Cycle 6 BMP Workshop

Question 1

Define:

Endosymbiosis

Answer 1

Organelles coming together to live together within the cell
(Endo - “Within”, Syn - “Come together”, Biosis - “Living”)

Question 2

Explain:

Specialization in the Cell

Answer 2

• Prokaryotic energy production is inefficient
• Specialization of certain organelles increases efficiency
• Specialized organelles allow for more efficient eukaryotic cells

Question 3

True or False:

Organelles do not have their own electron transport chains

Answer 3

False. Organelles do have their own electron tranport chains and own ways of synthesizing proteins, similar to free floating prokaryotes

Question 4

Do organelles divide separately from the cell?

Answer 4

Yes, organelles divide separately from the cell. Furthermore, organelles cannot be created by the cell once destroyed

Question 5

True or False:

Organelles RNA is different from cellular DNA

Answer 5

True. Mitochondrial genome resembles that of heterotrophic bacteria while chloroplast genome resembles that of cyanobacteria

Question 6

True or False:

The genome sizes of the modern mitochondria and chloroplast are larger than genome sizes of the ancestral organisms they originate from

Answer 6

False, the are significantly SMALLER than the genome sizes of the ancestral organisms they originate from

Question 7

Where the genes from ancestral organisms of mitochondria and chloroplast go?

Answer 7

1. Redundancy: Many genes found in aerobic bacteria and cyanobacteria are already found in the host cell
2. Horizontal Gene Transfer (HGT): Overtime, genes of one genome can be relocated to another genome

Question 8

What changes in HGT?

Answer 8

Gene location, not gene function

Question 9

What is required for proteins encoded by nuclear genes that need to be transported to other organelles?

Answer 9

A signal peptide

Question 10

Why is HGT performed?

Answer 10

1. Integrative control: The nuclear genome is the main boss, giving it more genes means more control
2. Safety: Nucleus is much safer compared to the highly reactive environments of the mitochondria and chloroplast

Question 11

How are the environments of mitochondria and chloroplast reactive? (Give example)

Answer 11

The electron transport chain creates reactive oxygen series, which can cause DNA damage

Question 12

How is Horizontal Gene Transfer detected?

Answer 12

DNA Hybridization

Question 13

Desribe:

The process of DNA hybridization

Answer 13

1. Make labelled probe; SS DNA probe that identifies gene of interest
2. Allow for hybridization of labelled probe with SS nuclear and mitochondrial DNA
3. If gene of interest is present in genome, labelled probe will bind to the SS DNA

Question 14

How can we tell if the gene of interest is present in a DNA Hybridization?

Answer 14

There is a band present

Question 15

What are proteins uniquely found in eukaryotes called?

Answer 15

Eukaryotic signature proteins (ESPs)

Question 16

Where are ESPs also found? What do they do?

Answer 16

Found in a group of archaea called Asgard
* DNA packaging, nuclear proteins, protein synthesis, cell signalling, cytoskeleton

Question 17

True or False:

Eukaryotes have a mixture of archeal and bacterial genes

Answer 17

True

Question 18

What do the genes from Archaea and Bacteria do in a Eukaryote?

Answer 18

• Archaea: Genes for information processing and structure
• Bacteria: Genes for Metabolism

Question 19

What characteristics do bacteria have as a prokaryote?

Answer 19

• Fast doubling time
• No nucleus, but circular chromosomal DNA
• Plasmids non chromosomal DNA

Question 20

How are bacteria categorized? Explain the difference

Answer 20

Gram +ve/-ve; by using staining procedures:
* Gram +ve stains purple
* Gram -ve stains pink

Question 21

Describe:

The wall and membrane structure of Gram +ve/-ve bacteria

Answer 21

• Gram +ve bacteria have a thick peptidoglycan wall with a cell membrane
• Gram -ve bacteria have a thinner peptidoglycan wall sandwiched between two membranes (cell membrane and outer membrane)

Question 22

Describe:

Penicillin Mechanism of Action

Answer 22

• Mimics the substrate in the active site

Question 23

What kind of inhibitor is penicillin?

Answer 23

Competitive inhibitor (irreversible; forms a covalent bond)

Question 24

Describe:

Bacterial cell wall (Peptidoglycan)

Answer 24

• Peptide + Sugar (polysaccharide)
• Cross-linking of peptide chains catalyzed by transpeptidase

Question 25

# List: Modes of Action by Antibiotics

Answer 25

* Attack cell wall formation (e.x. penicillin, vancomycin) * Attack metabolic pathways (e.g. sulfonamides attack folate biosynthesis) * Attack protein synthesis (e.x. kanamycin, tetracycline, lincomycin) * Attack DNA replication/transcription (e.x. ciprofloxacin)

Question 26

How do we determine the proper antibiotic to use?

Answer 26

Exploit the biochemical differences between bacterial vs. our cells

Question 27

# List: Methods that differences between bacterial cells and our cells that antibiotics exploit

Answer 27

* Humans do not make folate, thus antibiotics can be used to attack folate synthesis in bacteria * Antibiotics for attacking the ribosome for protein synthesis in bacteria * Human chromosomes are not circular, thus antibiotic can attack the processes required for DNA replication and synthesis

Question 28

# Define: DNA Gyrase

Answer 28

Circular genomes

Question 29

# True or False: Antiobiotic use will harm the mitochondria

Answer 29

Not necessarily * Mitochondria divide VERY slowly * Long term use of antibiotics may affect mitochondrial function but not for very long * Can switch antibiotics for long-term use

Question 30

How is antibiotic resistance detected?

Answer 30

By seeing if there is a deadzone (no bacterial growth) when antibiotic is dripped onto bacteria in culture plate

Question 31

How is antibiotic resistance developed?

Answer 31

1. Random mutations 2. DNA from already ressistant cells

Question 32

# True or False: Mutations in DNA are rarely deleterious

Answer 32

False. Mutations from DNA are usually deleterious or neutral, rarely advantageous

Question 33

If most mutations are deleterious or neutral, how do bacteria develop advantageous mutations?

Answer 33

Bacteria has a fast generation time (20 minutes), meaning there is a very high rate of mutations increasing the likelihood of advantageous mutations * REMEMBER: Mutations are NOT a response to antibiotics, they are RANDOM

Question 34

# List: Antibiotic Resistance Mechanisms (Intrinsic resistance)

Answer 34

1. **Increase expression of efflux pumps** (pumps antibiotic out of bacteria) 2. **New protein with same function** (antibiotic does not target that protein) 3. **Decrease expression of porin - influx** (prevents antibiotic from getting in) 4. **Inactivation by modifying enzymes** (targeting and breaking down antibiotics) 5. **Target site modification** (antibiotic cannot inhibit protein)

Question 35

# Define: Intrinsic resistance

Answer 35

The ability to resist the action of that antibiotic as a result of inherent structural or functional characteristics

Question 36

What is the "last resort" antibiotic used?

Answer 36

Carbapenems (carb), a highly effective antibiotic

Question 37

# True or False: Bacteria can become carbapenem resistant

Answer 37

True; a change in expression of one of three proin genes can prevent the antibiotic from entering