A2.1 Origin of cells Flashcards
What is cell theory?
All living organisms are made of cells, and all cells come from pre-existing cells
The first cells could not have come from pre-existing cells, so where did the first cells come from?
Non-living material
What did Louis Pasteur’s experiment prove?
It proved that cells only arise from pre-existing cells. No spontaneous generation.
How did Louis Pasteur’s experiment work?
He put sterilized bone broth in swan neck flasks. He left one flask sealed, and one unsealed.
What happened to the flask that was left sealed?
No microbial growth occurred
What happened to the flask that was left unsealed?
Microbial growth occurred
What are the four steps that led to the formation of the first cells?
- Production of simple organic molecules from non living materials
- Assembly of organic molecules into polymers
- Formation of a membrane
- Development of self-replicating molecules
What are some examples of simple organic molecules?
Amino acids, sugars
In the process of cell creation, the organic molecules (amino acids and sugars) assemble into polymers. What are some examples of these polymers?
Proteins, nucleic acids
In cell creation, when the membrane forms, the lipids form into bilayers, what does this result in?
Cell-like structures (protocells)
In cell creation, what is an example of a self replicating molecule?
RNA
What can RNA do?
Store information and catalyze reactions
What is the mnemonic for the steps of cell creation?
Peter saw orange monkeys nap lazily midday. All orange monkeys ponder fuzzy mangoes, devouring sweet ripe melons.
What is the symbiotic theory?
Eukaryotic cells evolved from prokaryotic cells through engulfing.
What is the definition of a eukaryotic cell?
A larger, more complex cell with a nucleus and membrane-bound organelles.
What is the definition of a prokaryotic cell?
A small, simple cell without a nucleus or membrane-bound organelles.
What are examples of eukaryotic cells?
Animal and plant cells.
What is an example of a prokaryotic cell?
Bacteria
Does a eukaryotic cell have a nucleus?
Yes, there is a nucleus that contains DNA.
Does a prokaryotic cell have a nucleus?
No, there is no nucleus or complex organelles.
Which has larger ribosomes, a prokaryote or a eukaryote cell?
Eukaryotic cells have 80S ribosomes and prokaryotic cells have 70s ribosomes.
How do eukaryotic cells reproduce?
Meosis or mitosis.
What is meiosis?
A single cell divides twice to produce four cells containing half the original amount of genetic information.
What is mitosis?
When a cell replicates its chromosomes and then segregates them, producing two identical nuclei.
How do prokaryotic cells reproduce?
Binary fission
What is binary fission?
Simple cell division
Do eukaryotic cells have a cell wall?
Only plant cells have a cell wall.
In eukaryotic plant cells, what is the cell wall made of?
Cellulose
Do prokaryotic cells have a cell wall?
Bacteria has a cell wall.
In prokaryotic bacteria cells, what is the cell wall made of?
Peptidoglycan
What is the purpose of mitosis?
Growth & repair
What is the purpose of meosis?
Sexual reproduction
What cells are produced in mitosis?
2 identical cells
What cells are produced in meiosis?
4 unique cells
How does the number of chromosomes change in mitosis?
It stays the same
How does the number of chromosomes change in meosis?
The number of chromosomes is halved.
What is an example where mitosis is used?
Skin healing after a cut
What is an example of where meosis is used?
Sperm & egg production
In endosymbiotic theory a larger prokaryote engulfs a smaller prokaryote. What happens next?
The smaller prokaryote lives inside and develops an organelle.
Where does mitochondria come from?
Aerobic bacteria
What does the mitochondria do?
Allows cells to use oxygen for energy
Where do chloroplasts come from?
Photosynthesis bacteria
What do chloroplasts do?
Enable photosynthesis in plant cells.
What is the evidence for endosymbiotic theory?
Mitochondria and chloroplasts have many similarities with bacteria.
What do mitochondria and chloroplasts have in common with bacteria?
Double membranes
Own circular DNA
Own ribosomes
Reproduce by binary fission
What causes the double membranes in mitochondria and chloroplasts?
The engulfing process
