Genetics exam 4

DNA operator sequence

Noncoding region between the promoter and the start point of transcription. Sometimes has binding sites for allosteric effectors

Genetic switches

Gene expression regulator, positive if activator is present and negative is repressor is present

Activator

Sensor protein that monitors the environment, recruits polymerase to make transcription happen

Repressor

Sensor protein that monitors the environment, prevents recruitment of polymerase and prevents transcription

DNA binding domain

Site on allosteric effectors that binds DNA

Allosteric site

Site on allosteric effector that is bound by an environmental signal to change protein’s shape

Positive regulation/induction

Allosteric effector increases gene expression via shape change

Negative regulation

Allosteric effector decreases gene expression via shape change

Operon

A unit made up of linked genes that regulates other genes responsible for protein synthesis

lacZ

Encodes B-galactoside, which modifies lactose do it can be metabolized

lacY

Encodes permease, which transports lactose into the cell

lacA

Encodes transacetylase

lac structural genes

lacZ, lacY, lacA. Their overall purpose is to encode enzymes

lac I repressor gene

Allosteric transition

When allolactose binds repressor

Cis regulatory element

Promoter, CAP binding site, and operator are all …

Trans regulatory element

Repressor protein, CAP and cAMP are all …

Rotational symmetry

Cis regulatory sequence based on palindrome sequences

Helix-turn-helix

Common DNA binding motif, lambda represser and cro are both examples

Enhancers

Cis regulators far from the promoter

Proximal enhancers

Cis regulators far from the promoter

Core promoter

DNA sequence that includes the startpoint of transcription

Transcription factors

Major type of trans regulator

General transcription factors

Transcription factors that bind to core promoter

Coactivators

Serve as a bridge for TFs and RNA polymerases

Corepressors

Block TFs and RNA polymerases fro

Eukaryotic cis regulators

proximal enhancer elements, enhancers, insulators, promoters

Ligand binding domain

TFs often require binding of some ligand to function

Activation/repression domain

A domain that when bound can change the function of TF

Nucleosomes

Main unit of chromatin

Histones

Bobbins for DNA to wrap around, comprised of chromatin

H1

Linker histone

H2A, H2B, H3, H4

Core histones

Tails

Heterochromatin

Compact nucleosomes, tight and difficult to transcribe

Euchromatin

Loose nucleosomes, open for easy transcription

Position effect

Where a gene is can determine expression

X chromosome inactivation

Dosage compensation silences the genes on one chromosome. Why females don’t express twice as much X genes

Chromatin modification

Chemical changes to chromatin alter how they interact with DNA

Histone Acetyl transferase (HAT)

Add acetyl group on to lysine

Histone deacetylases (HDAC)

Removes acetyl groups from lysine

Methylation of histone tails

Tightens chromatin

Acetylation of histone tails

Loosens chromatin

DNA methyltransferases (DNMT)

Acts to repress transcription

TET enzymes

Remove methyl groups

Chromatin remodeling

Physical change of histone number or placement. Moves nucleosomes, opens or tightens DNA

Reader proteins

(transcription factors)

Writer and eraser

(enzymes)

Epigenetic inheritance

Inheritance of chromatin states is a type of …

Genomic imprinting

When an allele inherited by one parent is preferentially expressed and another is silent

Organizers

Tissues capable of controlling the development of other tissues

Housekeeping genes

Genes that control metabolism, biosynthesis, etc.

Genetic toolkit genes

Genes that determine morphology in development

Homeotic mutations

Changes in segmental identity (serially repeated structures)

Hox genes

Key source of homeotic mutations, establish morphological identity of each segment

Immunohistochemistry (IHC)

Method of studying spacial gene expression for proteins

In situ hybridization (ISH)

Method of studying spacial gene expression for RNA

Dorsal-Ventral

back to stomach

Anterior-posterior

head to butt

Maternal effect genes

Maternally expressed genes to start A-P axis

Zygotic genes

All genes expressed by the embryo

Gap genes

Establish major A-P boundaries

Pair rule genes

Establishes boundaries for pairs of segments

Segment polarity genes

Establish A-P axis of each segment

Distaless

Specifies leg growth on leg-identity segments