AP Bio Unit 6: Gene Expression and Regulation

Pyrimidines

These base pairs have a single ring structure (U,C,T)

Purines

These base pairs have a double ring structure (A,G)

Semiconservative Replication

Each old DNA strand during replication pairs with a new one

Plasmids

a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. Plasmids are much used in the laboratory manipulation of gene

Hydroxyl Terminus

Also known as the 3’ end of DNA. DNA is read from this end

Phosphate Terminus

Also known as the 5’ end of DNA. Nucleotides are added from this end

Leading Strand

This strand is synthesized continuously during DNA replication

Lagging Strand

This strand is synthesized discontinuously during DNA replication s it goes “backwards”

Helicase

This enzyme unwinds DNA strands

Topoismerase

This relaxes the supercoil at the replication fork

Ligase

This enzyme acts as a “glue” to join fragments on the DNA lagging strand during replication

RNA Primase

This enzyme builds “chunks” of RNA on the lagging strand called Okazaki Fragments

Okazaki Fragments

short sections of DNA formed at the time of discontinuous synthesis of the lagging strand during replication of DNA

mRNA

This type of RNA is a temporary RNA version of a DNA recipe

DNA Replication

The act of copying DNA that happens during S Phase. This happens in the NUCLEUS

RNA transcription

This is making an RNA copy of DNA

A tiny specific portion is made into mRNA on a gene by gene basis

rRNA / Ribosomal

This type of RNA makes up ribosomes

tRNA

This RNA shuttles amino acids to ribosomes and brings them into place

Initiation, Elongation, Termination

The steps of RNA transcription

AUG

Start Codon

Antisense Strand

The template DNA being copied in RNA transcription

Sense Strand / Coding Strand

The strand not being copied in RNA transcription

RNA Polymerase

This enzyme adds RNA nucleotides to the 3’ side (building 5’ to 3’)

Processed

In eurkaryotes, RNA must be ______ before leaving the nucleus

Exons

Coding regions for proteinsI

Introns

Non-coding regions of mRNA

Spliceosome

Intron remover

Poly(A) Tail

This is added to protect an mRNA strand with codons at the 3’ end

GTP Cap

This is added to protect an mRNA strand with codons at the 5’ end

Translation

Transforming an mRNA into a protein (on ribosomes in the cytoplasm and the rough ER)

Anti-codon of tRNA bonds with the mRNA codon

Codon

A group of 3 nucleotides —> each represents an amino acid

Anticodon

On the other end of tRNA opposite of the codon (3 complementary nitrogenous bases)

Wobble Pairing

The third position of a codon is more flexible with pairing (ex: might pair G and U)

A Site

This site on the Ribosome attaches new RNA

P Site

This site on the Ribosome is in charge of creating the polypeptide

E site

This site on a ribosome is the exit site

Initiation

This is when RNA polymerase attaches to a promoter in transcription

Elongation

This is when RNA polymerase makes the RNA strand during transcription

Termination

When RNA polymerase leaves the DNA after completing transcription

Initiation

In translation, this is when a ribosome attaches to mRNA

Elongation

In translation, addition of amino acids (brought by tRNA). Link with peptide bonds

Termination

In translation, when the ribosome reaches the end of an mRNA strand (stop codon)

3

A ribosome reads mRNA in groups of ____ called codons

Transcription Factors

These encourage or inhibit DNA unwinding and polymerase bonding

Epigenetic Changes

These are changes to the DNA package (usually too tightly wrapped around histones, meaning that DNA cannot be read) caused by he environment

Operons

In bacteria, a gene cluster is controlled by a single promoter

Structural Genes

These code for enzymes

Promoter Gene

RNA polymerase binds here to begin transcription

Operator

This controls whether transcription occurs (IN BACTERIA)

Regulatory Gene

This gene codes for a repressor (blocks transcription)

Post-Transcriptional Regulation

In this gene regulation process, unneeded DNA is destroyed

Post-Translational Regulation

In this gene regulation process, a cell makes a protein but does no use it

Base Substitution / Point Mutations

A single nucleotide base is substituted for another

Nonsense Mutation

When the original codon is replaced with a stop codon —> early termination

Missense Mutation

The original codon is replaced with a different amino acid

Silent Mutation

The original codon is replaced with a different one, but it still codes for the same amino acid

Insertion / Deletion

A type of gene rearrangement: The gain or loss of DNA or a gene —> DEVASTATING CONSEQUENCES (frameshift)

Frameshift

This gene rearrangement shifts how a sequence is read (sets of 3 become jumbled) and results from an insertion or deletion

Duplications

A type of gene rearrangement: an extra copy of gene causes new traits and results from unequal crossing over

Inversions

A type of gene rearrangement: change in orientation

Translocation

A type of gene rearrangement: 2 chromosomes break and rejoin so DNA is lost / replaced / or interrupted

Transposons

A type of gene rearrangement: gene segments are cut and pasted throughout a genome

Conjugation

Bacteria swap DNA to create genetic diversity

Recombinant DNA

A type of biotechnology: Combining DNA from multiple sources

Polymerase Chain Reaction / PCR

A type of biotechnology: amplifying genes

Transformation

A type of biotechnology: bacteria is induced to do something based off of a human gene (transcribe and translate)

Gel Electrophoresis

A type of biotechnology: DNA fragments (alleles) are separated by weight and charge

DNA Sequencing

A type of biotechnology: determining the order of nucleotides

Alternative Splicing

a cellular process in which exons from the same gene are joined in different combinations