BRAIN POP:WHAT DOES IT MEAN TO MIMIC

SOMETHING?

FROM DNA TO RNA

WHAT IS THE POINT?

• DNA is a nucleic acid, made of long chains of nucleotides

DNA AND RNA ARE MADE UP OF NUCLEOTIDES

Figure 10.2A

Nucleotide

Phosphate group

Nitrogenous base

Sugar

Polynucleotide Sugar-phosphate backbone

DNA nucleotide

Phosphategroup

Nitrogenous base(A, G, C, or T)

Thymine (T)

Sugar(deoxyribose)

•DNA has four kinds of bases….•A, T, C, and G

Figure 10.2B

Pyrimidines

Thymine (T) Cytosine (C)

Purines

Adenine (A) Guanine (G)

•RNA is also a nucleic acid, yet it has–A different sugar

(ribose)

–Uracil instead of Thymine

–Single strand, usually

Figure 10.2C, DSugar

(ribose)

• James Watson and Francis Crick worked out the three-dimensional structure of DNA, based on work by Rosalind Franklin

DNA IS A DOUBLE-STRANDED HELIX

Figure 10.3A, B

• Hydrogen bonds between bases hold the strands together: A and T, C and G

Figure 10.3D

Ribbon model Partial chemical structure Computer model

Hydrogen bond

Helicase unzips and untwists the DNA strand and gets it ready to be used as a template for a new strand

Figure 10.4B

• In transcription, DNA helix unzips

–RNA nucleotides line up along one strand of DNA, following the base-pairing rules

Figure 10.9B

MAKING A PROTEINEXITS OUT OF THE NUCLEUS…

•Many RNAs needed•3 types…•mRNA, tRNA, rRNA

MESSENGER RNA (MRNA)

• Carries coded instructions for protein synthesis (translation) • From the DNA in the nucleus to the ribosome

TRANSFER RNA (TRNA)

• Brings amino acids to the ribosome so it can build proteins

RIBOSOMAL RNA (RRNA)

•Makes up ribosomes