AP Bio Unit 6: Gene Expression and Regulation Cheat Sheet by julescrisfulla

Eukaryotic modifi­cations to primary transcript (pre mRNA)

~ bond altera­tions to the ends

regulate gene activity

RNA -> protein

1) codon recogn­ition

3) transl­ocation

what makes cells different:

~ cells use the DNA in the nucleus differ­ently

differ­ent­ation:

~ cells become specia­lized in structure and function

~ the expression of different genes by cells with the same genome

chromatin: a complex of DNA and protein

"off switch­"

genes can not be transc­ribed

gene expression is reduced

barr bodies: one X chromosome condenses because of DNA methyl­ation

"on switch­"

genes can be transc­ribed

DNA is made up of DNA

gene regulation determines which genes are turned on/off

point mutations:

~ ex:

_~ still codes, but not properly (sickle cell anemia)

_~ altera­tions codes for a stop codon

_~ a change in DNA but not a change in the amino acid sequence

~ caused by insertions and deletions of base pairs

phosphate group

nitrog­enous base

in S phase of Mitosis

nucleo­tides can only be added to the 3' end of a nucleotide

enzymes mediate the process of DNA replic­ation

2) topois­omerase prevents overwi­nding and single­-strand binding proteins support the replic­ation bubble

4) DNA polymerase III adds nucleo­tides in 5' to 3' direction on leading strand

6) DNA ligase seals together okazaki fragments (short segments of DNA that grow 5' to 3' that are added onto the lagging strand)

mRNA:

~ carries genetic code to the ribosome

tRNA:

~ transfers amino acids to the ribosome

rRNA:

~ makes up ribosomes

made in nucleotide

A site: holds amino acids

some are free and some are fixed

need RNA primer from DNA primase

can not add nucleo­tides at 5' end

operon: way of regulating genes and is usually made up of a few genes that involve enzymes

operator: a part of the DNA where a repressor can bind, if repressor is bound to operator it blocks RNA polymerase which means mRNA can not be made so neither can proteins

~ there is a gene that codes for the repressor production and this gene has its own promoter

~ if lactose is present, the lactose (sugar) binds to the repressor (repressor can not bind to operator) and RNA polymerase finds its promoter, binds, and transc­ribes to make mRNA from the genes on operon, the mRNA will be used to make enzymes to break down the lactose sugar

trp operon:

~ tryptophan is on amino acid which moves proteins

~ if bacteria does not have trypto­phan, there is a number of genes that are required to make it

~ if a lot of tryptophan is present, then we do not want to make more so the repressor is going to set operator in "­off­"

involves a change in the structure or number of chromo­somes

duplic­ation: reverses the direction of parts of a chromosome

transl­oca­tion: part of one chromosome break off and attaches to another chromosome

when a cell changes from one type to another

DNA contains genes and genes contain proteins that change the way cells look and act

using genes -> expressing -> turned "­on"

cells decide what they will be based on internal or external enviro­nmental cues

external: (induc­tion) (like peer pressure) a group of cells can induce another group to differ­entiate by using signals (like diffusion, direct contace, gap junctions)

double helix

~ "­run­gs": nitrog­enous bases

Eukary­otic: replic­ation before mitosis or meiosis (inter­phase)

~ breaks the hydrogen bonds holding bases together

~ replicates DNA molecules to build new strand of DNA

~ makes the primer so that DNA polymerase can figure out where to go to start to work

~ helps glue/bind DNA fragments together

starts at the origin (ident­ified by DNA sequence)

~ single stranded binding protein bind to DNA strands to prevent the strands from going back together

2) primase makes RNA primers on both strands

~ this means it moves along old template strand in 3' to 5' direction

4) ligase takes care of gaps between Okazaki fragments

~ semi-c­ons­erv­ative: each copy contain a new and original strand

DNA -> RNA

~ promoter sites: region of the DNA where the RNA polymerase binds

~~ transc­ription factors: binding protein

2) Elongation

~~ separates and untwists helix

3) Termin­ation

5' cap: GTP is added

1) protects transcript from hydrolytic enzymes

s' end: last to be translated

~ inhibits degrad­ation

~ attached to stop codon

~ removal of introns (noncoding sequences) (inter­vening sequences)

small nuclear ribonu­cle­opr­oteins found in nucleus (snRNP; snurps): complexes of small RNA units and proteins found in nucleus

codons:

~ start codon: AUG

reading frame:

antico­dons:

redund­ancy: more than one codon for an amino acid

early evolution since shared among living species

primer is several nucleo­tides

once you have primer, polymerase can add on DNA at 3' end (5' to 3')

slower process

~ RNA is replaced with DNA