L15 Hox Genes and EvoDevo (Imported from Quizlet)

Most of the genes are all the same in all animals (True or False)

True

Much of what makes us different (morphologically) is caused by what?

Changes in expression of a common set of genes

What can be applied to any organism and what does it provide?

CRISPR, it provides genetic modelling

Genes control what?

Morphology

Bryoza is also known as ...?

Ectoprocta

How do we determine if proteins are similar?

Protein blast alignment

How does protein blast alignment work?

Input the amino acid sequence of the proposed protein

The blast program searches huge databases for other proteins which have similar sequences

This shows an alignment of an uncharacterised protein (query) to a protein called zen (subject)

Similarity between protein sequence suggests what?

That the protein evolved from the same common ancestor and that the proteins have similar molecular functions

There are ___ vertebrate FGFs that fall into _ clusters based upon protein sequence alignment

22, 4

What has a single representative in each of the 4 groups?

Ciona (Ci)

What does this single representative suggest?

That the common ancestor of the sea squirt and vertebrates had 4 FGFs

How do so many FGFs arise?

Gene duplication: changes in ploidy (entire genome duplication) and local duplications (smaller areas duplicate)

New copes of genes that arise in the genome are called ...?

Paralogues

All these different FGFs are _________, share the same ancestor through duplication events

Paralogues

After duplication, it is likely that the duplicate gene are at first what?

Redundant

What is neofunctionalization?

1 normal gene and 1 with a new function

Whole regions being duplicated is an error during ...?

Mitosis

The extra copy can change in what ways?

Pattern of expression, structural in the protein (both small changes caused by point mutations and big changes caused by domain swapping)

Changes in ________ are thought to be the most common driving force in the morphological evolution of animals

Expression

Why are changes in expression patterns of genes thought to play a major role in morphological evolution?

Because enhancers can change easily (they are promiscuous)

What is meant by crossing over?

Exchange the ends of their chromosomes, could bring an enhancer close to the gene

It should be relatively easy to add or delete sites by ...?

Rearrangements, insertions, deletions or base pair substitution

Changes that effect protein structure (changing amino acids) would have to be more precise so as not do what?

Introduce a stop, change the reading frame, interfere with the protein's folding or disrupt RNA splicing

Mutations in proteins are more likely to be __________

Damaged

What is the cervical?

Neck vertebrae

What is the thoracic?

Chest vertebrae

What do hox genes specify?

Segment identity

Transcription factors that are found in clusters in the genome, all have similarity suggesting what?

That they originated from the same gene

What does changing hox gene expression result in?

Changes in segmental identity

Humans also have hox genes (True or False)

True

Changes in segmental identity is seen in _______, especially in the ________

Humans, somites

Changes in expression of regulatory genes can correlate to what?

Morphological changes

Expression of the gene C6 starts more _______ in chick

Posteriorly

What does the position of the expression of C6 in chick correlate with?

A longer neck (more cervical vertebrae) and less chest (fewer thoracic vertebrae) than in mice

Limbs form at the junction between the _____ and ________ vertebrae

Cervical, thoracic

Pythons lack what?

Limbs

Pythons have no ___________ and severely reduced _________

Forelimb, hindlimbs

All vertebrae anterior to the hindlimb have _____ and a mixed ________/________ morphology (except for the atlas)

Ribs, cervical/thoracic

Shift in hox gene expression may explain what in snake evolution?

Loss of limbs

Expansion of HoxC6 and HoxC8 could confer many of the _____________ ________ (shift towards thoracic) seen during the evolution of snakes

Morphological changes

There is also a lot of evidence that changes in hox gene expression had roles in the evolution of _______ and ______

Insects, limbs

By experimentally changing expression of a single gene we can create ________ organs

Ectopic

Organs are very complex structures, so genes that are capable of such big tasks are called ...?

Master regulatory genes

What do master regulatory genes regulate?

Whole gene networks

This adaptability that takes place during development is sometimes referred to as ...?

Evolutionary robustness

Crustaceans have legs on their __________ but insects don't

Abdomen

Why do crustaceans have legs on their abdomen but insects don't?

Because of changes in the protein sequence

What evolution may explain why insects don't have legs on their abdomen?

Ubx

In fly embryo, the ____ _________ _______ specifies leg precursor cells

Dlx transcription factor

In fly embryos, Ubx is expressed in the ________ where it ________ Dlx expression

Abdomen, represses

Crustacean Ubx does not act as what?

A repressor of Dlx

Ubx is __________ in the abdomen of crustacean embryos, but it doesn't _____ ____ Dlx expression

Expressed, turn off

It is thought that the Ubx gene became able to ________ ____ in an ancestor of drosophila

Repress Dlx