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Nucleotides Essay Research Paper I nucleotides sub

Nucleotides Essay Research Paper I nucleotides sub units dna a Phosphate group B carbon sugar molecule deoxyribose C nitrogen base Adenine Guanine Thymine Cytosine Chargaff base pairing rule and II Maurice Wilkins and Rosalind Essay Research PaperI nucleotides sub units dnaa Phosphate groupB carbon sugar molecule deoxyriboseC.

Nucleotides Essay, Research Paper

I. nucleotides: sub units ?? DNA

A. Phosphate group

B. 5-carbon sugar molecule (deoxyribose)

C. nitrogen base

1. Adenine

2. Guanine

3. Thymine

4. Cytosine

Chargaff ?? base pairing rule: 1 = 3 and 2 = 4

II. Maurice Wilkins and Rosalind Frankilin ?? X-ray diffraction photos of DNA molecule

- DNA molecules: tightly coiled helix and composed of two or three chains of nucleotides

III. Chargaff builds a model of the double helix: ??a spiral staircase?? of 2 strands of nucleotides twisting around a central axis.

A. alternating sugar and phosphate units

B. purine and pyrimidines paired up

- A can only form hydrogen bonds with T

- C can only for ?? ?? with G.

?? 2 strands that are complementary to each other

IV. Copying of DNA:

A. Replication: process of synthesizing a new strand of DNA.

B. Helices: open up the double helix by breaking the hydrogen bonds that link the complementary bases.

C. Two strands separated: additional enzymes and proteins attach to the individual strands and hold them apart ?? twisting prevented

D. Replication fork : where double helix separates

1. DNA polymerases: enzymes that move along each strand ?? adding nucleotides to the exposed bases.

2. Proofreading

?? one old and one new DNA strand

8.3 The Structure of a Gene

- genes hold info specifying how to build particular proteins

- affects the phenotype of an individual because of the activity of the protein that it specifies

- DNA encoded info that specifies particular proteins; each gene is made of a specific sequence of nucleotides

I. Genes in Eukaryotes

A. interruped by necleotides that have no coding info.

1. Introns:: noncoding sequences/ intervening

- must be removed

2. Exons :nucleotide segments that code for amino acids

-stitched together once all introns are removed

II. Multigene families: clusters of almost identical sequences; cells exist in multiple copies

A. Some are ??silent?? genes: don??t make protein

B. Some are only active during embryonic or fetal development

C. Some encode the two chains of

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