Std.6 DNA and Protein Synthesis Review

Std.6 DNA and Protein Synthesis Review

Describe the structure of DNA and summarize the process of DNA replication. / Identify and describe the steps in proteins synthesis (hint: transcriptiontranslation)

• Name the 4 nitrogenousbases for DNA:______

______

• DNAbase Pairing rules: adenine (A) → ______(T); and ______(G) → cytosine (C)

• Name the 3 types of RNA: ______

• RNA base pairing rules: adenine (A) → ______(U); and guanine (G) → ______(C)

• Define DNA mutation: ______

• How can a mutation affect a protein: ______

______/
Question Analysis: Identify key terms/info. in each question and provide a response
The mRNA strand of mRNA containing the repeating sequence AAGAAGAAGAAG could code for aminoacid sequences?
______- ______- ______- ______
The below sequence of DNA is part of a gene. How many amino acids are coded for by this segment?
5’ ATCAGCGCTGGC / A scientist puts nucleotide chains of UUUUUU in a test tube under conditions allowing protein synthesis. Soon the test tube is full of polypeptide chains composed of only the amino acid phenylalanine. What does this experiment indicate?
Semi-conservative replication of DNA refers to the idea that…
What would be the base sequence for mRNA for the following DNA sequence: ACAGTGC
mRNA → ______
One human disease is caused by a change in one codon in a gene from GAA to GUA. This disease is the result of a:
______
Although there are a limited number of amino acids, many different types of proteins exist because: / This segment of DNA below has undergone a mutation in which three nucleotides have been deleted. A repair enzyme would replace them with what?
5’ GTA_ _ _ AA 3’ → Replacement =
3’ CATGCATT 5’ ______
Mutations within a DNA sequence are (write correct letter) _____
a. natural processes that produce genetic diversity.
b. natural processes that always affect the phenotype.
c. unnatural processes that always affect the phenotype.
d. unnatural processes that are harmful to genetic diversity.

Std.6 DNA Study Guide

I. DNA

• Structure – double stranded helix (twisted)
• Sugar phosphate backbone
• Location: nuclus
• Monomers (subunits) = nucleotides
• Nucleotide – 3 parts:
• 5 carbon sugar (deoxyribose)
• Phosphate Group
• Nitrogenous Base

DNA Base Pairing Rules:

• Adenine – Thymine → A - T
• Guanine – Cytosine → G – C

II. DNA Replication

• Replication = copying of DNA
• Semiconservative Replication

1) Enzyme (helicase) “unzips” DNA
2) Each original strand serves as a template
3) Enzyme (DNA polymerase) attachsnucleotides following base paring rules(A-T & C-G)
4) DNA polymerase “proof reads” strands for errors

• End result: 2 completeidentical DNA molecules

III. RNA & Protein Synthesis

• RNA = Single stranded
• Does not use nitrogenous base Thymine
• New base = Uracil

RNA Base Pairing Rules:

• Adenine – Uracil → A - U
• Guanine – Cytosine → G – C

• 3 Types of RNA: mRNA, tRNA, & rRNA

Steps to Protein Synthesis:

• 1 Gene codes for 1 protein
• 2 Parts to Protein Synthesis: Transcription & Translation

Transcription
1) Single gene on DNA opens
2) mRNA made from gene template following RNA base paring rules
3)mRNA carries “instructions” to build protein to the ribosome
Translation
4)mRNA is read in series of 3 nucleotides at a time → codon (aau, gcg, agc, etc)
5)tRNA brings correct amino acids to ribosome to build protein
IV. Mutations

• Random changes in DNA sequence
• Results from “mistakes” in replication of DNA
• Mutations can involve single genes or entire chromosomes
• Examples: point mutationframe shift mutations

/