DNA Replication…NotesSteps:

1. A section of the DNA molecule unwinds and becomes a ___________________ladder.

2. The 2 nucleotide chains are separated by __________________enzymes, which break the hydrogen bonds between the bases.

3. DNA polymerases bind to the 2 sides of DNA moving along in opposite directions, attaching free ___________________to the existing DNA chain.

4. Covalent bonds join sugars and phosphates, __________________bonds join base pairs.

• The process of replication happens at many different locations along the DNA ________________________, not just from one end to the other.

• Result: 2 new strands of DNA that are exact copies of the original, and the cell is ready to undergo cell division (_______________!).

Picture: (see in your book 12-2,

pages 333-334)

Let’s watch an animation of how this happens!

Mutations…• When the bases mis-match themselves in

base-pairing, this is one type of ____________.

• There is about one error in every 10,000 paired nucleotides but DNA can proof-read itself and repair the mutation, helping keep the error rate to about one error per 1 __________nucleotides.

• This has serious effects in new ___________.• Mutations can be bad or good…

Good and Bad…• Mutations drive _______________to happen!• Good mutations – help the organism survive

longer so that their ___________can be passed down– Examples: camouflage, drug resistant bacteria (good

for them, bad for us!)

• Bad mutations – cause the organism to __________and not allow those genes to be passed down– Examples: genetic disorders that cause early death,

cancer

Transcription and TranslationProtein Synthesis

• What is it?– Transcription happens when DNA is

transcribed (making a ________________) into RNA– Translation is when the information is

translated into a ________________

Transcription: the process by which genetic information is copied from DNA to _______.

Steps:1. RNA transcription starts on the DNA strand (the

template) at the “____________” (initiator or start) gene.

2. RNA polymerase binds to the promoter gene and travels down one side of the ____________________(original DNA) attaching complementary RNA bases and nucleotides.

3. The base pairing rules are the same except U replaces T on the _________strand.

4. This continues until it reaches a DNA region called the “termination signal” (or _________).

5. The RNA polymerase _________________both the DNA molecule and the newly formed RNA molecule (travels to cytoplasm).

6. DNA _______________back up!

This newly formed strand is called mRNA or messenger RNA.

After mRNA is formed• We are able to make a protein in the cytoplasm.

(______________________)• Remember…– The amount and kind of ___________that are

produced in a cell determine the structure and function of the cell.

– In other words, proteins carry out the genetic __________________________(genes) encoded in our DNA.

• mRNA is now grouped into letters of ______ (a group of 3 letters is called a codon).– Each codon will code for one amino acid (AA).– AAs are the __________________blocks of proteins.– A few codons do not code for an AA, instead they

signal for translation of an mRNA to ______________(initiator/start codon/promoter) or stop (stop codon/ termination signal).

• mRNA is ready to be “_____________” by 2 other types of RNA…

• When the mRNA gets to the cytoplasm, rRNA (which is in __________________form) will attach itself over the strand.

• It helps attach the __________to the mRNA• This is where ribosomes are made!

rRNA or ________________RNA

• tRNA will locate the start ___________on the mRNA strand and will form the appropriate AA for that codon

• tRNA travels down the mRNA to the next codon and forms the appropriate ________ for that codon

• The second AA attaches to the 1st & the tRNA molecule ________________from the 1st mRNA codon

• This continues until a string/chain of AA are formed = a _________________is made!

__________ or Transfer RNA