BIO 204 Lab Midterm Study Guide - Natural Selection, Biomolecules, Diffusion and Osmosis, Enzymes

Natural selection

Process explaining changes in populations based on survival of the fittest

Environment

Influences traits in a population through natural selection

Trait variation

Different traits' fate described and graphed in a specific environment

Scientific method

4-step process: objective observations, hypothesis formation, hypothesis testing, analysis and conclusion

Positive control

Shows presence of the thing being tested (example - oil when testing for lipids)

Negative control

Shows absence of the thing being tested (example - DI water when testing for lipids)

Constant variables

Things unchanged throughout an experiment

Qualitative testing

Using reagents to detect biomolecules and interpret positive/negative results

Protein diversity

Caused by different R-groups

Protein conformation

Determines three-dimensional shape

Spectrophotometer

Measures absorbance of a specific concentration

Absorbance

Measured value related to concentration

Standard curve

Line showing relationship between concentration and absorbance

Beer's Law equation

Relates absorbance and concentration

Diffusion

Movement of solutes from high to low concentration

Osmosis

Movement of water from low to high solute concentration

Molarity

Solute particle concentration of a solution

Osmolarity

Total solute particle concentration of a solution

Tonicity

Effect of osmolarity on cell volume

Factors influencing diffusion

Different from factors influencing diffusion across dialysis tubing

Direction of water diffusion

Hyper-, hypo-, or isotonic conditions

Simple sugars vs. starch diffusion

Determining which can diffuse across a membrane

Results of blood and plant cells in different solutions

Hypertonic, hypotonic, and isotonic conditions

Internal Turgor pressure - when does it happen?

It happens with a hypo osmotic solution that increases and then plateaus

Enzyme

Catalytic protein with important conformation

Rate of enzymatic reaction

Determined by V0, the initial velocity

Denaturation

When the enzyme loses its structure and function

Substrate concentration, pH, and temperature

Factors affecting enzymatic reaction rate

KOH in enzyme lab

Used to stop the reaction and cause a color change because it reacts with the nitrophenyl phosphate which produces the yellow color to tell us how much product was made; the more yellow produced => more product produced (only appears at basic pH levels). KOH is a base so by adding it to the enzyme it denatures the enzyme, completely denaturing the enzyme

What is natural selection?

Process where individuals with certain traits survive and reproduce.

How does natural selection affect populations?

Individuals without traits will die off.

How does the environment influence traits through natural selection?

Traits that help survival will be more common.

Describe the fate of different traits in a given environment.

Traits that aid survival will become more common.

What is the first step of the scientific method?

Objective observation without bias.

What is the fourth step of the scientific method?

Analysis and conclusions.

What is an independent variable?

The manipulated variable (x-axis).

What is a dependent variable?

The measured variable (y-axis).

What type of graph is used for displaying variables?

Bar or scatter plot.

What is a control group?

A group that doesn't receive the treatment.

What is a scatter plot?

A graph comparing a change over time and it HAS A TRENDLINE

What is a bar graph used for?

To compare 2 or more groups AVERAGES and there is no trendline

What is a constant in an experiment?

Something that remains unchanged throughout the experiment.

Give an example of a constant in an experiment.

Keeping the amount of biuret constant in protein standards.

What are the key characteristics of carbohydrates?

Sugars and starches.

What are the key characteristics of lipids?

Fats, waxes, oils, and steroids.

What are the key characteristics of proteins?

Structural molecules and enzymes.

What are the key characteristics of nucleic acids?

DNA, RNA, and ATP.

What are the monomers of lipids?

Fatty acids and glycerol.

What are the polymers of lipids?

No true polymers for lipids.

What is a polymer?

A long molecule consisting of similar or identical building blocks (monomers).

What is the monomer of carbohydrates?

Monosaccharides.

What is the polymer of carbohydrates?

Polysaccharides.

What is the monomer of lipids?

Fatty acids.

What is the polymer of lipids?

Triglyceride.

What is the monomer of proteins?

Amino acids.

What is the polymer of proteins?

Polypeptide bonds.

Give examples of each class of biomolecule.

Carbohydrate: potato, Lipid: oil, Protein: insulin, Nucleic acid: DNA.

What reagent is used to detect carbohydrates?

Benedict's test.

What does Benedict's test detect?

All monosaccharides/simple sugars.

What color change indicates a positive result in Benedict's test?

Change from blue to another color after being BOILED!

What reagent is used to detect starch?

Lugol's Iodine test.

What does Lugol's Iodine test detect?

All starches.

What color change indicates a positive result in Lugol's Iodine test?

Change from violet, blue, or black.

What reagent is used to detect lipids?

Sudan IV Test.

What does Sudan IV Test detect?

Lipids.

What visual change indicates a positive result in Sudan IV Test?

Rises above water and has a slight pink/red color.

What reagent is used to detect proteins?

Biuret Reagent Test.

What does Biuret Reagent Test detect?

Proteins.

What color change indicates a positive result in Biuret Reagent Test?

Change color to purple after it's placed in the spectrometer

What is the purpose of positive and negative controls in testing for biomolecules?

To help determine the outcome of the sample being tested.

Why are proteins so diverse?

The R-group (side chain) of amino acids can vary.

What determines the three-dimensional shape of a protein?

The sequence of amino acids.

What does a spectrometer do?

Measures the intensity of light as a function of color.

How is absorbance measured?

By measuring the intensity of light absorbed by a substance.

How does the concentration of a substance relate to its absorbance value?

The higher the concentration, the higher the absorbance value.

What is absorbance?

Amount of light sample absorbs.

What does a higher absorbance indicate?

Darker solution.

What is a standard curve used for?

Shows relationship between concentration and absorbance.

Describe the process of setting up a standard curve.

Plot absorbance vs. concentration of known solutions.

What does 'standard' mean in the context of a standard curve?

Solutions with known concentrations.

What does the R2 value indicate?

How well the equation fits the data.

What is the equation for a standard curve?

y=mx or A=ec.

How can the standard curve and Beer's Law equation be used to find concentrations of specific molecules in an unknown sample?

By determining the relationship between concentration and absorbance.

What is Brownian motion?

Random motion of molecules.

What is diffusion?

Spontaneous spreading of molecules from high to low concentration.

Is diffusion passive or directed?

Passive.

When does net movement in diffusion stop?

When concentration equilibrium is reached.

What is osmosis?

Diffusion of water across a semipermeable membrane.

Can all solutes diffuse across a membrane?

No, not all solutes can.

How does molarity differ from osmolarity?

Molarity is concentration of solute, osmolarity is concentration of water.

How does osmolarity differ from tonicity?

Osmolarity looks at concentration, tonicity looks at direction of water movement.

What does hyperosmotic mean?

Higher osmolarity than another solution.

What does hypoosmotic mean?

Lower osmolarity than another solution.

What does isosmotic mean?

Equal solute concentration between two solutions.

What does tonicity depend on?

Total solute concentration and solute permeability of membrane.

What does isotonic mean?

Same solute concentration as cell.

What is diffusion?

Movement of molecules from high to low concentration.

Why can simple sugars like monosaccharides diffuse?

They are small enough to pass through a membrane.

Why can't disaccharides diffuse?

They are too big to pass through a membrane.

What is starch?

A glucose polymer made up of multiple monosaccharides.