Unit 6: Gene Expression and Regulation

double stranded, backbone made of phosphate groups and deoxyribose (5 and 3 prime ends), nitrogenous bases (ATGC) in middle attached by hydrogen bonds

single stranded, backbone made of phosphate groups and ribose (5 and 3 prime ends), nitrogenous bases (AUGC)

purine- A and G, double ring

pyrimidine- C U and T, single ring

1. DNA helicase unwinds DNA and breaks hydrogen bonds b/w bases

2. topoisomerase relaxes the coil (sugar/phosphate backbone) of DNA

3. single stranded binding proteins prevent DNA from coiling back together

4. RNA primase puts down primer to tell DNA polymerase where to start

5. DNA polymerase brings nucleotides to form complimentary strands

6. DNA ligase joins Okazaki fragments together on lagging strand

RNA polymerase can only build in the 5 to 3 direction

leading strand- built in the same direction as the replication fork, polymerase can start at 5 end and follow fork to 3 end

lagging strand- built in opposite direction as the fork, polymerase must begin close to the fork and work away from it in pieces (Okazaki fragments)

enzymes that proofread new DNA strands to check for errors

point mutation where one nucleotide is substituted for another

substitution; change still codes for same amino acid, no effect

substitution, change results in a different amino acid, can result in different protein made

substitution; change results in stop codon, protein ends earlier than it is supposed to

nucleotide is inserted or deleted, altering reading frame of genetic info; codes for completely different protein than it is supposed to

large scale; section of DNA is duplicated within a chromosome

large scale; section of DNA is deleted from a chromosome

large scale; section of DNA is flipped within a chromosome

large scale; section of DNA is taken out of one chromosome and put in another

large scale; when chromosomes don’t separate properly during meiosis, results in incorrect number of chromosomes

uses electric current to move DNA across gel to a positive charge, separates fragments by size, used to analyze or identify DNA

done before gel electrophoresis, makes copies of DNA segment to amplify sample size

1. denaturation- DNA template is turned into single strands

2. annealing- primers attached to each strand for DNA synthesis

3. extension- new DNA strands built from primers

virus- not living cell, intracellular parasite, smaller than bacteria, vaccines/antiviral treatments prevent, made of DNA/RNA + capsid

bacteria- prokaryotic cell, larger, antibiotics kill

ways virus can infect cells

lytic- uses host machinery to replicate + release copies

lysogenic- virus DNA (provirus for animals or prophage for bacteria) incorporated into host DNA and replicated along with it

bacteria intaking DNA and expressing it

1. transcription- DNA unwinds, RNA polymerase attaches complimentary RNA bases, mRNA strand leaves nucleus

2. translation- mRNA attaches to ribosome, lines up complimentary tRNA molecules (anticodons match codons), tRNA brings correct amino acid, amino acids form peptide bonds and then a protein

mRNA- carry protein information from the DNA in a nucleus to cytoplasm

tRNA- helps decode a messenger RNA sequence into a protein

rRNA- direct the stitching together of amino acids to make a protein molecule

DNA- triplet

RNA- codon

amino acids

group of genes that can be turned on/off

promoter- where RNA polymerase can attach

operator- on/off switch

genes- code for related enzymes in pathway

transcription is usually off, but can be started

transcription is usually on, but can be stopped

codes for protein that breaks down lactose

inducible

when allolactose (simple form of lactose) present, it pulls off repressor and allows RNA polymerase to start transcription

codes for tryptophan (amino acid)

repressible

if enough tryptophan present, it will bind to repressor and stop production

enhancer, promoter, and genes

1. activators attach to enhancers, which fold operon

2. enhancer triggers the transcription factors

3. transcription factors allow RNA polymerase to start transcription

has a sugar ring at the end

has an OH group at the end