Cell Biology 1 Flashcards
Name 3 types of microscopy and give examples
Optical microscopy:
Conventional microscopy, Fluorescence microscopy, confocal/multiphoton microscopy and stimulated emission depletion microscopy
Scanning probe microscopy:
Scanning Tunneling Microscope (STM), Atomic Force Microscopy, Near-field scanning optical microscopy and more
2. Electron microscopy
Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), focus ion beam microscopy (FIB)
What is the definition of magnification and resolution?
Magnification- the increase in the apparent size of an object
Resolution- the measure of the clarity of an image. In other words, it is the ability of an instrument to show two objects as separate
Steps of optical microscopy
- Light passed through specimen- focused by glass lenses
- Image formed on human retina
- Max magnification about 1000 x
- Resolves objects separated by 0.2 micrometer, 500 x better than human eye
Describe the details of a Transmission Electron Microscope
Electrons are passed through the specimen
Focused by magnetic lenses
Image formed on fluorescent screen- similar to TV screen- image is then photographed
Resolves objects separated by 0.00002 micrometers, 100,000x better than human eye
Describe the details of confocal microscopy
- Narrow laser beam scanned across transparent specimen
- Beam is focused at a very thin plane
- Allows microscopist to optically section a specimen
- Sections made at different levels
- Allows assembly of 3D image on the computer screen that can be rotated
What is the average range in cell size?
1mm - 1 micrometer
Why do cells need a large surface area of plasma membrane?
To adequately exchange materials
The SA to volume ratio requires that cells be small
Large cells- SA to volume ratio requires that cells be small
Large cells- SA to volume decreases
Volume is living cytoplasm- demands nutrients and produces wastes
Cells specialized in absorption utilize membrane modifications eg. microvilli to gently increase SA per unit volume
Describe a prokaryotic cell
Lack a membrane-bound nucleus
Structurally smaller and simpler than eukaryotic cells
Placed in 2 taxonomic domains (bacteria, archae)
Domains are structurally similar but biochemically different
Archae- live in extreme habitats
What is the average size of bacteria?
Extremely small- 1 - 1.5 micrometers wide and 2 - 6 micrometers long
What are the 3 basic shapes?
Spherical coccus, rod-shaped bacillus, spiral spirillum (if rigid) and spirochete (if flexible)
What does the cell envelope include?
Plasma membrane
mesosomes
cell wall
Glycocalyx
Capsule
Flagella
Ribosomes
Nucleoid
What do eukaryotic cells (domain eukarya) include?
Protists
Fungi
Plants
Animals
Cells contain membrane-bound nucleus that houses DNA, specialized organelles, plasma membrane & much larger than prokaryotic cells
What is the cell membrane structure and function like?
Phospholipid bilayer with proteins that function as channels, markers & receptors
Contains cholesterol- gives rigidity
Cell membrane function- selectively permeable boundary between the cell and the external environment
What is the nucleus structure and function?
Is a sphere that contains another sphere (nucleolus)
function- storage center of cell’s DNA & manages cell functions
What is the cell wall’s structure and function?
A rigid wall made up of cellulose, proteins & carbohydrates
Function- boundary around the plant cell membrane that provides structure and support
What is the cytoplasm’s structure and function?
Gelatin-like fluid that lies inside the cell membrane
Function- contains salts, minerals and organic molecules, surrounds the organelles- NOT CYTOSOL
What is the cytoskeleton’s structure and function?
A network of thin, fibrous elements made up of microtubules (hollow tubes) and microfilaments (threads made out of actin)
Function- acts as a support system for organelles and maintains cell shape
What are the ribosomes structure and function?
Consists of 2 subunits made of protein and RNA
Function- location of protein synthesis
What is the endoplasmic reticulum’s structure and function?
A system of membraneous tubules and sacs
Function- intercellular highway- a path along which molecules move from one part of the cell to another
Two types- rER & sER
rER structure and function
Prominent in cells that make large amounts of proteins to be exported from the cell or inserted into the cell membrane. Covered with ribosomes.
sER structure and function
Involved in the synthesis of lipids & breakdown of toxic substances- not covered with ribosomes
Golgi apparatus structure and function
stacked flat sacs
Function- receives proteins from the rER & distributes them to other organelles or out of the cell (receiving, processing, packaging and shipping)
Mitochondria structure and function
It is a folded membrane within an outer membrane, the folds of the inner membrane are called cristae.
Function- converts energy stored in food into usable energy for work as well as cellular respiration
C6H12O6 + O2 —> CO2 + H2O + ATP
Lysosomes structure and function
Structure- spherical organelles that contain hydrolytic enzymes within single membranes
Function- breaks down food particles, invading objects , or worn-out cell parts
Peroxisomes structure and function
Structure- Spherical organelles that contain enzymes within single membranes
Function- degrade hydrogen peroxide, a toxic compound that can be produced during metabolism
2H2O —> catalase 2H2O + O2
Cilia and flagella structure and function
Structure- hair-like organelles that extend from the surface of cells
- Present in large numbers- cilia
- Less numerous & longer- flagella
- Both organelles are composed of 9 pairs of microtubules arranged around a central pair
Function- cell motility
Centrioles structure and function
Structure- composed of nine sets of triplet microtubules arranged in a ring
Exist in pairs
Function- play a major role in cell division (mitosis)
Three types of plastids
- Chloroplast
- Chromoplasts: synthesize and store pigments
- Leucoplasts: store food such as starches, proteins & lipids
Chloroplasts structure and function
Structure- stacked sacs (thylakoids) that contain chlorophyll surrounded by a double membrane.
Function- photosynthesis (conversion of light energy to chemical energy stored in the bonds of glucose) CO2 + H2O —> light C6H12O6 + O2
Animal cells don’t have chloroplasts, are not surrounded by cell walls, the vacuoles in plants are much larger
Cell cycle definition
Cell cycle- the series of events that cells go through as they grow and divide
Interphase- the period of growth that occurs between the cell divisions- 95%
What is the prokaryotic cell cycle include?
Growth, DNA replication, cell division begins to replicate, copy, their DNA once they have grown to a certain size.
Once DNA replication is complete, cells divide- binary fission
Asexual reproduction- 2 genetically identical cells are produced eg. bacteria reproduces by binary fission
How many stages are in the cell cycle and what are they?
Consists of 4 phases- G1, S, G2 and M
Stages of the cell cycle
Interphase- time between divisions
Period of growth- G1, S and G2 phases
M phase is the period of cell division M phase: cell division
How many stages are there in eukaryotic cell division and what are they?
2 stages and they are mitosis and cytokinesis
Mitosis definition and cytokinesis definition
Mitosis- division of the cell nucleus
Cytokinesis- division of the cytoplasm
What is cell differentiation?
When the cells become specialized it changes the cell in its shape, size & energy requirements
It is not linear and it is an irreversible process
There are 3 categories- germ cells, somatic cells, & stem cells
What are stem cells?
Stem cells are undifferentiated or partially differentiated cells.
Earliest type of cell in a cell lineage
Properties- self-renewal and potency
Stem cells classification- embryonic and adult stem cells
What is cell potency?
The ability to differentiate into other cell types. The more number of cells a cell can differentiate, the more cell potency there will be
What is meant by totipotent?
The ability to differentiate into all possible cell types (organism)
What is meant by pluripotent?
The ability to differentiate into almost all cell types (not whole organism)
What is meant by multipotent?
The ability to differentiate into a closely related family of cells
What is meant by oligopotent?
The ability to differentiate into a few cells
What is meant by unipotent?
The ability to only produce cells of their own type, but have the property of self-renewal required to be labelled a stem cell
What are viruses like?
They are made up of nucleic acid and a protein coat
Virus structure
Nucleic acid (DNA or RNA)
Protein coat (capsid) surrounds the nucleic acid
In some cases the membrane like structure envelope surrounds the capsid.
There are projections on the envelope (glycoproteins) for attachment to host
What do viruses cause?
They cause different diseases like HIV, common cold, SARS-COV-2
The economic impact- COVID-19
What are the types of viruses?
Helical viruses, polyhedral viruses, spherical viruses, complex viruses
How does a virus infect a host cell?
- Virus becomes attached to a cell
- The cell engulfs the virus
- Viral genetic materials are released in the cell, and begin replication using cellular mechanisms
- The cell replicates viral proteins, which begin forming new viral particles
- New viral particles are released from the cell while the cell continues to replicate the virus within
