UNIT 15: Genes and Genomes Name: _____________________

Essential Idea(s):Chromosomes carry genes in a linear sequence that is shared by members of a species.

IB Assessment Statements

U3.1.1 A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic. Define gene.

U3.1.2 A gene occupies a specific position on a chromosome. Define gene locus.

U3.1.6 The genome is the whole of the genetic information of an organism Define genome. State the size in base pairs of the human genome.

U3.1.3 The various specific forms of a gene are alleles. Define allele. List two examples of genes with multiple alleles. State a similarity between alleles of the same gene.

U3.1.4 Alleles differ from each other by one or only a few bases. State the difference between alleles of the same gene.

U3.1.5 New alleles are formed by mutation. State the source of new alleles of a gene.

U3.4.10 Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer. State two factors that can increase the mutation rate. Outline the effects of gene mutations in body cells and gamete cells.

A3.4.4 Consequences of radiation after nuclear bombing of Hiroshima and accident at Chernobyl . Outline the effects of radiation exposure after nuclear exposure at Hiroshima and Chernobyl.

U3.1.7 The entire base sequence of human genes was sequenced in the Human Genome Project Define “sequence” in relation to genes and/or genomes. State the aim of the Human Genome Project. Outline two outcomes of the Human Genome Project.

A7.1.3 Use of nucleotides containing dideoxyrubonucleic acid to stop DNA replication in preparation of samples for base sequencing

Outline the process of DNA sequencing, including the role of chain terminator nucleotides, fluorescence, and electrophoresis.

NOS3.1 Developments in scientific research follow improvements in technology-gene sequencers are used for the sequencing of genes.

Outline the technological improvements that have sped the DNA sequencing process. Determine a DNA sequence from an electropherogram.

S3.2.1 Use of databases to identify the focus of a human gene and its polypeptide product. Search NCBI or OMIM for a given gene. Determine the gene locus, abbreviated gene name, and description of the gene.

A3.1.2 Comparison of the number of genes in humans with other species. State the number of genes in the human genome. Describe the relationship between the number of genes in a species and the species complexity in structure,

physiology and behavior.

S3.1.1 Use of a database to determine differences in the base sequence of a gene in two species. Explain why cytochrome oxidase 1 is often used to assess the differences in the base sequences of a gene

between two species. Use NCBI to BLAST search for COX1 sequences for different species. Use a computer software tool to create an alignment of the gene sequences between different species. Outline information that can be determined given gene sequence alignment data.

NOS7.3 Developments in scientific research follow improvements in computing- the use of commuters has enabled scientists to make advances in bioinformatics applications such as locating genes within genomes and identifying conserved sequences.

Define bioinformatics. Outline why computers are necessary for genome analysis. List five species for which the entire genome has been sequenced.

Gene locus:

Alleles

Definition:

Formation:

How are alleles of the same gene the same?

How are alleles of the same gene different?

Examples:

GENE Allele Allele Allele

Note: even though there can be more than two alleles in the population, there are a maxiumum of two alleles in any single individual. Why?

Effects of Radiation

Case Study What? When? How? Effect?

Vertus Hardiman

Hiroshima

Chernobyl

The Sequencing and Mapping of Entire Genomes

AIMS OF THE HUMAN GENOME PROJECT:Visit the website http://www.ornl.gov/sci/techresources/Human_Genome/home.shtml. Record the bulleted summaries of the goals of the Human Genome Project within this box.

METHOD OF THE HUMAN GENOME PROJECT:Dr. Fred Sanger developed the most commonly used sequencing technique, called chain termination sequencing, in 1977. View the animation at http://www.dnalc.org/ddnalc/resources/cycseq.html and answer the following questions:

o What are the main ingredients in a sequencing reaction and what is each used for (hint: there are 5)?

o Why must the strands be initially heated?

o What happens when the temperature is again lowered?

o What happens when a dideoxynucleotide is added to the strand?

o How are the DNA fragments separated?

o How is the DNA sequence read?

o What is an electropherogram?

DNA Sequencing 1.

2.

4.

3.

Bioinformatics and DNA Sequence Alignment:What?

Bioinformatics Sequence Alignment

Why?

One reason we would do this is to determine what parts of the sequences are conserved from one species to the next. Another reason would be to see how much an organism has diverged from other organisms simply by comparing their DNA sequences. The more similar two gene sequences are to one another, the more closely the organisms are related. And the more dissimilar the two sequences, the farther the two genes are in evolutionary relationship.

How?

Comparison of GenomesOrganism Sketch Genome Size # of GenesT2 phage

Escherichia coli

Drosophila melanogaster

Homo sapiens

Paris japonica

What is the relationship between organism “complexity,” genome size and the total number of genes