Molecular Biology Flashcards

Flashcards about Molecular Biology

DNA Nucleotide base-pairing

Adenine and thymine, cytosine and guanine

RNA Nucleotide base pairing

Adenine and uracil, cytosine and guanine

Pyrimidines

Single ring structure (i.e.: T, U, and C)

Purines

Double ring structure (i.e.: A and G)

Prokaryotic

Circular, smaller, contains plasmids in the cytosol

Eukaryotic

Linear, larger, contains plasmids in the nucleus

Leading strand

synthesized continuously (5’ to 3’)

Lagging strand

synthesized in fragments (because the DNA strand is 3’ to 5’)

Helicase

Unwinds DNA

Topoisomerase

Relaxes the supercoil at the *replication fork

DNA polymerase

Synthesizes the new strands of DNA

Ligase

Join the fragments on the lagging strand

*Semiconservative

Each original strand of DNA serves as a template to synthesize a complementary strand

*Antiparallel

The 5’ end is opposite the 3’ of the complementary strand

*Replication fork

Location where the two strands are separate

Template strand

Noncoding, minus, or antisense

Non-template strand

Coding

Messenger RNA (mRNA)

Carries genetic information from DNA to the ribosomes

Transfer RNA (tRNA)

Carries a unique amino acid to create a specific polypeptide sequence

Ribosomal RNA (rRNA)

Adds amino acids to assemble protein

Poly-A tail on 3’ end

Increase stability and helps export it out the nucleus

GTP (modified guanine) cap of the 5’

Protect the transcript and attach the mRNA to the ribosome

Introns

Do not code for amino acids and are removed from the mature mRNA transcript

Exons

Do code for amino acids and are kept and connected to each other in the mature RNA transcript

*Alternative splicing

The removal of introns and connecting retained exons in the mature mRNA transcript

*Anticodon

A three-base sequence on tRNA that it complementary to the three-base sequence on mRNA

Epigenetic changes

Reversible modifications of DNA or *histones

Transcription factors

Proteins that promote or inhibits transcription

Operons

Closely linked genes that produce a single mRNA molecule in transcription

*Operator unit

A sequence that inhibits or promotes transcription depending on if it binds to the regulatory protein

Inducible Operons

Genes that are typically “off ” and require a *inducer molecule to turn it on

*Inducer molecule

Molecules that bind to the regulatory protein and change its shape

Repressible Operons

Genes that are typically “on” and require a repressor protein to turn off

*histones

Proteins that wrap around DNA (may be tightly coiled or loosely coiled)

Promoters

DNA sequences upstream (toward the 5’ end of a coding strand) of the *transcription start site

*Transcription Start Site

RNA polymerase and transcription factors bind

Mutations

Changes in the genome of an organism

Horizontal transfer of information

Exchange of genetic information between different genomes or unrelated organisms

Transformation

Taking in *naked DNA

*naked DNA

DNA note protected by proteins

Transduction

Transmission of foreign DNA into a cell

Conjugation

Cell-to-cell transfer of DNA

Transposition

Movement of DNA segments between DNA molecules

Electrophoresis

Separation of molecules according to size and charge

Polymerase chain reaction

Amplification of DNA fragment

DNA sequencing

Establish the order of nucleotides in a DNA strand