Lecture 1 - introduction

Question 1

How does development occur in an adult?

Answer 1

Tissue maintenance (by adult stem cells)

Question 2

What are the 2 broad phases of life involved in development?

Answer 2

BUILD-UP - of the body during embryonic-foetal development, childhood and adolescence

DECLINE - in adulthood

Question 3

When is the optimal capacity and health experienced?

Answer 3

At the beginning of adulthood

Question 4

What can adverse early life experiences lead to?

Answer 4

Reduced functioning during both the Build-up and the Decline phase

Question 5

What are new developmental challenges for society?

Answer 5

• UK population is ageing (population growth between 2015-2020 = 3%)(65+ population growth = 12)(85+ population = 18%)
• 55% (£144 billion in 2014-15) UK welfare budget is allocated to older people of pensionable age.

Improving healthy life expectancy for all requires a 2nd understanding of developmental processes.

Question 6

What contributes to developmental biology?

Answer 6

• cell behaviour (movement, proliferation, differentiation)
• genetic program (expression, function)
• cell-cell communication (signalling)

Question 7

What are the impacts of developmental biology on biomedical science?

Answer 7

• Fertility
• Congenital disease
• Stem cell therapy
• Degenerative disease
• Ageing
• Regenerative medicine
• Cancer

Question 8

What are the 2 theories of developmental biology?

Answer 8

• Epigenesis
• Preformationism

Question 9

What is epigenesis?

Answer 9

Upon origin, organisms develop progressively through the generation of new structures, leading to gradual increase in biological complexity.

Question 10

What is preformationism?

Answer 10

organisms develop from miniature version of themselves: homunculus (little man)

Question 11

What is the cell theory?

Answer 11

1. All organisms are composed of one or more cells.
2. The cell is the most basic unit of structure, function and organization in all organisms.
3. All cells arise from pre-existing living cell

Question 12

What does the fertilized egg develop into?

Answer 12

Multicellular embryo

Question 13

What are germ cells?

Answer 13

gametes

Question 14

What is the Germ Plasm Determinants Theory?

Answer 14

Sperm and oocyte cells contain cell determinants which are segregated into different parts of the egg.
These then lead to different cells differentiated.

Question 15

What is the process from DNA to proteins?

Answer 15

DNA (Transcription) mRNA (translation) Protein

Question 16

How is differential gene expression achieved?

Answer 16

• mainly by selectively activating transcription of particular genes in specific genes (Genome vs Transcriptome)
• selective splicing, translation of mRNAs and protein processing may also affect gene expression.

Question 17

Where does DNA splicing (processing occur)?

Answer 17

in the nucleus

Question 18

What are intrinsic cues that can establish differential gene expression?

Answer 18

act within a cell to trigger it differentiation.

Asymmetric cell division - segregation of cell fate determinants

Question 19

What are extrinsic cues that can establish differential gene expression?

Answer 19

signals produced by one cell to influence/instruct another cell

Question 20

How can cell division itself be a way to get different cells?

Answer 20

Localisation of a cell fate determinant prior to cell division is one way to accomplish differences in daughter cells

Question 21

How can cell-cell communication lead to the generation of differences between cells?

Answer 21

One cell will tell another to become different
- Paracrine
- Autocrine
- Juxtacrine

Question 22

What type of cell-cell communication do Shh, Wnt, TGFbeta, BMP, FGF signalling all exhibit?

Answer 22

Paracrine & Autocrine

Question 23

What type of signalling does Notch signalling exhibit?

Answer 23

Juxtacrine

Question 24

What is required of signal reception?

Answer 24

Signal receptor requires cell to be competent (e.g. contain receptor and transduction components)

Question 25

What can signals be?

Answer 25

Signals can be instructive (initiates a new program) or permissive (provides a favourable environment for a specific program)

Question 26

How can signals act as a morphogen?

Answer 26

Signals that instruct distinct cell fates according to their concentration

Question 27

What does signal transmission to the nucleus often lead to?

Answer 27

Signal transduction cascade - cell surface, cytoplasmic and nuclear proteins that relay proteins that relay signals from the cell surface to the nucleus)

Question 28

What are the 3 common features in signal transduction pathways?

Answer 28

- Receptor - Transduction - Response

Question 29

What are receptors?

Answer 29

The ligand (growth factor, signalling molecule) binds to a cell surface receptor and activates it

Question 30

What is transduction?

Answer 30

receptor activation induces the transduction of the signal from the membrane to the nucleus, via a cascade of messenger activation

Question 31

What are responses?

Answer 31

a transcription factor is activated and induces the transcription of specific target genes

Question 32

Explain how Gene A can be activated in different regions of the embryo.

Answer 32

Gene A (e.g. shh) is activated in different regions of the embryo using the different transcription factors, which bind to different enhancer sequences in the regulatory of gene A. Different signalling pathways may activate different transcription factors

Question 33

When will an Shh mutant animal show a phenotype?

Answer 33

Only in tissues where Shh is needed, which is usually where Shh is expressed