Chapter 15 Flashcards Preview

Genetics And Evolution > Chapter 15 > Flashcards

Flashcards in Chapter 15 Deck (20)
Loading flashcards...


Species that are more closely related gave similar DNA than those which are distantly related

Universal nature of genetic code and has a biochemical nature.

DNA codes everything, mainly proteins.



Complete set of DNA of an organism.


Endogenous retroviruses

Viral sequence that has become part of an organisms genome.

The more ERV's they have in common, the more common ancestors they have.

ERV's are an example of Junk DNA (does nothing).


Junk DNA

Sections of DNA that don't code for a particular characteristic.

More similarities in Junk DNA = closer ancestor.


Mitochondrial DNA

Occurs in the mitochondria.
Only can get it from your mum - because part of the sperm is left behind when it reaches the egg.
The fast mutation rate means it's more useful for the relationships between species (tracking heritage).

- used to rack migratory patterns, relationships between species and verifying evidence for evolution.


Protein studies

Less similarities = less identical amino acid sequences.
There's less differences between proteins than DNA - because protein is doing something.
Proteins have an amino acid sequence.
Suggests a common ancestor.


Ubiquitous proteins

Every organism contains them.

Everyone from a simple bacterium to a complex multicellular organism use cytochrome-C for cellular respiration to create ATP, this tells us that we have originated from a common ancestor.



Using computer software to map and compare genomes.

What we use to interpret DNA and proteins.

Measures changes in different species DNA rather than their physical taxonomy.


Comparative genomes

Comparing complete genomes, showing differences and similarities.


Comparative embryology

Comparing the very early stages of development of vertebrate organisms - suggests all vertebrates share a common ancestor.

Early embryos of all species have: gill arches, gill pouches, tails, no limbs, two chambered hearts and similar brain development.


Homologous structures

Organs that have similar in structure but they perform different actions and functions - this suggests they have a common ancestor.

For example, forelimb bones are homologous organs (whales and humans).


Vestigial organs

Structures of reduced size that appear to have no function.

Two examples:
Verminform appendix - useful for when we were mostly vegetarian (grass) - now we eat more meat.
Coccyx - left over tail (ancient ancestor had a tail).


Geographical distribution

Isolated land areas and islands have evolved their own distinct plant and animal population.

E.g. Finches in Galapagos Islands off South America -> gradual change/evolution of beak shapes to increase survival -> speciation (changing or evolving so differently they can no longer interbreed).


How do retroviruses become endogenous?

If it's inserted into a sex cell, it can be passed down.


Biotechnology for DNA comparison

1. PCR amplifies (makes more) DNA.
2. DNA is sequenced by gel electrophoresis and bacterial enzymes.


Why is the fossil record important for evolution?

Provides examples of organisms which now may be extinct
Suggests a common ancestor
Shows which organisms lived on earth in the past
How the earths surface has changed overtime


What is needed for fossilisation to occur?

Quick burial - protected from scavengers
Dry/cold conditions - protected from decay by micro-organisms
Absence of oxygen
Alkaline - for bones
Or acidic - for tissues
A long period of stability - lack of movement, must be left undisturbed


Why are fossils difficult to find?

Been destroyed by erosion
Human activity
Buried in a location you can't excess
May be looking in the wrong places


What else can preserve fossils well?

Peat bog


Hybrid DNA

Heat up to 86 degrees
Allow to cool down
More degrees lost to separate = further ancestor
1 degree = a 1% difference