Rhizopus and Bacterial Biology

Practice flashcards covering the biological characteristics, structures, reproduction, and growth factors of Rhizopus and bacteria based on lecture notes.

What is the nutritional classification of Rhizopus?

Rhizopus is a Heterotrophic and Saprophytic organism.

What is the common name for Rhizopus, and why is it called that?

It is commonly called bread mould or black pin mould because it looks like pins and the sporangiums are black.

Contrast the terms 'aseptate' and 'multinucleate' as used to describe Rhizopus.

Aseptate means there are no cross walls separating the cells, and multinucleate means the organism is made up of many nuclei along a hyphal thread.

What substance makes up the cell walls of Rhizopus?

Chitin, which is a polysaccharide carbohydrate.

What are the functions of Rhizoids in Rhizopus?

They anchor Rhizopus to the substrate (such as bread) and are involve in digestion and sexual reproduction.

Define the term 'Stolon'.

A horizontal Hypha that allows Rhizopus to spread across the substrate.

What is the role of the Columella in the structure of Rhizopus?

It is a membrane that separates the sporangiophore from the sporangium.

Under what conditions does sexual reproduction occur in Rhizopus?

Sexual reproduction occurs in adverse (unsuitable) conditions only.

Name the steps of asexual reproduction (sporulation) in Rhizopus.

1) Sporangiophore grows up; 2) Top enlarges to form sporangium; 3) Mitosis forms cells inside; 4) Cells form hard walls (spores); 5) Sporangium dries; 6) Spores are released; 7) Land on suitable substrate; 8) Form new hypha; 9) Form mycelium; 10) Form new Rhizopus.

Which bacterium is used in the pharmaceutical industry to make yogurt?

Lactobacillus bacteria.

Define 'Antibiotics' according to the lecture notes.

Chemicals produced by micro-organisms that stop the growth of or kill other micro-organisms without damaging human tissues.

What is 'Biological Control' in agriculture?

Using one species to control the growth or spread of another species.

What are the five phases of a typical bacterial growth curve?

Lag Phase, Log Phase, Stationary Phase, Death/Decline Phase, and Survival Phase.

What characterizes the 'Stationary Phase' of bacterial growth?

There is no increase or decrease in numbers because the number of bacteria produced equals the number of bacteria dying off due to limited food, space, moisture, or oxygen.

Explain the 'Survival Phase' in bacteria.

A small number of bacteria survive harsh conditions by producing endospores.

How do bacteria evolve antibiotic resistance so quickly?

Bacteria have a very short life cycle, which allows mutations to spread very quickly.

Define 'Binary Fission'.

Asexual reproduction where DNA replicates, the cell elongates, DNA separates, and cytokinesis occurs to form 2 identical bacterial cells.

What is the function of a bacterial 'Plasmid'?

A ring of DNA that contains antibiotic resistance genes and is used in genetic engineering processes.

What temperature is typically used to incubate agar plates to avoid growing human pathogens?

$20\,^{\circ}\text{C}$ (incubation at human body temperature, $37\,^{\circ}\text{C}$, is avoided).

What happens to bacteria when the external solute concentration is higher than the bacterial cytoplasm?

Water moves out of the bacteria by osmosis, causing it to dehydrate, which slows and eventually stops growth.

What is 'Bioprocessing'?

The use of living things or their parts to produce useful products.

What are the three common shapes of bacteria?

Spherical (Cocci), Rod (Bacilli), and Spiral.

Contrast 'Autotrophic' and 'Heterotrophic' bacteria.

Autotrophic bacteria make their own food (via photosynthesis or chemosynthesis), while Heterotrophic bacteria cannot make their own food (Parasitic or Saprophytic).

What is an endospore?

A resistant, thick-walled structure formed around a copy of bacterial DNA to withstand unfavourable environmental conditions.

Define the term 'Sterile'.

Something that is free of all micro-organisms.

What is the purpose of an 'Autoclave' in microbiology?

To sterilise equipment and agar plates after use, typically at $120\,^{\circ}\text{C}$ for $15\,\text{minutes}$, to kill all bacteria.