Biology gonna make me nut on BASHIR

DNA

Deoxyribonucleic acid; the molecule that stores hereditary genetic information in cells.

Why did early scientists think proteins were genetic material?

Proteins seemed more complex because they are made of 20 different amino acids while DNA only has 4 bases.

Transformation

Process where a cell takes in foreign DNA and incorporates it into its own genome.

Griffith's Experiment

Fred Griffith discovered transformation when harmless R bacteria became virulent after taking DNA from heat-killed S bacteria.

Hershey-Chase Experiment

Used bacteriophages and radioactive labeling to prove DNA is the genetic material, not protein.

Chargaff's Rule

Adenine pairs with thymine and guanine pairs with cytosine; A=T and G=C.

Who discovered base pairing ratios?

Erwin Chargaff.

Who produced X-ray images of DNA?

Rosalind Franklin.

Who built the first DNA model?

James Watson and Francis Crick.

Shape of DNA

Double helix.

Sides of DNA

Sugar-phosphate backbone.

Rungs of DNA

Nitrogen base pairs.

Four nitrogen bases

Adenine, Thymine, Cytosine, Guanine.

Base pairing rules

Adenine pairs with Thymine; Guanine pairs with Cytosine.

Hydrogen bonds in A-T pair

2 hydrogen bonds.

Hydrogen bonds in G-C pair

3 hydrogen bonds.

Purines

Double ring bases: Adenine and Guanine.

Pyrimidines

Single ring bases: Cytosine and Thymine.

Nucleotide

The basic unit of DNA.

Parts of a nucleotide

Phosphate group, deoxyribose sugar, nitrogen base.

Antiparallel DNA

One strand runs 5'→3' and the other runs 3'→5'.

When does DNA replication occur?

S phase of interphase.

Purpose of DNA replication

To produce identical copies of DNA before cell division.

Replication fork

Y-shaped region where DNA strands separate during replication.

Helicase

Enzyme that unwinds and separates DNA strands.

Single-strand binding proteins

Keep DNA strands apart during replication.

Topoisomerase

Relieves twisting stress ahead of replication forks.

Primase

Enzyme that creates RNA primers.

RNA primer

Short RNA sequence that allows DNA polymerase to begin replication.

DNA polymerase

Enzyme that adds nucleotides to build a new DNA strand.

Direction DNA polymerase works

5' to 3'.

Leading strand

DNA strand synthesized continuously toward the replication fork.

Lagging strand

DNA strand synthesized discontinuously away from the replication fork.

Okazaki fragments

Short DNA segments formed on the lagging strand.

DNA ligase

Enzyme that joins Okazaki fragments together.

Semiconservative replication

Each new DNA molecule contains one original strand and one new strand.

Proofreading

Correction of DNA replication errors by enzymes.

DNA excision repair

Damaged DNA is removed and replaced with correct nucleotides.

Central dogma

DNA → RNA → Protein.

Transcription

Process of copying DNA into mRNA.

Enzyme for transcription

RNA polymerase.

Where transcription occurs

Nucleus.

mRNA

Messenger RNA that carries genetic instructions from DNA to ribosomes.

Translation

Process where ribosomes read mRNA to build proteins.

Where translation occurs

Ribosomes on the rough ER or in the cytoplasm.

tRNA

Transfer RNA that carries amino acids to the ribosome.

rRNA

Ribosomal RNA that forms ribosomes and catalyzes protein formation.

Codon

Three-base sequence on mRNA coding for an amino acid.

Anticodon

Three-base sequence on tRNA complementary to a codon.

Start codon

AUG (codes for methionine).

Stop codon

Codon that signals the end of protein synthesis.

Peptide bond

Bond that forms between amino acids during protein synthesis.

Mutation

A change in the DNA sequence.

Point mutation

A single base substitution.

Insertion mutation

Addition of one or more bases into DNA.

Deletion mutation

Removal of one or more bases from DNA.

Why mutations can be harmful

They may produce a nonfunctional protein.

Somatic mutation

Mutation occurring in body cells; usually not inherited.

Germline mutation

Mutation occurring in sex cells that can be passed to offspring.

Sickle cell anemia

A disease caused by a mutation in the hemoglobin gene.

Biotechnology

The use of living organisms to produce useful products.

Recombinant DNA

DNA combined from two different sources.

Genetic engineering

Artificial manipulation of genetic material.

Why bacteria are used in biotechnology

They reproduce quickly and are easy to genetically modify.

Plasmid

Small circular DNA molecule in bacteria used as a vector.

Vector

A carrier used to transfer DNA into a cell.

Restriction enzymes

Enzymes that cut DNA at specific sequences.

Restriction site

Specific DNA sequence recognized by restriction enzymes.

Sticky ends

Overlapping DNA ends that allow fragments to join together.

PCR (Polymerase Chain Reaction)

Method used to amplify small amounts of DNA.

Gel electrophoresis

Method used to separate DNA fragments by size using an electric current.

Genetically modified organism (GMO)

Organism whose DNA has been altered by genetic engineering.

Gene therapy

Treatment where defective genes are replaced with healthy ones.

Transgenic organism

Organism containing genes from another species.

Biotech forensic use

DNA fingerprinting used to identify individuals.

Environmental biotech

Genetically modified bacteria can clean oil spills or toxic waste.

Pharm animals

Transgenic animals that produce human proteins such as medicines.

BT corn

Corn genetically modified to produce a bacterial toxin that kills insect pests.

Golden rice

Rice genetically modified to produce vitamin A.