Cellular Biology 1 Flashcards
What is the cell theory
A set of principles developed over time via multiple investigations. The discovery of the cell was made through the invention of the microscope between 1665-1838.
Cell Theory
There are 3 major parts of the cell theory:
All organisms are made of cells.
All existing cells are produced by other living cells.
The cell is the most basic unit of life.
Limiting factor of cell
Cell size is limited.
As cell size increases, it takes longer for materials to diffuse from the cell membrane to the interior of the cell
Surface area-to-volume ratio:
as a cell increases in size, the volume increases 10x faster than the surface area
Microscopes
Microscopes are required to visualize cells.
Light microscopes can resolve structures that are 200nm apart. (What is a nanometer?)
10,000,000 nm = 1 cm
Electron microscopes can resolve structures that are 0.2nm apart.
Contributors to the cell theory
Robert Hooke
Anton van Leeuwenhoek
Matthias Schleiden
Theodor Schwann
Rudolf Virchow
Robert Hooke
First scientist to use a microscope to see cellular structure. Came up with “cell” term from looking at cork.
- English Scientist
- Used the compound microscope to observe cork
- Hooke observed that cork is composed of small, hollow compartments
- The parts prompted Hooke to think of small rooms (cells) in a monastery, so he gave them the same names :CELLS
- Investigated cork through experimenting with the compound microscope and came up with the name cells
Anton van Leeuwenhoek
Helped create more power lens (270x) and discovered other living cells such as bacteria and protozoa
- Dutch Tradesmen
- Study new approaches for creating lenses to observe cloth
- Leeuwenhoek’s microscope was more powerful than Hooke’s compound microscope
- From investigating and experimenting with his microscope, Leeuwenhoek became one of the first scientists to refer to living cells when he observed an abundant number of single-celled organisms, which he called animalcules (plant & animals), swimming in a drop of pond water
Matthias schleiden
- German Scientist
- Fascinated with plant cells, Schleiden used the compound microscope and studied plant cells.
- From investigating and experimenting with plants, projected plant parts are made of cells!
- Discussed what he observed with his dear friend, German scientist Theodor Schwann.
Theodor Schwann
- German Scientist
- Studied plant & animal cells, and was intrigued by the similarities between the two.
- From investigating and experimenting with plant & animal cells, Schwann was able to determine that all animals are made of cells!
- Schwann published the 1st statement of the cell theory: all living things are made of cells and cell products!
Rudolf Virchow
Based on his investigations and experiments, he stated that all cells come from preexisting cells, which is the 2nd part of the cell theory: all existing cells are produced by other living cells!
Robert Hooke was the first person to see cells.
T
Bacteria cells have a cell membrane.
T
The Cell Theory was developed by a single scientist.
F
Plant cells have cytoplasm.
T
Cells taken from fungi do not have DNA.
F
Cells can only come from pre-existing cells.
T
It only took five years to develop the Cell Theory.
F
What is a prokaryotic cell?
Same bacteria have a tail-like structure called a flagella, that helps it to move
A capsule surrounds tome bacteria and helps them avoid the body’s immune system
Simple cells
Bacteria
These cells do not have a nucleus, their DNA is circular and floats in the cytoplasm
Pro = before; karyon = nucleus
Relatively small 5 - 10 um
Lack membrane-bound organelles
Earliest cell type
Characteristics of a Prokaryotic cell
No membrane bound organelles
DNA not enclosed in membrane bound nucleus
–> DNA is localized in a nucleoid region
Genome is one circular chromosomes
DNA is not associated with histones
Cell wall made of peptidoglycan
Divide by binary fission
Generally: Smaller & less complex than eukaryotic cells
What are archaeas?
Prokaryotes
Relatively small 5 - 10 um
lack membrane-bound organelles
Usually live in extreme environments (thermophiles, halophiles)
What is an eukaryotic cell?
Cells found in plants, animals, protists, and fungi.
The cell is composed of 4 main parts:
1. Cell membrane
2. Cytoplasm
3. Nucleus - “control center” of cell, DNA
4. Organelles - small structures that carry out specific functions (“little organs”)
Characteristics of an eukaryotic cell
Eukaryotic cells have a nucleus
Have many membrane-bound organelles (mitochondria, vacuole, endoplasmic reticulum, ribosomes, lysosomes, plastids in plants)
DNA contained in “linear chromosomes”
Cytoplasm present
Outer boundary is cell membrane except in plant cells - well made of cellulose
Cell membrane inside wall (plants)
Some have flagella/cilia for movement
Larger, more complex
Examples: protozoans, algae, fungi, plants, animals
the comparison traits between bacteria, archaea and eukaryotes (1)
Bacteria
Cell type: Prokaryotic
Cell Wall: Made of peptidoglycan
Sensitivity to antibiotics :Yes
First amino acid during protein synthesis: Formylmethionine
DNA: Mostly circular chromosome and plasmids
Histones: No
Organelles: No
Ribosomes: 70S
the comparison traits between bacteria, archaea and eukaryotes (2)
Archea
Cell type: Prokaryotic
Cell Wall: Does not contain peptidoglycan
Sensitivity to antibiotics : No
First amino acid during protein synthesis: Methionine
DNA: Circular chromosome and plasmids
Histones: Yes
Organelles: No
Ribosomes: 70S
the comparison traits between bacteria, archaea and eukaryotes (3)
Eukaryotic
Cell type: Eukaryotic
Cell Wall: In plants and fungi, composed of polysaccharides
Sensitivity to antibiotics : No
First amino acid during protein synthesis: Methionine
DNA: Linear chromosome, rarely plasmids
Histones: Yes
Organelles: Yes
Ribosomes: 80S
All cells have a nucleus.
F
All cells have a cell membrane.
T
Eukaryote cells are the only cells to have a flagellum.
F
The nucleus contains the cell’s DNA.
T
Chromatin will become chromosomes.
T
The nucleolus makes the cell’s DNA.
F
What is the difference between prokaryotic and eukaryotic (1)
Small cells 5ym
Always unicellular
No nucleus or any membrane-bound organelles, such as mitochondria
DNA is circular, without proteins
Ribosomes are small (70s)
No cytoskeleton
Motility by rigid rotating flagnellum. Made of flagellin
Cell division by binary fission
Reproduction is always asexual
High variety of metabolic pathways
What is the difference between prokaryotic and eukaryotic (2)
Larger cells 10ym
Often multicellular
always have nucleus and other membrane bund organelles
DNA is linear and associated with proteins to form chromatin
Ribosomes are large (80s)
Always has a cytoskeleton
Motility by flexible waving cilia or flagellae. Made of tubulin
Cell division by mitosis or meiosis
Reproduction is asexual or sexual
Common metabolic pathways
Nucleus
Controls every organelle (little organ) in the cytoplasm;
contains the genetic matter necessary for cell reproduction as well as control over activity within in the cell’s cytoplasm;
responsible for the cell’s metabolism, growth, and reproduction.
Has a nuclear membrane & nuclear pores
Contains cell’s DNA in one of 2 forms
chromatin - DNA and proteins, becomes…
chromosomes -during cell division
Nucleolus-which makes the cell’s ribosomes
mitochondria
Involved in cellular metabolism and respiration;
provides the principle source of cellular energy and is the place where complex,
energy-releasing chemical reactions occur continuously;
The mitochondria is sometimes called the “powerhouse” of the cell
Ribosomes
the site of protein synthesis in the cell
composed of ribosomal RNA and proteins
found within the cytosol of the cytoplasm and attached to internal membranes
Make enzymes and other proteins; nicknamed “protein factories”.
Endomembrane system
-a series of membranes throughout the cytoplasm
-divides cell into compartments where different cellular functions occur
1. endoplasmic reticulum 2. Golgi apparatus 3. lysosomes
endoplasmic reticulum (1)
Smooth endoplasmic reticulum (SER)
functions:
synthesis of membrane lipids
calcium storage
detoxification of foreign substances
endoplasmic reticulum (2)
Rough endoplasmic reticulum (RER) :
membranes that create network of channels throughout the cytoplasm
Attachment of ribosomes to the membrane gives a rough appearance
involved in the synthesis of proteins, which will be secreted and sent to lysosomes or plasma membrane
Golgi Apparatus (body)
chemically processes the molecules from the endoplasmic reticulum and then packages them into vesicles; nicknamed “chemical processing and packaging center”.
synthesis of cell wall components
AKA post office.
Lysosome
membrane bound vesicles containing digestive enzymes to break down macromolecules
destroy cells or foreign matter that the cell has engulfed by phagocytosis
Aka ”digestive bags”
Cytoskeleton
- Helps cell maintain support & shape; movement
- Network of protein fibers found in all eukaryotic cells
- Keeps organelles in fixed locations
- Helps move materials within the cell
microtubules- hollow tubes
microfilaments-threadlike
centrioles- only in animal cells; used during cell division(paired)/cell reproduction
Cytoskeleton fibers
-actin filaments – responsible for cellular contractions, crawling, “pinching”
-microtubules – provide organization to the cell and move materials within the cell
-intermediate filaments – provide structural stability
Cell Movement
Cell movement takes different forms.
- Crawling is accomplished via actin filaments and the protein myosin.
- Flagella undulate to move a cell.
- Cilia can be arranged in rows on the surface of a eukaryotic cell to propel a cell forward.
Flagella and Cilia
Support movement (externally)
“Tail” of the sperm that enables for the sperm to “swim” or move toward the ovum.
Hair-like processes that project from epithelial cells; help propel mucus, dust particles, and other foreign substances from the respiratory tract.
Vacuole
storage area for water and other substaces, plant cells usually have a large central vacuole
There are different types of vacuoles:
- central vacuole in plant cells
- contractile vacuole of some protists
- vacuoles for storage
