Dna, Rna, and molecular biology - 11

Nucleic Acids

Nucleic acids store and transmit genetic information.

DNA

DNA stores hereditary information.

RNA

RNA carries genetic instructions for protein synthesis.

Nucleotide

A nucleotide consists of a sugar, phosphate group, and nitrogen base.

DNA Sugar

DNA contains deoxyribose sugar.

RNA Sugar

RNA contains ribose sugar.

Purines

Purines include adenine and guanine.

Pyrimidines

Pyrimidines include cytosine, thymine, and uracil.

Chargaff's Rules

A pairs with T and G pairs with C.

Antiparallel Strands

DNA strands run in opposite directions.

Double Helix

DNA forms a twisted ladder structure.

Hydrogen Bonds in DNA

Base pairs are held together by hydrogen bonds.

DNA Replication

DNA replication copies DNA before cell division.

Origin of Replication

The site where DNA replication begins.

Replication Fork

The area where DNA strands separate.

DNA Polymerase

DNA polymerase synthesizes new DNA strands.

Direction of DNA Synthesis

DNA is synthesized in the 5' to 3' direction.

Leading Strand

The leading strand is synthesized continuously.

Lagging Strand

The lagging strand is synthesized in fragments.

Okazaki Fragments

Short DNA fragments on the lagging strand.

Primase

Primase synthesizes RNA primers.

RNA Primer

RNA primers initiate DNA synthesis.

DNA Ligase

Ligase joins Okazaki fragments.

Helicase

Helicase unwinds DNA.

Topoisomerase

Topoisomerase relieves DNA strain.

Single-Strand Binding Proteins

They stabilize separated DNA strands.

Telomeres

Telomeres protect chromosome ends.

Telomerase

Telomerase extends telomeres.

DNA Proofreading

DNA polymerase corrects replication errors.

Mutation

A mutation is a change in DNA sequence.

DNA Repair Mechanisms

Cells repair damaged DNA.

Nucleotide Excision Repair

Removes damaged DNA sections.

Thymine Dimers

UV light causes thymine dimers.

Central Dogma

DNA → RNA → Protein.

Gene

A gene is a DNA segment that codes for a product.

Transcription

Transcription produces RNA from DNA.

Template Strand

The DNA strand used for transcription.

mRNA

mRNA carries the genetic code to ribosomes.

Codon

A codon is a three-nucleotide sequence.

Start Codon

AUG signals the start of translation.

Stop Codons

UAA, UAG, and UGA end translation.

Translation

Translation builds proteins from mRNA.

Ribosome

Ribosomes synthesize proteins.

tRNA

tRNA brings amino acids to the ribosome.

Anticodon

The anticodon pairs with an mRNA codon.

Polypeptide

A polypeptide is a chain of amino acids.

RNA Processing

mRNA is modified before leaving the nucleus.

Introns

Introns are noncoding RNA segments.

Exons

Exons code for proteins.

Spliceosome

The spliceosome removes introns.

Alternative Splicing

One gene produces multiple proteins.

Ribozymes

Ribozymes are RNA molecules with catalytic activity.

Universality of Genetic Code

The genetic code is shared by all life.