Cell Structure A2.2 Flashcards
What are the three parts to the cell theory?
- all living things are made out of cells
- cells are the smallest units of life
- cells come only from other cells
What does cell membranes do?
separates inside of a cell from the outside
What does genetic material do?
in the form f DNA is the hereditary set of information which hold instructions for all building blocks
What does cytoplasm do?
allows the dissolution of substances in the cell, needed for chemical reactions, transport of materials
What is an eye piece graticule?
a transparent scale embedded within the lens of microscopes, the scale is dimensionless
What calibrates an eyepiece graticule?
a scale with precisely know units; a stage micrometer
What is the formula to find the magnification of the image (ex. 400x)?
Magnification = image size (measured) / actual size
What is resolution?
the ability to distinguish between two objects very close together.
the higher the resolution the greater detail can be seen
What is resolution limited by?
the energy source used to view the sample.
What determines the ability to see an object under the microscope?
the wavelength of the light measured in nm.
- objects smaller than the wavelength of radiation used do not interrupt the waves, and therefore are not detected
Light microscopes, wavelength, magnification?
400-700nm, 1000-5000x
Transmission electron microscope characteristics, size, magnification
can not produce colored images because sample is dyed with heavy metal ions
visualization of structures up to 2nm.
1,000,000x
Scanning electron microscope characteristics, size, magnification
electrons are reflected off of the surface of the specimen and are stained with harsh chemicals. sample is dead of killed in process.
3D appearance images (imagining software)
2nm
1,000,000x
What is methylene blue?
a positively charged dye which binds to negatively charged structures such as DNA RNA.
- used to visualize genetic material or nucleus of cells
What is fluorescent dye?
dyes that target specific molecules and are able to absorb light at one wavelength while emitting at longer wavelength
What is immonofluorescence?
uses cells of the immune system (anti-bodies) that have a fluorescent marker.
- images produces upon binding with a target
What is metal staining?
use of metals to stain a sample under a TEM or SEM
- denser/protein containing structures appear darker
What is cryogenic electron microscopy?
a preparation technique that is used for researching the structure of proteins
What does Cryo-EM do?
analyzes proteins at the instant in time when they freeze, unmoving.
patterns if many diff oriented proteins are produced which then are used to form a 3D shape
What is freeze-fracture electron microscopy?
a preparation technique where cells are frozen inside of liquidated propane, fracturing allows cell to be broke along lines of weakness, the cell membrane
What does freeze-fracture EM do?
gives insight into the surface of cells
What are prokaryotes and their characteristics?
the first organisms to evolve on Earth.
- simple cell structure very small (0.5-6 micrometers)
- lack a nucleus
- cell wall + membrane
- smaller protein producing ribosomes (70S)
What are eukaryotes and their characteristics?
a cell or organism that possess a clearly defined nucleus.
- complex cell structures
- compartmentalization
- many organelles
- bigger protein (80S)
Animal cell characteristics?
- boxy spherical shape
- centrioles
- cilia or flagella
- DONT have large vacuole
- DONT have chloroplasts
Plant cell characteristics?
- retangular
- cell wall
- chloroplasts
- large vacuole
- DONT have cilia or flagella
- DONT have centrioles
Fungus cell characteristics?
- spherical
- cell wall
- large vacuole
- DONT have chloroplasts
- DONT have centrioles
- DONT have cilia or flagella
What are the characteristics of the nucleus & nucleolus?
- spherical
- double membrane
- pores in membrane
- chromatin stained dark
- nucleolus contains RNA & proteins, 25% of nucleus
What are the functions of nucleus & nucleolus?
- stores genetic info in form of chromosomes
- nucleolus produces rRNA
What are the characteristics of free ribosomes?
- composed of RNA and protein
- no membrane
- 80S
- composed of 2 subunits
What are the functions of free ribosomes?
- produces proteins to function in the cytoplasm for use
What are the characteristics of mitochondrion?
- double membrane
What are the functions of mitochondrion?
- site of ATP production by aerobic cell respiration
- fat digestion if used as energy source in cell
What are the characteristics of RER?
ribosomes attached
What are the characteristics of SER?
no ribosomes
What are the functions of RER?
production of membrane proteins, pinched off in vesicles to the golgi for further investigation
What are the functions of SER?
produces phospholipids and cellular lipids, sex hormones
- in muscle cells store calcium ions for contraction of muscle fibers
What are the characteristics of chloroplast?
- double membrane
- stacks of thylakoids
What are the functions of chloroplasts?
- productions of glucose and other organic compounds by photosynthesis
What are the characteristics of lysosomes?
- formed from golgi vesicles which bud off
- one membrane
- high concentration of enzymes meaning it will stain heavily
- only in animal cells
What are the functions of lysosomes?
- breakdown of food or damaged substances
What are the characteristics of vacuoles/vesicles?
- one membrane
- plants: large and permanent
- animals: small and temporary
What are the functions of vacuoles/vesicles?
- plant: maintenance of water balance and internal pressure
- animal: transport of substances within cells
What are the characteristics of flagellum/cilia?
- whip-like
- a ring of 9 double microtubules and 2 central ones
- flagella: longer, one
- cilia: shorter, multi
What are the functions of flagellum/cilia?
- flagella: movement, sperm
- cilia: move liquid over surfaces
What are the characteristics of microtubules?
- small cylindrical fibres
- composed of polymer tubulin
What are the functions of microtubules?
- move chromosomes to opposite side of cell during cell division
- help construct cell walls
What are the characteristics of centrioles?
- 2 groups of 9 triple microtubules
- in animal cells
What are the functions of centrioles?
- move toward poles of a cell, serving as an anchor point for microtubules during cell division
What are the characteristics of cytoskeleton?
- constructed from protein fibers like tubulin and actin
What are the functions of cytoskeleton?
- microfilaments help animal cells maintain shape
What are the characteristics of cell wall?
extracellular components, not an organelle
- cellulose
What are the functions of cell wall?
- permeable, no effect on transportation in and out
- strong support for prevention of membrane bursting under pressure
Examples of atypical cell structures in eukaryotes?
- striated muscle cell
- aseptate fungal hypae
- red blood cells
- phloem sieve tube cells
Striated muscle cell
- multi-nucleated
- larger than most animal cells
Aseptate fungal hypae
- multi-nucleated
- continued cell division
Red blood cells
- dont have nucleus
- pinched off during development and digested by the immune system
- makes smaller and flexible
- can not review self and limited life span
Phloem sieve tube cells
- movement of sap through cylindrical tubes need less resistance so walls are perforated with pores and nucleus and large organelles are missing.
- development stage nucleus and organelle break down
What is endosymbiotic theory?
it explains the origin of eukaryotic cells
- smaller unicellular organisms are engulfed and became a part of larger organisms and eventually specialized to become organelles within the cell.
What is the symbiotic relationship in the endosymbiotic theory?
- the smaller prokaryotic cell is supplied with nutrients and food
- larger cell receives energy from the aerobic cell respiration and sugars from photosynthetic bacteria
Where is mitochondria derived from?
purple bacteria or proteobacteria
Where are chloroplasts derived from?
cyanobacteria, capable of photosynthesis
What are evidence for endosymbiotic theory?
mitochondria and chloroplasts have…
- own genes
- double membranes
- are divided by binary fission
- own 70s ribosomes
- produced by division of pre-existing
ALL are typical of prokaryotes
What does cell differentiation result in?
the formation of cells with specialized function.
How and where does cell differentiation happen?
development of specialized cells happen at an embryonal stage, diff genes are switched on resulting in expression of genes only required for a specific function
- triggered by changes in environment
Advantages of evolution of multicellularity
- longer life span, death of one cell does not kill
- organism is larger, helps exploitation of niches
- complexity within organism
Examples of the evolution of multicellularity
- algae
- sponge
Algae as example of the evolution of multicellularity
algae is made up of 1-3k photosynthetic algae that are grouped together into a hollow sphere.
- the transition from single algae cells to this colony took 35 mil years
Sponge as example of the evolution of multicellularity
structural similarities between single celled choanoflagellates and sponge prompted ideas on shared ancestry.
