top of page
3D model of an animal virus with spike proteins

Viruses

​

It may seem a bit strange to include the topic of viruses in the biotechnology/genomes section, but as you will learn, viruses are not considered living things.  They are essentially a protein coat containing genetic material inside.  

 

​

Virus Structure:

  • Capsid = protein coat, sometimes covered with a viral envelope (especially common in animal viruses)
     

  • Contains single-stranded or double-stranded DNA or RNA inside

This article has nicely labeled diagrams for both animal viruses and bacteriophages

 

​

Types of Viruses:

  • Bacteriophages = infect bacteria.  Most common is the T4 phage
     

  • Animal viruses, such as adenoviruses and influenza viruses

    • Retroviuses = type of animal virus.  It is very important to understand their replicative cycle.  They have a special enzyme called reverse transcriptase, which allows them to transcribe RNA back to DNA.  Use this diagram to study the steps

 

​

Virus replication cycles:

Viruses can only replicate inside host cells.  Viruses can switch between two types of cycles, the lytic and lysogenic cycles.  Watch this Khan Academy video for the differences between the two

  • Lytic = the last stage of this cycle lyses (bursts open) the host cell, thus killing it.  Those that only replicate via the lytic cycle are called virulent phages  
     

  • Lysogenic = this involves a prophage (or provirus, for animal host cells), which is the genetic material inserted by the virus into the host.  That genetic material gets incorporated into the host’s DNA, and it remains dormant until it switches to the lytic cycle at some point.  Even though it’s dormant, the prophage is replicated each time the host cell (e.g., bacterium) reproduces

 

​

Other terms to know:

  • Vaccines -- how are they made?  What is their purpose?
     

  • Prions (infectious proteins; these were the cause of Mad Cow Disease)

Closeup of a Petri Dish

Biotechnology

​

This chapter covers a lot of different and new techniques in biotechnology and bioengineering.  Many of the methods involve genetic engineering, which is the practice of manipulating genes in a useful way.

For an overview and diagrams of the most common techniques to know for the AP, read this section from OpenStax Biology.

 

​

Some key concepts/terms:

  • Plasmids.  What are they and where are they found?  What are some real examples of how can they be used in biotechnology?  What is the difference between a plasmid and a vector?  

    • Also understand the different steps and materials needed to create a recombinant plasmid and a cloning vector.  For example, you should know what sticky ends, restriction enzymes, and DNA ligase are
       

  • Genomic libraries.  There are several different ways of creating such a library; know what bacterial artificial chromosomes, cDNA, and cDNA libraries are
     

  • PCR.  This is a very important topic and comes up often on the exam.  PCR is a common method of rapidly amplifying (making many copies) DNA.  Know the 3 PCR stages: denaturation, annealing, and extension, as well as the relative temperature required for each stage. Khan Academy has a good overview of PCR.
     

  • Gel electrophoresis.  Another important tool.  Understand how it works and what the purpose is.  Know that it is often used in conjunction with PCR

 

​

Understanding Gene Expression

There are also tools used to understand when or where a particular gene is expressed.  Examples of tools to know:

  • In situ hybridization -- often called FISH (F stands for fluorescent)
     

  • In vitro mutagenesis -- knocking out a gene and observing what happens

 

​

Understand the basics of cloning and how stem cells can help with the process

 

There is a lot of vocabulary in this chapter.  Below is a visualized summary of the tools and terms to know:

Biotechnology - AP biology vocabulary cheatsheet

Genomes

​

Understand the basic purpose and steps of the whole-genome shotgun approach to genome sequencing

 

​

Types of DNA in eukaryotes:

  • Exons (coding segments of DNA)
     

  • Introns (noncoding segments)
     

  • Transposable elements and short tandem repeats (STRs).  These are all repetitive DNA

    • Know the difference between transposons and retrotransposons, and how each works.  This section from Libretext Biology is great for reviewing this topic.  Refer to the diagram below for a comparison:

[insert diagram]
 

  • Homeobox, a DNA sequence that specifies the physical arrangement/order of body parts

​

​

Understand multi-gene families and how they evolved over time.  Alpha- and beta-globin genes are a great example of a multi-gene family

In addition to knowing the concepts and terminology, it's also crucial to apply them by doing plenty of practice problems.  If you're struggling to find good problems to work through, check out our popular Practice Portal!  

bottom of page