AP Biology

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AP Biology Tests back today Curve was 12 points Grades on test haven’t had 12 points added (they are correct in ps) Study guide changes rip out page 7 (that is a different chapter) Test is December 20

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AP Biology. Tests back today Curve was 12 points Grades on test haven’t had 12 points added (they are correct in ps ) Study guide changes rip out page 7 (that is a different chapter) Test is December 20. History of DNA. Griffith. Conclusion:. Phage. Hershey/Chase. Hershey/Chase. - PowerPoint PPT Presentation

Transcript of AP Biology

AP Biology Tests back today Curve was 12 points Grades on test haven’t had 12 points

added (they are correct in ps) Study guide changes rip out page 7

(that is a different chapter) Test is December 20

History of DNA

Thomas Morgan 1900

Frederick Griffith 1928

Oswald Avery 1940

Hershey and Chase

1952

Erwin Chargaff

1950

Rosalind Franklin

1950

Watson and Crick

1953

Griffith

Conclusion:

Phage

Hershey/Chase

Hershey/Chase

Hershey/Chase

Conclusion:

Franklin

Franklin

Watson/Crick

AP Biology Review from last class

Continue DNA talk

Replication today

DNA Replication

Watson/Crick

Semiconservative: when a double helix replicates, each of the daughter molecules has one old strand and one new

Vocab on Replication Origin of replication- special sites where

replication begins Replication fork- a “bubble” where parental

strands are unwound Helicase- unzips parent strand Single-stranded binding protein- binds to

unpaired DNA to stabilize them Topoisomerase- relieves strain from twisting

Replication

Vocab contd. Primer- initial nucleotide is a short

stretch of RNA Primase- an enzyme that synthesizes

the primer DNA polymerase- catalyzes the

synthesis of new DNA by adding nucleotides to a preexisting chain

Replication

DNA

3’ vs 5’

The 5’ 3’ runs in the opposite direction as the: 3’ 5’

Antiparallel- the two strands of DNA are oriented in opposite directions to each other.

DNA

DNA can ONLY add nucleotides from the 3’ side on parent Strand

DNA daughters are “built” from 5’ 3’

DNA Leading strand- the continuous strand Lagging strand- the strand that is copied

away from the fork Lagging strands called- Okazaki fragments.

DNA

Chapter 17 Gene expression and protein synthesis

Test next Thursday

Proteins

Proteins are link between genotype and phenotype

Gene expression- process by which DNA directs protein synthesis, includes two stages called transcription and translation

DNA RNA Protein

DNA

Protein Review

Amino acids - building blocks of protein

Polymer - many building blocks covalently bonded

Peptide bonds- covalent bond between amino acids

20 total amino acids

DNA/RNA

DNA RNA

Double helix Single strand

A,T,C,G A,U,C,G

Deoxyribose sugar Ribose sugar

mRNA rRNA tRNA

Protein Synthesis

Codons

How many nucleotides could there be if:

1. Each kind of nucleotide base were translated into an amino acid?

2. If a two-letter sequence was in place?

3. If there were triplet bases?

Codons – the mRNA nucleotide triplets, written normally in the 5’ 3’ direction

CCU AUG AGC AGG

Codons

Vocabulary: RNA polymerase- separates DNA and

joins RNA nucleotides together, nucleotide bases assemble in a 5’ 3’ direction (no primer required)

Promoter- When RNA polymerase initiates transcription sequence

Terminator- when RNA polymerase signals the end of transcription

Transcription

Steps of Transcription1. Initiation- RNA synthesis begins2. Elongation- the RNA strand gets bigger3. Termination- the RNA transcript is

released

Transcription

Transcription

RNA Processing

Pre-mRNA must be altered before it travels outside of the nucleus Alternation of mRNA ends1. 5’ cap – a modified guanine added to

the 5’ end2. Poly-A tail- 50-250 adenine nucleotides

are added to the 3’ side

Pre-mRNA must be altered before it travels outside of the nucleus RNA splicing- removal of large portions of

the RNA molecule (cut-and-paste) This means that there are long noncoding

portions of DNA are not coding for anything. Introns - noncoding regions Exons – coding regions

RNA Processing

Vocabulary: Anticodon- attached to tRNA molecules,

a nucleotide triplet. Complementary to the mRNA codon

Wobble – the flexible base pairing at the third nucleotide position.

Translation

Translation

Translation

Translation

Translation

Steps of Translation1. Initiation- brings together mRNA and

tRNA to begin synthesizing proteins2. Elongation – Amino acids are added3. Termination – A stop codon reaches A

site, and the amino acids (polypeptide) is released

Translation

Translation