the anchoring junction
desmosomes
what is the communication junction
gap junction
what animal structure is similar to plasmodesmata in plants
gap junction
cells rely on the ______ of structure and organelles to _____
integration and function
Eggs are larger than any other cell in the human body by
about 100 mm
