Unit 2 Week 10/12 Flashcards
Prokaryotic cell
A cell without membrane bound organelles
Single cellular but can aggregate
Bacteria and archaebacteria
Archaebacteria
NOT BACTERIA
live in extreme environments (salty/hot/acidic)
Nucleoid
Region where DNA is found
-DNA of prokaryotes are circular
Pilli
Attachment appendages
- fimbria
- sex pilli- helps in bacterial conjugation (transferring DNA in bacteria)
- type IV pilli- attaches to surface and then contracts movement
How do prokaryotic organisms perform cellular functions without compartmentalizing areas?
The cell membrane forms pockets of compartments
What is the cell theory?
Three parts
1) all cells come from pre existing cells (but what about the first cell?
2) all life is made of cells (chloroplasts and mitochondria can replicate on its own and has own DNA)
3) cells are the smallest, basic unit of life
Endomembranous system
Series of membranous organelles connected physically or by vesicles
Advantage of having a nucleus
Protection of materials inside it
Advantage of prokaryote not having nucleus
Transcription and translation can occur simultaneously
How are cells able to move?
- cytoskeleton
- flagella
- cilia (only in eukaryotes)
- pili (only in prokaryotes)
How does the flagella move?
Eukaryotes- whip like motion back and forth, driven by ATP
Prokaryotes- rotor movement, driven by proteins
Microtubules
Structure/protein type: Tubulin
Diameter: 25nm
Location: extends throughout the cell
Microtubules function
- attaches to chromosomes and moves them in cell division
- structure~resists compression (spring shape)
- provides a track for organelles to move on
Kenesin
Moves organelles toward the plus end
Dynein
Moves organelles to minus end
Microtubules: cell motility
- found in flagella and cilia
- 9+2 array (9 pairs of Microtubules surrounding 2 central Microtubules) found in motile cilia
Primary cilia
- 9+0 array, doesn’t help movement
- the proteins connecting the Microtubule pairs are Dynein (sliding) and nexin (leads to bending)
Dynamic istability
The depolymerizing and repolymerizing
Microfilaments
Structure/protein shape: actin (g alone, f with 2 strands
Diameter: 7-9 nm
Location: found on the perimeter of the cell (tends to be found in the folds (microvilli) of cells in the small intestine)
Functions of Microfilaments
- structure: resists shear/tension
- works with myosin in muscle contractions
- helps pinch in cell during cell division
- participates in cytoplasmic streaming
Microfilament motility
- as actin polymerizes, it expands the cell membrane forward
- myosin dependent contractions propel cell forward
Intermediate filaments
Types of protein- keratin, many proteins
Diameter: 8-12 nm
Functions: permanent scaffold in the cell, throughout the cell
Thick filaments
Types of protein: myosin
Functions: muscle contractions and helps cytoplasm propel forward
Endosymbiotic theory
Evidence the mitochondria was once it’s own:
1) has its own DNA
2) DNA is round, similar to DNA in prokaryotic cells
3) can replicate on their own
4) similar inner membrane in proteins it carries to prokaryotes
- same evidence with chloroplasts
