Origin of cell & cell structure Flashcards
why viruses are considered to be non-living?
- No cellular structure
- Dependence on host cells/lack of independent metabolism
- No autonomous movement / no response to stimuli
- No composed of cells
5.No genetic independence
What are the certain commonalities in cells?
They all contain :
- a cell membrane
- genetic materials
- chemical reactions catalyzed by enzymes
- the production of energy (ATP) through cellular respiration
How does cell theory describe what unifies cells & what do the 3 main aspects consist of?
- All living organisms are composed of cells
- Cells are the smallest unit of life
- All cells come from pre-existing cells (basic unit of reproduction)
[carrying out all the functions of life]
(recently added)
[4. All cells contain hereditary information (DNA) which is passed on from the cell during cell division.]
Why is skeletal (striated muscle cells) an exception to cell theory?
It challenges the idea that a cell has one nucleus AND is much larger than a typical cell
features other than that :
1. made up of contractile filaments that side past each other
2. one single surrounding membrane could possibly contain 100’s of nuclei)
3.average 30mm long
What is required to develop a perfect set of circumstances for the first cell?
- Enzymes catalyzed reactions
- Self-replication of molecules
- Self-assembly of multiple parts
- Emergence of compartmentalization
How was the atmosphere 3.9 billion years ago?
-Lack of Oxygen and ozone臭氧层
-Contained higher concentrations of carbon dioxide (CO) and methane (CH4)
-had higher temperature (>100 degrees Celsius)
-Experienced high radiation (cosmic & solar, including UV light)
What was the condition when the first cell was produced 3.5-3.9 billion years ago?
- comets & asteroids added water (H2O) and other compounds
- Volcanic eruption released methane (CH4) and ammonia (NH4)
- Extreme weather produced electrical storms (lightning)
process of
LUCA
The last Universal Common Ancestor
- All other life on earth has evolved from LUCS over time through speciation.
LUCA is believed to:
~be a single-celled, autotrophic microbe
~have an RNA genome
~exsit 2.5 to 3.5 billion years ago
What are the evidences of LUCA?
-The genetic code is universal
-There are shared genes cross all organisms
-Fossil evidence from hydrothermal vents
What are Eukaryotic真核 cells?
It is the cells with membrane-bound organelles
What is Endosymbiotic theory?
The theory that eukaryotic cells evolved by engulfing吞噬 （infolded of the plasma membrane, specifically nucleus, Golgi, Endoplasmic reticulum）and incorporating融合 （forming Mitochondria, Chloroplasts） prokaryotic原核 cells, which then became organelles within the eukaryotic cell.
What is mitochondria? And what’s its function?
Mitochondria were originally free-living heterotrophic prokaryotes that developed the ability for aerobic respiration.
It converts glucose into ATP and does cellular respiration.
Chemical equation to show aerobic respiration?
Oxygen+Glucose——-Water+Carbon dioxide +ATP/heat energy
O2+C6H12O6——-6H2O+6CO2+ATP/heat energy
Evidence for Mitochondria evolved from small prokaryotes?
· Double membrane with a small volume of intermembrane space
· Large surface area of cristae (formed by highly folded inner membrane)
· Compartmentalization区域化 of enzymes and substrates of the Krebs cycle (key pathway in cell respiration) in the mitochondria matrix
说白了就是吃豆人游戏，大的吃小的，小的保留了原结构但是变成了其他细胞的器官
(follow by card 18) Why natural selection favor this?
- Both large & small prokaryotes benefited
-Larger cell-supplied nutrients (e.g glucose )to small cell - Small cell supplied ATP energy to large cell
