1-22-24 Genes

What is a chromosome?

A discrete unit of the genome carrying many genes.

What is a structural gene?

A gene that encodes any RNA or polypeptide product other than a regulator.

Define allele.

One of several alternative forms of a gene occupying a given locus on a chromosome.

What does locus refer to in genetics?

The position on a chromosome at which the gene for a particular trait resides.

What is genetic recombination?

A process by which separate DNA molecules are joined into a single molecule, due to processes such as crossing over or transposition.

What evidence supports that DNA is the genetic material in bacteria?

Bacterial transformation, where genetic properties are transferred between bacterial strains through DNA.

What is the transforming principle?

DNA that is taken up by a bacterium and whose expression then changes the properties of the recipient cell.

How was it shown that DNA is the genetic material of viruses?

Through phage infection experiments that demonstrated only DNA is transmitted to progeny phages, not proteins.

What is transfection in eukaryotic cells?

The acquisition of new genetic markers by incorporation of added DNA.

What structural difference exists between DNA and RNA?

DNA has a deoxyribose sugar (2′–H) whereas RNA has a ribose sugar (2′–OH).

Name the nitrogenous bases found in DNA.

Adenine, guanine, cytosine, and thymine.

What is supercoiling in DNA?

The coiling of closed duplex DNA in space so that it crosses over its own axis.

What is semiconservative replication?

DNA replication accomplished by separation of the strands of a parental duplex, each serving as a template for a complementary strand.

Define denaturation in the context of DNA.

The separation of the two strands due to breaking of hydrogen bonds between bases.

What does the central dogma of molecular biology state?

Information cannot be transferred from protein to protein or protein to nucleic acid, only between nucleic acids and from nucleic acid to protein.

What are frameshift mutations?

Mutations that insert or delete individual bases, causing a shift in the triplet sets after the site of mutation.

What is an open reading frame (ORF)?

A sequence of DNA consisting of triplets that can be translated into amino acids, starting with an initiation codon and ending with a termination codon.

Describe a complementation test.

A test that determines whether two mutations are alleles of the same gene by crossing different recessive mutations with the same phenotype.

What happens when a gene undergoes a null mutation?

It completely eliminates the function of the gene.

What is gene expression?

The process by which the information in a sequence of DNA in a gene is used to produce RNA or a polypeptide.

Define ribosome.

A large assembly of RNA and proteins that synthesizes polypeptides under direction from an mRNA template.

What distinguishes cis-acting mutations?

They identify sequences of DNA that are targets for recognition by trans-acting products and affect only the contiguous stretch of DNA.

What is DNA?

Deoxyribonucleic acid, a molecule that carries the genetic instructions for life.

What are genes?

Segments of DNA that code for proteins or functional RNA.

What is a phenotype?

The observable physical or biochemical characteristics of an organism, determined by genetic and environmental factors.

What is a genotype?

The genetic constitution of an individual, specifically the alleles present at a locus.

Define transcription.

The process of copying a segment of DNA into RNA.

What is translation?

The process by which ribosomes synthesize proteins using the mRNA template.

Name the types of RNA involved in protein synthesis.

Messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).

What is a mutation?

A change in the DNA sequence that can lead to variation in traits.

What is a dominant allele?

An allele that expresses its phenotype even in the presence of a recessive allele.

What is a recessive allele?

An allele that only expresses its phenotype when two copies are present.

What are homologous chromosomes?

Pairs of chromosomes that are similar in shape, size, and genetic content.

Define crossing over.

The exchange of genetic material between homologous chromosomes during meiosis.

What is polygenic inheritance?

A mode of inheritance where multiple genes influence a trait.

What is epistasis?

Interaction between genes in which the presence of one gene can inhibit or mask the expression of another.

Define genetic drift.

A mechanism of evolution that involves random changes in allele frequencies in a population.

What is natural selection?

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

What is speciation?

The formation of new and distinct species in the course of evolution.

Define chromatid.

One half of a duplicated chromosome, joined by a centromere.

What is a centromere?

The region of a chromosome where two sister chromatids are joined.

What are telomeres?

Protective caps located at the ends of chromosomes that prevent degradation.

What is a plasmid?

A small circular DNA molecule found in bacteria that is independent of chromosomal DNA.

Define biotechnology.

The use of living systems and organisms to develop or make products.

What is gene therapy?

A technique that modifies a person's genes to treat or prevent disease.

What is CRISPR?

A genome editing technology that allows for precise modifications to DNA.

Define recombinant DNA.

Dna that has been artificially made by combining constituents from different organisms.

What is a DNA probe?

A nucleic acid sequence that can bind to a specific DNA sequence for detection purposes.

What are restriction enzymes?

Proteins that cut DNA at specific sequences, often used in genetic engineering.

Define a locus.

A fixed position on a chromosome where a particular gene or genetic marker is located.

What is mRNA splicing?

The process of editing the primary RNA transcript by removing introns and connecting exons before translation.

What is a genetic marker?

A gene or DNA sequence with a known location on a chromosome that can be used to identify individuals.

What is gene dosage?

The number of copies of a gene present in a genome, which can affect phenotype.

},{