bio 190 final

Griffith experiment

Discovered transformation in bacteria using S and R strains.

Avery, MacLeod, McCarty

Identified DNA as the transforming factor in bacteria.

Hershey and Chase

Used radioactive labeling to show DNA is the genetic material.

Chargaff's Rules

%A = %T and %G = %C; base pair ratios vary by species.

Rosalind Franklin

Used X-ray diffraction (Photo 51) to reveal DNA's helical shape.

Watson and Crick

Built double helix model of DNA using Franklin's photo.

Meselson and Stahl

Demonstrated DNA replication is semiconservative.

Antiparallel

Describes DNA strands running in opposite 5' to 3' directions.

Hydrogen bonds

Hold base pairs together: A-T (2), G-C (3).

Phosphodiester bond

Connects 3' and 5' carbons of adjacent nucleotides.

Purines

Double-ring bases: Adenine and Guanine.

Pyrimidines

Single-ring bases: Cytosine and Thymine (Uracil in RNA).

Helicase

Unzips DNA by breaking hydrogen bonds.

Topoisomerase

Relieves supercoiling ahead of replication fork.

Single-strand binding proteins

Stabilize separated DNA strands.

Primase

Lays down RNA primers to initiate DNA synthesis.

DNA polymerase III

Adds new DNA nucleotides to growing strand.

DNA polymerase I

Replaces RNA primers with DNA.

DNA ligase

Seals gaps between Okazaki fragments.

Okazaki fragments

Short DNA fragments on lagging strand.

Telomerase

Extends telomeres in germ/stem cells to prevent shortening.

Mismatch repair

Corrects errors missed by DNA polymerase proofreading.

Nucleotide excision repair

Replaces damaged DNA sections using ligase and polymerase.

Recombinant DNA

Combines DNA from different sources using enzymes.

PCR

Amplifies DNA using Taq polymerase.

Taq polymerase

Heat-resistant enzyme used in PCR.

DNA fingerprinting

Identifies individuals by analyzing DNA fragments.

CRISPR

Gene-editing system using Cas enzymes and guide RNA.

DNA sequencing

Determines the order of DNA nucleotides.

Central Dogma

DNA → RNA → Protein

mRNA

Carries genetic message from DNA to ribosome.

tRNA

Brings amino acids to ribosome; contains anticodon.

rRNA

Forms core of ribosome, catalyzes peptide bonds.

snRNA

Part of spliceosome, removes introns from pre-mRNA.

Promoter

Region where RNA polymerase binds to start transcription.

RNA polymerase

Synthesizes RNA from DNA template.

Codon

Three-nucleotide mRNA sequence coding for amino acid.

Start codon

AUG; codes for methionine.

Stop codon

UAA, UAG, UGA; ends translation.

Peptide bond

Links amino acids in a growing polypeptide chain.

Exons

Coding regions kept after RNA splicing.

Introns

Noncoding regions removed during RNA splicing.

Alternative splicing

Generates multiple mRNAs from one gene.

Poly-A tail

Added to 3’ end of mRNA; protects and aids export.

5' cap

Modified G added to 5’ end for ribosome binding.

Silent mutation

Does not change the amino acid sequence.

Missense mutation

Changes one amino acid.

Nonsense mutation

Creates a stop codon.

Frameshift mutation

Caused by insertion or deletion, shifts reading frame.

Morphogenesis

Physical processes that give shape to organisms.

Cell differentiation

Process where cells become specialized.

Cytoplasmic determinants

Molecules in egg that guide early development.

Induction

One cell's signals influence neighboring cells.

Homeotic genes

Control body plan and pattern formation.

Totipotent

Can become any cell including placenta.

Pluripotent

Can become any embryonic cell type.

Multipotent

Can become a limited range of cells.

iPS cells

Adult cells reprogrammed to act like pluripotent stem cells.

Proto-oncogenes

Genes that promote normal cell growth.

Oncogenes

Mutated proto-oncogenes that cause cancer.

Tumor suppressor genes

Inhibit cell growth; mutations can lead to cancer.

p53 gene

Tumor suppressor that guards the genome.

RAS gene

Proto-oncogene involved in signaling for growth.