Lesson 1: Reproduction in Prokaryotes, Protists & Fungi

What is the definition of reproduction?

Biological process by which organisms produce offspring to ensure species continuation.

Define asexual reproduction?

Reproduction involving one parent producing genetically identical offspring.

Define sexual reproduction?

Reproduction involving two parents or gametes producing genetically diverse offspring.

What is the main asexual reproduction method used by prokaryotes?

Binary fission.

Define binary fission in prokaryotes?

An asexual process where a parent cell divides into two genetically identical clones.

What happens in Step 1 of prokaryotic binary fission?

Replication of the circular chromosome begins at the origin.

In what directions does prokaryotic DNA replication occur during binary fission?

In both directions at once.

What happens in Step 2 of prokaryotic binary fission?

The cell elongates and FtsZ proteins move to the midpoint.

What does the acronym FtsZ stand for?

Filamenting temperature-sensitive mutant Z.

What happens in Step 3 of prokaryotic binary fission?

Duplicated chromosomes move apart and FtsZ proteins form a ring around the midpoint of the cell.

What happens in Step 4 of prokaryotic binary fission?

A septum forms as plasma membrane and cell wall materials accumulate.

What is a septum?

A thin wall or membrane that divides two cavities, spaces, or soft tissues in an organism.

What happens in Step 5 of prokaryotic binary fission?

The cell pinches into two identical daughter cells.

Give an advantage of binary fission.

It is very fast and works well in stable environments.

Give a disadvantage of binary fission.

It produces little genetic variation, leaving populations vulnerable to diseases.

Define horizontal gene transfer (HGT).

The process by which bacteria exchange genes to gain genetic variation.

What type of genes can be exchanged via horizontal gene transfer to make bacteria pathogenic?

Virulence genes.

Define conjugation in bacteria.

A type of horizontal gene transfer where DNA is transferred through a sex pilus.

What structure is used to transfer DNA during bacterial conjugation?

A sex pilus.

What circular DNA structures are often involved in bacterial conjugation?

Plasmids.

Why is bacterial conjugation not considered true sexual reproduction?

No gametes or fertilization occur, and no offspring are directly produced.

Define baeocyte formation.

An asexual method where numerous baeocytes are made via cytoplasmic fissions from one cell.

Name a bacterium that reproduces via baeocyte formation.

Staniera sp.

Define unequal cell division in Epulopiscium spp.

A mother cell forms, engulfs two small offspring cells, and eventually dies as they emerge.

Why can protists reproduce both sexually and asexually?

They are eukaryotes with a true nucleus.

Why did sexual reproduction evolve in eukaryotes?

To increase genetic variation for better survival in changing environments.

What are the two essential features for sexual reproduction in protists?

Haploid gametes/mating types via meiosis, and fertilization to form a diploid zygote.

What is the definition of gametes?

Haploid reproductive cells or opposing mating types formed through meiosis.

Define binary fission in protists.

Divides equally into 2 new cells using mitosis

Define multiple fission?

An asexual process where a parent cell divides into several daughter cells.

Give an example of a protist that undergoes multiple fission?

Amoeba or Plasmodium.

Define plasmotomy?

Cytoplasmic division in multinucleated protists without nuclear division, producing multinucleate offspring.

Name an organism that undergoes plasmotomy.

Opalina.

Define spore formation in protists?

The development of protective capsules during harsh conditions that later germinate.

Define protist budding?

A small outgrowth develops and separates from the parent. (involves mitosis)

Define syngamy?

The complete fusion of gametes that results in a diploid zygote.

Define isogamy?

The fusion of two structurally similar gametes.

Define anisogamy?

The fusion of two structurally dissimilar gametes.

Define oogamy?

The fertilization of a large non-motile gamete by a smaller motile one.

Define conjugation in protists?

A temporary union of two individuals to exchange haploid pronuclei through a cytoplasmic bridge.

What material makes up fungal cell walls?

Chitin.

Define Imperfect Fungi (Deuteromycota).

Fungi with no observed sexual cycle that rely exclusively on asexual reproduction.

Give an example of an Imperfect Fungus.

Penicillium.

When do fungi favor asexual reproduction?

During favorable environmental conditions for rapid colonization.

When do fungi favor sexual reproduction?

During unfavorable or harsh environmental conditions to increase adaptability.

Define fragmentation in fungi?

A process where a fragment of a hypha breaks off and develops into a new fungus.

Define conidiospores?

Mitotic spores produced externally on specialized hyphae called conidiophores.

Define sporangiospores?

Mitotic spores produced inside a sac-like sporangium.

Define homothallic fungi?

Self-fertile fungi where compatible mating types are found within the same mycelium.

Define heterothallic fungi?

Fungi requiring two genetically different but compatible mycelia to reproduce.

Define plasmogamy in fungi?

The fusion of the cytoplasm of two compatible fungal mycelia.

Define karyogamy in fungi?

The fusion of haploid nuclei to form a diploid zygote nucleus.

Define the use of meiosis in fungi reproduction?

Happens to the diploid zygote inside the gametangium(gametangia), producing haloid spores that are released and germinate into new fungi.