Curriculum

17 Sections
1548 Lessons
100 Days

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U01.01 Biochemistry
This biochemistry review for USMLE Step 1 covers essential topics including metabolism, enzymology, and molecular biology.
126
U01.02 Immunology
Prepare for USMLE Step 1 Immunology with a comprehensive review covering foundational concepts, immune system mechanisms, and key disorders to solidify your understanding and boost exam readiness.
42
U01.03 Microbiology
Review essential microbiology topics for the USMLE Step 1, covering key pathogens, mechanisms of disease, and antimicrobial principles critical for mastering infectious disease concepts.
172
U01.04 General Pathology
Explore key concepts in general pathology essential for the USMLE Step 1. This review covers fundamental principles, disease mechanisms, and clinical correlations to help you excel in your medical exam.
35
U01.05 Pharmacology
Master key pharmacology concepts for the USMLE Step 1 with a focus on drug mechanisms, therapeutic uses, adverse effects, and interactions essential for high-yield exam performance.
43
U01.06 Public Health Sciences
Review essential Public Health Sciences topics for the USMLE Step 1, covering epidemiology, biostatistics, health policy, and ethics to strengthen your understanding of foundational public health principles.
53
U01.07 Cardiovascular system
Comprehensive review of essential cardiovascular system topics to help you excel in the USMLE Step 1 exam, covering key concepts from anatomy to pathology.
73
U01.08 Endocrine system
Master essential concepts of the endocrine system for USMLE Step 1, covering hormone regulation, feedback mechanisms, and key disorders to boost your exam readiness.
51
U01.09 Gastrointestinal system
Review key topics in the gastrointestinal system for the USMLE Step 1, covering essential concepts in anatomy, physiology, pathology, and pharmacology to reinforce your understanding and test readiness.
131
U01.10 Hematology and Oncology
This review covers essential Hematology and Oncology topics for the USMLE Step 1, including hematopoiesis, coagulation, anemias, leukemias, lymphomas, and neoplastic syndromes.
148
U01.11 Musculoskeletal, Skin, and Connective Tissue
Review essential topics for the USMLE Step 1 Musculoskeletal, Skin, and Connective Tissue systems, covering anatomy, physiology, pathology, and pharmacology fundamentals critical for exam success.
178
U01.12 Neurology and Special Senses
Master the foundational concepts of Neurology and Special Senses with our USMLE Step 1 review, covering essential topics like neuroanatomy, neurophysiology, and sensory pathways.
143
U01.13 Psychiatry
Psychiatry for the USMLE Step 1 focuses on understanding the pathophysiology, diagnosis, and treatment of psychiatric disorders, with an emphasis on key concepts like neurotransmitter imbalances, mental health disorders, and pharmacology.
83
U01.14 Renal System
The Renal System review for USMLE Step 1 covers key concepts including renal physiology, nephron function, acid-base balance, electrolyte regulation, and renal pathology, crucial for understanding both normal and abnormal kidney functions.
81
U01.15 Reproductive System
The USMLE Step 1 Reproductive System review covers key concepts in human reproduction, including anatomy, physiology, endocrinology, and common pathologies affecting both male and female reproductive health.
124
U01.16 Respiratory System
The Respiratory System review for the USMLE Step 1 covers key concepts in anatomy, physiology, pathophysiology, and pharmacology essential for understanding respiratory diseases and treatments.
61
U01.17 Rapid Review
he USMLE Step 1 Rapid Review covers essential topics across multiple disciplines, providing a concise, high-yield overview to reinforce key concepts and optimize your exam preparation.
5

U01.01.037 Blotting procedures

Blotting techniques are widely used in molecular biology to analyze specific biomolecules such as DNA, RNA, and proteins. These methods help assess gene expression, genotype, and protein function. Below is a breakdown of the key blotting procedures and their applications, essential for students preparing for the USMLE Step 1.

1. Southern Blot

The Southern blot is a method for detecting specific DNA sequences in a sample. It involves several key steps:

Procedure:

DNA Cleavage: The DNA sample is enzymatically cleaved into smaller fragments.
Gel Electrophoresis: The cleaved DNA fragments are separated by size using gel electrophoresis.
Transfer to Filter: The separated DNA is transferred onto a filter (typically a nylon or nitrocellulose membrane).
Probe Hybridization: The filter is exposed to a radiolabeled DNA probe, which binds to its complementary DNA sequence on the membrane.
Visualization: The probe-bound DNA is visualized by exposing the filter to film, where the labeled DNA appears as a band.

Southern Blot Pedigree Example:

Genotype	Parent	Child
Aa	Aa	aa
AA	Aa	Aa
Aa	Aa	Aa

Key Points to Remember:

Southern blot detects DNA sequences.
It’s essential for genotype analysis and can be used to identify mutations or gene variations.

2. Northern Blot

Similar to the Southern blot but used to analyze RNA samples.

Procedure:

RNA Isolation: RNA is extracted from cells.
Electrophoresis: The RNA sample is separated by size on an agarose gel.
Transfer to Filter: The separated RNA is transferred onto a membrane.
Probe Hybridization: A labeled DNA or RNA probe is used to bind complementary RNA sequences.
Visualization: The probe-bound RNA is visualized similarly to Southern blotting.

Key Points to Remember:

Northern blot is used for studying mRNA levels, reflecting gene expression.
It helps identify gene transcription and can be used to compare the expression of genes across different conditions.

3. Western Blot

The Western blot is used to detect and analyze proteins in a sample.

Procedure:

Protein Separation: Proteins are separated by size using gel electrophoresis.
Transfer to Membrane: The proteins are transferred onto a membrane (usually nitrocellulose).
Antibody Binding: A labeled antibody specific to the target protein is added to bind to the protein of interest.
Visualization: The antibody binding is visualized by chemiluminescence or other detection methods.

Key Points to Remember:

Western blot detects proteins.
It is essential for analyzing protein expression, protein modifications (e.g., phosphorylation), and protein-protein interactions.

4. Southwestern Blot

A specialized blotting technique used to identify DNA-binding proteins.

Procedure:

Protein Separation: Proteins are separated by electrophoresis and transferred onto a membrane.
Probe Hybridization: Labeled double-stranded DNA probes are used to identify DNA-binding proteins on the membrane.

Key Points to Remember:

Southwestern blot is used to identify proteins that bind specifically to DNA (e.g., transcription factors like c-Jun, c-Fos).

SNoW DRoP Mnemonic

An easy way to remember the types of blotting techniques:

Southern = DNA
Northern = RNA
Western = Protein

Summary Table:

Type of Blotting	Sample Analyzed	Key Application
Southern Blot	DNA	Gene mutation detection, genotype analysis
Northern Blot	RNA	mRNA expression analysis, gene transcription
Western Blot	Protein	Protein detection, expression, and modifications
Southwestern Blot	Protein (DNA-binding)	Identifying DNA-binding proteins (e.g., transcription factors)

Points to Remember:

Southern blot is for DNA, used in mutation analysis.
Northern blot is for RNA, useful for studying gene expression.
Western blot is for proteins, used to analyze protein levels and modifications.
Southwestern blot identifies DNA-binding proteins, essential for studying transcription factors.

USMLE Step 1 Review Series

Curriculum

U01.01.037 Blotting procedures

1. Southern Blot

Procedure:

Southern Blot Pedigree Example:

Key Points to Remember:

2. Northern Blot

Procedure:

Key Points to Remember:

3. Western Blot

Procedure:

Key Points to Remember:

4. Southwestern Blot

Procedure:

Key Points to Remember:

SNoW DRoP Mnemonic

Summary Table:

Points to Remember:

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