DNA Replication, Transcription, Translation, and Gene Expression

Flashcards summarizing DNA replication, transcription, translation, and factors affecting gene expression based on lecture notes.

Helicase

Enzyme that breaks hydrogen bonds between complementary bases, unwinding and exposing the DNA bases.

DNA Polymerase

Enzymes that add free DNA nucleotides to exposed bases on separated DNA strands during replication.

Complementary Base Pair Rule

Adenine (A) binds with Thymine (T), and Cytosine (C) binds with Guanine (G).

Five to Three Direction

The new DNA is synthesized in this direction during replication.

Pre-mRNA

Contains both introns and exons before splicing.

Introns

Non-coding regions spliced out of pre-mRNA to form mature mRNA.

Exons

Coding regions retained in mRNA after splicing.

Transcription

Process where mRNA is made from a gene on the DNA strand, occurring in the nucleus.

RNA Polymerase

Enzyme that separates DNA strands and joins RNA nucleotides during transcription.

Translation

Process where a polypeptide chain is created, occurring at the ribosome.

tRNA anticodon

Complementary to the codon on mRNA and carries an amino acid.

Histone Proteins

DNA is packed with these proteins to form chromatin.

Acetylation of Histone Proteins

Causes chromatin to decondense (loose packing), allowing gene expression.

Deacetylation of Histone Proteins

Causes chromatin to condense (tight packing), preventing gene expression.

Methylation of Histone Proteins

Can increase or decrease gene expression depending on the amino acid and number of methyl groups added.

Gene Switched On

Active, open chromatin state with unmethylated cytosine and acetylated histones.

Gene Switched Off

Silent DNA state with methylated cytosines and deacetylated histones.

Transcription Factor Activators

Bind to DNA and increase the rate of transcription.

Repressors

Bind to DNA and slow or stop transcription.

DNA Methylation

Addition of a methyl group (CH3) to the cytosine base, stopping RNA polymerase from binding.

Factors Controlling Translation

Affects gene expression by acting on mRNA or miRNA.

miRNA (microRNA)

Noncoding RNA that regulates gene expression after transcription by binding to mRNA.

siRNA (small interfering RNA)

Silencing RNA that binds to and destroys specific mRNA.

Long Noncoding RNA

Binds to miRNA, preventing it from binding to mRNA, thus promoting gene expression.

Factors Affecting Gene Expression

Gender, chemicals, temperature, diet, lifestyle, and trauma.

Tumor Suppressant Gene (TSG)

Methylation of this gene switches it off, preventing tumor suppression and leading to uncontrolled cell division.

DNA Repair Gene

Methylation of this gene switches it off, preventing DNA repair and potentially leading to cancer.

Oncogene

Codes for proteins that promote cell division; uncontrolled expression can lead to cancer.

Germline Cells

Cells that give rise to an individual's egg/gamete mutation.