Biology Chapter 10 Notes

DNA, RNA and Protein Synthesis

10.1 and 10.2 – Discovery and Structure of DNA

Griffith - 1928

-

Avery – 1940s

-

Chargaff - 1949

Hershey and Chase - 1952

Hershey and Chase – -

Watson and Crick (and Franklin) - 1953

-

Human Genome Project - 1990

Attempt to record a complete human genome (all of the A,T,C,G’s). Completed in 2001, but still being interpreted.

Dolly the Sheep -- 1999

• The first cloned animal

Structure of DNA

Structure of DNA

• DNA is a double helix structure made up of 2 long chains of repeating nucleotides

• A nucleotide has 3 parts: – -– -– -(Adenine, Guanine, Cytosine or Thymine)

• The two chains of nucleotides are held together by __________that form between the nitrogenous bases

Structure of DNA

Some of the bases have 2 rings -purines and some have 1 ring - pyrimidines

_________: Adenine and Guanine (A and G)____________: Cytosine and Thymine (C and T)

DNA is complementary – if you know one side, you know the other

--Fill out the missing letters

-- Show the H-bonds

T

FUN FACTS!!

The human DNA code is made up of about 3 billion nucleotide pairs (6 billion bases total!!)

If the total DNA in one person were laid in a straight line, it would stretch to the sun and back over 600 times (it's 93 million miles from here to the sun).

Less than 2% of the DNA in your genome actually codes for proteins

Experiments showed that DNA is the hereditary factor that passes on traits

1. Hershey and Chase2. Chargaff3. Watson and Crick4. Dolly the sheep

Used a photograph from Rosalind Franklin to determine the structure of

DNA

1. Hershey and Chase2. Chargaff3. Watson and Crick4. Dolly the sheep

How is the structure of DNA best described?

1. Trapezoidal2. Double Helix3. Circular4. Triple Lutz

Always combines with Cytosine…

1. Adenine2. Thymine3. Guanine4. None of the above

Holds the 2 strands of DNA together…

1. Magic2. Covalent bonds

between bases3. Hydrogen bonds

between bases4. Ionic bonds

between bases

What would the genetic code of the complementary DNA strand be?

CGG ATA ACG GAC

1. CGG ATA ACG GAC2. GCC TAT TGC CTG3. ATT GCG GTA ACT4. TGG CGC TAG CAG

Chapter 10.3 – DNA Replication

During what phase of the cell cycle does DNA replication occur?

DNA Replication

• -• Enzymes play a key role

– http://www.youtube.com/watch?v=Luw5_z8mIrI&feature=related

Steps of DNA Replication1. The complementary strands ________

– Helicases break H-bonds between the 2 strands– Creates replication forks (Prokaryotes have 2, Eukaryotes

have thousands at once)2. Complementary nucleotides are added to each strand

– ___________“preps” the strand by adding a short segment of RNA

– ___________adds complementary nucleotides from 5’->3’ on the leading and lagging strands

– Gaps are filled in with the help of DNA ligase3. Enzymes are released and 2 identical DNA molecules

result

DNA Replication is a “semi-conservative” process

Replication in Prokaryotes

-- Replication starts at one replication fork and works its way around the entire loop of DNA

-- -

Replication in Eukaryotes

• Many replication forks occur at the same time (thousands!!!) on any given chromosome

• If only one formed per chromosome, would take 53 days to replicate the largest human chromosome!!!

DNA Errors in Replication

• Only 1 error occurs in about 1 billion nucleotides (enzymes correct most errors)

• Only mutations present in gametes (egg and sperm) can be passed on to offspring

• -• Some beneficial : HIV resistance• -

When does Replication occur?

1. G1 Phase2. S Phase3. G2 Phase4. Mitosis

What is the Y-shaped region that occurs when the DNA strands separate

called?1. Template2. Helicase3. DNA Polymerase4. Replication Fork

Put the following enzymes in the order in which they are involved in the

replication process1. RNA Primase – Helicase -

DNA Polymerase - Ligase2. RNA Primase - DNA

Polymerase - Helicase - Ligase

3. Helicase – RNA Primase - DNA Polymerase – Ligase

4. Helicase – DNA Polymerase - RNA Primase - Ligase

How can we remember the order of enzymes?

• Helicase• RNA Primase• DNA Polymerase• Ligase

• “Helicopter Rides Don’t Last” ????

The ________ strand has nucleotides added continuously while the ________ strand has them

added in segments called Okazaki fragments

1. leading ; lagging2. lagging ; leading3. left ; right4. right ; left

Leading versus Lagging Strand

• http://nobelprize.org/educational/medicine/dna/a/replication/index.html

Nucleotides are always added in a ______ direction

1. top to bottom2. bottom to top3. 5’ 3’4. 3’ 5’

Can you meet the Replication Challenge?????

• http://nobelprize.org/educational/medicine/dna_double_helix/dnahelix.html

Chapter 10.4 – Protein Synthesis

• What are proteins?• What are they made of?• Where in the cell are they made?

• Today you will learn how they are made!!!

Protein Synthesis

• DNA contains the instructions for making proteins. The steps in the process are divided into 2 major stages: _____________ and _______________

• DNA _________________, so it depends on RNA molecules to transmit the directions for making proteins.

THE MAIN IDEA SECTIONS 3 AND 4!

Structure of mRNA

• It is ___________• It has sugar and phosphate as it’s backbone –

but the sugar is __________• The four nucleotides that attach to the sugars

are• Cytosine• Guanine• Adenine• ________

There are 3 Types of RNA

• _________(messenger RNA) – carries instructions from the DNA in the nucleus out to the cytoplasm

• _______(ribosomal RNA) -- part of the structure of ribosomes

• ________(transfer RNA) -- transfers amino acids to the ribosomes to make proteins

Transcription making RNA

• Transcribing the genetic material into an mRNA molecule

• http://www.youtube.com/watch?v=ztPkv7wc3yU&feature=related

Steps of Transcription

1. ______________binds to a promoter (a sequence of nucleotides that initiates transcription), causing the DNA to unwind for that gene

2. RNA polymerase adds complementary nucleotides to ___________(“sense strand”) of the DNA molecule

3. The RNA polymerase releases the DNA and the new mRNA once it reaches the end of the gene __________= specific sequence of nucleotides)

4. mRNA can now leave the ________ and take the genetic instructions into the ___________

Translation - Making Proteins

Translation = translating the genetic instruction (genetic code) in the mRNA to make a ______

Every 3 adjacent nucleotides in an mRNA molecule is called a codon.

Each codon in mRNA specifies a particular amino acid. Long strings of amino acids = a protein!!

Steps in Translation1. Initiation

-- The ribosome, mRNA and tRNA (carrying methionine) bind together2. Elongation

– The tRNA carrying the amino acid corresponding to the next mRNA codon travels to the ribosome

– A peptide bond forms between the methionine and the next amino acid

– The first tRNA detaches and leaves the methionine behind– Elongation continues and the polypeptide chain grows longer

3. Termination– A stop codon is reached (it does not code for any amino acid and

has no complementary anticodon)– The ribosome releases the mRNA and the newly made protein

From DNA -> Protein

• http://www.youtube.com/watch?v=NJxobgkPEAo&feature=related

What’s are the Amino Acids?

• DNA sequence: TAC ACU CUU GGC AAC ATT• mRNA codon: __________________________• tRNA anticodon: ___________________________• Amino acids: ___________________________