Biology: Scientific Reports, Protein Assays, Cell Division, Genetics, and DNA Analysis

Parts of a scientific report

Title, Introduction, Methods, Results, Discussion, References.

What belongs in the Introduction?

Background info, purpose, hypothesis.

What belongs in the Methods section?

Step-by-step procedure written in past tense.

What belongs in the Results section?

Data only—graphs, tables, summaries (no interpretation).

What belongs in the Discussion section?

Interpretation of results, significance, errors, limitations.

How should graphs be labeled?

Labeled axes with units, clear title, figure number below graph.

Objective of the Biuret protein assay

Determine the protein concentration of an unknown sample.

What is a standard curve?

A graph of known concentrations vs absorbance used to estimate unknowns.

Which protein was used as the standard?

Bovine Serum Albumin (BSA).

What does a spectrophotometer measure?

Absorbance of light.

What does SDS do?

Denatures proteins.

What does centrifugation do?

Separates components by spinning.

What do glass beads do?

Break open cells mechanically.

What does vortexing do?

Mixes samples thoroughly.

What does the Biuret reagent detect?

Peptide bonds; turns purple if protein is present.

How is color related to protein concentration?

Darker purple = higher protein concentration.

What is the purpose of a standard curve?

To estimate the concentration of unknown samples.

What happens in Prophase?

Chromosomes condense, spindle forms, nuclear envelope breaks down.

What happens in Metaphase?

Chromosomes line up in the center of the cell.

What happens in Anaphase?

Sister chromatids separate.

What happens in Telophase?

Nuclear membranes reform, chromosomes de-condense.

What happens during Cytokinesis?

The cell divides into two daughter cells.

Difference between plant and animal mitosis

Plants form a cell plate; animals form a cleavage furrow.

How to identify plant vs animal cells

Plant cells are boxy with cell walls; animal cells are rounder.

Scientific name of the fruit fly

Drosophila melanogaster (underlined when handwritten).

Why Drosophila melanogaster is a good model organism

Short life cycle, many offspring, cheap, easy to maintain, well-studied genetics.

Male fruit fly characteristics

Smaller body, dark rounded abdomen, sex combs on front legs.

Female fruit fly characteristics

Larger body, pointed striped abdomen, no sex combs.

Inheritance pattern of the white-eye mutation

X-linked recessive.

Dissecting vs compound microscope

Dissecting = low magnification, 3D; compound = high magnification, 2D.

What is DNA fingerprinting?

A method that compares DNA band patterns to identify individuals.

What are polymorphic regions?

DNA segments that vary among individuals.

What does PCR do?

Amplifies (copies) specific DNA sequences.

Purpose of restriction enzymes

Cut DNA at specific sequences.

Purpose of agarose gel

Separates DNA fragments by size.

Purpose of ethidium bromide

Stains DNA so bands glow under UV light.

Purpose of loading dye

Adds color and weight to samples so they sink into wells.

Purpose of running buffer

Conducts electricity through the gel.

Purpose of DNA ladder

Provides reference fragment sizes.

Charge of DNA

Negative.

Direction DNA travels in electrophoresis

Toward the positive electrode (anode).

Which DNA fragments travel farther in a gel?

Smaller fragments.