Biodiversity (Single-celled)

Question 1

Characteristics of prokaryotic cells

Answer 1

1. No nucleus
2. DNA in an unbound region called the nucleoid
3. No membrane-bound organelles
4. Cytoplasm bound by the plasma membrane
5. Have a cell wall

Question 2

Where do prokaryotes live

Answer 2

Nearly anywhere, they’re highly adaptable

Question 3

What do prokaryotes use for movement

Answer 3

1. Flagella
   - use long whip-like structure(s) to swim - - most common structure used for movement
   - scattered about the surface or concentrated at one or both ends of a cell
   - differs in structure, mechanism of propulsion, and molecular composition as compared to eukaryotes
2. Pili
   - short hairlike structures
   - longer than fibriae
   - allow prokaryotes to exchange DNA
3. Chemotaxis
   -attraction to chemicals
   -determines direction

Taxis: the ability to move toward or away from a stimulus

Question 4

How do prokaryotes reproduce

Answer 4

1. Asexual (binary fission) - produces identical daughter cells
2. Diverse, some other methods (budding, forming within mother cell, forming within cell wall)

Question 5

How do prokaryotes feed

Answer 5

diffusion, osmosis, active transport, facilitated diffusion

Question 6

Presence of peptidoglycan in cell wall

Answer 6

1. Gram-positive bacteria: peptidoglycan traps crystal violet which MASKS the red safranin dye; more susceptible to antibiotics
2. Gram-negative bacteria: crystal violet is easily rinsed away, REVEALING the red safranin dye

Question 7

Bacterial capsule

Answer 7

sticky outer layer of polysaccharide or protein, allows adherence to substrate, can shield pathogenic bacteria from the host immune system

Question 8

Endospores

Answer 8

metabolically inactive, can remain viable in harsh conditions

Question 9

Fimbriae

Answer 9

hairlike appendages, allow bacteria to stick to substrate or other individuals in a colony

Question 10

Plasmids

Answer 10

small rings of independently replicating DNA

Question 11

Genome shape

Answer 11

circular chromosome

Question 12

Genetic diversity factors

Answer 12

1. Rapid reproduction
2. Mutation
3. Genetic recombination

Question 13

Conjugation

Answer 13

• the process by which one bacterium transfers genetic material to another through direct contact (type of genetic recombination)
• donor cell attaches to a recipient by a pilus and transfers DNA through a structure called the mating bridge

Question 14

Gene transfer

Answer 14

movement of genes among individuals from different species (type of genetic recombination)

Question 15

F factor

Answer 15

a piece of DNA that’s required for the production of pili

Question 16

Phototrophs

Answer 16

obtain energy from light

Question 17

Chemotrophs

Answer 17

obtain energy from chemicals

Question 18

Autotrophs

Answer 18

require CO2 or related compounds as a carbon source

Question 19

Heterotrophs

Answer 19

require an organic nutrient to make organic compounds

Question 20

Energy & carbon sources are combined to give four major modes of nutrition

Answer 20

Photoautotroph
Chemoautotroph
Photoheterotroph
Chemoheterotroph

Question 21

Obligate aerobes

Answer 21

require O2 for cellular respiration

Question 22

Obligate anaerobes

Answer 22

poisoned by O2 and live by fermentation or use substances other than O2 for anaerobic respiration

Question 23

Facultative anaerobes

Answer 23

use O2 if its present or carry out fermentation or anaerobic respiration if it is not

Question 24

What is nitrogen essential for

Answer 24

the production of amino acids and nucleic acids in all organisms

Question 25

Heterocysts

Answer 25

nitrogen-fixing cell

Question 26

Biofilms

Answer 26

surface-coating colonies

Question 27

Chlamydias

Answer 27

parasites that live within animal cells

Question 28

Cyanobacteria

Answer 28

• Gram-negative photoautotrophs that generate O2
• Plant chloroplasts likely evolved from them by endosymbiosis
• Abundant components of freshwater and marine phytoplankton

Question 29

Spirochetes

Answer 29

• helical gram-negative heterotrophs
• some are parasites

Question 30

Gram-positive bacteria

Answer 30

• colony-forming groups

Question 31

Extremophiles

Answer 31

Extreme environments occupied by some archaea

Question 32

Extreme halophiles

Answer 32

live in highly saline environments

Question 33

Extreme thermophiles

Answer 33

thrive in very hot environments

Question 34

Methanogens

Answer 34

archaea that live in swamps and marshes and produce methane as a waste product

Question 35

Endosymbiosis

Answer 35

a relationship between two species in which one organism lives inside the cell or cells of the other organism (the host)

Question 36

Similarities between mitochondria and chloroplasts and bacteria

Answer 36

• enveloped by a double membrane
• contain free ribosomes and circular DNA molecules
• grow and reproduce somewhat independently in cells

leads to endosymbiont theory

Question 37

Evidence for endosymbiont theory

Answer 37

• chloroplasts and mitochondria have own DNA
• DNA is similar to bacterial DNA (circular)
• autonomous
• have own cell membrane

Question 38

Protists overview

Answer 38

• some species live freely while others live a parasitic lifestyle
• photosynthetic autotrophs, heterotrophs, or mixotrophs, phototrophs
• singular or colonial
• flagellattes, ciliates
• asexual reproduction, conjugation (sexual reproduction)
• some related to animals and fungi (opisthokonts), some to plants (red and green algae)