Unit 6 Gene Expression and Regulation

Translocation

When the tRNAs in the large ribosomal subunit move to the next site so that elongation may occur.

Inversion

A nucleotide is added into a codon, a framework mutation.

Deletion

A nucleotide is deleted from a codon, a framework mutation.

Horizontal gene transfer

The process by which a gene or genes from one organism is transferred to another organism.

Transformation

When a bacteria takes in a plasmid from its environment if another cell sheds it or that cell dies.

Conjugation

Plasmid can be shared directly with another bacteria that lacks that gene.

Transposition

Transposons (pieces of DNA) hop randomly to different parts of a DNA sequence.

Point mutation

One nucleotide is changed, affecting only that specific codon.

Duplication

A DNA sequence is repeated.

Transduction

Virus inserts DNA into bacteria to make essentially a 'virus-making bacteria factory' by hijacking the bacteria.

Substitution

A type of point mutation that involves replacing a nucleotide with another.

Silent mutation

Mutation in DNA sequence that doesn’t affect the resulting amino acid.

Missense mutation

When one nucleotide change creates a different protein.

Nonsense mutation

Mutation in DNA sequence that results in a stop codon from forming.

Frameshift mutation

A mutation where the removal or addition of an amino acids affects all the following amino acids.

Operon

System of genes that has controlling elements, can be turned on or off.

Promoter

Region where RNA Polymerase binds, TATA box for eukaryotes.

Operator

Part of operon where repressor binds, where system is regulated.

Inducible

An operon that is otherwise off but can be turned on if an inducer is present.

Cytoplasmic determinants

When eggs are developing, affect gene expression and determine differentiation.

Regulatory gene

Codes for regulatory proteins, usually the repressor protein.

Histone acetylation

Loosens up DNA winding around histones and allows transcription to happen.

Histone methylation

Affects how DNA is wound around histones and inhibits transcription.

Epigenetic inheritance

DNA is modified or its expression is changed without affecting the nucleotides.

Differentiation

Cells differentiate because they express different genes.

Morphogenesis

The development of an organism or cell.

Repressible

An operon that is otherwise always on, can be repressed if co-repressor is present.

Homeotic genes

Genes that regulate differentiation during morphogenesis.

Gel electrophoresis

A laboratory technique used to separate molecules based on their size and charge.

PCR

Replicates DNA sequence so that it’s visible to the eye.

Restriction enzymes

Find specific sites and cut parts of DNA.

Gene

Instructions to build proteins are encoded in these segments of DNA.

Genome

Set of all DNA instructions in an organism.

Plasmid

Prokaryotes have a circular shape of DNA.

Double helix

Shape of DNA.

Nucleotide

Their organization is transcribed to create proteins.

Nitrogenous base

Bond together with hydrogen bonds.

5’

Phosphate group end of a nucleotide.

3’

Hydroxyl/bottom of sugar end of a nucleotide.

Directionality

DNA runs from 5’ to 3’.

Semi-conservative

Term that describes DNA replication.

Topoisomerase

Prevents strain by relaxing supercoiling.

Helicase

Enzyme that initiates DNA replication by splitting the strands.

Primase / RNA polymerase

Lays down the RNA primers for DNA Polymerase III.

Origin of replication

Sequence of nucleotides that helicase recognizes.

DNA polymerase III

Sets down matching nucleotide bases while reading the parent strand.

Telomeres

Nucleotide sequence caps placed on the ends of DNA.

Telomerase

Places the telomeres on the DNA.

DNA polymerase I

Replaces RNA primers with DNA.

DNA ligase

Seals the gaps between Okazaki fragments.

Single strand binding proteins (SSBPs)

Ensure that the double helix doesn’t rewind during replication.

Parent strand

Strand of DNA from the original, untouched molecule.

New strand

Strand of DNA that was synthesized during replication.

Central dogma

Concept that describes how genetic information creates proteins.

Transcription

DNA to RNA (in cytoplasm for prokaryotes, nucleus for eukaryotes).

Translation

From RNA to proteins (in cytoplasm for eukaryotes and prokaryotes).

Coding, sense, or plus strand

Strand of DNA that the mRNA is a copy of.

Template, Noncoding, antisense, or minus strand

Strand of DNA that gets transcribed into RNA.

mRNA

Strand coded by RNA polymerase, contains codons.

Initiation for transcription

When RNA polymerase attaches to the promoter region.

RNA Polymerase

Enzyme that initiates transcription by pairing RNA nucleotides.

Elongation

mRNA is constructed and the DNA double helix is reformed.

Termination

The sequence that signals the release of the pre-mRNA strand.

mRNA processing

mRNA must undergo modifications before it is ready for translation.

codon

mRNA nucleotide triplets.

Start codon

(AUG) the first codon read by RNA polymerase.

Stop codon

Signals for the end of protein synthesis.

5’ GTP cap

A pre-mRNA modification where the 5’ end is given a 'cap' of guanines.

3’ poly-A tail

A pre-mRNA modification where the 3’ end is given several adenine nucleotides.

Intron

Non-coding sequences between exons on mRNA.

Exon

Expressed sequences of mRNA.

Splicing

Getting rid of introns and joining exons together.

Alternative splicing

When different combinations of exons create variants of one gene.

rRNA

RNA that makes up ribosomes, important for translation.

Ribosome

Complex made up of units where translation occurs.

A site

Arrival site, where tRNA arrives with its amino acid.

P site

Placement site, where tRNA attaches its amino acid to the ongoing chain.

E site

End site, where tRNA moves to leave the ribosome.

tRNA

Transfer RNA that brings amino acids to ribosomes during translation.

anticodon

The complementary RNA sequence to each codon of mRNA.