Unit 5 Microbial genetics

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Questions and Answers

What does adaptation refer to in a population?

The introduction of new genetic information

Rapid cell division due to environmental changes

The survival of the weakest individuals

A successful mutation becoming predominant (correct)

Which phase of DNA replication involves the unwinding of the DNA strand?

Initiation (correct)

Replication

Termination

Elongation

What is the role of primase during DNA replication?

To bind Okazaki fragments together

To add nucleotides to the leading strand

To unwind the DNA strands

To initiate the synthesis of new DNA strands (correct)

Which method of gene transfer introduces genetic diversity through viral infection?

Bacterial Transduction Signup and view all the answers

What occurs during the elongation phase of DNA replication?

Nucleotide bases are paired at the replication fork Signup and view all the answers

What characterizes bacterial conjugation?

Transfer of genetic information between donor and recipient Signup and view all the answers

In which phase does DNA replication stop at the Tus-Ter sequence?

Termination Signup and view all the answers

What is the main goal of genetic engineering?

To alter genetics for desired traits Signup and view all the answers

What are the three components of a nucleotide?

Sugar, Phosphate, Nitrogenous base Signup and view all the answers

Which type of mutation results in the production of a non-functional protein?

Nonsense mutation Signup and view all the answers

Which of the following best describes a genotype?

The collection of genes an organism can have Signup and view all the answers

During which process is DNA converted into messenger RNA?

Transcription Signup and view all the answers

How do point mutations primarily affect the DNA sequence?

They substitute a single base with another base Signup and view all the answers

What role do alleles play in genetics?

They represent different versions of a gene Signup and view all the answers

What effect does a silent mutation have on protein synthesis?

It has no effect on the protein produced Signup and view all the answers

In which type of organisms are chromosomes typically circular?

Prokaryotes Signup and view all the answers

Study Notes

Microbial Genetics

DNA is made up of nucleotides, which are composed of a sugar (deoxyribose), a phosphate, and a nitrogenous base.
There are four nitrogenous bases: Adenine, Thymine, Guanine, and Cytosine.
Nucleic acids store and transfer genetic information.
- DNA is the storage molecule for the instructions for all proteins and metabolic reactions.
- DNA can be replicated and passed down to offspring.
- DNA can be transcribed into RNA for protein synthesis.
Chromosomes are made of DNA and can be circular (Prokaryotes) or linear (Eukaryotes).
A gene is a sequence of nucleotides located on a chromosome.
Alleles are different versions of a gene.
Genotype refers to the complete set of genes an organism possesses.
Phenotype refers to the observable characteristics of an organism resulting from the interaction of genes and the environment.

Protein Synthesis

Transcription uses DNA as a template to produce messenger RNA (mRNA).
Translation uses mRNA to produce a specific protein.
The codon table decodes mRNA codons into amino acids. Each three-base codon codes for a specific amino acid.

Mutations

A mutation is a heritable change in the DNA sequence.
Mutations can lead to changes in phenotype when compared to the wild type, which is the most common form in nature.

Types of Mutations

Point mutations involve the substitution of a single base.
Insertions are the addition of one or more bases.
Deletions are the removal of one or more bases.

Effects of Mutations on Proteins

Silent mutations have no effect on the protein sequence.
Missense mutations result in the incorporation of a different amino acid into the protein.
Nonsense mutations convert a codon into a stop codon, usually leading to a non-functional protein.

Adaptation and Mutation

A mutation can be successful if it leads to an adaptive advantage, where the mutant is more successful than the non-mutant form.
A mutation can be neutral if there is no difference in success between the mutant and non-mutant form.
A mutation can be deleterious if the mutant is less successful than the non-mutant form.
Adaptation occurs when a successful mutation spreads throughout a population, becoming the dominant form.

DNA / Chromosome Replication

Replicated in three phases: Initiation, Elongation, and Termination

Initiation (DNA Replication)

Origin of replication (oriC) is a specific DNA sequence that marks the start of replication.
The DNA strand unwinds at the oriC, creating two single strands.
- Helicase unwinds the DNA.
- This creates two replication forks.

Elongation (DNA Replication)

Polymerase replicates the two strands.
- Polymerase cannot start replication, it can only extend an existing strand.
- Primase primes the strands for replication by adding short primers that are recognized by polymerase.
Replication occurs in both directions: leading and lagging strands.
Okazaki fragments are created on the lagging strand.
- Ligase binds these fragments to create a contiguous strand.
Topoisomerases (like gyrase) resolve winding issues that arise during replication.

Termination (DNA Replication)

Termination (Tus-Ter) sequence is recognized by the polymerase.
Replication stops at the Tus-Ter sequence.
Two new loops are formed and migrate toward opposite ends of the bacterium.
A septum begins to form, leading to the creation of two new cells.

Gene Transfer

Binary fission is the simple asexual division of bacteria.
- It does not create genetic diversity.
Bacterial conjugation involves the transfer of genetic information from a donor cell to a recipient cell.
- It introduces genetic diversity.
Bacterial transformation allows bacteria to pick up genetic information from the environment.
- It can confer new characteristics, increasing diversity.
Bacterial transduction involves the transfer of bacterial DNA using bacteriophages (viruses that infect bacteria).
- Viral DNA is inserted into bacterial DNA.
- The virus replicates, incorporating bacterial and viral DNA.
- Newly formed viruses can then infect other bacteria, transferring bacterial DNA.

Biotechnology

Biotechnology uses living systems to benefit humankind.
Genetic engineering alters an organism's genetics to achieve desired traits.

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Description

Explore the fundamentals of microbial genetics and the intricate process of protein synthesis. This quiz covers essential concepts such as DNA structure, gene function, and the roles of genotype and phenotype in genetics. Test your knowledge on how nucleic acids store genetic information and how proteins are synthesized from these codes.