DNA, Genes, Chromosomes, and Genetic Expression

DNA

Deoxyribonucleic acid, genetic material in cells.

Nucleotide

Building block of DNA; contains sugar, base, phosphate.

Nitrogenous Bases

Adenine, Thymine, Cytosine, Guanine in DNA.

Purines

Double-ringed nitrogenous bases: Adenine and Guanine.

Pyrimidines

Single-ringed nitrogenous bases: Thymine and Cytosine.

Nucleoside

Sugar and nitrogenous base without phosphate.

Phosphodiester Bond

Bond linking nucleotides in DNA strand.

5' End

Free phosphate group at the beginning of DNA.

3' End

Free hydroxyl group at the end of DNA.

Antiparallel Strands

Two DNA strands run in opposite directions.

Double Helix

Twisted ladder structure of DNA.

Hydrogen Bonds

Hold complementary base pairs together in DNA.

A-T Pairing

Adenine pairs with Thymine via two hydrogen bonds.

G-C Pairing

Guanine pairs with Cytosine via three hydrogen bonds.

Griffith's Experiment

Showed DNA as the central molecule of life.

Avery-Macleod-McCarty Experiment

Identified DNA as the genetic material.

Transformation

Process of nonvirulent bacteria becoming virulent.

Gene Propagation

Transmission of genetic information across generations.

Base Pairing Rules

A=T and G=C in DNA structure.

DNA Stability

Maintained by hydrogen bonding and base stacking.

DNA Compaction

Necessary for fitting DNA within cellular dimensions.

Free 5' Phosphate

Unattached phosphate group at the 5' end.

Free 3' Hydroxyl

Unattached hydroxyl group at the 3' end.

Direction of Synthesis

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

Chromosome

Linear DNA molecule packaged with proteins.

Histones

Proteins that interact with DNA to form chromatin.

Chromatin

Histone-DNA complexes that compact DNA.

Karyotype

Visual representation of an organism's chromosomes.

DNA Replication

Process of copying DNA to create daughter strands.

Semiconservative Replication

One parental strand and one new strand produced.

Conservative Replication

Both strands are newly synthesized, leaving parental strands.

Meselson & Stahl Experiment

Confirmed semiconservative nature of DNA replication.

Eukaryotic DNA Replication

Follows semiconservative principles in eukaryotic cells.

DNA Polymerase

Enzyme that adds nucleotides to growing DNA strands.

RNA Primer

Short RNA sequence necessary for DNA synthesis initiation.

Continuous Replication

Smooth replication on leading strand, same direction as fork.

Discontinuous Replication

Fragmented replication on lagging strand, opposite direction of fork.

Okazaki Fragments

Short DNA segments formed during lagging strand replication.

DNA Ligase

Enzyme that joins Okazaki fragments into continuous DNA.

3'-OH Group

Free hydroxyl group needed for DNA polymerase action.

Helicase

Enzyme that unwinds the DNA double helix.

Topoisomerase II

Relieves tension during DNA unwinding.

Single Stranded Binding Proteins (SSBP)

Stabilize single DNA strands during replication.

Trombone Model

Simultaneous synthesis of both DNA strands.

Proofreading

Error-checking process after nucleotide addition.

Mutations

Errors in DNA sequence during replication.

S-phase

Cell cycle phase where DNA replication occurs.

DNA polymerase

Enzyme that synthesizes DNA strands during replication.

Proofreading

Error-checking mechanism of DNA polymerase.

Okazaki fragments

Short DNA segments on the lagging strand.

Mutations

Permanent changes in DNA sequence.

Replication origins

Sites where DNA replication begins.

Telomeres

Repeating sequences at chromosome ends.

Telomere repeats

1500-3000 nucleotide sequences at telomeres.

Telomerase

Enzyme that extends telomeres in cells.

Cell division cessation

Occurs when telomeres shorten to 100 repeats.

Aging indicators

Telomere length correlates with biological age.

PCR

Technique to amplify specific DNA sequences.

Template DNA

Original DNA strand used in PCR.

Deoxyribonucleoside triphosphates

Building blocks for DNA synthesis in PCR.

Primers

Short DNA sequences that initiate PCR amplification.

Amplification cycle

Each PCR cycle doubles the DNA amount.

Gel electrophoresis

Technique to separate DNA by size and charge.

DNA editing

Techniques to modify DNA sequences.

CRISPR/Cas

Tool for precise DNA editing.

CFTR gene

Gene coding for chloride ion channel.

Cystic fibrosis

Disease caused by CFTR gene mutations.

Hydration of airways

Prevents mucus buildup in cystic fibrosis.

Organoid

Cell assembly mimicking an organ for research.

CFTR

Chloride channel activated by forskolin.

F508Del

Mutation causing cystic fibrosis in CFTR.

Deletion

Genetic mutation removing a segment of DNA.

Forskolin

Chemical that activates CFTR channels.

CRISPR

Gene-editing technology correcting genetic mutations.

mRNA

Messenger RNA transcribed from DNA.

Transcription

Process of synthesizing RNA from DNA.

Central Dogma

Framework describing DNA to RNA to protein.

Ribose

Sugar in RNA with hydroxyl (-OH) group.

Deoxyribose

Sugar in DNA lacking hydroxyl (-OH) group.

Uracil

RNA base replacing thymine found in DNA.

Thymine

DNA base with a methyl group.

RNA Polymerase

Enzyme synthesizing RNA from DNA template.

Nucleoside Triphosphate

Building block for RNA synthesis.

RNA Primer

Short RNA segment initiating DNA synthesis.

Nucleotide

Basic building block of nucleic acids.

Amino Acid

Building block of proteins, represented by F.

Nucleoside Monophosphate

Basic building block of DNA formed first.

RNA World Hypothesis

Theory suggesting RNA was first nucleic acid.

Enzymatic Properties of RNA

RNA can catalyze biochemical reactions.

Stability of DNA

DNA is more stable than RNA molecules.

RNA Functions

RNA stores information and has coding sequences.

Central Dogma

Describes flow of genetic information: DNA to RNA.

Transcription

Process where DNA is converted to RNA.

Template Strand

DNA strand used to synthesize RNA transcript.

Nontemplate Strand

Complementary DNA strand not used for transcription.

Promoter Sequences

DNA regions where transcription factors bind to start transcription.

TATA Box

Conserved DNA sequence in eukaryotic promoters.

Transcription Factors

Proteins that bind to DNA to initiate transcription.

RNA Polymerase

Enzyme that synthesizes RNA from DNA template.

Terminator

Sequence where transcription ends.