Bio 331 Exam 2

Binary fission

A method of asexual reproduction in bacteria where a single cell divides into two identical daughter cells.

Bacterial growth curve phases

The four phases of bacterial growth include lag phase, log phase, stationary phase, and death phase.

Carrying capacity

The maximum population size of bacteria that an environment can support, reached when resources are scarce and waste accumulates.

Plaque assay

A technique used to measure viral infection by mixing bacteriophages with bacteria in agar to form plaques representing lysed bacterial cells.

Lytic cycle

A viral replication cycle where the virus hijacks the host cell machinery to produce new viruses, eventually causing the cell to burst.

Lysogenic cycle

A viral replication cycle where the phage DNA is incorporated into the bacterial genome and replicates alongside it without killing the host.

Replica plating

A method of transferring bacterial colonies from one plate to another by using a stamp-like apparatus (sterile velvet on a block) to study their growth conditions under different treatments.

Lamarckian evolution

The theory that individuals can evolve during their lifetime and pass these adaptations to their offspring.

Darwinian evolution

The theory that populations evolve over time through natural selection, with advantageous traits being passed down.

Bradford Assay

A method used to measure protein concentration in a sample by determining the intensity of color change when Coomassie Blue dye binds to proteins.

SDS-PAGE

A technique used for separating proteins based on size and charge by denaturing them with sodium dodecyl sulfate.

What enzyme activity factors influence enzyme activity?

Temperature, pH, and substrate concentration influence enzyme activity, with each having an optimal range.

Protein structure levels

The four levels include primary (amino acid sequence), secondary (local folding), tertiary (3D structure), and quaternary (multiple chains).

Lock-and-Key model

A model of enzyme activity where the substrate fits perfectly into the enzyme's active site, leading to reaction.

Induced-Fit model

A model of enzyme activity where the active site changes shape when the substrate binds, enhancing enzyme action.

Electrophoresis

A technique used to separate DNA, RNA, and proteins based on their size and net charge.

Sodium dodecyl sulfate (SDS)

An anionic detergent used in protein electrophoresis that denatures proteins and gives them a uniform negative charge.

What is a virus?

A virus is a microscopic infectious agent that can only replicate inside a host cell.

What is the structure of a virus?

Viruses typically consist of genetic material (DNA or RNA) encased in a protein coat called a capsid.

What are plasmids?

Plasmids are small, circular DNA molecules found in bacteria that can replicate independently of chromosomal DNA.

What is antibiotic resistance?

Antibiotic resistance is the ability of bacteria to survive and grow in the presence of substances that would normally inhibit or kill them.

What is a bacteriophage?

A bacteriophage is a type of virus that specifically infects and replicates within bacteria.

What role do ribosomes play in cells?

Ribosomes are cellular structures that synthesize proteins by translating messenger RNA.

What is fermentation?

Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen.

What are the functions of cell membranes?

Cell membranes protect cells, control the movement of substances in and out, and facilitate communication between cells.

What is horizontal gene transfer?

Horizontal gene transfer is the transfer of genetic material between organisms other than by vertical transmission (from parent to offspring).

What are antigens?

Antigens are molecules or substances that are recognized by the immune system, triggering an immune response.

Fill in the blank: __________ is a method of asexual reproduction in bacteria.

Binary fission.

Fill in the blank: The maximum population size of bacteria that an environment can support is called __________.

Carrying capacity.

Fill in the blank: The four phases of bacterial growth include lag phase, log phase, __________ phase, and death phase.

stationary.

Fill in the blank: A __________ assay is used to measure viral infection by mixing bacteriophages with bacteria in agar.

plaque.

Fill in the blank: The __________ cycle hijacks the host cell machinery to produce new viruses, eventually causing the cell to burst.

lytic.

Fill in the blank: In the __________ cycle, the phage DNA is incorporated into the bacterial genome without killing the host.

lysogenic.

Fill in the blank: __________ is a method of transferring bacterial colonies from one plate to another to study their growth conditions.

Replica plating.

Fill in the blank: The __________ model of enzyme activity describes how the active site changes shape when the substrate binds.

Induced-Fit.

Fill in the blank: Antibiotic resistance is the ability of bacteria to __________ and grow in the presence of antibiotics.

survive.

Fill in the blank: __________ are small, circular DNA molecules found in bacteria that can replicate independently of chromosomal DNA.

Plasmids.

When is the carrying capacity reached?

When the environment can no longer support population growth due to scarce resources, and the accumulation of waste.

Why does the stationary phase occur?

Due to limited nutrients, end-product accumulation and limited space

How does binary fission lead to exponential growth?

Binary fission leads to a doubling of the number of viable bacteria cells, causing the cell population to be constantly doubling.

Why are bacteria grown in pure culture in a lab?

To control the environment, ensure it is not interfered with by other microorganisms, and provide necessary nutrients.

What is evolution?

Change over time of a population, not an individual.

What causes antibiotic resistance?

Some bacteria within a population carry a gene that gives them resistance to an antibiotic and when exposed to that antibiotic they do not die, these bacteria will start a new population where every organism has the resistance gene to the antibiotic.

If Lamarckian evolution was true, what would bacterial colonies look like on a plate after replica plating? What about Darwinian evolution?

In Lamarckian evolution, bacterial colonies would be in various locations on different plates, in Darwinian evolution the bacterial colonies should remain in the same location on different plates.

Why is the North Point important for replica plating?

The north point helps us get a reference for the replica plates to ensure the apparatus is oriented in the same direction for each plate.