Microbiology Genetics and Virology Review Flashcards

A complete 80-card vocabulary flashcard set created from lecture notes covering microbiology genetics, molecular biology processes, operons, mutations, and virology.

Genetics

The study of genes, function, and genomes.

Gene

Heritable units of genetic material that determine a particular trait.

Genomes

The entire collection of genetic material in a cell or virus.

Cellular vs Viral Genetic Material

Viruses have DNA or RNA; eukaryotic or prokaryotic cells have DNA only.

Central Dogma

Theory that genetic material flows from DNA to RNA to protein ($\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$).

Prokaryotic Chromosomes

Single circular chromosomes located in the nucleoid region.

Eukaryotic Chromosomes

Numerous linear chromosomes located in the nucleus.

Escherichia coli Gene Count

$E.\,coli$ has $4,400$ genes.

Yeast Gene Count

Yeast has $6,000$ genes.

Human Gene Count

Humans have $24,000$ genes.

Chromosomes

Packaged strands of DNA associated with organizational proteins.

DNA Main Parts

Phosphate group, Sugar (deoxyribose), and Nitrogen Base (Adenine-Thymine, Cytosine-Guanine).

Purines vs Pyrimidines Structure

Purines are double rings, while Pyrimidines are single rings.

Pyrimidines in DNA

Thymine (T) and Cytosine (C).

Purines in DNA

Adenine (A) and Guanine (G).

Antiparallel Strands

DNA strands run in opposite directions and are complementary; one strand runs $5'$ to $3'$, while the other runs $3'$ to $5'$.

RNA Structure

Has the sugar ribose, contains uracil to replace thymine, is often single-stranded, and folds on itself to form helical and loop structures.

DNA Replication

Unwinding of original DNA $\rightarrow$ copying DNA $\rightarrow$ rewinding parent DNA and newly made DNA.

Replication Fork

Site created at the origin of replication that is used for DNA replication.

Helicase

Unwinds the DNA by breaking hydrogen bonds between nitrogen bases.

Primase

Lays down RNA primers to initiate replication.

Gyrase and Topoisomerases

Relieve the coiling tension that develops as the DNA helix unwinds.

Single Stranded DNA Binding Proteins

Bind DNA strands to keep them separated until they are copied.

DNA Polymerase III

Main enzyme that builds DNA in the $5'$ to $3'$ direction; requires a $3'\text{-OH}$ group and cannot make a new strand from scratch.

DNA Polymerase I

Replaces RNA primers with DNA and plays a role in DNA repair.

Ligase

Forms phosphodiester bonds to seal nicks in the DNA sugar-phosphate backbone.

Leading Strand

Continuously synthesized new strand made in the same direction as helix unwinding, proceeding toward the replication fork.

Lagging Strand

New strand synthesized in the opposite direction of helix unwinding, proceeding away from the replication fork.

Transcription

Process that produces 3 types of RNA from a DNA template using RNA polymerase, promoters, and terminators.

Translation

Process that produces protein using mRNA, tRNA with anticodons, and ribosomes.

Transcription Location

Occurs in the nucleus in eukaryotic cells and in the cytoplasm in prokaryotic cells.

Promoter Sequence

DNA sequence where RNA polymerase binds to start transcription.

Terminator Sequence

DNA sequence that stops transcription when reached by RNA polymerase.

Reverse Transcription

Process where some cells and viruses use RNA as a template to build a copy of DNA.

Messenger RNA (mRNA)

RNA containing codons that code for either an amino acid or a stop signal.

Transfer RNA (tRNA)

RNA with an anticodon loop complementary to a codon, carrying amino acids to build proteins.

Ribosomal RNA (rRNA)

RNA that combines with proteins to form ribosomes.

Eukaryotic Ribosome

Active translation complex formed when a small $40S$ subunit and a large $60S$ subunit come together ($60S + 40S = 80S$ ribosome).

Start Codon

$AUG$.

Stop Codons

$UAA$, $UAG$, and $UGA$.

Translation Initiation

Ribosome attaches to mRNA, scans until it reaches the start codon, which pairs with the anticodon on initiator tRNA in the P site.

Translation Elongation

Ribosome moves down mRNA to make peptide bonds between matching amino acids.

Translation Termination

Ribosome encounters a stop codon, then releases the protein and detaches from mRNA.

Operon

Collection of genes controlled by a shared regulatory element.

Operon Repressor

Protein element that blocks transcription.

Operon Operator

Regulatory region that binds the repressor to block transcription.

Inducible Operons

Operons naturally off until activated to start transcription; involve an inducer and repressor.

Repressible Operons

Operons naturally on until repressed to be off; involve a repressor and corepressor.

Substitution Mutation

Mutation in which a nucleotide in DNA is replaced with a different one.

Insertion Mutation

Mutation where one or more nucleotides are added to DNA.

Deletion Mutation

Mutation where one or more nucleotides are removed from DNA.

Spontaneous Mutations

Naturally occurring mutations due to errors in DNA replication.

Mutagens

Chemical, physical, or biological agents that increase the rate of mutation.

Silent Mutation

A substitution mutation that results in no change in the amino acid.

Missense Mutation

A substitution mutation that results in a change in the amino acid.

Nonsense Mutation

A substitution mutation that codes for a stop codon instead of an amino acid.

Vertical Gene Transfer

Process when cells pass genetic information to the next generation.

Horizontal Gene Transfer

Passes genetic information between cells of the same generation via conjugation, transformation, or transduction.

Conjugation

Horizontal gene transfer where DNA is transferred through a conjugation (or sex) pilus.

Transformation

Horizontal gene transfer occurring when bacteria take up DNA from the environment.

Transduction

Introduction of new genetic material into a bacterial cell by a virus.

Viruses

Acellular, nonliving, infectious agents that are obligate intracellular pathogens infecting nearly all life forms.

Virion

A single, infectious virus particle.

Viral Genome

Internal nucleic acid component of a virus, consisting of DNA or RNA (not both).

Capsid

Exterior protective protein coat of a virus composed of capsomere subunits.

Capsomeres

Protein subunits that make up the viral capsid; their arrangement helps identify the virus.

Helical Capsid

Viral capsid structure that looks like a hollow tube.

Icosahedral Capsid

Viral capsid structure that looks like 3D polygons.

Complex Capsids

Deviations or variations from standard helical or icosahedral capsid structure.

Enveloped Viruses

Viruses that have an outer lipid envelope surrounding their capsid.

Naked Viruses

Viruses that lack an outer lipid envelope.

Spikes (Viral)

Protrusions from viral capsid or envelope that aid in attachment and bind only to specific host cell factors.

Influenza Spike Proteins

Hemagglutinin (HA) and Neuraminidase (NA).

Host Range

Collection of species that a virus can infect.

Tropism

Specific tissues or cells within the host that a virus can infect (cellular, tissue, host).

Broad Tropism vs Narrow Tropism

Broad tropism infects a wide range of host cells or tissues; narrow tropism infects only one type.

dsDNA Virus Pathway

$\text{dsDNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$.

ssRNA+ Virus Pathway

$\text{ssRNA+} \rightarrow \text{Protein}$ (can be immediately translated into protein).

Single Stranded RNA Retrovirus Pathway

$\text{ssRNA} \rightarrow \text{DNA} \rightarrow \text{mRNA} \rightarrow \text{Protein}$.

Antigenic Drift

Minor genetic changes that alter viral spike proteins (e.g., HA or NA), preventing rapid immune system recognition.