Cell Theory Flashcards
What is the first part of the cell theory
The cell is the basic unit of life
What is the second part of the cell theory
All living things are composed of cells
What is the third part of the cell theory
Cells come from preexisting cells
Example of the first part of the cell theory that states that the cell is the basic unit of life
A cell is alive, but the subcellular components are not alive
Subcellular components have never been seen to perform the functions of life whereas full cells have
What evidence is there to support the part of the cell theory that says that all living things are composed of cells
Viruses are not living and are not made of cells
Bacteria, fungus, animals, and plants are living
From the 17th century on, biologists examined tissues from both plants and animals ( later from fungi, bacteria and protists) and saw that every specimen contained at least one or more cells.
What evidence is there to support the part of the cell theory that states that cells come from preexisting cells
Cells can only be formed by division of pre-existing cells. Except at the original origin of life, cells do not spontaneously generate
We have observed cells coming from other cells, but never observed spontaneous generation
How does the word theory differ in common language vs. scientific language.
In daily use: a theory is a guess, there is doubt.
In scientific use: a theory has been shown to be true through repeated observations and experiments. There is no current doubt. As of yet, no evidence has been collected that does not support the idea
Professional definition of the scientific theory
A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not “guesses” but reliable accounts of the real world
First functional characteristic of life
M
Metabolism
In a paramecium and chlamydomonas:
Most metabolic reactions are catalysed by enzymes and take place in the cytoplasm.
Second functional characteristic of life
G
Growth
Paramecium: as it consumes food, the paramecium enlarges. Once it reaches a certain size it will divide into two daughter cells
Chlamydomonas: production of organic molecules during photosynthesis and absorption of minerals causes the organism to increase in size. Once it reaches a certain size it will divide into two daughter cells
Third functional characteristic of life.
R
Response
Paramecium: the wave action of the beating cilia helps to propel paramecium in response to changes in the environment, ex. Towards warmer water and away from cool temperatures
Chlamydomonas: chlamydomonas senses light changes in its environment using its eye spot and then uses its flagella to move towards a brighter region to increase the rate of photosynthesis
Fourth functional characteristic of life
H
Homeostasis
Paramecium and chlamydomonas: it’s constant internal environment is maintained by collecting excess water in the contractile vacuoles and then expelling it through the plasma membrane. This process is called osmoregulation and helps paramecium and chlamydomonas to maintain their water balance
Fifth functional characteristic of life
N
Nutrition
Paramecium: paramecium is a heterotroph. It engulfs food particles in vacuoles where digestion takes place. The soluble products are then absorbed into the cytoplasm of the cell. It feeds on microorganisms such as bacteria, algae, and yeasts
Chlamydomonas: chlamydomonas is an autotroph; it uses its large chloroplast to carry out photosynthesis to produce its own food
Sixth functional characteristic of life
R
Reproduction
Paramecium: it can carry out both sexual and asexual reproduction, though the latter is more common. The cell divides into two daughter cells in process called binary fission ( asexual reproduction)
Chlamydomonas: it can carry out both sexual and asexual reproduction. When chlamydomonas reaches a certain size, each cell reproduces, either by binary fission or sexual reproduction
Seventh functional characteristic of life
E
Excretion
Paramecium: digested nutrients from the food vacuoles pass into the cytoplasm, and the vacuoles shrinks when the vacuole, with its fully digested contents, reaches the paramecium’s anal lore, it ruptures, expelling it’s waste contents to the environment
Chlamydomonas: it uses the whole surface of its plasma membrane to excrete it’s waste products
