Nucleic Acids

(How much do you recall?)- Structure- Replication- Packaging

Refer to chapter 12.1, 12.2 in text.

Types of organic molecules; 3 of 4

Nucleic Acids

Polymers of 4 nucleotidesUses: Information transformation

from cell generation to generation (DNA)and from genome to protein (RNA)

DNA replication(making sure that all cells get the same information),

Transcription (DNA sequence directing RNA sequence), and

Translation(RNA directing amino acid sequencein proteins).

(What do you recall about nucleic acid structure?)

Note: - nucleotides have three parts, which are…- differences between DNA and RNA…

←ribose carbons are numbered

1’ to 5’

- Structure

original.britannica.com/eb/art-106485/The-hum...

Note:-complementary base pairing-held together by hydrogen bonds,-to form the double helix.-Chains run in opposite directions:

antiparallel

www.web-books.com/MoBio/Free/Ch3A5.htm

← phosphodiester linkageis between one 5’C andthe previous 3’C

Campbell CD 16.1 (1st and 2nd)http://www.pbs.org/wgbh/nova/body/DNA-photograph.html

↑explanation of photo 51

NB

covalent bonds here ←

H bondshold 3Dstructure →

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organization of eukaryotic DNA

Unique DNA: found only one time in a given genome.- These are often protein coding segments,

which tend to vary little or none between individuals, and even between species.

- RNA- and protein-coding DNA is about 1.5% of the human genome.

Repetitive DNA: uh, repeated sequences.typically 5-300 base pairs in length,

repeated up to 105 times per genome. - Most of the non-coding DNA is repetitive.

transposons can “jump” about the genome by cut/copy and paste of DNA

retrotransposons are reverse-transcribed segments from RNAsatellite DNA: short repeats (many copies)

often clumped at centromere and telomeres.- Often used to evaluate evolutionary relatedness.- These areas are used in forensic DNA “fingerprinting”.

(19.4 in text)

- Replication

Why would DNA have to be replicated?(Note - answer isn’t written here.)

Again, what do you recall of the process?

Helix “unzips”.DNA nucleotides brought in

and plugged in to proper pair.Result of this semi conservative replication

is two identical strands,each composed of one old and one new strand.

http://www.youtube.com/watch?v=4jtmOZaIvS0Less detail, more realistic

http://www.youtube.com/watch?v=teV62zrm2P0Brief, includes helicase, SSBP, Pol III, I, okazaki fragments, ligase

YouTube videos:

Campbell text animations,chapter 16.2 (1st and 2nd activities)

a quick summary… in French

Replication terms: origin of replication replication fork replication bubble helicase→ topoisomerase aka → gyrase single-stranded binding protein primase (RNA polymerase) primer deoxynucleoside triphosphate template strand leading strand lagging strand 5’ to 3’ direction DNA polymerase III DNA polymerase I Okazaki fragments ligase→nucleotide excision repair→telomere→telomerase

Animations are helpful here,or work from the text.

DNA packaging

- In eukaryotes, DNA is wrapped around proteins called histones.- 8 histones are wrapped in two loops of DNA,

held in place by a linker (here H1) histone. This is a nucleosome.

- This aids in organizing/ further packaging of DNAand has a role in gene regulation.

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You have about 2 mof DNA in every cell!

↑ Linker histones stabilize this packing, too.

http://www.geneticengineering.org/chemis/Chemis-NucleicAcid/Graphics/Pack.gif

When it comes time for cell division,the DNA will be further “crunched”

← into heterochromatin…

← Double helix

← Nucleosomes

← Euchromatin fiber(during G phases)

http://www.youtube.com/watch?v=bW5JnYZImJA

Video showing packaging

Editing:1. Base pair shape leads to proper matching.2. DNA polymerases check and correct the work.3. Subsequent proofing can catch errors later.

↓

http://en.wikipedia.org/w

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http://www.nature.com/scitable/topicpage/dna-replication-and-causes-of-mutation-409

but some errors will squeak by…

… which leads to genetics.

DNA replication in prokaryotes

The differences between eukaryotic and prokaryotic DNA:- Prokaryotes have a lone loop of double-stranded DNA.- It is not packaged in nucleosomes.

(At 1 mm, still 500 times length of cell...)- Bacteria may have plasmids – independent DNA loops.

Comparing the replication processes:- Cell division is organism’s reproduction: binary fission

Recall: Not mitosis, because…?- Similar enzymes are at work:

helicase, SSB proteins, Pol III, Pol I, ligase….- Still antiparallel,

so Okazaki fragments made.- One origin of replication ….

www.sciencebuddies.org/mentoring/plugin_bacte...

Walk through the process of eukaryotic DNA replication.

Explain leading vs. lagging strand.

Why does DNA need to be replicated?

Why do prokaryotes not have mitosis?

List all of those DNA replication proteins.Describe what each does.

“Draw and label a simple diagramof the molecular structure of DNA.”

3.3.5

What are the bases?Match each with its base pair. Which are the purines?

Nucleosome?

DNA replication genome

transcription repetitive DNA

translation transposon

nucleotide retrotransposon

pyrimidine satellite DNA

purine semi conservative

nucleoside triphosphate histone

complementary base pairing nucleosome

double helix euchromatin

antiparallel heterochromatin

unique DNA plasmid

The rest of the terms

DON’T FORGET THE VOCABULARY PULLED EARLIER!