Biology Chapter 27 Flashcards

Vocabulary flashcards covering prokaryotes, cellular structures, reproduction, gene transfer mechanisms, and ecological interactions based on lecture slides.

Conjugation

In prokaryotes, the direct transfer of DNA between two cells that are temporarily joined. When the two cells are members of different species, conjugation results in horizontal gene transfer.

Nitrogen fixation

The conversion of atmospheric nitrogen ($N_2$) to ammonia ($NH_3$). Biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants.

Symbiosis

An ecological relationship between organisms of two different species that live together in direct and intimate contact.

Mutualism

A positive-positive ecological interaction that benefits individuals of both interacting species.

Commensalism

A positive-neutral ecological interaction that benefits the individuals of one species but neither harms nor helps the individuals of the other species.

Parasitism

A positive-negative ecological interaction in which one organism, the parasite, benefits by feeding upon another organism, the host, which is harmed; some parasites live within the host (feeding on its tissues).

Capsule

In many prokaryotes, a dense and well-defined layer of polysaccharide or protein that surrounds the cell wall and is sticky, protecting the cell and enabling it to adhere to substrates or other cells.

Binary fission

A method of asexual reproduction in single-celled organisms in which the cell grows to roughly double its size and then divides into two cells. In prokaryotes, binary fission does not involve mitosis, but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process.

Horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

Transformation

A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer.

Transduction

A process in which phages (viruses) carry bacterial DNA from one bacterial cell to another.

Prokaryote

A single-celled organism of the domain Bacteria or Archaea.

Bacteria

One of two prokaryotic domains, the other being Archaea.

Archaea

One of two prokaryotic domains, the other being Bacteria.

Cell wall

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of cell walls.

Cell membrane

A structure that separates the inside and outside of a cell. It is made of two layers of lipids (and other molecules) and allows some substances to cross into or out of the cell.

Taxon

A name taxonomic unit at any given level of classification

Clade

A group of species that includes an ancestral species and all of its descendants, equivalent to a monophyletic group

protist

an informal term applied to any eukaryotes that is not a plant, animal, or fungus

gram positive

A category of bacteria that retain the crystal violet stain used in the Gram staining procedure, appearing purple under a microscope, they have a peptidoglycan outer layer

gram negitive

does not retain staining from gram staining procedure, has a thin layer of peptidoglycan that is surrounded by lipopolysaccharide outer membrane, more likely to be threatening to humans because lipopolysaccharides have greater resistance to antibiotics

capsule

a dense and re-defined layer that surrounds the cell wall and is sticky

slime layer

a loosely attached layer that surrounds the cell wall in some prokaryotes and is sticky

fimbriae

short,hair like structures on the surface of prokaryotic cells that help them adhere to surfaces or host tissues

endospores

a dormant structure formed by certain batceria, allowing them to survive harsh conditions by being inactive, then becoming active again when in better conditions

taxis

directional movement of prokaryotes

chemotaxis

moving toward nutrient or away from toxin

phototaxis

moving toward or away from light

prokaryotes

umbrella term for bacteria and archaea

do prokaryotic have ribosomes

yes

photoautotrophs

using light energy to synthesize the organic compunds they need from carbon dioxide

chemoautotrophes

only need carbon dioxide and oxidize substances like hydrogen sulfate for energy that they need

photoheterotrophs

use light for energy but need carbon from organic form, relying on carbs, fatty acids, and alcohols

chemoheterotrophs

organic molecules for energy and carbon

obligat aerobes

need oxygen

obligate anaerobes

oxygen is toxic to them

facultative anaerobes

don’t need oxygen but will use it if accessible

nitrogen fixation

converting N2 to ammonia, making nitrogen more accessible to others

plasmid

different set of DNA, genes that relate to bacterial resistance, can give plasmids to another prokaryote introducing new DNA

bacterial cell wall

peptidoglycan

archaean cell walls

polysaccharides and proteins

opportunistic pathogens

a pathogen that does not normally hurt the human unless under stressed circumstances (ex- weaken immune system, medical treatments, antibiotics)

antibiotic resistance

this can happen when taking the antibiotic too much allowing germs to evolve and be able to resist the medication.

plasmolysis

the process where a plant cell loses water in a hypertonic solution, causing the cytoplasm and plasma membrane to shrink and pull away from the rigid cell wall.

flagella

tail like part of cell that helps them move and some can even detect temperature change or chemicals

halophiles

an organism that thrives and lives in high salt concentrated areas

thermophiles

organisms that thrive in hot temperatures

methanogens

microscopic single-celled organisms in the domain Archaea that produce methane gas as a byproduct of their unique energy metabolism. Most are obligate anaerobes ( don’t need O2)