Chapter 12 DNA and RNA #21 Base Pairing Rules

DNA Double Helix

Single Stranded

RNA

5b. Know Base-pairing rules for DNA replication. Know transcription of information from DNA into mRNA.

Chargaff’s Rules- Cytosine-Guanine and Thymine-Adenine are the base pairs.

C

CH2

O CH2OH

O

G

T

CH2

O CH2OH

O

A

CH2

O

GCH2

C

O

CH2

OAA

CH2OHT

O

DNA Base-Pairing Rules

pyrimidinepurine

DNA Replication

During Mitosis, the nucleus replicates its DNA in a copying process called replication. During DNA replication, the DNA molecule is separated by DNA polymerase into two strands, then each strand produces two new complementary strands following the rules of base pairing.

Each strand of the double helix of DNA serves as a template, or model, for the new strand.

Double Stranded Helix DNA

AGCTTAAT CGAATT

What are the complements of the following single DNA strands?

TCGAATT

RNA Synthesis

RNA molecules are produced by copying part of the nucleotide sequence of DNA into a complementary sequence of RNA, in a process called transcription.During transcription, RNA polymerase binds to DNA and separates the DNA strand.

Transcription-

RNA polymerase then uses one portion of the DNA strand as a template from which nucleotides are assembled into a strand of mRNA.

TranscriptionDNA

TAC AAA TTT GGG CCC ATG ACT

Extra Credit: Printout Congratulations 25 pts http://www.thinkquest.org/library/site_sum.html?tname=20465&url=20465/g_DNATranscription.html

mRNA Codon Start Codon (1 of 3 Stop Codon)

AUG GGC UUA CCG AUA GGC UGA

Genetic CodeThe code for Amino Acids

What would the new amino acid sequence be if the circled nucleotide were removed?This is an example of a frameshift mutation. Here a nucleotide is remove. What isGoing the happen to the amino acid sequence? Remember three nucleotides are read at time.

New Protein -___ -___ -___-___ -___-___- ___

UUU AAA CCC GGG UAC

Protein synthesis or the assembly of amino acids is based on a three nucleotide code found on the mRNA is known as a codon. 1 Codon = 1 Amino Acid.Each codon codes for a specific amino acid that will be added to a polypeptide chain during translation.

1. (Genetics 5B) During DNA Replication , a DNA strand that has the base sequence of AGCTTG produces the following complementary strand?

C. TCGACA D TCGAACA. GATCCA B. UCGAAC

DNA Strand AGCTTG Complementary DNA Strand TCGAAC

2. (Genetics 5B) During mRNA transcription, a portion of a DNA strand that has the bases AGCTTG produces a messenger RNA transcript that has the following sequence of bases.A. TCGACA B. UCGCCAC. GATCCA D. UCGAAC

DNA Strand AGCTTGmRNA Strand UCGAAC

3. (DNA&RNA 5b) What is produced during transcription?A. RNA molecules B. DNA moleculesC. RNA polymerase D.proteinsDuring transcription, RNA polymerase binds to DNA and separates the DNA strand. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of mRNA.

4. (DNA&RNA 5b) How many nucleotide make up a codon?

A. 6 B. 2

C. 3 D. 1

5. (Genetics 5B) Because of base pairing in DNA, the percentage of?A. Adenine molecules is equal to cytosineB. Thymine molecules is equal to cytosine

C. Guanine molecules is equal to cytosine

D. Uracil molecules is equal to cytosine

6. (DNA&RNA 5b) The copy made of a portion of DNA in the nucleus is called_____?A. tRNA B. mRNA

C. rRNA D. polymerase

7. (DNA&RNA 5b) In addition to the start and stop codons, how many codons are need for 4 more amino acids?A. 6B. 2C. 4D. 3