Unit 1 KA8

Question 1

Genomic sequencing

Answer 1

Determining the base sequence of genes and of whole organisms.

Question 2

Bioinformatics

Answer 2

The use of molecular biology, statistics and computer technology to map and analyse DNA sequences.

Question 3

Genome shotgun approach

Answer 3

Used to sequence whole genomes.

The genome is copied many times and is broken into fragments using a mixture of restriction endonucleases which cut the DNA in different places.

Each fragment is sequenced, and the order of bases is worked out using a computer program that looks for overlaps.

Question 4

Restriction endonucleases

Answer 4

Enzymes that cut DNA at a specific short sequence (recognition site).

There are many different types which can cut DNA in different places, with different types of cuts. (eg. straight/staggered cuts).

Question 5

Sequenced genomes

Answer 5

Include humans, pest species (eg. mosquito), important foods (eg. rice), disease causing organisms (eg. malaria) and model organisms (eg. fruit flies).

Question 6

Comparative genomics

Answer 6

Compares the sequenced genomes of different species, individuals of the same species or cells from the same individual. (eg. cancerous/non-cancerous).

Looks for similarities and differences to discover degree of relatedness or causes of disease.

Question 7

Highly conserved genes

Answer 7

These genes are very similar, with very few base differences, even though they come from different species.

They are often key genes eg. proteins involved in respiration, that have mutated very little (as any mutations would be fatal).

Question 8

Phylogenetics

Answer 8

The study of evolutionary history and the relationships between groups of organisms, using genome sequence data.

It has advantages over comparison of structural features, as many closely related species look very different, whereas organisms that appear to be similar are unrelated.

Question 9

Phylogenetic tree

Answer 9

A diagram that shows evolutionary relationships, and how recently groups diverged from a common ancestor.

Divergence is estimated by looking at genome differences. Closely related species have similar genomes. The greater the difference, the larger the evolutionary distance between groups.

Question 10

Molecular clock

Answer 10

It is assumed that mutations accumulate at a steady rate over time.

The number of mutations that accumulate is proportional to the elapsed time since 2 groups diverged. ie. the more differences, the longer ago 2 groups of organisms diverged.

Base changes in DNA or amino acid differences in highly conserved genes can be used as molecular clocks.

Question 11

Fossil evidence

Answer 11

Used in combination with structural and genome sequence data to determine evolutionary relationships.

Question 12

Common ancestor

Answer 12

An ancestor that is shared between groups of organisms.

Found at the start of a phylogenetic tree, and at branch points where groups diverge.

Question 13

Domain

Answer 13

A group of living organisms.

There are 3 domains - bacteria, archaea (both prokaryotes) and eukaryotes.

Archaea branch off the eukaryote line, which diverged from the bacteria line.

Relationships were investigated using rRNA (highly conserved).

Question 14

Personal genomics

Answer 14

Sequencing an individual’s genome to predict the likelihood of genetic diseases or disorders.

Question 15

Pharmacogenetics (personalised medicine)

Answer 15

The use of genome information in the choice of drugs or dosages.

Question 16

Order of evolutionary events

Answer 16

Life appeared on Earth 4500 million years ago, followed by prokaryotes, eukaryotes, multicellular organisms, animals, vertebrates and then land plants.