Lecture 2- Prokaryotes Flashcards
A(n) _____ is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently.
Plasmid
What organism is thought to be the ancestor of chloroplasts?
Cyanobacteria
Which domain do methanogens belong to?
Archaea
Which type of horizontal gene transfer involves the incorporation of foreign DNA as plasmids or into bacterial genome?
Transformation
_____ is a carbohydrate polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall
Peptidoglycan
What is the difference between positive and negative taxis?
Positive taxis is movement towards a stimulus, whereas negative taxis is movement away from a stimulus
What color do gram-positive bacteria appear after gram staining?
Purple
How do prokaryotes reproduce?
Binary fission
True or False: Both prokaryotic and eukaryotic flagella are covered by a plasma membrane
False; only eukaryotic flagella are covered by plasma membrane
What color do gram-negative bacteria appear after gram staining?
Pink
What is the difference between vertical gene transfer and horizontal gene transfer?
Vertical gene transfer is the transfer of genetic material from parent to offspring, whereas horizontal gene transfer is the transfer of genetic material NOT from parent to offspring
______ is the process by which foreign DNA is introduced into a cell by a virus
Transduction
True or False: Cell walls of plant cells contain peptidoglycan
False; peptidoglycan is exclusive to bacteria
What is the most recent ancestor of the mitochondria?
Alpha proteobacteria
What are halophiles?
Extremophiles that thrive in high salt concentrations
Why do gram-positive bacteria appear purple after gram staining?
Due to the thick peptidoglycan layer in their cell wall
______ is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane(s)
Transformation
A(n) ____ _____ is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent
Facultative anaerobe
What are thermophiles?
Extremophiles that thrive in high temperatures
What is the outer membrane of gram-negative bacteria composed of?
Lipopolysaccharides (LPS) and a thin peptidoglycan layer
______ is the transfer of genetic material between bacterial cells by direct cell-to-cell contact
Bacterial conjugation
A gram stain is conducted and the bacteria appears pink in color. What type of bacteria has been stained?
Gram-negative
True or False: Binary fission is the source of genetic diversity in prokaryotes
False; binary fission produces identical copies
A(n) _____ is a hair-like appendage required for bacterial conjugation
pilus
A gram stain is conducted and the bacteria appears purple in color. What type of bacteria has been stained?
Gram-positive
Transformation, transduction, and conjugation are all mechanisms of ________
horizontal gene transfer
Which domain do extremophiles belong to?
Archaea
Describe the cellular organization of prokaryotes
Smaller than eukaryotes, simpler than eukaryotes, lack membrane bound organelles, plasma membrane often folded inward, contains enzymes for respiration and photosynthesis
Purpose of cell wall in prokaryotes
- Protects cell
- Maintains shape
- Prevents bursting
Gram _________ bacteria have a thick wall, composed of peptidoglycan
Positive
Gram ___________ bacteria have a thin peptidoglycan inner layer and a lipopolysaccharide (LPS) outer membrane
Negative
Gram ________ often more likely to cause serious disease
Negative
Flagella
Most common motility structure in prokaryotes. Found in bacteria, archaea, eukaryotes. Similar function but arose independently (convergent evolution-> analogous structures)
Prokaryotic vs. Eukaryotic flagella
Prokaryotic flagella is 1/10th as wide as eukaryotic flagella and is not covered with plasma membrane. They differ in mechanism and structure
Flagellum function
H+ pump across plasma membrane by electron transport chain, forms gradient, H+ diffuses through motor, energy from diffusion turns motor (Proton motive force)
Prokaryotic reproduction
Reproduce by binary fission, asexual (1 cell divides into 2), under optimal conditions very rapid
What promotes genetic diversity in prokaryotes?
Rapid reproduction and mutation
How does genetic recombination work in prokaryotes?
Prokaryotes do not go through meiosis. Instead, they have recombination between cells: Horizontal gene transfer
Transformation
Prokaryotic cell takes up foreign DNA from environment
Transduction
Phages transfer prokaryotic genes from one cell to another
What are the 3 recombination mechanisms?
Transformation, transduction, and conjugation
Conjugation
An F+ cell with the F (fertility) factor sends a pilus to an F cell (lacking the F factor). The F factor is then copied and transferred to the F cell, converting it into an F+ cell as well. This process can also result in the transfer of chromosomal DNA, contributing to genetic diversity among bacterial populations.
Where do phototrophs get their energy from?
Light
Where do chemotrophs get their energy from?
Chemicals
What carbon source do autotrophs need?
CO2 or other inorganic carbon (because they are producers)
What carbon source do heterotrophs need?
Organic carbon e.g. glucose (because they are consumers)
Obligate anaerobes
Poisoned by O2
Obligate anaerobes
Poisoned by O2, 2 alternatives:
Fermentation- make ATP without ETC
Anaerobic respiration- ATP with ETC, different e- acceptor
What are thermophiles/hyperthermophiles?
Extremophiles that thrive in hot environments
What are methanogens?
Extremophiles- release methane as a byproduct of metabolism. Obligate anaerobes, often in swamps and marshes
