Chapter 3: Cell Structure and Function Flashcards
define cell
smallest unit of life
define microscope
instrument that magnifies object
define micrograph
image taken with a microscope
define light microscope
produces an image from light passing through the specimen
define dissecting microscope
used to give a magnified 3D view of tissue structures and anatomy
define electron microscope
uses beam of electrons instead of light to magnify images
can you see a cell with the naked eye
no; its too small
what must a specimen be to be seen with a light microscope
thin or translucent
what must you do to most biological specimens like bacterial cells before observing through a light microscope
stain them because they are translucent
how many lenses are used in light microscopes
- two
- objective
- ocular
do light microscopes produced inverted or non inverted images
inverted
what is the magnification range of a light microscope
40 to 1000x
explain how to find total magnification
objective magnification x ocular magnification
how does the magnification of a dissecting microscope compare to that of a light microscope
dissecting microscope has lower magnification
what kind of specimens are observed with a dissecting micrscope
thicker objects
what is the magnification range of a dissecting microscope
20 to 80x
do dissecting microscopes produces inverted or non inverted images
- non inverted
- optics correct orientation
describe a scanning electron microscope
- beam moves back and forth across cell surface
- detailed image of cell surface
describe transmission electron microscope
- beam transmitted through cell
- details of cells internal structure
advantages of electron miscroscopy
- higher magnification
- high resolution
disadvantages of electron miscroscopy
- kills sample
- cannot be used to view living cells
- expensive
cell theory states:
- all living things are composed of one or more cells
- cell is basic unit of life
- all new cells come from pre-existing cells
who began the idea of cell theory and how
- Antony van Leeuwenhoek in 1600s
- observed protists and sperm
- discovered bacteria and protozoa
who coined the term cell and what was he looking at when he did
- Robert Hooke in 1665
- looking at cork
which two scientists proposed a unified cell theory
Matthias Schleiden and Theodor Schwann in the late 1830s
define unicellular
made of one cell
define multicellular
made of many cells
define plasma membrane
- outer covering of a cell
- separates cell interior from environment
define cytoplasm
- inside of cell
- jelly-like cytosol and cellular structures
define ribosomes
organelle responsible for protein synthesis
how many human and bacterial cells is the human body made of
- 30 trillion human cells
- 39 trillion bacterial cells
what 4 things do all cells have
- plasma membrane
- cytoplasm
- DNA
- ribosomes
what are the 3 key differences in prokaryotic cells
- unicellular
- lack nucleus and membrane-bound organelles
- DNA in single large loop with circular chromosome
are prokaryotic or eukaryotic cells bigger
- eukaryotic
- 10 to 100 times larger
which type of cell is more abundant on earth
prokaryotic
which type of cell is more diverse
eukaryotic
define phospholipid bilayer
two layers of phospholipids that are the main component of the plasma membrane
define cytosol
gel-like substance inside of the cell that makes up the cytoplasm
define nuclear envelope
surrounds the nucleus
define cytoskeleton
- network of protein fibers within the cytoplasm
- microfilaments (actin filaments), intermediate filaments, and microtubules
define microfilaments (actin filaments)
- thinnest cytoskeletal fiber
- moves cellular components during cell division
- maintain structure
- responsible for muscle cell contraction
define intermediate filaments
- maintain cell shape
- anchor organelles
define microtubules
- thickest cytoskeletal fiber
- hollow tubes that dissolve and reform quickly
- pull chromosomes apart during cell division
- structure of flagella and cilia
define flagella
- long structures that extend from plasma membrane
- used to move entire cell
- on sperm or bacteria
define cilia
- short projections along surface of the plasma membrane
- move entire cell or substance along outer surface
- moves ovum through fallopian tubes, moves matter through respiratory tract
define endomembrane system
- group of membranes and organelles in eukaryotic cells
- things that work to modify, package, and transport proteins and lipids
define nucleus
- houses cells DNA as chromatin
- directs protein synthesis and ribosome synthesis
define chromatin
DNA and proteins in the nucleus
define nucleolus
darkly stained area within the nucleus
define rough endoplasmic reticulum
- synthesizes phospholipids
- modified proteins
- has ribosomes on the outside
- packages products in vesicles and sends to golgi apparatus
define smooth endoplasmic reticulum
- continuous of RER
- no ribosomes on outside
- synthesizes carbohydrates, lipids, and steroids
- detoxification of medications, alcohol metabolism, calcium storage
define golgi apparatus
- flattened sacs
- sort, tag, package, and distribute lipids and proteins
define lysosomes
- garbage disposal
- usually only in animal cells
- bud off from golgi apparatus
- filled with enzymes
- breakdown proteins, polysaccharides, lipids, nucleic acids, and worn out organelles
- digestion of food and recycling of organelles in single celled eukaryotes
define vesicles
- sac for storage and transport
- smaller than vacuoles
- fuse with other membranes within the cell
define peroxisomes
- small round organelles enclosed by single membranes
- oxidation reactions to breakdown fatty acids and amino acids
define cell wall
- rigid covering outside the plasma membrane
- protects the cell, provides structural support, gives cell shape
- made of peptidoglycan and cellulose
define chloroplast
- function in photosynthesis
- have their own DNA and ribosomes
- inner and outer membranes
define vacuole
- sac for storage and transport
- larger than vesicles
- does not fuse with membranes of other cellular components
what are the components of the plasma membrane
- phospholipid bilayer
- embedded proteins
- carbohydrates (outside of cell)
- cholesterol (animals cells only)
what is the function of carbohydrates on the outside of the plasma membrane
cell communication
what is the function of cholesterol in the plasma membrane of animal cells
temperature buffer so cells don’t rupture
what is the difference between a peripheral membrane protein and an integral membrane protein in the plasma membrane
- peripheral: only on one side of the membrane, usually enzymes or structural attachments
- integral: goes through both sides of the membrane, often serve as channels or pumps
what is the function of the plasma membrane
- separates internal contents of the cell from the environment
- regulates passage of substances
what is cytoplasm made of
- organelles
- cytosol
- cytoskeleton
- various chemicals
- 70-80% water
where do many metabolic reactions take place within a cell
cytoplasm
functions of the cytoskeleton
- structural support
- secures organelles in place
- allows cytoplasm and vesicles to move within the cell
- enables movement of unicellular organisms
what is included in the endomembrane system
- nuclear envelope
- endoplasmic reticulum
- vesicles
- lysosomes
- golgi apparatus
- plasma membrane
where are ribosomes located
- freely in cytoplasm
- attached to plasma membrane
- attached to endoplasmic reticulum
where does protein synthesis finish
endoplasmic reticulum
do vesicles or vacuoles fuse with membranes of other cell components
vesicles
are peroxisomes part of the endomembrane system
no
define mitochondria
- energy center of the cell
- oval shaped
- double membrane bound
- have their own ribosomes and DNA
- make ATP
what are some key differences between animal and plant cells
- plant cells have large central vacuole, cell wall, and chloroplasts
- animal cells have lysosomes and centrioles
describe a plant cells central vacuole
- occupies most of the cell
- regulates cell concentration of water
- provides turgor pressure to keep plant rigid
what is the plasma membrane
- a delicate two layered structure of lipid and proteins
- outer boundary of the cell membrane
2 characteristics of the plasma membrane
- flexible
- selectively permeable
5 functions of the plasma membrane
- defines outer border of cells and some organelles
- provides structure and support; tethers cytoskeleton
- controls what enters and exits the cell
- cellular communication
- cellular interaction
what is the fluid mosaic model of the plasma membrane
- describes the membrane as a fluid structure with mosaic of various proteins
- contains carbohydrates, phospholipids, proteins, and cholesterol (animal cells only)
what is the main fabric of the plasma membrane
phospholipids
phospholipids are amphipathic meaning they have
hydrophilic and hydrophobic regions
are the two layers of phospholipids in the plasma membrane attached
no
what are the two examples of phospholipid movement in the plasma membrane and which happens more often
- lateral movement: side to side; very often
- flip-flop: switching layers; once a month
which portion of a phospholipid is polar and which is nonpolar
- head: polar, hydrophilic
- tail: nonpolar; hydrophobic
what is the second major component of plasma membranes
proteins
what are the functions of proteins in the plasma membrane
- enzymes
- anchor points for cytoskeleton
- cell recognition sites
- transporters
what is the third major component of plasma membranes
carbohydrates
where are carbohydrates located on the plasma membrane
always on the exterior
what are the two types of carbohydrates on plasma membranes
- glycoproteins: bound to proteins
- glycolipids: bound to lipids
what is the purpose of carbohydrates on the plasma membrane
- allow cells to recognize each other
- cellular communication
which component of the cell membrane is only in animal cells
cholesterol
what is the purpose of cholesterol in animal cell plasma membranes
- flexibility
- temperature buffer: increases fluidity at low temperatures and decreases fluidity at high temperatures
define passive transport
- substances easily pass through the plasma membrane
- requires no energy
- includes diffusion, facilitated diffusion, and osmosis
define diffusion
- passive transport
- expends no energy
- substances move from high concentration to low concentration
what type of substances can diffuse through a plasma membrane and why
- nonpolar or small uncharged molecules
- because of the nonpolar center of the phospholipid bilayer
does diffusion work better in colder or warmer temperatures
warmer
what 4 things affect that rate of diffusion
- temperature: high temp=diffuse faster
- concentration gradient: higher gradient=diffuse faster
- size of particles: smaller particles=diffuse faster
- solvent density: less dense=diffuse faster
what density/state of matter of solvent causes the slowest diffusion and which causes the fastest
- solid: slowest
- liquid: medium
- gas: fastest
define facilitated diffusion
- passive transport
- requires no energy
- needed to diffuse ions and large polar molecules
- moves substances down concentration gradient
- uses channel proteins and carrier proteins
define osmosis
- passive transport
- no energy required
- movement of water across membrane
- occurs when the solute can’t cross the membrane
- water moves from lower solute concentration to higher solute concentration
how are osmosis and diffusion different
- osmosis is only with water
- diffusion moves solute from high solute concentration to low concentration while osmosis moves water from low solute concentration to high concentration
define water potential
the tendency of water to move from one place to another
define tonicity
the ability of a solution to cause a cell to gain or lose water
what type of cell does tonicity have the greatest impact on
- cells without cell walls
- animal cells
what are the three tonicity conditions
- isotonic
- hypotonic
- hypertonic
define an isotonic solution
- concentration of solute is the same inside and outside the cell
- no net movement of water; equal flow
define hypotonic solution
- concentration of solute is less outside than inside the cell
- cell will take in water
- causes hemolysis
define hypertonic solution
- concentration of solute in higher outside than inside the cell
- cell will lose water
- causes cell to shrivel up
if you have a hypotonic solution, what is the cell
- hypertonic cell
- less solute outside the cell; more solute inside the cell
if you have a hypertonic solution, what is the cell
- hypotonic cell
- more solute outside the cell; less solute inside the cell
define turgor pressure
pressure exerted by the plasma membrane against the cell wall
what type of solution do plant cells like to be in to maintain turgor pressure
- hypotonic
- less solute outside; cell will take in water
define active transport
- when molecules need to move against the concentration gradient (low to high concentration) or against the electrochemical gradient
- requires energy in the form of ATP or energy from the electrochemical gradient
when is energy used in the form of ATP during active transport
- primary active transport
- bulk transport
when is energy used from the electrochemical gradient during active transport
secondary active transport
explain the sodium potassium pump
- Na+ binds to carrier protein from inside the cell
- phosphate group attaches to carrier protein inside the cell
- Na+ leaves the cell
- K+ attach to carrier protein from outside the cell
- phosphate group attaches to carrier protein inside the cell
- K+ enters the cell
define bulk transport
when cells need to import or export molecules/particles that are too large to pass through a transport protein
what are the two types of bulk active transport
- endocytosis
- exocytosis
what type of bulk transport is used for importing/taking in molecules
endocytosis
what type of bulk transport is used for exporting/releasing molecules into the extracellular environment
exocytosis
what are the 3 types of endocytosis
- phagocytosis
- pinocytosis
- receptor-mediated endocytosis
define phagocytosis
- type of endocytosis
- cell eating
define pinocytosis
- type of endocytosis
- cell drinking
define receptor-mediated endocytosis
- type of endocytosis
- targeted
- receptors bind to certain molecule and bring it in
SS: animal cell biol 107
1: cilia
2: mitochondria
3: cytoplasm
4: ribosome
5: rough endoplasmic reticulum
6: nucleolus
7: nucleus
8: golgi apparatus
9: cell membrane
10: cytoskeleton
11: lysosome
12: smooth endoplasmic reticulum
13: secretory vesicle
14: peroxisome
15: centrioles
16: flagella
SS: plant cell biol 107
1: golgi vesicles
2: ribosome
3: smooth endoplasmic reticulum
4: nucleus
5: nucleolus
6: rough endoplasmic reticulum
7: plasmodesmata
8: cytoskeleton
9: cell wall
10: peroxisome
11: golgi apparatus
12: central vacuole
13: chloroplast
14: cytoplasm
15: mitochondria
16: cell membrane
