Unit 2.2 Structure of Prokaryotic and Eukaryotic Cells

Comparing Eukaryotes and Prokaryotes

What is transformation? (prokaryotic horizontal gene transfer)

Transformation: bacteria picks up DNA fragments from their environment and integrate them into their own chromosomes

What is transduction? (prokaryotic horizontal gene transfer)

Transduction: genetic transfer between bacteria using a bacteriophage (viruses that affect bacteria)

What is conjugation? (prokaryotic horizontal gene transfer)

Conjugation: DNA is directly transferred from one bacterium to another via pilus or mating bridge

What does bacteria require for horizontal gene transfer?

• Antibiotic resistance

• Toxins

• Ability to use different nutrients

What is the Petidoglycan structure?

Differentiate Gram Positive bacteria vs. Gram Negative bacteria

Which Gram Bacteria is more susceptible to antibiotics and disinfectants?

Gram Positive bacteria

Describe glyococalyx’s role (sticky carbohydrate layer) in Eukaryotes

In eukaryotes, carbohydrates are bonded to proteins and lipids in the plasma membrane

• Glycocalyx functions to strengthen the cell’s surface and attach cells together

Describe glyococalyx’s role (sticky carbohydrate layer) in Prokaryotes

In prokaryotes, carbohydrates are outside the cell wall

Has two layers:

• Capsule: helps bacteria avoid phagocytosis

• Slime layer

What does taxis mean and what are the three taxis?

Taxis means movement of a cell

1. Phototaxis: response to light

2. Thermotaxis: response to temperature

3. Chemotaxis: response to a chemical or nutrient

Describe Positive Taxis vs. Negative Taxis

Positive taxis: cell moves towards the stimulus

Negative taxis: cell moves away from the stimulus

Eukaryotic Cell Movement

Consists of a flagella which is a long flexible tail and cilia which are small projections around the cell

Prokaryotic movement

If the bacteria wants to run/swim in a direction, it will move its flagella counter-clockwise

If the bacteria wants to prevent movement, it will move its flagella clockwise

Swarming is rapid-like movement

What are endospores? (things that only prokaryotes have)

A coat that protects prokaryotes from harsh conditions, only present in gram positive cells. In the right conditions, the endospore can revert to a vegetative state (growing)

What are fimbriae? (things that only prokaryotes have)

Bristle-like structures that enable attachment, numbering from a few to several hundred

What are pilus? (things that only prokaryotes have)

Longer hair-like structures that are used for motility and DNA transfer

• Only one or two per cell

What are inclusions? (things that only prokaryotes have)

Reserve nutrients in the cell when other nutrients cannot be found in the environment

What are axial filaments? (things that only prokaryotes have)

Found mostly inside spiral-shaped bacteria, where it causes the bacteria to move in a spiral motion