BIO 111 Lab Practical 2 Review: Enzymes, Photosynthesis, Mitosis, Genetics, DNA Technology, and Scientific Inquiry

Study Guide - Smart Notes

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Catalyst: A substance that increases the rate of a chemical reaction without being consumed.
Enzyme: A biological catalyst, typically a protein, that speeds up biochemical reactions.
Denatured: The loss of an enzyme's native structure, resulting in loss of function, often due to heat or pH changes.
Substrate: The reactant on which an enzyme acts.
Product: The substance(s) formed from the substrate(s) in an enzyme-catalyzed reaction.
Active Site: The region on the enzyme where the substrate binds.
Dependent Variable: The variable being measured in an experiment (e.g., rate of reaction).
Independent Variable: The variable that is changed or controlled (e.g., temperature).

Substrate: Hydrogen peroxide (H2O2).
Enzyme: Catalase (from yeast solution).
Products: Water (H2O) and oxygen gas (O2).
Observation: Pieces of paper dipped in yeast solution float to the top of hydrogen peroxide due to oxygen bubbles produced by catalase activity.

Identify control tubes (no enzyme or no substrate) to compare with experimental tubes.
Interpret data on enzyme activity at different temperatures (e.g., optimal temperature yields highest activity; extreme temperatures may denature the enzyme).
Dependent variable: Rate of paper floating (proxy for enzyme activity).
Independent variable: Temperature.
Graph type: Line graph (enzyme activity vs. temperature).

At optimal temperature, most paper disks float quickly; at high or low temperatures, fewer disks float due to decreased enzyme activity.

Leaf disks are placed in solutions with varying carbon dioxide concentrations and exposed to light or dark conditions.
Light conditions: Disks float as photosynthesis produces oxygen, forming bubbles in leaf tissue.
Dark conditions: Disks do not float because photosynthesis does not occur; no oxygen is produced.
Higher CO2 concentrations increase the rate of photosynthesis, resulting in more floating disks.
Dependent variable: Number of floating disks (rate of photosynthesis).
Independent variable: Light condition or CO2 concentration.

Paper chromatography separates plant pigments based on polarity.
Rf value: Ratio of distance moved by pigment to distance moved by solvent front.

Polar solvent: Water.
Non-polar solvent: Organic molecules (e.g., acetone, petroleum ether).
Movement of pigment depends on:
- Polarity of solute (pigment).
- Polarity of solvent.

Cell Cycle Stages (in order): Interphase (G1, S, G2), Mitosis (M), Cytokinesis.
Mitosis Stages (in order): Prophase, Metaphase, Anaphase, Telophase.

Interphase: Cell grows, DNA replicates, organelles duplicate.
Prophase: Chromosomes condense, spindle forms, nuclear envelope breaks down.
Metaphase: Chromosomes align at the cell equator.
Anaphase: Sister chromatids separate and move to opposite poles.
Telophase: Nuclear envelopes reform, chromosomes decondense.
Cytokinesis: Division of cytoplasm, forming two daughter cells.

Genotype: Genetic makeup of an organism (e.g., AA, Aa, aa).
Phenotype: Observable traits (e.g., flower color).
Recessive: Trait expressed only when two recessive alleles are present.
Homozygous: Two identical alleles (AA or aa).
Heterozygous: Two different alleles (Aa).
Complete dominance: One allele completely masks the other.
Co-dominance: Both alleles are fully expressed (e.g., AB blood type).
Incomplete dominance: Heterozygote shows intermediate phenotype (e.g., pink flowers from red and white parents).
Sex-linked traits: Traits controlled by genes on sex chromosomes (often X-linked).

Used to predict genotype and phenotype ratios for autosomal and sex-linked traits.
Recognize inheritance patterns based on phenotype and genotype data.

Restriction enzymes: Proteins that cut DNA at specific sequences (recognition sites).
They produce DNA fragments of predictable sizes.

Given a plasmid map, count the number of cut sites to determine the number and size of DNA fragments produced.

DNA fragments are separated by size using an electric field in agarose gel.
Direction of migration: DNA moves toward the positive electrode (anode) because DNA is negatively charged.
Relative distance: Smaller fragments move farther; larger fragments move less.
Interpret gel results: More bands = more fragments; largest fragment = closest to wells; smallest fragment = farthest from wells.