Lecture 2- Prokaryotes

Question 1

A(n) _____ is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently.

Answer 1

Plasmid

Question 2

What organism is thought to be the ancestor of chloroplasts?

Answer 2

Cyanobacteria

Question 3

Which domain do methanogens belong to?

Answer 3

Archaea

Question 4

Which type of horizontal gene transfer involves the incorporation of foreign DNA as plasmids or into bacterial genome?

Answer 4

Transformation

Question 5

_____ 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

Answer 5

Peptidoglycan

Question 6

What is the difference between positive and negative taxis?

Answer 6

Positive taxis is movement towards a stimulus, whereas negative taxis is movement away from a stimulus

Question 7

What color do gram-positive bacteria appear after gram staining?

Answer 7

Purple

Question 8

How do prokaryotes reproduce?

Answer 8

Binary fission

Question 9

True or False: Both prokaryotic and eukaryotic flagella are covered by a plasma membrane

Answer 9

False; only eukaryotic flagella are covered by plasma membrane

Question 10

What color do gram-negative bacteria appear after gram staining?

Answer 10

Pink

Question 11

What is the difference between vertical gene transfer and horizontal gene transfer?

Answer 11

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

Question 12

______ is the process by which foreign DNA is introduced into a cell by a virus

Answer 12

Transduction

Question 13

True or False: Cell walls of plant cells contain peptidoglycan

Answer 13

False; peptidoglycan is exclusive to bacteria

Question 14

What is the most recent ancestor of the mitochondria?

Answer 14

Alpha proteobacteria

Question 15

What are halophiles?

Answer 15

Extremophiles that thrive in high salt concentrations

Question 16

Why do gram-positive bacteria appear purple after gram staining?

Answer 16

Due to the thick peptidoglycan layer in their cell wall

Question 17

______ 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)

Answer 17

Transformation

Question 18

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

Answer 18

Facultative anaerobe

Question 19

What are thermophiles?

Answer 19

Extremophiles that thrive in high temperatures

Question 20

What is the outer membrane of gram-negative bacteria composed of?

Answer 20

Lipopolysaccharides (LPS) and a thin peptidoglycan layer

Question 21

______ is the transfer of genetic material between bacterial cells by direct cell-to-cell contact

Answer 21

Bacterial conjugation

Question 22

A gram stain is conducted and the bacteria appears pink in color. What type of bacteria has been stained?

Answer 22

Gram-negative

Question 23

True or False: Binary fission is the source of genetic diversity in prokaryotes

Answer 23

False; binary fission produces identical copies

Question 24

A(n) _____ is a hair-like appendage required for bacterial conjugation

Answer 24

pilus

Question 25

A gram stain is conducted and the bacteria appears purple in color. What type of bacteria has been stained?

Answer 25

Gram-positive

Question 26

Transformation, transduction, and conjugation are all mechanisms of ________

Answer 26

horizontal gene transfer

Question 27

Which domain do extremophiles belong to?

Answer 27

Archaea

Question 28

Describe the cellular organization of prokaryotes

Answer 28

Smaller than eukaryotes, simpler than eukaryotes, lack membrane bound organelles, plasma membrane often folded inward, contains enzymes for respiration and photosynthesis

Question 29

Purpose of cell wall in prokaryotes

Answer 29

- Protects cell - Maintains shape - Prevents bursting

Question 30

Gram _________ bacteria have a thick wall, composed of peptidoglycan

Answer 30

Positive

Question 31

Gram ___________ bacteria have a thin peptidoglycan inner layer and a lipopolysaccharide (LPS) outer membrane

Answer 31

Negative

Question 32

Gram ________ often more likely to cause serious disease

Answer 32

Negative

Question 33

Flagella

Answer 33

Most common motility structure in prokaryotes. Found in bacteria, archaea, eukaryotes. Similar function but arose independently (convergent evolution-> analogous structures)

Question 34

Prokaryotic vs. Eukaryotic flagella

Answer 34

Prokaryotic flagella is 1/10th as wide as eukaryotic flagella and is not covered with plasma membrane. They differ in mechanism and structure

Question 35

Flagellum function

Answer 35

H+ pump across plasma membrane by electron transport chain, forms gradient, H+ diffuses through motor, energy from diffusion turns motor (Proton motive force)

Question 36

Prokaryotic reproduction

Answer 36

Reproduce by binary fission, asexual (1 cell divides into 2), under optimal conditions very rapid

Question 37

What promotes genetic diversity in prokaryotes?

Answer 37

Rapid reproduction and mutation

Question 38

How does genetic recombination work in prokaryotes?

Answer 38

Prokaryotes do not go through meiosis. Instead, they have recombination between cells: Horizontal gene transfer

Question 39

Transformation

Answer 39

Prokaryotic cell takes up foreign DNA from environment

Question 40

Transduction

Answer 40

Phages transfer prokaryotic genes from one cell to another

Question 41

What are the 3 recombination mechanisms?

Answer 41

Transformation, transduction, and conjugation

Question 42

Conjugation

Answer 42

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.

Question 43

Where do phototrophs get their energy from?

Answer 43

Light

Question 44

Where do chemotrophs get their energy from?

Answer 44

Chemicals

Question 45

What carbon source do autotrophs need?

Answer 45

CO2 or other inorganic carbon (because they are producers)

Question 46

What carbon source do heterotrophs need?

Answer 46

Organic carbon e.g. glucose (because they are consumers)

Question 47

Obligate anaerobes

Answer 47

Poisoned by O2

Question 48

Obligate anaerobes

Answer 48

Poisoned by O2, 2 alternatives: Fermentation- make ATP without ETC Anaerobic respiration- ATP with ETC, different e- acceptor

Question 49

What are thermophiles/hyperthermophiles?

Answer 49

Extremophiles that thrive in hot environments

Question 50

What are methanogens?

Answer 50

Extremophiles- release methane as a byproduct of metabolism. Obligate anaerobes, often in swamps and marshes