Review: DNA  RNA  Protein

Review: DNA RNA Protein • In a cell, genetic information flows from DNA to RNA in the nucleus and RNA to protein at the ribosome.

RNA polymerase Transcription Nucleus DNA mRNA Intron Figure 10.20-1

RNA polymerase Transcription Nucleus DNA mRNA Intron RNA processing Cap Tail mRNA Intron Amino acid Ribosomal subunits tRNA Enzyme ATP Initiation of translation Amino acid attachment Figure 10.20-4

RNA polymerase Transcription Polypeptide Nucleus DNA Stop codon mRNA Intron RNA processing Cap Termination Tail mRNA Intron Anticodon Amino acid Ribosomal subunits Codon tRNA Enzyme Elongation ATP Initiation of translation Amino acid attachment Figure 10.20-6

Transcription and translation are how genes control: • The structures • The activities of cells

Mutations • A mutation is any change in the nucleotide sequence of DNA. • Mutations can change the amino acids in a protein. • Mutations can involve: • Large regions of a chromosome • Just a single nucleotide pair, as occurs in sickle cell anemia

How can Mutations be BAD? How can Mutations be GOOD?

Although mutations are often harmful, they are the source of genetic diversity, which is necessary for evolution by natural selection.

Mutagens • Mutations may result from: • Errors in DNA replication • Physical or chemical agents called mutagens • UV rays, X-rays, gamma rays, chemicals

Types of Mutations • Mutations within a gene can occur as a result of: • Nucleotide substitution, the replacement of one nucleotide by another • Nucleotide deletion, the loss of a nucleotide • Nucleotide insertion, the addition of a nucleotide

If a mutation changed a codon from GGU to GGA then what would happen? If a mutation changed a codon from GGA to UGA then what would happen?

Normal hemoglobin DNA Mutant hemoglobin DNA mRNA mRNA Sickle-cell hemoglobin Normal hemoglobin Figure 10.21

Insertions and deletions can: • Change the reading frame of the genetic message • Lead to disastrous effects

mRNA and protein from a normal gene Base substitution Figure 10.22a

mRNA and protein from a normal gene Deleted Nucleotide deletion Figure 10.22b

mRNA and protein from a normal gene Inserted Nucleotide insertion Figure 10.22c

mRNA and protein from a normal gene (a) Base substitution Deleted (b) Nucleotide deletion Inserted (c) Nucleotide insertion Figure 10.22

Mutation by Deletion:

The Human Genome Project • Begun in 1990, the HumanGenomeProject was a massive scientific endeavor: • To determine the nucleotide sequence of all the DNA in the human genome and • To identify the location and sequence of every gene • Aims of the project: - to identify the estimated 100,000 genes in the human DNA.

At the completion of the project in 2004: • Over 99% of the genome had been determined to 99.999% accuracy • 3.2 billion nucleotide pairs were identified • About 24,000 genes were found • About 98% of the human DNA was identified as noncoding

The Human Genome Project can help map the genes for specific diseases such as: • Alzheimer’s disease • Parkinson’s disease

Table 12.1

Benefits of Human Genome Project research - improvements in medicine. - microbial genome research for fuel and environmental cleanup. - DNA forensics. - improved agriculture and livestock. - better understanding of evolution and human migration. - more accurate risk assessment.

Making Humulin • In 1982, the world’s first genetically engineered pharmaceutical product was sold. • Humulin, human insulin: • Was produced by genetically modified bacteria • Was the first recombinant DNA drug approved by the FDA • Is used today by more than 4 million people with diabetes

Today, humulin is continuously produced in gigantic fermentation vats filled with a liquid culture of bacteria.

If a strand of DNA has the sequence AAGCTC, transcription will result in a(n) ______. A) single RNA strand with the sequence TTCGAG B) DNA double helix with the sequence AAGCTC for one strand and TTCGAG for the complementary strand C) single DNA strand with the sequence TTCGAG D) single RNA strand with the sequence UUCGAG E) RNA double helix with the sequence UUCGAG for one strand and AAGCUC for the complimentary strand

Translation converts the information stored in ______ to ______. A) DNA . . . RNA B) RNA . . . a polypeptide C) protein . . . DNA D) DNA . . . a polypeptide E) RNA . . . DNA

Where is translation accomplished? A) lysosomes B) smooth endoplasmic reticulum C) peroxisomes D) ribosomes E) nucleoli

A mutation within a gene that will insert a premature stop codon in mRNA would ______. A) result in a polypeptide that is one amino acid shorter than the one produced prior to the mutation B) result in a shortened polypeptide chain C) result in a missense mutation D) change the location at which transcription of the next gene begins E) have the same effect as deleting a single nucleotide in the gene

What is the smallest number of nucleotides that must be added or subtracted to change the triplet grouping of the genetic message? A) one B) two C) three D) four E) five

Examine the genetic code table, shown below. The codon AGC codes for the amino acid ______. A) serine B) arginine C) threonine D) alanine E) glycine

A mutation would be most harmful to the cells if it resulted in ______. A) a single nucleotide insertion near the start of the coding sequence B) a single nucleotide deletion near the end of the coding sequence C) a single nucleotide in the middle of an intron D) substitution of a base pair E) deletion of a triplet near the middle of the gene

In a DNA double helix, adenine pairs with ______ and guanine pairs with ______. A) cytosine . . . thymine B) guanine . . . adenine C) uracil . . . cytosine D) thymine . . . cytosine E) cytosine . . . uracil

RNA contains the nitrogenous base ______ instead of ______, which is only found in DNA. A) a deoxyribose sugar . . . a ribose sugar B) nucleotides . . . nucleic acids C) uracil . . . thymine D) cytosine . . . guanine E) adenine . . . guanine

If one strand of a DNA double helix has the sequence GTCCAT, what is the sequence of the other strand? A) ACTTGC B) TGAACG C) CAGGTA D) CAGGUA E) CUGGTU

What name is given to the collection of traits exhibited by an organism? A) holotype B) genotype C) typology D) phenotype E) morphology

How many nucleotides make up a codon? A) one B) two C) three D) four E) five

Review: DNA  RNA  Protein