Cell Biology and Microbiology

Flashcards of key vocabulary terms from the lecture notes.

Chi Square Test

A statistical test to determine whether an observed set of results matches an expected outcome.

Chance

A random factor which must be considered when interpreting experimental results.

Inherent Variability

Variability due to the fact that measurements involving living organisms are under study.

Error

Mistakes introduced into experimental work in performing steps of procedures and in making measurements.

Critical Value of Chi Square

A predetermined chi square value that reflects how much difference can be accepted as insignificant, caused by random chance.

Selection of Critical Value of Chi Square

Having calculated a χ2 value for the data in experiment #1, we now need to evaluate that χ2 value. To do so we must compare our calculated χ2 with the appropriate critical value of χ2 from the table shown on the last page here.

Chi Square Test Interpretation

If calculated χ2 ≤ critical χ2, then we conclude that there is no statistically significant difference between the two distributions. That is, the observed results are not significantly different from the expected results, and the numerical difference between observed and expected can be attributed to chance.

Chi Square Test Common Mistake

The sum of observed values for all groups must equal the sum of expected values for all groups.

Null Hypothesis

Says that the difference found between observed distribution and expected distribution is not significant, i.e. that the difference is just due to random chance.

Tetrad

A foursome where duplicated homologous chromosomes associate themselves with one another.

Principle of Independent Assortment

The orientation of each tetrad in metaphase 1 is independent of the orientation of all other tetrads.

Principle of Independent Segregation

For every homologous pair, the homologues are separated from each other. Stated another way, it is the separation of alleles from each other at every locus.

Crossing Over

Can occur between homologous chromosomes as long as the homologues remain together as tetrads, i.e. during prophase I and metaphase I.

Bacteriology

Study of bacteria

Mycology

Study of fungi

Culture Tubes and Dishes

Containers in which microbes are grown.

Culture Medium

The nutrient base, which contains water, minerals, and organic nutrients, with proper pH.

Culture

The container + the medium + the microbe growing in or on that medium.

Slant

A tube containing slanted agar medium.

Colony

A mass of bacterial or fungal cells growing on the surface of an agar medium or stationary liquid medium.

Transfer

To move cells from a colony in one tube or dish to fresh medium in another container.

Sterile

No biological agents (bacteria, viruses, etc.) capable of reproducing are present.

Pure Culture

A culture that contains only one species, no contaminating species present.

Contaminant

An unwanted microbe that appears in a culture.

Aseptic technique

All methods, practices, procedures used to prevent spread of microbes in the work area and to prevent entry of contaminating microbes into your pure cultures or sterile media.

Positive Stain

A basic (a positively charged molecule) or acidic (a negatively charged molecule) stain that will bind to some component of cells.

Negative Stain

a negative stain such as nigrosin does not penetrate the cells, does not stain molecules of the cells. Instead, the stain darkens the background so that the unstained cells stand out as whitish light specks.

Binary Fission

Cell division in bacteria. This is a means of asexual reproduction: reproduction in which an individual gives rise to more genetically identical individuals without involvement of gametes and fertilization.

Non Pigmented bacteria

Cells are not pigmented (no color). They appear more or less white, in mass, on the surface of the agar medium

Gram-negative Species

One whose cells were decolorized by the alcohol wash step.

Bacterial Capsules

The individual cells secrete an extracellular (external) coating, called a capsule, which is made of polysaccharide molecules primarily.

Bacterial Spores

These microscopically small cells are readily carried on air currents and may give rise to new colonies if they happen to settle out of the air onto a source of nutrition

Statistical Tests

Statistical tests are tools that scientists use to analyze experimental results.

Sampling

Selection of the test individuals.

Sample

A subset of the population

T-test

Test a null hypothesis which states that the means (averages) of the two samples are equal, i.e. not significantly different.

Standard Deviation

An indication of how much the individual observations are spread out on either side of the mean value.

Null hypothesis

The means (averages) of the two samples are equal, i.e. not significantly different.

Accuracy

The true value, with all sources of error and bias eliminated.

Precision

The reproducibility of a measurement.

Turbidity

The haziness, or cloudiness of the air or water .

Turbidity

The scattering and reflecting of that light, light of all wavelengths ("white" light) from cells

Metaphase 1

These are the molecules that move with the solvent tend to spread out and form a band, or zone

Resolution

The degree of separation

Elution

Where the band of each dye dissolves off the paper

Contrast

Refers to how well an object stands out against its background.

Qualitative Test

A test to determine whether the suspected molecule is present at all

Quantitative Test

A test that also reveals the concentration of the molecule of interest in the solution; not just whether the molecule is present, but how much is present.

Osmotic Pressure

The pressure that would have to be applied to the solution in the bag to prevent pure water (on the other side of the membrane) from diffusing into the bag

Osmole

One mole of osmotically active particles

Water Osmosis

the pore size will allow the water molecules to pass through but not the solute molecules.

One to Ten

Means to combine one part of the given solution with nine parts of the solvent, not ten parts of solvent

One to Four

Means to add one part of any given solution to three parts the solvent, not four “parts” added, one (what is “given/there” to be extracted or diluted

What is precipitation?

Precipitation is any form of water, liquid or solid, that falls from the atmosphere to the Earth's surface.

What is condensation?

Condensation is the process by which water vapor in the air is changed into liquid water, typically forming clouds.

What is collection in the water cycle?

Collection is the stage where precipitation gathers in bodies of water, such as rivers, lakes, and oceans.

What drives the water cycle?

The sun drives the water cycle by providing the energy necessary for evaporation.

What is evaporation?

Evaporation is the process where liquid water is transformed into water vapor, entering the atmosphere.

What role does the sun play in the water cycle?

The sun provides the energy that drives the processes of evaporation and transpiration in the water cycle.

What is transpiration?

Transpiration is the process by which water is absorbed by plants from the soil and then evaporated into the atmosphere from their leaves.

How do human activities affect the water cycle?

Human activities, such as deforestation and urbanization, can disrupt natural processes of the water cycle, leading to changes in precipitation patterns and increased runoff.

What is groundwater?

Groundwater is the water stored beneath the Earth's surface in soil pore spaces and fractures of rock formations, which can be an important part of the water cycle.

What is the significance of watershed?

A watershed is an area of land that drains all the streams and rainfall to a common outlet, playing a critical role in the collection and distribution of water in the water cycle.

What is the water table?

The water table is the upper surface of groundwater, representing the level below which the ground is saturated with water.

Define aquifer.

An aquifer is a geological formation that can store and transmit groundwater, often tapped for human use through wells.

What is meant by the term 'hydrosphere'?

The hydrosphere encompasses all the water on Earth's surface, including oceans, rivers, lakes, and water vapor in the atmosphere.

Explain the process of infiltration.

Infiltration is the process by which water on the ground surface enters the soil, replenishing groundwater supplies.

What is the correlation between climate change and the water cycle?

Climate change can alter the water cycle by changing precipitation patterns, increasing evaporation rates, and affecting groundwater recharge.

Discuss the importance of the water cycle for ecosystems.

The water cycle is crucial for maintaining ecosystems as it helps regulate temperature, supports plant growth, and sustains wildlife habitats.

What are surface runoff and its environmental impacts?

Surface runoff is the water that flows over the land's surface toward water bodies; it can lead to erosion and transport pollutants, affecting water quality.

What is the process of sublimation?

Sublimation is the process where a solid changes directly into a vapor without becoming a liquid, often observed with ice or snow under certain conditions.

Describe the concept of relative humidity.

Relative humidity is the ratio of the current amount of water vapor in the air to the maximum amount of water vapor the air can hold at a given temperature, expressed as a percentage.

How can human pollution influence the water cycle?

Human pollution can contaminate water sources, disrupt natural purification processes, and contribute to acid rain, which affects ecosystems and water quality.

Define the term 'evapotranspiration'.

Evapotranspiration is the sum of evaporation and transpiration from the Earth's surface to the atmosphere, playing a critical role in the water cycle.

What is a climate zone, and how does it relate to the water cycle?

A climate zone is a region with distinct climatic conditions; it influences the intensity and distribution of precipitation and evaporation in the water cycle.

Explain the term 'thermal pollution' and its effect on water systems.

Thermal pollution refers to the degradation of water quality by changes in temperature, often due to industrial processes, affecting aquatic ecosystems and water's oxygen levels.

What is nutrient runoff, and how does it affect aquatic systems?

Nutrient runoff occurs when excess fertilizers wash into water bodies, leading to algal blooms that deplete oxygen and harm aquatic life.

What is watershed management?

Watershed management involves the careful management and conservation of water resources in a watershed to maintain water quality and ecosystem health.

Describe the role of wetlands in the water cycle.

Wetlands act as natural buffers, absorbing excess water from precipitation and providing habitat while filtering pollutants before they enter larger water bodies.

What is the impact of urbanization on the water cycle?

Urbanization can increase impervious surfaces, leading to higher runoff, reduced groundwater recharge, and altered local precipitation patterns.

Explain the significance of the hydrological cycle in climate regulation.

The hydrological cycle plays a critical role in regulating climate by distributing heat and moisture across the planet, impacting weather patterns and temperature.

What are the consequences of over-extraction of groundwater?

Over-extraction of groundwater can lead to decreased water availability, land subsidence, and deterioration of water quality due to higher concentrations of contaminants.

Define water pollution and its primary sources.

Water pollution refers to the contamination of water bodies, primarily from industrial discharge, agricultural runoff, sewage, and plastic waste.

What is a climate model?

A climate model is a scientific tool that simulates the interactions of the atmosphere, oceans, land surface, and ice to predict future climate changes and their impacts.

Define the term 'drought'.

A drought is an extended period of significantly lower precipitation than normal, resulting in water shortages and adverse environmental impacts.

What is the relationship between the water cycle and agricultural practices?

Agricultural practices can influence the water cycle through irrigation, soil management, and land use changes, affecting water availability and quality.

How does groundwater recharge occur?

Groundwater recharge occurs when water from precipitation and surface water infiltrates into the ground, replenishing aquifers and groundwater supplies.

Explain the concept of a water footprint.

A water footprint measures the total volume of freshwater used directly and indirectly by an individual, community, or product over a specific period.

What are 'blue water' and 'green water' in the context of the water cycle?

'Blue water' refers to freshwater in rivers, lakes, and aquifers, while 'green water' refers to water stored in soil and vegetation, critical for plant growth and ecosystems.