2.1-2.2-2.3 bio quiz help me god

Who discovered the DNA double helix and in what year?

James Watson and Francis Crick in 1953.

What crucial images aided in the discovery of the DNA structure?

X-ray diffraction images, particularly 'Photo 51' by Rosalind Franklin.

What is the structure of DNA?

A double helix made of two antiparallel strands composed of nucleotides.

What are the components of a nucleotide?

A phosphate group, a deoxyribose sugar, and a nitrogenous base.

Which bases pair together in DNA?

Adenine (A) with Thymine (T) and Guanine (G) with Cytosine (C).

What is DNA replication and its direction?

The process of copying DNA that occurs in the 5' → 3' direction.

What are the leading and lagging strands in DNA replication?

The leading strand is synthesized continuously, while the lagging strand is synthesized in Okazaki fragments.

What enzyme is responsible for adding new nucleotides during DNA replication?

DNA polymerase.

What does the Central Dogma of molecular biology describe?

The flow of genetic information: DNA → RNA → Protein.

What are codons and their role in the genetic code?

Three-base units that specify one of the 20 amino acids used to build proteins.

What is a mutation in the context of DNA?

Any change in the nucleotide sequence of DNA.

What is base substitution and its significance?

A mutation where one nucleotide is replaced with another, causing conditions like Sickle Cell Anemia.

What are deletions and insertions in DNA?

Changes that add or remove nucleotides, potentially altering the reading frame of codons.

What are exons and introns in eukaryotic genes?

Exons are coding regions, while introns are non-coding regions within a gene.

What happens during RNA processing?

A 5' cap and a 3' poly-A tail are added, introns are removed, and exons are spliced together.

What is mitosis and its outcome?

Cell division for growth and repair that results in two genetically identical diploid daughter cells.

What is meiosis and its significance?

Cell division that produces gametes, resulting in four genetically distinct haploid cells.

What is a karyotype?

A display of all the chromosomes in a cell, showing 23 pairs in humans.

What is an operon in prokaryotic gene regulation?

A cluster of genes controlled by a single on/off switch for efficient regulation.

What is the lac operon?

An inducible system that regulates lactose digestion genes based on lactose presence.

What is differential gene expression?

The process by which cells with the same DNA become specialized by expressing different sets of genes.

What is epigenetics?

Heritable changes in gene expression that do not alter the DNA sequence itself.

What are transcription factors?

Proteins that bind to DNA to regulate gene expression by activating or repressing transcription.

What are Hox genes and their importance?

A class of transcription factors that establish the body plan of an embryo, conserved across species.

What is alternative RNA splicing?

A process that allows one gene to produce multiple proteins by splicing exons in different combinations.

What is RNA interference (RNAi)?

A mechanism that silences genes post-transcription by destroying target mRNA molecules.