Cells Flashcards
Why is the development of microscopes important for the discovery of cells and the study of biological specimens?
It allows us to see things. Humans don’t believe things until they see it.
Gives us a view of what’s going on (oh, this cell has all these organelles in it, etc)
Which type of light microscope is typically used?
bright field
Fluorescent microscopes allow you to…
label proteins and structures in a cell with a fluorescent tag.
The laser then activates the tag
Confocal microscopes allow you to…
get a 3D image by taking cross sections of the object.
What is the main drawback of electron microscopes?
You cannot examine live specimens, as you have to freeze them.
What is the difference between bacteria and archaea?
There is a huge difference in the membrane, suggesting they split up really early
Bacteria as peptidoglycan cell wall, archaea has none
Sperms and eggs are not unicellular organism because…
They’re missing half their DNA. They are alive, but they cannot reproduce, so are not considered organisms
Give a brief time line on microscope inventions
1000 - Reading Stone made from quartz
1284 - Salvino D’Aramate invented wearable eyeglasses
1590 - Zaccharalas and Hans Jannesen made first compound microscope and telescope
1665 - Robert Hooke examined the first cells in cork tissue
1674 - Antonie van Leeuwenhoek build single lens microscope with 270X magnification
1800s - Innovations reduced chromatic aberration of lenses
1870’s & 1880s - Car Zeiss and others improved lens quality, viewing, and calculation of max resolution. They could still only study objects the size of a wavelength of light
1903 - Richard Zsigmondy developed the ultramicroscope that could study objects below the wavelength of light
1932 - Fritze Zernike invented the phase-contrast microscope that enabled study of colorless and transparent biological specimens
1928 - Ernst Ruska co-invented the electron microscope that uses electrons to greatly improve resolution
1981 - Cerd Binnig and Heinrich Rohrer invented scanning tunneling microscope that gives 3D images of objects down to atomic levels
What are 2 types of electron microscopes?
Transmission electron microscope (TEM) - Electrons pass through very thing sections of specimens
scanning electron microscope (SEM) - Scans the surface of a specimen with a focused beam of electrons
During the mid 1600’s, who discovered the first plant cells and what did he call them?
Robert Hooke looked at plant cork tissue and called them cellulae
During the mid 1600’s, who discovered the first animal cells and what did he call them?
Antonie van Leeuwenhoek observed sperm, protists, and bacteria and called them animalcules
During the early 1800s, who were 3 scientists that advanced cell theory?
Robert Brown: Detected nuclei within plant cells
Mathias Jakob Schleiden: Suggested entire plant body is made up of cells and nucleus is involved in development
Theodore Schwann: Suggested animals have cells, all cells contain a nucleus, and cells are the individual units of life
During the mid 1800s, who were 2 scientists that advanced cell theory?
Rudolf Virchow and Robert Remak: Proposed that the entire animal body is made up of cells and that existing cells originate from pre-existing cells through division
What are the 3 laws in Cell Theory?
- All organisms are composed of one or more cells
- The cells is the basic structural and functional unit of all living organisms
- Cells only arise from the divisions of pre-existing cells
Cells are either prokaryotes or eukaryotes. Describe them.
Prokaryotes: Smaller, simpler, no organelles usually. APPEARED 3.5 BILLION YEARS AGO
Eukaryotes: More complex, have internal membrane-enclosed organelles with specific functions. APPEARED 2.1 BILLION YEARS AGO
What parts to bacteria still have?
Cell wall, plasma membrane, pili, nucleoid, ribosomes, flagellum
________ are diverse and includes groups living in the most extreme environments on earth
Archaea
Most archaea are obligate _________
anaerobes
Archaeans have been found to inhabit the human ____, but does not cause disease
gut
Review some organelles in eukaryotic animal cells
Lysosome - Garbage collector Ribosome - Protein creator Nucleus - Contains DNA ER - Transport and modification of proteins etc
What are 3 organelles in animal cells but not plant cells?
- Lysosomes
- Centrioles
- Flagella
What are 4 organelles in plant cells but not animal cells?
- Chloroplasts
- Central vacuole and tonoplast
- Cell wall
- Plasmodesmata (cell-cell communication)
Around how many cells are in the human body? How many unique cells are in the body?
37 trillion total, 200+ unique
How to bacteria/archaea, protists, algae, and fungus relate to unicellular-icity?
- Bacteria/Archaea are unicellular without a true nucleus
- Protists are eukaryotic and unicellular. They are diverse group of organisms that are not animals or plants or fungus
- Some algae are unicellular with chlorophyll
- Some fungi are unicellular. Most are multicellular though
That parasites that case Malaria are unicellular ______ in the genus plasmodia
protists
While most protists are single-celled, the ______ _____ is an exception
giant kelp.
_____ cells are usually the smallest cells in a multicellular organism. The exception to this is the fruit fly
sperm
_____ cells are usually the largest cells in a multicellular organism. The largest of these comes from the Ostrich.
egg
The smallest unicellular organism is the ________.
Mycoplasma
Review Size of bacteria and viruses
Generally:
Eukaryotes (~10 microns) > Bacteria (0.3 to 5 microns) > Viruses (~0.1 microns)
What are 2 of the largest unicellular organisms in the world?
Valonia Ventricose
Caulerpa Taxifolia
Describe the Endosymbiosis Theory of Eukaryotic Cells evolution
- Membrane-bound organelles evolved from infolding of plasma membrane, like the nucleus and endoplasmic reticulum
- Eukaryotes formed when an archaea merged with an aerobic bacteria. This bacteria then evolved into mitochondria. This is the 1st endosymbiotic event
- In the 2nd endosymbiotic event, and eukaryote engulfed a photosynthetic bacteria, giving rise to chloroplasts
