Topic 12 - Evolutionary Development

Question 1

What is evolutionary biology?

Answer 1

How organisms evolve and change over time

Question 2

What is developmental biology?

Answer 2

Examines how changes in gene expression / gene function modify phenotype, & how patterning arises

Question 3

What is Evolutionary Developmental Biology?

Answer 3

Looks at the genetics basis of phenotypes and how new structures arise

Question 4

What is intial intracellular differentiation?

Answer 4

Gradients of mRNA molecules are organized in human egg cells prior to fertilization

Question 5

What are 3 important things about Maternal effect genes?

Answer 5

i) Phenotype determined by mother’s genotype
ii) At the top of the transcriptional cascade
iii) Distributed to different cell lineages

Question 6

What two things does signaling between distant & neighbour cells do?

Answer 6

i) Allows for co-ordination
ii) Essential for division & differentiation

Question 7

How are cells defined?

Answer 7

By the types & amounts of proteins they make

Question 8

What are master control genes?

Answer 8

Transcription factors

Question 9

What are morphogens?

Answer 9

Transcription factors that control morphological development

Question 10

What are the functions of morphogens?

Answer 10

i) Usually proteins that determine animal body plan
ii) They are extracellular which makes them influence tissue morphogenesis
iii) Different concentrations of the morphogen result in the induction or inhibition of gene expression of other genes

Question 11

The activity of morphogens is dependent on what?

Answer 11

Its concentration

Question 12

What are Developmental Cascades?

Answer 12

Cascades and the spatial distribution of gene expression / protein products result in segmental patterning

Question 13

What is the order of Developmental Cascades?

Answer 13

Maternal gradients -> Gap genes -> Pair-rule genes -> Segment Polarity genes -> Homeotic genes

Question 14

How did biologists discover genes that determine animal body plan?

Answer 14

By studying rare mutations that caused changes in fruit fly development

Question 15

What are Hox genes?

Answer 15

Key regulators of development

Question 16

What are homeotic mutations / Hox gene mutations?

Answer 16

Homeotic mutations are genetic changes that cause one body part to develop into another (e.g., a leg growing where an antenna should be) due to misexpression of developmental control genes.

Question 17

What is the homeobox?

Answer 17

A similar stretch of 180 nucleotides that control body pattern genes. Contains homeotic genes

Question 18

What capital letters represent homeotic genes?

Answer 18

THE

Question 19

What do all animals rely on?

Answer 19

The same baisc Hox-gene complex

Question 20

Can Hox genes be inherited?

Answer 20

Yes

Question 21

What is serial homology?

Answer 21

Serial homology is when similar body structures are repeated in the same organism (e.g., vertebrae or segments) because they share the same developmental origin.

Question 22

According to Evo-Devo, how do new biological structures evolve?

Answer 22

New structures do not evolve from scratch (de novo); they evolve by modifying existing structures and genetic regulatory circuits from earlier organisms.

Question 23

T or F: nearly identical genes control the body plan throughout the animal kingdom?

Answer 23

True

Question 24

Where are Maternal effect genes expressed?

Answer 24

In the mother’s ovaries

Question 25

What mRNAs are produced by the Maternal effect genes?

Answer 25

bicoid & nanos mRNA

Question 26

Where is bicoid mRNA located in the egg?

Answer 26

Anterior

Question 27

Where is nanos located in the egg?

Answer 27

Posterior

Question 28

What does the Bicoid protein determine?

Answer 28

In Drosophila it determines the expression of other body plan genes, such as hunchback & knirps and segmentation

Question 29

What is segmentation controlled by? | *segmentation = repeating units

Answer 29

The interaction of various master genes throughout development

Question 30

What is the effect of increased Bicoid concentration on larval development?

Answer 30

Bicoid determines head development thus the greater concentration of Bicoid the larger the head