21 Genomes And Their Evolution

Front 1

What is a genome?

Back 1

A genome is the genetic materialtransmitted from parents to offspring.

Front 2

The Human Genome Project

Back 2

§ the Human Genome Project began in1990§ largely completed by 2003§ The genome was completed usingsequencing machines and the dideoxychain termination method§ Complete nucleotide sequence of eachchromosome

Front 3

is the application ofcomputational methods to the storageand analysis of biological data

Back 3

Bioinformatics

Front 4

Number of genes identified in the human genome

Back 4

§ Human genome is about 21,000 genes

Front 5

is the study of whole sets ofgenes and their interactions

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Genomics

Front 6

Bioinformatics used to analyze genomes and their functions

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The Human Genome Project established databases and refined analytical software to make data available on the internet

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whole-genome shotgun approach

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sequences random DNA fragments and assembles the DNA sequence using overlapping edges (uses dideoxynucleotide method)

Front 8

Steps in DNA Sequencing

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1) Cut the DNA from many copies of an entire chromosome into overlapping fragments short enough for sequencing

2) Clone the fragments into plasmid vectors

3) Sequence each fragments

4) Order the sequences into one overall sequence w/ computer software

Front 9

Personalized Medicine

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• Every individual’s genome is unique.

• An individual’s genome can potentiallyindicate• Disease susceptibillity

• Drug sensitivities

• Best treatment plans individual’s“blueprint.”

Front 10

Genomes vary in size, number ofgenes, and gene density

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§ Genome size: measured in million basepairs (Mb)

§ No relationship between genome sizeand organism’s complexity

Front 11

Gene Density and Noncoding DNA

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§ Humans and other mammals have thelowest gene density, or number of genes,in a given length of DNA

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Noncoding DNA: Pseudogenes

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are former genes that have accumulated mutations and are nonfunctional

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Noncoding DNA: Repetitive DNA

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is present in multiple copies in the genome

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Noncoding DNA: transposable elements

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§ About three-fourths of repetitive DNA ismade up of transposable elements andsequences related to them

Front 15

Transposable Elements

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§ Transposons can move from one location to another within genome using enzyme transposase

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Transposable Elements

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§ These transposable elements move fromone site to another in a cell’s DNA; theyare present in both prokaryotes andeukaryotes

§ Most abundant type of repetitive DNA inmulticellular eukaryotes

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Retrotransposons

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move after synthesis single-stranded RNA intermediate, reverse transcriptase

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alu elements

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related to transposable elements; very short sequences about; many are transcribed into RNA ; function unknown

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§ In humans & primates, Alu elementsmake up large portion of transposableelements

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§Short (300 nucleotides long)

§Do not code for any protein

§Transcribed into RNA§May help regulate gene expression

Front 20

Repetitive DNA

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§ Long repeated sequences of DNAmake genome sequencing difficult;often longer than automatedsequencing machines will output, andrepeat may not be detected

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Repetitive DNA:tandem repeats

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next to each other

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Repetitive DNA:dispersed repeats

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spread throughout genome

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Repetitive DNA: Short tandem repeats (STR)

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have sequences of DNA have 2 - 5 nucleotides long

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Comparing Genomes

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§ Genome comparisons of closely related species help us understand recent evolutionary events

§ Relationships among species can be represented by a tree-shaped diagram