LESSON 8 – DNA, RNA, and Central Dogma

Kuya Gk's Transes

What is the basic principle of DNA replication?

Base pairing to a template strand.

What model of DNA replication did Watson and Crick propose?

Semiconservative replication.

What does semiconservative replication mean?

Each daughter DNA has one old strand and one new strand.

Which scientists confirmed semiconservative replication?

Matthew Meselson and Franklin Stahl.

What isotope was used in the Meselson-Stahl experiment?

Heavy nitrogen.

What is a chromosome?

A DNA molecule packed together with proteins.

What type of DNA do bacteria have?

Double-stranded circular DNA.

Where is bacterial DNA found?

In the nucleoid.

What is chromatin?

DNA–protein complex in eukaryotic cells.

What proteins are DNA wrapped around?

Histones.

What is euchromatin?

Loosely packed chromatin.

What is heterochromatin?

Highly condensed chromatin.

Why is heterochromatin less expressed?

Dense packing limits gene expression.

What are nucleic acids?

Polymers that store genetic information.

What are the two types of nucleic acids?

DNA and RNA.

What is the function of DNA?

Stores and transfers genetic information.

What is the function of RNA?

Protein synthesis.

What are nucleotides?

Building blocks of nucleic acids.

What are the components of a nucleotide?

Sugar, phosphate, and nitrogenous base.

What sugar is found in DNA?

2′-deoxyribose.

What sugar is found in RNA?

Ribose.

What bases are pyrimidines?

Thymine, cytosine, uracil.

What bases are purines?

Adenine and guanine.

Which base is unique to DNA?

Thymine.

Which base is unique to RNA?

Uracil.

What is a nucleoside?

Sugar bonded to a nitrogenous base.

How is a nucleotide formed?

By adding a phosphate to a nucleoside.

What bond links nucleotides?

3′–5′ phosphodiester linkage.

In what direction is DNA read?

5′ to 3′.

What forms the DNA backbone?

Sugar–phosphate backbone.

What is Chargaff’s rule?

A=T and C=G.

What is the structure of DNA?

Double helix.

What does antiparallel mean?

Strands run in opposite directions.

What bonds hold base pairs together?

Hydrogen bonds.

Which bases pair together?

A–T and G–C.

What stabilizes the DNA double helix?

Hydrogen bonding and base stacking.

What enzyme synthesizes DNA?

DNA polymerase.

In what direction does DNA polymerase work?

5′ to 3′.

What is the leading strand?

Continuously synthesized strand.

What is the lagging strand?

Discontinuously synthesized strand.

What are Okazaki fragments?

Short DNA segments on the lagging strand.

What enzyme joins Okazaki fragments?

DNA ligase.

What is bidirectional replication?

Replication proceeds in both directions.

What are homologous chromosomes?

Paired chromosomes with the same genes.

What are the two stages of protein synthesis?

Transcription and translation.

What is hnRNA?

Primary RNA transcript.

What is mRNA?

RNA that carries protein instructions.

What is rRNA?

RNA that forms ribosomes.

What is tRNA?

RNA that delivers amino acids.

What is transcription?

DNA-directed synthesis of RNA.

What enzyme controls transcription?

RNA polymerase.

What is a gene?

DNA segment that codes for RNA.

What is RNA splicing?

Removal of introns and joining of exons.

What are introns?

Noncoding DNA segments.

What are exons?

Coding DNA segments.

What is alternative splicing?

Production of multiple proteins from one gene.

What is a codon?

Three-nucleotide mRNA sequence.

How many codons exist?

64 codons.

What is the start codon?

AUG.

What are stop codons?

UAA, UAG, UGA.

What is an anticodon?

Three-base sequence on tRNA.

What is translation?

Protein synthesis from mRNA.

What is a ribosome?

rRNA–protein complex.

What are the main steps of translation?

Initiation, elongation, termination.