Tuesday Novermber 29, 2011

This is the process of DNA becoming tRNA.

1. DNA Replication- Before a cell divides, it must first duplicate its DNA- replication


2. Transcription- A molecule of DNA is copied into a complementary strand of mRNA


3. Translation- tRNA anticodons (3 nucleotides) complement the mRNA and bring in the corresponding amino acids


4. Protein Synthesis- Amino acid are bonded together to form a polypeptide

RNA has-

1. ribose sugar



2. 1 strand



3. Uracil instead of Thymine



4. smaller size than DNA- can go inside/outside nucleus



5. 3 types- messenger- mRNA, transfer- tRNA, ribosomal- rRNA(its the one that form ribosomes)

Steps of Transcription

1. Initiation- RNA polmerase attaches to the DNA promoter nucleotide sequence on DNA. RNA is synthesized

2. RNA elongation- RNA grows longer, peels away from DNA, DNA strands come back together (uses DNA as a template)

3. Termination- RNA polymerase reaches the terminator- end of the gene. polymerase molecule detaches from RNA molecule and the gene

Processing RNA

in prokaryotes, RNA is ready(mRNA)

in eukaryotes, it needs to process it, add extra nucleotides

• cap and tail protect RNA from enzymes and help ribosomes recognize it as mRNA



• introns-non coding regions (useless junk)



• exons-are the coding regions

introns are removed before RNA leaves the nucleus=RNA splicing

• mRNA is now ready

Steps of Translation

1. initiation-

• a mRNA binds to small ribosomal subunit. tRNA with attached amino acid (Met) (UAC) binds to start codon, AUG on mRNA



• large ribosomal subunit binds to small one, creating a functional ribosome

2. elongation- amino acids are added one by one to the first amino acid

3. a stop codon (UGA, UAG, UAA) does not code for an amino acid. tells translation to stop. Polypeptide is freed ( several hundred amino acid) ribosome splits into its subunits

Review

DNA->RNA->Protein. genes determine the protein, which makes your appearance and your cell capabilities

1. Mutations

• change in nucleotide sequence of DNA-a. base substitution- replacement of one base for another. no change, or critical, bad or good~b. base insertion or deletions- adding or subtracting nucleotides. often disastrous results- can disrupt entire sequences of triple pairing (insertions are always bad)



• mutagens- physical and chemical agents, such as UV light, x-rays, chemicals, carcinogens. can cause mutations. Can also lead to diversity. DNA errors are also due to unknown causes.

next scribe Dana

11/16/2011 ? on tonights homework

For question numbers 4 on page 75 and 9 on page 76 on tonights homework. On question 4 i didnt get the first or third part of the question because i dont remember going over it, and how do we set up the punnett square on problem 9

9/9/11

ch. 19 notes
properties of a communtiy
-diversity
-form of vegitation
-stability
-trophic structures
interactions in communities
-interspecific competition
-ecological niche
-resource parting
-predator
-prey
-predator abdaptation
-plant defence
-animal defence
-batesian mimicry
-mullerian mimicry
-keystone mimicry
symbiotic relationships
-parasitism
-mutualism
-commensalism
disturbances in ecosystems
-ecological succession
-primary succession
-secondary succession
-pioneer species
-climax community
ecosystem dynamics
-energy flow
-chemical cycling
-food chain/ food web (producers, herbivoresprimary consumer, canrivores, secondary comsumers, tetriary consumers, quaternary consumers, detritivores[decomposers], omnivores)
chemical cycling in ecosystems
-CO2
-nitrogen cycle
-phosphorus cycle
-water cycle
biomes